ifosfamide (Rx)

Germ Cell Testicular Cancer

Indicated in combination with other antineoplastic agents for third-line germ cell testicular cancer

1.2 g/m²/day IV infusion over 30 minutes on days 1-5 q3-4wk or after recovering from hematologic toxicity (>100,000 cells/mm³ plateletes or ≥4,000 cells/mm³ WBC)  

Off-label: 2 g/m²/day IV infusion on days 1-3 (MAID regimen, for total dose of 6 g/m²); doses as high as 5 g/m² over 24hr via continuous IV infusion in combination with other antineoplastic agents used

Administration

Use concomitant mesna (240 mg/m² IV at 0, 4, 8 hr) to prevent hemorrhagic cystitis

Maintain oral or IV hydration >2 L fluid/day

Monitor: CBCs

Bone Sarcomas (Orphan)

Orphan indication sponsor

• Bristol-Myers Squibb Company; P.O. Box 4000, Mail Stop D12-02; Princeton, NJ 08543-4000

Soft Tissue Sarcomas (Orphan)

Orphan indication sponsor

• Bristol-Myers Squibb Company; P.O. Box 4000, Mail Stop D12-02; Princeton, NJ 08543-4000

Renal Impairment

Dose adjustments not described in package insert; some clinicians have used the following guidelines

CrCl >60 mL/min: 100% of regular dose

CrCl 30-60 mL/min: 75% of regular dose

CrCl 10-30 mL/min: 50% of regular dose

CrCl <10 mL/min: Not recommended

Hepatic Impairment

Dose adjustments not described in package insert; some clinicians have used the following guidelines

Bilirubin >3 mg/dL: 25% of regular dose

Other Indications & Uses

Off-label: Cancer of lung, breast, ovary, cervix, pancreas, bladder, and stomach; NHL; sarcomas

Safety and efficacy not established

Contraindicated (13)

• adenovirus types 4 and 7 live, oral

  ifosfamide decreases effects of adenovirus types 4 and 7 live, oral by pharmacodynamic antagonism. Contraindicated. Immunosuppressives may diminish therapeutic effects of vaccines and increase risk of adverse effects (increased risk of infection). Live-attenuated vaccines should be avoided for at least 3 mo. after cessation of immunosuppressive therapy.

• influenza virus vaccine quadrivalent

  ifosfamide decreases effects of influenza virus vaccine quadrivalent by pharmacodynamic antagonism. Contraindicated. Immunosuppressives may diminish therapeutic effects of vaccines and increase risk of adverse effects (increased risk of infection). Live-attenuated vaccines should be avoided for at least 3 mo. after cessation of immunosuppressive therapy.

• influenza virus vaccine quadrivalent, cell-cultured

  ifosfamide decreases effects of influenza virus vaccine quadrivalent, cell-cultured by pharmacodynamic antagonism. Contraindicated. Immunosuppressives may diminish therapeutic effects of vaccines and increase risk of adverse effects (increased risk of infection). Live-attenuated vaccines should be avoided for at least 3 mo. after cessation of immunosuppressive therapy.

• measles (rubeola) vaccine

  ifosfamide decreases effects of measles (rubeola) vaccine by pharmacodynamic antagonism. Contraindicated. Immunosuppressives may diminish therapeutic effects of vaccines and increase risk of adverse effects (increased risk of infection). Live-attenuated vaccines should be avoided for at least 3 mo. after cessation of immunosuppressive therapy.

• measles mumps and rubella vaccine, live

  ifosfamide decreases effects of measles mumps and rubella vaccine, live by pharmacodynamic antagonism. Contraindicated. Immunosuppressives may diminish therapeutic effects of vaccines and increase risk of adverse effects (increased risk of infection). Live-attenuated vaccines should be avoided for at least 3 mo. after cessation of immunosuppressive therapy.

• measles, mumps, rubella and varicella vaccine, live

  ifosfamide decreases effects of measles, mumps, rubella and varicella vaccine, live by pharmacodynamic antagonism. Contraindicated. Immunosuppressives may diminish therapeutic effects of vaccines and increase risk of adverse effects (increased risk of infection). Live-attenuated vaccines should be avoided for at least 3 mo. after cessation of immunosuppressive therapy.

• rotavirus oral vaccine, live

  ifosfamide decreases effects of rotavirus oral vaccine, live by pharmacodynamic antagonism. Contraindicated. Immunosuppressives may diminish therapeutic effects of vaccines and increase risk of adverse effects (increased risk of infection). Live-attenuated vaccines should be avoided for at least 3 mo. after cessation of immunosuppressive therapy.

• rubella vaccine

  ifosfamide decreases effects of rubella vaccine by pharmacodynamic antagonism. Contraindicated. Immunosuppressives may diminish therapeutic effects of vaccines and increase risk of adverse effects (increased risk of infection). Live-attenuated vaccines should be avoided for at least 3 mo. after cessation of immunosuppressive therapy.

• smallpox (vaccinia) vaccine, live

  ifosfamide decreases effects of smallpox (vaccinia) vaccine, live by pharmacodynamic antagonism. Contraindicated. Immunosuppressives may diminish therapeutic effects of vaccines and increase risk of adverse effects (increased risk of infection). Live-attenuated vaccines should be avoided for at least 3 mo. after cessation of immunosuppressive therapy.

• talimogene laherparepvec

  ifosfamide, talimogene laherparepvec. Either increases effects of the other by immunosuppressive effects; risk of infection. Contraindicated. Patients on concomitant immunosuppressants or with impaired immune systems are contraindicated to receive talimogene laherparepvec because of increased risk for serious infections.

• varicella virus vaccine live

  ifosfamide decreases effects of varicella virus vaccine live by pharmacodynamic antagonism. Contraindicated. Immunosuppressives may diminish therapeutic effects of vaccines and increase risk of adverse effects (increased risk of infection). Live-attenuated vaccines should be avoided for at least 3 mo. after cessation of immunosuppressive therapy.

• yellow fever vaccine

  ifosfamide decreases effects of yellow fever vaccine by pharmacodynamic antagonism. Contraindicated. Immunosuppressives may diminish therapeutic effects of vaccines and increase risk of adverse effects (increased risk of infection). Live-attenuated vaccines should be avoided for at least 3 mo. after cessation of immunosuppressive therapy.

• zoster vaccine live

  ifosfamide decreases effects of zoster vaccine live by pharmacodynamic antagonism. Contraindicated. Immunosuppressives may diminish therapeutic effects of vaccines and increase risk of adverse effects (increased risk of infection). Live-attenuated vaccines should be avoided for at least 3 mo. after cessation of immunosuppressive therapy.

Serious - Use Alternative (18)

• bacitracin

  ifosfamide and bacitracin both increase nephrotoxicity and/or ototoxicity. Avoid or Use Alternate Drug. Avoid concurrent use of bacitracin with other nephrotoxic drugs

• deferiprone

  deferiprone, ifosfamide. Either increases toxicity of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Avoid use of deferiprone with other drugs known to be associated with neutropenia or agranulocytosis; if an alternative is not possible, monitor absolute neutrophil count more frequently.

• fexinidazole

  fexinidazole will increase the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Fexinidazole inhibits CYP3A4. Coadministration may increase risk for adverse effects of CYP3A4 substrates.

• fingolimod

  ifosfamide, fingolimod. Either increases effects of the other by immunosuppressive effects; risk of infection. Avoid or Use Alternate Drug. Avoid concomitant use of fingolimod and other immunosuppressants when possible. If combined, closely monitor patients for additive immunosuppressant effects (eg, infections). When switching to fingolimod after discontinuation of another immunosuppressant, consider the duration of action of the discontinued drug to avoid additive immunosuppressive effects.

• influenza virus vaccine quadrivalent, adjuvanted

  ifosfamide decreases effects of influenza virus vaccine quadrivalent, adjuvanted by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Immunosuppressive drugs may reduce the immune response to influenza vaccine.

• influenza virus vaccine trivalent, adjuvanted

  ifosfamide decreases effects of influenza virus vaccine trivalent, adjuvanted by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Immunosuppressive drugs may reduce the immune response to influenza vaccine.

• lonafarnib

  ifosfamide will increase the level or effect of lonafarnib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration of lonafarnib (a sensitive CYP3A substrate) with weak CYP3A inhibitors is unavoidable, reduce to, or continue lonafarnib at starting dose. Closely monitor for arrhythmias and events (eg, syncope, heart palpitations) since lonafarnib effect on QT interval is unknown.
  
  lonafarnib will increase the level or effect of ifosfamide by affecting hepatic enzyme CYP2C19 metabolism. Avoid or Use Alternate Drug. Lonafarnib may increase the AUC and peak concentration of CYP2C19 substrates. If coadministration unavoidable, monitor for adverse reactions and reduce the CYP2C19 substrate dose in accordance with its approved product labeling.

• natalizumab

  ifosfamide, natalizumab. Either increases effects of the other by immunosuppressive effects; risk of infection. Avoid or Use Alternate Drug. Concomitant therapy is expected to increase the risk of immunosuppression. Use caution when switching patients from long-acting therapies with immune effects.

• nivolumab

  ifosfamide, nivolumab. Either increases effects of the other by immunosuppressive effects; risk of infection. Avoid or Use Alternate Drug. Avoid use of immunosuppressants (eg, systemic corticosteroids) prior to initiation of nivolumab. Use of immunosuppressants after administration of nivolumab (eg, for treatment of immune-related adverse reactions) is unlikely to affect nivolumab efficacy.

• ocrelizumab

  ifosfamide, ocrelizumab. Either increases effects of the other by immunosuppressive effects; risk of infection. Avoid or Use Alternate Drug. Concomitant therapy is expected to increase the risk of immunosuppression. Use caution when switching patients from long-acting therapies with immune effects.

• palifermin

  palifermin increases toxicity of ifosfamide by Other (see comment). Avoid or Use Alternate Drug. Comment: Palifermin should not be administered within 24 hr before, during infusion of, or within 24 hr after administration of antineoplastic agents. Coadministration of palifermin within 24 hr of chemotherapy resulted in increased severity and duration of oral mucositis.

• pimecrolimus

  ifosfamide, pimecrolimus. Either increases effects of the other by immunosuppressive effects; risk of infection. Avoid or Use Alternate Drug.

• tacrolimus

  ifosfamide, tacrolimus. Either increases effects of the other by immunosuppressive effects; risk of infection. Avoid or Use Alternate Drug.

• tacrolimus ointment

  ifosfamide, tacrolimus ointment. Either increases effects of the other by immunosuppressive effects; risk of infection. Avoid or Use Alternate Drug. Consider avoiding such combinations when clinically appropriate. If such a combination is used, monitor the patient closely for clinical response.

• tofacitinib

  ifosfamide, tofacitinib. Either increases toxicity of the other by immunosuppressive effects; risk of infection. Avoid or Use Alternate Drug. Avoid use in combination with potent immunosuppressants; concurrent use with antirheumatic doses of methotrexate or nonbiologic disease modifying antirheumatic drugs (DMARDs) is permitted. Agents considered as potent immunosuppressants are not specified, but lower corticosteroid doses (ie, equivalent to prednisone 10 mg/day or less), leflunomide, and antirheumatic doses of methotrexate were permitted in clinical studies.
  
  ifosfamide will increase the level or effect of tofacitinib by Other (see comment). Avoid or Use Alternate Drug. Avoid use in combination with potent immunosuppressants; concurrent use with antirheumatic doses of methotrexate or nonbiologic disease modifying antirheumatic drugs (DMARDs) is permitted. Agents considered as potent immunosuppressants are not specified, but lower corticosteroid doses (ie, equivalent to prednisone 10 mg/day or less), leflunomide, and antirheumatic doses of methotrexate were permitted in clinical studies.

• tucatinib

  ifosfamide will increase the level or effect of tucatinib by Other (see comment). Avoid or Use Alternate Drug. Coadministration of tucatinib (a CYP2C8 substrate) with a strong or moderate CYP2C8 inhibitors increases tucatinib plasma concentrations and risk of toxicities.
  
  tucatinib will increase the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid concomitant use of tucatinib with CYP3A substrates, where minimal concentration changes may lead to serious or life-threatening toxicities. If unavoidable, reduce CYP3A substrate dose according to product labeling.

• voxelotor

  voxelotor will increase the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Voxelotor increases systemic exposure of sensitive CYP3A4 substrates. Avoid coadministration with sensitive CYP3A4 substrates with a narrow therapeutic index. Consider dose reduction of the sensitive CYP3A4 substrate(s) if unable to avoid.

• warfarin

  ifosfamide, warfarin. Either increases toxicity of the other by nephrotoxicity and/or ototoxicity. Avoid or Use Alternate Drug. Monitor for increased INR/effects of coumarin derivatives when ifosfamide is initiated/dose increased, and decreased INR/effects when ifosfamide is discontinued/dose decreased.

Monitor Closely (226)

• abiraterone

  abiraterone will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• acalabrutinib

  acalabrutinib, ifosfamide. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Coadministration may increase risk of myelosuppressive effects.

• ado-trastuzumab emtansine

  ifosfamide, ado-trastuzumab emtansine. Other (see comment). Use Caution/Monitor. Comment: Risk of developing cardiotoxic effects increase in patients with prior or concomitant treatment with other cardiotoxic agents.

• alemtuzumab

  ifosfamide, alemtuzumab. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Coadministration with ifosfamide may increase the risk of immunosuppression and myelosuppression.

• amiodarone

  amiodarone will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• amobarbital

  amobarbital increases effects of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• amphotericin B cholesteryl sulfate

  ifosfamide increases toxicity of amphotericin B cholesteryl sulfate by unknown mechanism. Use Caution/Monitor. Monitor for possible increases in renal toxicity, bronchospasm, and hypotension if amphotericin is given concomitantly with ifosfamide.

• amphotericin B deoxycholate

  ifosfamide increases toxicity of amphotericin B deoxycholate by unknown mechanism. Use Caution/Monitor. Monitor for possible increases in renal toxicity, bronchospasm, and hypotension if amphotericin is given concomitantly with ifosfamide.

• amphotericin B liposomal

  ifosfamide increases toxicity of amphotericin B liposomal by unknown mechanism. Use Caution/Monitor. Monitor for possible increases in renal toxicity, bronchospasm, and hypotension if amphotericin is given concomitantly with ifosfamide.

• amphotericin B phospholipid complex

  ifosfamide increases toxicity of amphotericin B phospholipid complex by unknown mechanism. Use Caution/Monitor. Monitor for possible increases in renal toxicity, bronchospasm, and hypotension if amphotericin is given concomitantly with ifosfamide.

• anthrax vaccine adsorbed

  ifosfamide decreases effects of anthrax vaccine adsorbed by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• apalutamide

  apalutamide increases effects of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration of apalutamide, a strong CYP3A4 inducer, with drugs that are CYP3A4 substrates can result in lower exposure to these medications. Avoid or substitute another drug for these medications when possible. Evaluate for loss of therapeutic effect if medication must be coadministered. Adjust dose according to prescribing information if needed.

• aprepitant

  aprepitant decreases effects of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor for ifosfamide neurotoxicity (eg, visual and auditory hallucinations, somnolence, confusion, delirium) if combined with fosaprepitant. Consider also monitoring for decreased ifosfamide efficacy.

• armodafinil

  armodafinil increases effects of ifosfamide by affecting hepatic enzyme CYP2B6 metabolism. Use Caution/Monitor. Coadministration of ifosfamide with CYP2B6 inducers may increase metabolism of ifosfamide to its metabolite. Monitor for increased effects/toxicities if combined with CYP2B6 inducers.
  
  armodafinil increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• atazanavir

  atazanavir will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Coadministration of CYP3A4 inhibitors may decrease the metabolism of ifosfamide to its active alkylating metabolites and decrease the efficacy of ifosfamide.

• atogepant

  ifosfamide will increase the level or effect of atogepant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• axitinib

  ifosfamide increases levels of axitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• azathioprine

  ifosfamide, azathioprine. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Coadministration with ifosfamide may increase the risk of immunosuppression and myelosuppression.

• baricitinib

  ifosfamide, baricitinib. Either increases effects of the other by immunosuppressive effects; risk of infection. Use Caution/Monitor.

• belatacept

  belatacept and ifosfamide both increase immunosuppressive effects; risk of infection. Use Caution/Monitor.

• belimumab

  ifosfamide, belimumab. Either increases effects of the other by immunosuppressive effects; risk of infection. Use Caution/Monitor.

• belzutifan

  belzutifan will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. If unable to avoid coadministration of belzutifan with sensitive CYP3A4 substrates, consider increasing the sensitive CYP3A4 substrate dose in accordance with its prescribing information.

• bendamustine

  bendamustine, ifosfamide. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Additive myelosuppression.

• bexarotene

  bexarotene increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• bicalutamide

  bicalutamide will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• bosentan

  bosentan increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• brigatinib

  brigatinib increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• bupivacaine implant

  ifosfamide, bupivacaine implant. Either increases toxicity of the other by Other (see comment). Use Caution/Monitor. Comment: Local anesthetics may increase the risk of developing methemoglobinemia when concurrently exposed to drugs that also cause methemoglobinemia.

• busulfan

  busulfan, ifosfamide. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Additive myelosuppression.
  
  busulfan increases toxicity of ifosfamide by Other (see comment). Use Caution/Monitor. Comment: Coadministration with ifosfamide may increase the risk of immunosuppression and myelosuppression. Busulfan may increase the risk of hemorrhagic cystitis during ifosfamide treatment. Follow standard guidelines for hydration, mesna administration, and use of urinalysis.

• butabarbital

  butabarbital increases effects of ifosfamide by affecting hepatic enzyme CYP2B6 metabolism. Use Caution/Monitor. Coadministration of ifosfamide with CYP2B6 inducers may increase metabolism of ifosfamide to its metabolite. Monitor for increased effects/toxicities if combined with CYP2B6 inducers.
  
  butabarbital increases effects of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• butalbital

  butalbital increases effects of ifosfamide by affecting hepatic enzyme CYP2B6 metabolism. Use Caution/Monitor. Coadministration of ifosfamide with CYP2B6 inducers may increase metabolism of ifosfamide to its metabolite. Monitor for increased effects/toxicities if combined with CYP2B6 inducers.
  
  butalbital increases effects of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• cannabidiol

  cannabidiol will increase the level or effect of ifosfamide by affecting hepatic enzyme CYP2C19 metabolism. Modify Therapy/Monitor Closely. Consider reducing the dose of sensitive CYP2C19 substrates, as clinically appropriate, when coadministered with cannabidiol.

• capreomycin

  ifosfamide, capreomycin. Either increases toxicity of the other by nephrotoxicity and/or ototoxicity. Use Caution/Monitor. Monitor renal function.

• carbamazepine

  carbamazepine increases effects of ifosfamide by affecting hepatic enzyme CYP2B6 metabolism. Use Caution/Monitor. Coadministration of ifosfamide with CYP2B6 inducers may increase metabolism of ifosfamide to its metabolite. Monitor for increased effects/toxicities if combined with CYP2B6 inducers.
  
  carbamazepine increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• carboplatin

  carboplatin, ifosfamide. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Additive myelosuppression.

• carmustine

  carmustine, ifosfamide. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Additive myelosuppression.

• cenobamate

  cenobamate will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Increase dose of CYP3A4 substrate, as needed, when coadministered with cenobamate.
  
  cenobamate will increase the level or effect of ifosfamide by affecting hepatic enzyme CYP2C19 metabolism. Modify Therapy/Monitor Closely. Consider a dose reduction of CYP2C19 substrates, as clinically appropriate, when used concomitantly with cenobamate.

• ceritinib

  ceritinib will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• chlorambucil

  chlorambucil, ifosfamide. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Additive myelosuppression.

• chloramphenicol

  ifosfamide, chloramphenicol. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Ifosfamide may enhance the toxicities of myelosuppressive agents. Monitor for increased risk of myelosuppression.
  
  chloramphenicol will increase the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely.

• cidofovir

  ifosfamide, cidofovir. Either increases toxicity of the other by nephrotoxicity and/or ototoxicity. Modify Therapy/Monitor Closely. Ifosfamide may enhance renal toxicity. .

• ciprofloxacin

  ciprofloxacin will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• cisplatin

  cisplatin, ifosfamide. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Additive myelosuppression.

• clarithromycin

  clarithromycin will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Coadministration of CYP3A4 inhibitors may decrease the metabolism of ifosfamide to its active alkylating metabolites and decrease the efficacy of ifosfamide.

• clobazam

  clobazam increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• clotrimazole

  clotrimazole will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• clozapine

  ifosfamide, clozapine. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Ifosfamide may enhance the toxicities of myelosuppressive agents. Monitor for increased risk of myelosuppression.

• cobicistat

  cobicistat will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Coadministration of CYP3A4 inhibitors may decrease the metabolism of ifosfamide to its active alkylating metabolites and decrease the efficacy of ifosfamide.

• conivaptan

  conivaptan will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Coadministration of CYP3A4 inhibitors may decrease the metabolism of ifosfamide to its active alkylating metabolites and decrease the efficacy of ifosfamide. Caution advised during and 7 days after conivaptan treatment.

• crizotinib

  crizotinib will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• cyclophosphamide

  cyclophosphamide, ifosfamide. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Additive myelosuppression.
  
  ifosfamide, cyclophosphamide. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Coadministration with ifosfamide may increase the risk of immunosuppression and myelosuppression.

• dabrafenib

  dabrafenib increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• dacarbazine

  dacarbazine, ifosfamide. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Additive myelosuppression.

• darunavir

  darunavir will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Use alternatives if available. May decrease formation to active metabolite and increase toxicity of active metabolite

• daunorubicin

  ifosfamide, daunorubicin. Other (see comment). Use Caution/Monitor. Comment: Risk of developing cardiotoxic effects increase in patients with prior or concomitant treatment with other cardiotoxic agents.

• dengue vaccine

  ifosfamide decreases effects of dengue vaccine by immunosuppressive effects; risk of infection. Use Caution/Monitor. Immunosuppressive therapies (eg, irradiation, antimetabolites, alkylating agents, cytotoxic drugs, corticosteroids [greater than physiologic doses]) may reduce immune response to dengue vaccine.

• denosumab

  ifosfamide, denosumab. Other (see comment). Use Caution/Monitor. Comment: Caution should be taken in patients on concomitant immunosuppressants or with impaired immune systems because of increased risk for serious infections.
  
  ifosfamide, denosumab. Either increases effects of the other by immunosuppressive effects; risk of infection. Use Caution/Monitor.

• desipramine

  desipramine will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• dexamethasone

  ifosfamide, dexamethasone. Either increases effects of the other by immunosuppressive effects; risk of infection. Use Caution/Monitor.

• dichlorphenamide

  dichlorphenamide and ifosfamide both decrease serum potassium. Use Caution/Monitor.
  
  dichlorphenamide, ifosfamide. Either increases toxicity of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Both drugs can cause metabolic acidosis.

• diltiazem

  diltiazem will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• diphtheria & tetanus toxoids

  ifosfamide decreases effects of diphtheria & tetanus toxoids by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• diphtheria & tetanus toxoids/ acellular pertussis vaccine

  ifosfamide decreases effects of diphtheria & tetanus toxoids/ acellular pertussis vaccine by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• diphtheria & tetanus toxoids/acellular pertussis/poliovirus, inactivated vaccine

  ifosfamide decreases effects of diphtheria & tetanus toxoids/acellular pertussis/poliovirus, inactivated vaccine by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• doxycycline

  doxycycline will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• dronedarone

  dronedarone will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• echinacea

  echinacea decreases effects of ifosfamide by Other (see comment). Use Caution/Monitor. Comment: Echinacea is reported possess immunostimulatory activity demonstrated by activation of macrophages (releasing interleukin-1), and proliferation of B-lymphocytes; theoretically, may oppose the therapeutic effects of immunosuppressants.

• efavirenz

  efavirenz increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.
  
  efavirenz increases effects of ifosfamide by affecting hepatic enzyme CYP2B6 metabolism. Use Caution/Monitor. Coadministration of ifosfamide with CYP2B6 inducers may increase metabolism of ifosfamide to its metabolite. Monitor for increased effects/toxicities if combined with CYP2B6 inducers.

• elagolix

  elagolix will increase the level or effect of ifosfamide by affecting hepatic enzyme CYP2C19 metabolism. Modify Therapy/Monitor Closely. Elagolix is a weak CYP2C19 inhibitor. Caution with sensitive CYP2C19 substrates.
  
  elagolix decreases levels of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Elagolix is a weak-to-moderate CYP3A4 inducer. Monitor CYP3A substrates if coadministered. Consider increasing CYP3A substrate dose if needed.

• elvitegravir/cobicistat/emtricitabine/tenofovir DF

  elvitegravir/cobicistat/emtricitabine/tenofovir DF increases levels of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Cobicistat is a CYP3A4 inhibitor; contraindicated with CYP3A4 substrates for which elevated plasma concentrations are associated with serious and/or life-threatening events.

• enzalutamide

  enzalutamide increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• ertugliflozin

  ifosfamide, ertugliflozin. Either increases toxicity of the other by nephrotoxicity and/or ototoxicity. Use Caution/Monitor. Monitor renal function in patients with severe renal impairment, severe intestinal inflammation, or prolonged use >2 gm/day.

• erythromycin base

  erythromycin base will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• erythromycin ethylsuccinate

  erythromycin ethylsuccinate will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• erythromycin lactobionate

  erythromycin lactobionate will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• erythromycin stearate

  erythromycin stearate will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• eslicarbazepine acetate

  eslicarbazepine acetate increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• etanercept

  ifosfamide, etanercept. Either increases effects of the other by immunosuppressive effects; risk of infection. Use Caution/Monitor.

• etravirine

  etravirine increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• exenatide injectable solution

  ifosfamide, exenatide injectable solution. Either increases toxicity of the other by nephrotoxicity and/or ototoxicity. Use Caution/Monitor. Monitor renal function.

• exenatide injectable suspension

  ifosfamide, exenatide injectable suspension. Either increases toxicity of the other by nephrotoxicity and/or ototoxicity. Use Caution/Monitor. Monitor renal function.

• fedratinib

  fedratinib will increase the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Adjust dose of drugs that are CYP3A4 substrates as necessary.
  
  fedratinib will increase the level or effect of ifosfamide by affecting hepatic enzyme CYP2C19 metabolism. Use Caution/Monitor. Adjust dose of drugs that are CYP2C19 substrates as necessary.

• fexinidazole

  fexinidazole will increase the level or effect of ifosfamide by affecting hepatic enzyme CYP2C19 metabolism. Use Caution/Monitor.

• filgrastim

  ifosfamide will decrease the level or effect of filgrastim by Other (see comment). Modify Therapy/Monitor Closely. Do not use filgrastim in the period 24 hr before through 24 hr after the administration of cytotoxic chemotherapy.

• finerenone

  ifosfamide will increase the level or effect of finerenone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Monitor serum potassium during initiation and dosage adjustment of either finererone or weak CYP3A4 inhibitors. Adjust finererone dosage as needed.

• flibanserin

  ifosfamide will increase the level or effect of flibanserin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Increased flibanserin adverse effects may occur if coadministered with multiple weak CYP3A4 inhibitors.

• fluconazole

  fluconazole will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• flucytosine

  ifosfamide, flucytosine. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Ifosfamide may enhance the toxicities of myelosuppressive agents. Monitor for increased risk of myelosuppression.

• fluvoxamine

  fluvoxamine will decrease the level or effect of ifosfamide by affecting hepatic enzyme CYP2B6 metabolism. Use Caution/Monitor. CYP2B6 inhibitors may decrease metabolism of ifosfamide to its active metabolite, potentially reducing ifosfamide therapeutic effects

• fosamprenavir

  fosamprenavir will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inhibitors may decrease the metabolism of ifosfamide to its active alkylating metabolites, perhaps decreasing the effectiveness of ifosfamide treatment.

• fosphenytoin

  fosphenytoin increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4/CYP2B6 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• fostamatinib

  fostamatinib decreases effects of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• ganciclovir

  ifosfamide, ganciclovir. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Ifosfamide may enhance the toxicities of myelosuppressive agents. Monitor for increased risk of myelosuppression.

• grapefruit

  grapefruit will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration of CYP3A4 inhibitors may decrease the metabolism of ifosfamide to its active alkylating metabolites and decrease the efficacy of ifosfamide.

• guselkumab

  ifosfamide, guselkumab. Either increases effects of the other by immunosuppressive effects; risk of infection. Use Caution/Monitor.

• haemophilus influenzae type b vaccine

  ifosfamide decreases effects of haemophilus influenzae type b vaccine by pharmacodynamic antagonism. Modify Therapy/Monitor Closely. Avoid vaccination during chemotherapy or radiation therapy if possible because antibody response might be suboptimal. Patients vaccinated within a 14-day period before starting or during immunosuppressive therapy should be revaccinated =3 months after therapy is discontinued if immune competence has been restored. .

• haloperidol

  haloperidol decreases effects of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• hepatitis A vaccine inactivated

  ifosfamide decreases effects of hepatitis A vaccine inactivated by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• hepatitis a/b vaccine

  ifosfamide decreases effects of hepatitis a/b vaccine by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• hepatitis b vaccine

  ifosfamide decreases effects of hepatitis b vaccine by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• HIV vaccine

  ifosfamide decreases effects of HIV vaccine by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• human papillomavirus vaccine, nonavalent

  ifosfamide decreases effects of human papillomavirus vaccine, nonavalent by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• human papillomavirus vaccine, quadrivalent

  ifosfamide decreases effects of human papillomavirus vaccine, quadrivalent by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• hydroxyurea

  ifosfamide, hydroxyurea. Other (see comment). Use Caution/Monitor. Comment: Combination may increase risk of myelosuppression.
  
  ifosfamide, hydroxyurea. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Coadministration with ifosfamide may increase the risk of immunosuppression and myelosuppression.

• idelalisib

  idelalisib will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inhibitors may decrease the metabolism of ifosfamide to its active alkylating metabolites, perhaps decreasing the effectiveness of ifosfamide treatment.

• iloperidone

  iloperidone decreases effects of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Iloperidone is a time-dependent CYP3A inhibitor and may lead to increased plasma levels of drugs predominantly eliminated by CYP3A4.

• imatinib

  imatinib decreases effects of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• indinavir

  indinavir will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration of CYP3A4 inhibitors may decrease the metabolism of ifosfamide to its active alkylating metabolites and decrease the efficacy of ifosfamide.

• infliximab

  ifosfamide, infliximab. Either increases effects of the other by immunosuppressive effects; risk of infection. Use Caution/Monitor.

• influenza A (H5N1) vaccine

  ifosfamide decreases effects of influenza A (H5N1) vaccine by pharmacodynamic antagonism. Use Caution/Monitor. Immunosuppressive therapies may reduce immune response to H5N1 vaccine.
  
  ifosfamide decreases effects of influenza A (H5N1) vaccine by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• influenza virus vaccine (H5N1), adjuvanted

  ifosfamide decreases effects of influenza virus vaccine (H5N1), adjuvanted by pharmacodynamic antagonism. Use Caution/Monitor. Immunosuppressive therapies may reduce immune response to H5N1 vaccine.
  
  ifosfamide decreases effects of influenza virus vaccine (H5N1), adjuvanted by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• influenza virus vaccine quadrivalent

  ifosfamide decreases effects of influenza virus vaccine quadrivalent by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• influenza virus vaccine quadrivalent, adjuvanted

  ifosfamide decreases effects of influenza virus vaccine quadrivalent, adjuvanted by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• influenza virus vaccine quadrivalent, cell-cultured

  ifosfamide decreases effects of influenza virus vaccine quadrivalent, cell-cultured by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• influenza virus vaccine quadrivalent, recombinant

  ifosfamide decreases effects of influenza virus vaccine quadrivalent, recombinant by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• influenza virus vaccine trivalent

  ifosfamide decreases effects of influenza virus vaccine trivalent by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• influenza virus vaccine trivalent, adjuvanted

  ifosfamide decreases effects of influenza virus vaccine trivalent, adjuvanted by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• influenza virus vaccine trivalent, recombinant

  ifosfamide decreases effects of influenza virus vaccine trivalent, recombinant by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• interferon beta 1a

  ifosfamide, interferon beta 1a. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Ifosfamide may enhance the toxicities of myelosuppressive agents. Monitor for increased risk of myelosuppression.

• interferon beta 1b

  ifosfamide, interferon beta 1b. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Ifosfamide may enhance the toxicities of myelosuppressive agents. Monitor for increased risk of myelosuppression.

• isavuconazonium sulfate

  ifosfamide will increase the level or effect of isavuconazonium sulfate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
  
  ifosfamide and isavuconazonium sulfate both decrease immunosuppressive effects; risk of infection. Use Caution/Monitor.

• istradefylline

  istradefylline will increase the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Istradefylline 40 mg/day increased peak levels and AUC of CYP3A4 substrates in clinical trials. This effect was not observed with istradefylline 20 mg/day. Consider dose reduction of sensitive CYP3A4 substrates.

• itraconazole

  itraconazole will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration of CYP3A4 inhibitors may decrease the metabolism of ifosfamide to its active alkylating metabolites and decrease the efficacy of ifosfamide.

• ixekizumab

  ifosfamide, ixekizumab. Either increases effects of the other by immunosuppressive effects; risk of infection. Use Caution/Monitor.

• Japanese encephalitis virus vaccine

  ifosfamide decreases effects of Japanese encephalitis virus vaccine by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• ketoconazole

  ketoconazole will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration of CYP3A4 inhibitors may decrease the metabolism of ifosfamide to its active alkylating metabolites and decrease the efficacy of ifosfamide.

• lapatinib

  lapatinib decreases effects of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• leflunomide

  ifosfamide increases toxicity of leflunomide by Other (see comment). Use Caution/Monitor. Comment: Consider not using a leflunomide loading dose in patients receiving other immunosuppressants. Monitor for bone marrow suppression at least monthly in patients concomitantly using leflunomide and another immunosuppressant.

• lemborexant

  ifosfamide will increase the level or effect of lemborexant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Lower nightly dose of lemborexant recommended if coadministered with weak CYP3A4 inhibitors. See drug monograph for specific dosage modification.

• letermovir

  letermovir decreases effects of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• lomitapide

  ifosfamide increases levels of lomitapide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Lomitapide dose should not exceed 30 mg/day.

• lomustine

  ifosfamide, lomustine. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Additive myelosuppression.

• lopinavir

  lopinavir will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration of CYP3A4 inhibitors may decrease the metabolism of ifosfamide to its active alkylating metabolites and decrease the efficacy of ifosfamide.

• lorlatinib

  lorlatinib will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• lumacaftor/ivacaftor

  lumacaftor/ivacaftor increases effects of ifosfamide by affecting hepatic enzyme CYP2B6 metabolism. Use Caution/Monitor. Coadministration of ifosfamide with CYP2B6 inducers may increase metabolism of ifosfamide to its metabolite. Monitor for increased effects/toxicities if combined with CYP2B6 inducers.
  
  lumacaftor/ivacaftor increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• magnesium citrate

  ifosfamide, magnesium citrate. Either increases toxicity of the other by nephrotoxicity and/or ototoxicity. Modify Therapy/Monitor Closely. Monitor electrolytes and renal function.

• mechlorethamine

  ifosfamide, mechlorethamine. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Coadministration with mechlorethamine may increase the risk of immunosuppression and myelosuppression.

• meningococcal A C Y and W-135 diphtheria conjugate vaccine

  ifosfamide decreases effects of meningococcal A C Y and W-135 diphtheria conjugate vaccine by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• meningococcal A C Y and W-135 polysaccharide vaccine combined

  ifosfamide decreases effects of meningococcal A C Y and W-135 polysaccharide vaccine combined by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• meningococcal group B vaccine

  ifosfamide decreases effects of meningococcal group B vaccine by pharmacodynamic antagonism. Use Caution/Monitor. Individuals with altered immunocompetence may have reduced immune responses to the vaccine.
  
  ifosfamide decreases effects of meningococcal group B vaccine by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• methotrexate

  ifosfamide, methotrexate. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Coadministration with ifosfamide may increase the risk of immunosuppression and myelosuppression.

• metronidazole

  metronidazole decreases effects of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• miconazole oral

  miconazole oral will decrease the level or effect of ifosfamide by affecting hepatic enzyme CYP2B6 metabolism. Use Caution/Monitor. Coadministration of ifosfamide with CYP2B6 inhibitors may decrease metabolism of ifosfamide to its metabolite, potentially reducing ifosfamide therapeutic effects.

• midazolam intranasal

  ifosfamide will increase the level or effect of midazolam intranasal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration of mild CYP3A4 inhibitors with midazolam intranasal may cause higher midazolam systemic exposure, which may prolong sedation.

• mifepristone

  mifepristone will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration of CYP3A4 inhibitors may decrease the metabolism of ifosfamide to its active alkylating metabolites and decrease the efficacy of ifosfamide.
  
  mifepristone will decrease the level or effect of ifosfamide by affecting hepatic enzyme CYP2B6 metabolism. Use Caution/Monitor. Coadministration of ifosfamide with CYP2B6 inhibitors may decrease metabolism of ifosfamide to its metabolite, potentially reducing ifosfamide therapeutic effects.

• mitotane

  mitotane increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• modafinil

  modafinil increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• nafcillin

  nafcillin increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• nefazodone

  nefazodone will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration of CYP3A4 inhibitors may decrease the metabolism of ifosfamide to its active alkylating metabolites and decrease the efficacy of ifosfamide.

• nelfinavir

  nelfinavir will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration of CYP3A4 inhibitors may decrease the metabolism of ifosfamide to its active alkylating metabolites and decrease the efficacy of ifosfamide.
  
  nelfinavir will decrease the level or effect of ifosfamide by affecting hepatic enzyme CYP2B6 metabolism. Use Caution/Monitor. Coadministration of ifosfamide with CYP2B6 inhibitors may decrease metabolism of ifosfamide to its metabolite, potentially reducing ifosfamide therapeutic effects.

• netupitant/palonosetron

  netupitant/palonosetron decreases effects of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration .

• nevirapine

  nevirapine increases effects of ifosfamide by affecting hepatic enzyme CYP2B6 metabolism. Use Caution/Monitor. Coadministration of ifosfamide with CYP2B6 inducers may increase metabolism of ifosfamide to its metabolite. Monitor for increased effects/toxicities if combined with CYP2B6 inducers.
  
  nevirapine increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4/CYP2B6 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• nilotinib

  nilotinib increases effects of ifosfamide by affecting hepatic enzyme CYP2B6 metabolism. Use Caution/Monitor. Coadministration of ifosfamide with CYP2B6 inducers may increase metabolism of ifosfamide to its metabolite. Monitor for increased effects/toxicities if combined with CYP2B6 inducers.
  
  nilotinib decreases effects of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• ofatumumab SC

  ofatumumab SC, ifosfamide. Either increases effects of the other by immunosuppressive effects; risk of infection. Use Caution/Monitor. Consider the risk of additive immune system effects when coadministering immunosuppressive therapies with coadministration. When switching from therapies with immune effects, take into account the duration and mechanism of action of these therapies when initiating ofatumumab SC.

• olaparib

  ifosfamide and olaparib both increase pharmacodynamic synergism. Use Caution/Monitor. Coadministration with other other myelosuppressive anticancer agents, including DNA damaging agents, may potentiate and prolongate the myelosuppressive toxicity.

• ombitasvir/paritaprevir/ritonavir & dasabuvir

  ombitasvir/paritaprevir/ritonavir & dasabuvir will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration of CYP3A4 inhibitors may decrease the metabolism of ifosfamide to its active alkylating metabolites and decrease the efficacy of ifosfamide.

• oxaliplatin

  oxaliplatin, ifosfamide. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Additive myelosuppression.

• oxcarbazepine

  oxcarbazepine increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• paclitaxel

  ifosfamide will increase the level or effect of paclitaxel by Other (see comment). Use Caution/Monitor. Paclitaxel levels/toxicity may increase when coadministered with CYP2C8 inhibitors

• paclitaxel protein bound

  ifosfamide will increase the level or effect of paclitaxel protein bound by Other (see comment). Use Caution/Monitor. Paclitaxel levels/toxicity may increase when coadministered with CYP2C8 inhibitors

• pegfilgrastim

  ifosfamide will decrease the level or effect of pegfilgrastim by Other (see comment). Modify Therapy/Monitor Closely. Concomitant use with pegfilgrastim efficacy (antagonistic effects, increased sensitivity of rapidly dividing myeloid cells to cytotoxic chemo)Give pegfilgrastim >14 days before or >24h after cytotoxic chemotherapy.

• peginterferon alfa 2a

  ifosfamide, peginterferon alfa 2a. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Ifosfamide may enhance the toxicities of myelosuppressive agents. Monitor for increased risk of myelosuppression.

• peginterferon alfa 2b

  ifosfamide, peginterferon alfa 2b. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Ifosfamide may enhance the toxicities of myelosuppressive agents. Monitor for increased risk of myelosuppression.

• pentamidine

  ifosfamide, pentamidine. Either increases toxicity of the other by nephrotoxicity and/or ototoxicity. Use Caution/Monitor. Monitor renal function.

• pentobarbital

  pentobarbital increases effects of ifosfamide by affecting hepatic enzyme CYP2B6 metabolism. Use Caution/Monitor. Coadministration of ifosfamide with CYP2B6 inducers may increase metabolism of ifosfamide to its metabolite. Monitor for increased effects/toxicities if combined with CYP2B6 inducers.
  
  pentobarbital increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• peramivir

  ifosfamide increases levels of peramivir by decreasing renal clearance. Use Caution/Monitor. Caution when peramivir coadministered with nephrotoxic drugs.

• phenobarbital

  phenobarbital increases effects of ifosfamide by affecting hepatic enzyme CYP2B6 metabolism. Use Caution/Monitor. Coadministration of ifosfamide with CYP2B6 inducers may increase metabolism of ifosfamide to its metabolite. Monitor for increased effects/toxicities if combined with CYP2B6 inducers.
  
  phenobarbital increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• phenytoin

  phenytoin increases effects of ifosfamide by affecting hepatic enzyme CYP2B6 metabolism. Use Caution/Monitor. Coadministration of ifosfamide with CYP2B6 inducers may increase metabolism of ifosfamide to its metabolite. Monitor for increased effects/toxicities if combined with CYP2B6 inducers.
  
  phenytoin increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• pioglitazone

  pioglitazone increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• pneumococcal vaccine 13-valent

  ifosfamide decreases effects of pneumococcal vaccine 13-valent by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• pneumococcal vaccine heptavalent

  ifosfamide decreases effects of pneumococcal vaccine heptavalent by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• pneumococcal vaccine polyvalent

  ifosfamide decreases effects of pneumococcal vaccine polyvalent by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• poliovirus vaccine inactivated

  ifosfamide decreases effects of poliovirus vaccine inactivated by pharmacodynamic antagonism. Modify Therapy/Monitor Closely. Avoid vaccination during chemotherapy or radiation therapy if possible because antibody response might be suboptimal. Patients vaccinated within a 14-day period before starting or during immunosuppressive therapy should be revaccinated =3 months after therapy is discontinued if immune competence has been restored. .

• posaconazole

  posaconazole will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration of CYP3A4 inhibitors may decrease the metabolism of ifosfamide to its active alkylating metabolites and decrease the efficacy of ifosfamide.

• prednisone

  ifosfamide, prednisone. Either increases effects of the other by immunosuppressive effects; risk of infection. Use Caution/Monitor.

• primaquine

  ifosfamide, primaquine. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Ifosfamide may enhance the toxicities of myelosuppressive agents. Monitor for increased risk of myelosuppression.

• primidone

  primidone increases effects of ifosfamide by affecting hepatic enzyme CYP2B6 metabolism. Use Caution/Monitor. Coadministration of ifosfamide with CYP2B6 inducers may increase metabolism of ifosfamide to its metabolite. Monitor for increased effects/toxicities if combined with CYP2B6 inducers.
  
  primidone increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CCYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• pyrimethamine

  ifosfamide, pyrimethamine. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Ifosfamide may enhance the toxicities of myelosuppressive agents. Monitor for increased risk of myelosuppression.

• quinupristin/dalfopristin

  quinupristin/dalfopristin will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• rabies vaccine

  ifosfamide decreases effects of rabies vaccine by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• rabies vaccine chick embryo cell derived

  ifosfamide decreases effects of rabies vaccine chick embryo cell derived by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• ribociclib

  ribociclib decreases effects of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects. .

• rifabutin

  rifabutin increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• rifampin

  rifampin increases effects of ifosfamide by affecting hepatic enzyme CYP2B6 metabolism. Use Caution/Monitor. Coadministration of ifosfamide with CYP2B6 inducers may increase metabolism of ifosfamide to its metabolite. Monitor for increased effects/toxicities if combined with CYP2B6 inducers.
  
  rifampin increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• rifapentine

  rifapentine increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• ritonavir

  ritonavir will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration of CYP3A4 inhibitors may decrease the metabolism of ifosfamide to its active alkylating metabolites and decrease the efficacy of ifosfamide.
  
  ritonavir increases effects of ifosfamide by affecting hepatic enzyme CYP2B6 metabolism. Use Caution/Monitor. Coadministration of ifosfamide with CYP2B6 inducers may increase metabolism of ifosfamide to its metabolite. Monitor for increased effects/toxicities if combined with CYP2B6 inducers.

• roflumilast

  roflumilast will increase the level or effect of ifosfamide by immunosuppressive effects; risk of infection. Use Caution/Monitor. Caution should be taken in patients on concomitant immunosuppressants or with impaired immune systems because of increased risk for serious infections.

• saquinavir

  saquinavir will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration of CYP3A4 inhibitors may decrease the metabolism of ifosfamide to its active alkylating metabolites and decrease the efficacy of ifosfamide.

• sargramostim

  ifosfamide will decrease the level or effect of sargramostim by Other (see comment). Modify Therapy/Monitor Closely. Do not administer simultaneously with or within 24 hours preceding/following cytotoxic chemotherapy or radiotherapy (due to the sensitivity of rapidly dividing hematopoietic progenitor cells).

• schisandra

  schisandra decreases effects of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration .

• secobarbital

  secobarbital increases effects of ifosfamide by affecting hepatic enzyme CYP2B6 metabolism. Use Caution/Monitor. Coadministration of ifosfamide with CYP2B6 inducers may increase metabolism of ifosfamide to its metabolite. Monitor for increased effects/toxicities if combined with CYP2B6 inducers.

• selexipag

  ifosfamide will increase the level or effect of selexipag by decreasing metabolism. Modify Therapy/Monitor Closely. Reduce selexipag dose to once daily if coadministered with moderate CYP2C8 inhibitors.

• semaglutide

  ifosfamide, semaglutide. Either increases toxicity of the other by nephrotoxicity and/or ototoxicity. Use Caution/Monitor. Monitor renal function.

• sertraline

  sertraline decreases effects of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration .

• siponimod

  siponimod and ifosfamide both increase immunosuppressive effects; risk of infection. Use Caution/Monitor. Caution if coadministered because of additive immunosuppressive effects during such therapy and in the weeks following administration. When switching from drugs with prolonged immune effects, consider the half-life and mode of action of these drugs to avoid unintended additive immunosuppressive effects.

• sipuleucel-T

  ifosfamide decreases effects of sipuleucel-T by pharmacodynamic antagonism. Modify Therapy/Monitor Closely.
  
  ifosfamide, sipuleucel-T. Either increases effects of the other by immunosuppressive effects; risk of infection. Use Caution/Monitor. Caution should be taken in patients on concomitant immunosuppressants or with impaired immune systems because of increased risk for serious infections.

• sirolimus

  ifosfamide, sirolimus. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Coadministration with ifosfamide may increase the risk of immunosuppression and myelosuppression.

• sodium sulfate/?magnesium sulfate/potassium chloride

  sodium sulfate/?magnesium sulfate/potassium chloride increases toxicity of ifosfamide by Other (see comment). Use Caution/Monitor. Comment: Coadministration with medications that cause fluid and electrolyte abnormalities may increase the risk of adverse events of seizure, arrhythmias, and renal impairment.

• sodium sulfate/potassium sulfate/magnesium sulfate

  sodium sulfate/potassium sulfate/magnesium sulfate increases toxicity of ifosfamide by Other (see comment). Use Caution/Monitor. Comment: Coadministration with medications that cause fluid and electrolyte abnormalities may increase the risk of adverse events of seizure, arrhythmias, and renal impairment.

• St John's Wort

  St John's Wort increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• stiripentol

  stiripentol, ifosfamide. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Stiripentol is a CYP3A4 inhibitor and inducer. Monitor CYP3A4 substrates coadministered with stiripentol for increased or decreased effects. CYP3A4 substrates may require dosage adjustment.
  
  stiripentol will increase the level or effect of ifosfamide by affecting hepatic enzyme CYP2C19 metabolism. Modify Therapy/Monitor Closely. Consider reducing the dose of CYP2C19 substrates, if adverse reactions are experienced when administered concomitantly with stiripentol.

• streptozocin

  ifosfamide, streptozocin. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Additive myelosuppression.

• tacrolimus

  ifosfamide, tacrolimus. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Ifosfamide may enhance the toxicities of myelosuppressive agents. Monitor for increased risk of myelosuppression.

• tazemetostat

  tazemetostat will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
  
  ifosfamide will increase the level or effect of tazemetostat by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• tecovirimat

  tecovirimat will increase the level or effect of ifosfamide by affecting hepatic enzyme CYP2C19 metabolism. Use Caution/Monitor. Tecovirimat is a weak inhibitor of CYP2C8 and CYP2C19. Monitor for adverse effects if coadministered with sensitive substrates of these enzymes.
  
  tecovirimat will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Tecovirimat is a weak CYP3A4 inducer. Monitor sensitive CYP3A4 substrates for effectiveness if coadministered.

• tenofovir AF

  ifosfamide, tenofovir AF. Either increases toxicity of the other by nephrotoxicity and/or ototoxicity. Modify Therapy/Monitor Closely. Monitor electrolytes and renal function.

• teriflunomide

  ifosfamide, teriflunomide. Either increases effects of the other by immunosuppressive effects; risk of infection. Use Caution/Monitor.

• tetanus & reduced diphtheria toxoids/ acellular pertussis vaccine

  ifosfamide decreases effects of tetanus & reduced diphtheria toxoids/ acellular pertussis vaccine by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• tetanus toxoid adsorbed or fluid

  ifosfamide decreases effects of tetanus toxoid adsorbed or fluid by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• tetracycline

  tetracycline decreases effects of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• thiotepa

  ifosfamide, thiotepa. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Additive myelosuppression.

• tinidazole

  ifosfamide will increase the level or effect of tinidazole by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• tipranavir

  tipranavir will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Use alternatives if available. May decrease formation to active metabolite and increase toxicity of active metabolite

• topotecan

  ifosfamide, topotecan. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Coadministration with ifosfamide may increase the risk of immunosuppression and myelosuppression.

• trabectedin

  ifosfamide, trabectedin. Other (see comment). Use Caution/Monitor. Comment: Risk of developing cardiotoxic effects increase in patients with prior or concomitant treatment with other cardiotoxic agents.

• trastuzumab

  trastuzumab, ifosfamide. Either increases toxicity of the other by immunosuppressive effects; risk of infection. Use Caution/Monitor. Neutropenia or febrile neutropenia incidence were increased when trastuzumab was coadministered with myelosuppressive chemotherapy. .

• trastuzumab deruxtecan

  trastuzumab deruxtecan, ifosfamide. Either increases toxicity of the other by immunosuppressive effects; risk of infection. Use Caution/Monitor. Neutropenia or febrile neutropenia incidence were increased when trastuzumab was coadministered with myelosuppressive chemotherapy. .
  
  ifosfamide, trastuzumab deruxtecan. Other (see comment). Use Caution/Monitor. Comment: Risk of developing cardiotoxic effects increase in patients with prior or concomitant treatment with other cardiotoxic agents.
  
  ifosfamide, trastuzumab deruxtecan. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Ifosfamide may enhance the toxicities of myelosuppressive agents. Monitor for increased risk of myelosuppression.

• triclabendazole

  triclabendazole will increase the level or effect of ifosfamide by affecting hepatic enzyme CYP2C19 metabolism. Use Caution/Monitor. If plasma concentrations of the CYP2C19 substrates are elevated during triclabendazole, recheck plasma concentration of the CYP2C19 substrates after discontinuation of triclabendazole.

• ustekinumab

  ifosfamide, ustekinumab. Either increases effects of the other by immunosuppressive effects; risk of infection. Use Caution/Monitor.

• vancomycin

  ifosfamide, vancomycin. Either increases toxicity of the other by nephrotoxicity and/or ototoxicity. Use Caution/Monitor. Monitor renal function.

• vedolizumab

  ifosfamide, vedolizumab. Either increases effects of the other by immunosuppressive effects; risk of infection. Use Caution/Monitor.

• verapamil

  verapamil decreases effects of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• voclosporin

  voclosporin, ifosfamide. Either increases toxicity of the other by nephrotoxicity and/or ototoxicity. Modify Therapy/Monitor Closely. Coadministration with drugs associated with nephrotoxicity may increase the risk for acute and/or chronic nephrotoxicity.

• voriconazole

  voriconazole will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration of CYP3A4 inhibitors may decrease the metabolism of ifosfamide to its active alkylating metabolites and decrease the efficacy of ifosfamide.

• zidovudine

  ifosfamide, zidovudine. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Ifosfamide may enhance the toxicities of myelosuppressive agents. Monitor for increased risk of myelosuppression.

• zoster vaccine recombinant

  ifosfamide decreases effects of zoster vaccine recombinant by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

Minor (4)

• digoxin

  ifosfamide will decrease the level or effect of digoxin by Other (see comment). Minor/Significance Unknown. Antineoplastic agents that cause significant mucositis/stomatitis may be more likely to impair digoxin tablet absorption

• ruxolitinib

  ifosfamide will increase the level or effect of ruxolitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

• vitamin A

  vitamin A, ifosfamide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Antioxidants such as vitamin A enhance the efficacy, and reduce toxicity, of antineoplastic drugs.

• vitamin E

  vitamin E, ifosfamide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Antioxidants such as vitamin E enhance the efficacy, and reduce toxicity, of antineoplastic drugs.

• abiraterone

  Monitor Closely (1)abiraterone will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• acalabrutinib

  Monitor Closely (1)acalabrutinib, ifosfamide. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Coadministration may increase risk of myelosuppressive effects.

• adenovirus types 4 and 7 live, oral

  Contraindicated (1)ifosfamide decreases effects of adenovirus types 4 and 7 live, oral by pharmacodynamic antagonism. Contraindicated. Immunosuppressives may diminish therapeutic effects of vaccines and increase risk of adverse effects (increased risk of infection). Live-attenuated vaccines should be avoided for at least 3 mo. after cessation of immunosuppressive therapy.

• ado-trastuzumab emtansine

  Monitor Closely (1)ifosfamide, ado-trastuzumab emtansine. Other (see comment). Use Caution/Monitor. Comment: Risk of developing cardiotoxic effects increase in patients with prior or concomitant treatment with other cardiotoxic agents.

• alemtuzumab

  Monitor Closely (1)ifosfamide, alemtuzumab. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Coadministration with ifosfamide may increase the risk of immunosuppression and myelosuppression.

• amiodarone

  Monitor Closely (1)amiodarone will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• amobarbital

  Monitor Closely (1)amobarbital increases effects of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• amphotericin B cholesteryl sulfate

  Monitor Closely (1)ifosfamide increases toxicity of amphotericin B cholesteryl sulfate by unknown mechanism. Use Caution/Monitor. Monitor for possible increases in renal toxicity, bronchospasm, and hypotension if amphotericin is given concomitantly with ifosfamide.

• amphotericin B deoxycholate

  Monitor Closely (1)ifosfamide increases toxicity of amphotericin B deoxycholate by unknown mechanism. Use Caution/Monitor. Monitor for possible increases in renal toxicity, bronchospasm, and hypotension if amphotericin is given concomitantly with ifosfamide.

• amphotericin B liposomal

  Monitor Closely (1)ifosfamide increases toxicity of amphotericin B liposomal by unknown mechanism. Use Caution/Monitor. Monitor for possible increases in renal toxicity, bronchospasm, and hypotension if amphotericin is given concomitantly with ifosfamide.

• amphotericin B phospholipid complex

  Monitor Closely (1)ifosfamide increases toxicity of amphotericin B phospholipid complex by unknown mechanism. Use Caution/Monitor. Monitor for possible increases in renal toxicity, bronchospasm, and hypotension if amphotericin is given concomitantly with ifosfamide.

• anthrax vaccine adsorbed

  Monitor Closely (1)ifosfamide decreases effects of anthrax vaccine adsorbed by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• apalutamide

  Monitor Closely (1)apalutamide increases effects of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration of apalutamide, a strong CYP3A4 inducer, with drugs that are CYP3A4 substrates can result in lower exposure to these medications. Avoid or substitute another drug for these medications when possible. Evaluate for loss of therapeutic effect if medication must be coadministered. Adjust dose according to prescribing information if needed.

• aprepitant

  Monitor Closely (1)aprepitant decreases effects of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor for ifosfamide neurotoxicity (eg, visual and auditory hallucinations, somnolence, confusion, delirium) if combined with fosaprepitant. Consider also monitoring for decreased ifosfamide efficacy.

• armodafinil

  Monitor Closely (2)armodafinil increases effects of ifosfamide by affecting hepatic enzyme CYP2B6 metabolism. Use Caution/Monitor. Coadministration of ifosfamide with CYP2B6 inducers may increase metabolism of ifosfamide to its metabolite. Monitor for increased effects/toxicities if combined with CYP2B6 inducers.
  
  armodafinil increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• atazanavir

  Monitor Closely (1)atazanavir will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Coadministration of CYP3A4 inhibitors may decrease the metabolism of ifosfamide to its active alkylating metabolites and decrease the efficacy of ifosfamide.

• atogepant

  Monitor Closely (1)ifosfamide will increase the level or effect of atogepant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• axitinib

  Monitor Closely (1)ifosfamide increases levels of axitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• azathioprine

  Monitor Closely (1)ifosfamide, azathioprine. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Coadministration with ifosfamide may increase the risk of immunosuppression and myelosuppression.

• bacitracin

  Serious - Use Alternative (1)ifosfamide and bacitracin both increase nephrotoxicity and/or ototoxicity. Avoid or Use Alternate Drug. Avoid concurrent use of bacitracin with other nephrotoxic drugs

• baricitinib

  Monitor Closely (1)ifosfamide, baricitinib. Either increases effects of the other by immunosuppressive effects; risk of infection. Use Caution/Monitor.

• belatacept

  Monitor Closely (1)belatacept and ifosfamide both increase immunosuppressive effects; risk of infection. Use Caution/Monitor.

• belimumab

  Monitor Closely (1)ifosfamide, belimumab. Either increases effects of the other by immunosuppressive effects; risk of infection. Use Caution/Monitor.

• belzutifan

  Monitor Closely (1)belzutifan will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. If unable to avoid coadministration of belzutifan with sensitive CYP3A4 substrates, consider increasing the sensitive CYP3A4 substrate dose in accordance with its prescribing information.

• bendamustine

  Monitor Closely (1)bendamustine, ifosfamide. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Additive myelosuppression.

• bexarotene

  Monitor Closely (1)bexarotene increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• bicalutamide

  Monitor Closely (1)bicalutamide will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• bosentan

  Monitor Closely (1)bosentan increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• brigatinib

  Monitor Closely (1)brigatinib increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• bupivacaine implant

  Monitor Closely (1)ifosfamide, bupivacaine implant. Either increases toxicity of the other by Other (see comment). Use Caution/Monitor. Comment: Local anesthetics may increase the risk of developing methemoglobinemia when concurrently exposed to drugs that also cause methemoglobinemia.

• busulfan

  Monitor Closely (2)busulfan, ifosfamide. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Additive myelosuppression.
  
  busulfan increases toxicity of ifosfamide by Other (see comment). Use Caution/Monitor. Comment: Coadministration with ifosfamide may increase the risk of immunosuppression and myelosuppression. Busulfan may increase the risk of hemorrhagic cystitis during ifosfamide treatment. Follow standard guidelines for hydration, mesna administration, and use of urinalysis.

• butabarbital

  Monitor Closely (2)butabarbital increases effects of ifosfamide by affecting hepatic enzyme CYP2B6 metabolism. Use Caution/Monitor. Coadministration of ifosfamide with CYP2B6 inducers may increase metabolism of ifosfamide to its metabolite. Monitor for increased effects/toxicities if combined with CYP2B6 inducers.
  
  butabarbital increases effects of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• butalbital

  Monitor Closely (2)butalbital increases effects of ifosfamide by affecting hepatic enzyme CYP2B6 metabolism. Use Caution/Monitor. Coadministration of ifosfamide with CYP2B6 inducers may increase metabolism of ifosfamide to its metabolite. Monitor for increased effects/toxicities if combined with CYP2B6 inducers.
  
  butalbital increases effects of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• cannabidiol

  Monitor Closely (1)cannabidiol will increase the level or effect of ifosfamide by affecting hepatic enzyme CYP2C19 metabolism. Modify Therapy/Monitor Closely. Consider reducing the dose of sensitive CYP2C19 substrates, as clinically appropriate, when coadministered with cannabidiol.

• capreomycin

  Monitor Closely (1)ifosfamide, capreomycin. Either increases toxicity of the other by nephrotoxicity and/or ototoxicity. Use Caution/Monitor. Monitor renal function.

• carbamazepine

  Monitor Closely (2)carbamazepine increases effects of ifosfamide by affecting hepatic enzyme CYP2B6 metabolism. Use Caution/Monitor. Coadministration of ifosfamide with CYP2B6 inducers may increase metabolism of ifosfamide to its metabolite. Monitor for increased effects/toxicities if combined with CYP2B6 inducers.
  
  carbamazepine increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• carboplatin

  Monitor Closely (1)carboplatin, ifosfamide. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Additive myelosuppression.

• carmustine

  Monitor Closely (1)carmustine, ifosfamide. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Additive myelosuppression.

• cenobamate

  Monitor Closely (2)cenobamate will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Increase dose of CYP3A4 substrate, as needed, when coadministered with cenobamate.
  
  cenobamate will increase the level or effect of ifosfamide by affecting hepatic enzyme CYP2C19 metabolism. Modify Therapy/Monitor Closely. Consider a dose reduction of CYP2C19 substrates, as clinically appropriate, when used concomitantly with cenobamate.

• ceritinib

  Monitor Closely (1)ceritinib will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• chlorambucil

  Monitor Closely (1)chlorambucil, ifosfamide. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Additive myelosuppression.

• chloramphenicol

  Monitor Closely (2)ifosfamide, chloramphenicol. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Ifosfamide may enhance the toxicities of myelosuppressive agents. Monitor for increased risk of myelosuppression.
  
  chloramphenicol will increase the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely.

• cidofovir

  Monitor Closely (1)ifosfamide, cidofovir. Either increases toxicity of the other by nephrotoxicity and/or ototoxicity. Modify Therapy/Monitor Closely. Ifosfamide may enhance renal toxicity. .

• ciprofloxacin

  Monitor Closely (1)ciprofloxacin will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• cisplatin

  Monitor Closely (1)cisplatin, ifosfamide. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Additive myelosuppression.

• clarithromycin

  Monitor Closely (1)clarithromycin will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Coadministration of CYP3A4 inhibitors may decrease the metabolism of ifosfamide to its active alkylating metabolites and decrease the efficacy of ifosfamide.

• clobazam

  Monitor Closely (1)clobazam increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• clotrimazole

  Monitor Closely (1)clotrimazole will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• clozapine

  Monitor Closely (1)ifosfamide, clozapine. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Ifosfamide may enhance the toxicities of myelosuppressive agents. Monitor for increased risk of myelosuppression.

• cobicistat

  Monitor Closely (1)cobicistat will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Coadministration of CYP3A4 inhibitors may decrease the metabolism of ifosfamide to its active alkylating metabolites and decrease the efficacy of ifosfamide.

• conivaptan

  Monitor Closely (1)conivaptan will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Coadministration of CYP3A4 inhibitors may decrease the metabolism of ifosfamide to its active alkylating metabolites and decrease the efficacy of ifosfamide. Caution advised during and 7 days after conivaptan treatment.

• crizotinib

  Monitor Closely (1)crizotinib will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• cyclophosphamide

  Monitor Closely (2)ifosfamide, cyclophosphamide. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Coadministration with ifosfamide may increase the risk of immunosuppression and myelosuppression.
  
  cyclophosphamide, ifosfamide. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Additive myelosuppression.

• dabrafenib

  Monitor Closely (1)dabrafenib increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• dacarbazine

  Monitor Closely (1)dacarbazine, ifosfamide. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Additive myelosuppression.

• darunavir

  Monitor Closely (1)darunavir will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Use alternatives if available. May decrease formation to active metabolite and increase toxicity of active metabolite

• daunorubicin

  Monitor Closely (1)ifosfamide, daunorubicin. Other (see comment). Use Caution/Monitor. Comment: Risk of developing cardiotoxic effects increase in patients with prior or concomitant treatment with other cardiotoxic agents.

• deferiprone

  Serious - Use Alternative (1)deferiprone, ifosfamide. Either increases toxicity of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Avoid use of deferiprone with other drugs known to be associated with neutropenia or agranulocytosis; if an alternative is not possible, monitor absolute neutrophil count more frequently.

• dengue vaccine

  Monitor Closely (1)ifosfamide decreases effects of dengue vaccine by immunosuppressive effects; risk of infection. Use Caution/Monitor. Immunosuppressive therapies (eg, irradiation, antimetabolites, alkylating agents, cytotoxic drugs, corticosteroids [greater than physiologic doses]) may reduce immune response to dengue vaccine.

• denosumab

  Monitor Closely (2)ifosfamide, denosumab. Other (see comment). Use Caution/Monitor. Comment: Caution should be taken in patients on concomitant immunosuppressants or with impaired immune systems because of increased risk for serious infections.
  
  ifosfamide, denosumab. Either increases effects of the other by immunosuppressive effects; risk of infection. Use Caution/Monitor.

• desipramine

  Monitor Closely (1)desipramine will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• dexamethasone

  Monitor Closely (1)ifosfamide, dexamethasone. Either increases effects of the other by immunosuppressive effects; risk of infection. Use Caution/Monitor.

• dichlorphenamide

  Monitor Closely (2)dichlorphenamide and ifosfamide both decrease serum potassium. Use Caution/Monitor.
  
  dichlorphenamide, ifosfamide. Either increases toxicity of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Both drugs can cause metabolic acidosis.

• digoxin

  Minor (1)ifosfamide will decrease the level or effect of digoxin by Other (see comment). Minor/Significance Unknown. Antineoplastic agents that cause significant mucositis/stomatitis may be more likely to impair digoxin tablet absorption

• diltiazem

  Monitor Closely (1)diltiazem will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• diphtheria & tetanus toxoids

  Monitor Closely (1)ifosfamide decreases effects of diphtheria & tetanus toxoids by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• diphtheria & tetanus toxoids/ acellular pertussis vaccine

  Monitor Closely (1)ifosfamide decreases effects of diphtheria & tetanus toxoids/ acellular pertussis vaccine by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• diphtheria & tetanus toxoids/acellular pertussis/poliovirus, inactivated vaccine

  Monitor Closely (1)ifosfamide decreases effects of diphtheria & tetanus toxoids/acellular pertussis/poliovirus, inactivated vaccine by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• doxycycline

  Monitor Closely (1)doxycycline will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• dronedarone

  Monitor Closely (1)dronedarone will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• echinacea

  Monitor Closely (1)echinacea decreases effects of ifosfamide by Other (see comment). Use Caution/Monitor. Comment: Echinacea is reported possess immunostimulatory activity demonstrated by activation of macrophages (releasing interleukin-1), and proliferation of B-lymphocytes; theoretically, may oppose the therapeutic effects of immunosuppressants.

• efavirenz

  Monitor Closely (2)efavirenz increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.
  
  efavirenz increases effects of ifosfamide by affecting hepatic enzyme CYP2B6 metabolism. Use Caution/Monitor. Coadministration of ifosfamide with CYP2B6 inducers may increase metabolism of ifosfamide to its metabolite. Monitor for increased effects/toxicities if combined with CYP2B6 inducers.

• elagolix

  Monitor Closely (2)elagolix will increase the level or effect of ifosfamide by affecting hepatic enzyme CYP2C19 metabolism. Modify Therapy/Monitor Closely. Elagolix is a weak CYP2C19 inhibitor. Caution with sensitive CYP2C19 substrates.
  
  elagolix decreases levels of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Elagolix is a weak-to-moderate CYP3A4 inducer. Monitor CYP3A substrates if coadministered. Consider increasing CYP3A substrate dose if needed.

• elvitegravir/cobicistat/emtricitabine/tenofovir DF

  Monitor Closely (1)elvitegravir/cobicistat/emtricitabine/tenofovir DF increases levels of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Cobicistat is a CYP3A4 inhibitor; contraindicated with CYP3A4 substrates for which elevated plasma concentrations are associated with serious and/or life-threatening events.

• enzalutamide

  Monitor Closely (1)enzalutamide increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• ertugliflozin

  Monitor Closely (1)ifosfamide, ertugliflozin. Either increases toxicity of the other by nephrotoxicity and/or ototoxicity. Use Caution/Monitor. Monitor renal function in patients with severe renal impairment, severe intestinal inflammation, or prolonged use >2 gm/day.

• erythromycin base

  Monitor Closely (1)erythromycin base will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• erythromycin ethylsuccinate

  Monitor Closely (1)erythromycin ethylsuccinate will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• erythromycin lactobionate

  Monitor Closely (1)erythromycin lactobionate will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• erythromycin stearate

  Monitor Closely (1)erythromycin stearate will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• eslicarbazepine acetate

  Monitor Closely (1)eslicarbazepine acetate increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• etanercept

  Monitor Closely (1)ifosfamide, etanercept. Either increases effects of the other by immunosuppressive effects; risk of infection. Use Caution/Monitor.

• etravirine

  Monitor Closely (1)etravirine increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• exenatide injectable solution

  Monitor Closely (1)ifosfamide, exenatide injectable solution. Either increases toxicity of the other by nephrotoxicity and/or ototoxicity. Use Caution/Monitor. Monitor renal function.

• exenatide injectable suspension

  Monitor Closely (1)ifosfamide, exenatide injectable suspension. Either increases toxicity of the other by nephrotoxicity and/or ototoxicity. Use Caution/Monitor. Monitor renal function.

• fedratinib

  Monitor Closely (2)fedratinib will increase the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Adjust dose of drugs that are CYP3A4 substrates as necessary.
  
  fedratinib will increase the level or effect of ifosfamide by affecting hepatic enzyme CYP2C19 metabolism. Use Caution/Monitor. Adjust dose of drugs that are CYP2C19 substrates as necessary.

• fexinidazole

  Monitor Closely (1)fexinidazole will increase the level or effect of ifosfamide by affecting hepatic enzyme CYP2C19 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)fexinidazole will increase the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Fexinidazole inhibits CYP3A4. Coadministration may increase risk for adverse effects of CYP3A4 substrates.

• filgrastim

  Monitor Closely (1)ifosfamide will decrease the level or effect of filgrastim by Other (see comment). Modify Therapy/Monitor Closely. Do not use filgrastim in the period 24 hr before through 24 hr after the administration of cytotoxic chemotherapy.

• finerenone

  Monitor Closely (1)ifosfamide will increase the level or effect of finerenone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Monitor serum potassium during initiation and dosage adjustment of either finererone or weak CYP3A4 inhibitors. Adjust finererone dosage as needed.

• fingolimod

  Serious - Use Alternative (1)ifosfamide, fingolimod. Either increases effects of the other by immunosuppressive effects; risk of infection. Avoid or Use Alternate Drug. Avoid concomitant use of fingolimod and other immunosuppressants when possible. If combined, closely monitor patients for additive immunosuppressant effects (eg, infections). When switching to fingolimod after discontinuation of another immunosuppressant, consider the duration of action of the discontinued drug to avoid additive immunosuppressive effects.

• flibanserin

  Monitor Closely (1)ifosfamide will increase the level or effect of flibanserin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Increased flibanserin adverse effects may occur if coadministered with multiple weak CYP3A4 inhibitors.

• fluconazole

  Monitor Closely (1)fluconazole will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• flucytosine

  Monitor Closely (1)ifosfamide, flucytosine. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Ifosfamide may enhance the toxicities of myelosuppressive agents. Monitor for increased risk of myelosuppression.

• fluvoxamine

  Monitor Closely (1)fluvoxamine will decrease the level or effect of ifosfamide by affecting hepatic enzyme CYP2B6 metabolism. Use Caution/Monitor. CYP2B6 inhibitors may decrease metabolism of ifosfamide to its active metabolite, potentially reducing ifosfamide therapeutic effects

• fosamprenavir

  Monitor Closely (1)fosamprenavir will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inhibitors may decrease the metabolism of ifosfamide to its active alkylating metabolites, perhaps decreasing the effectiveness of ifosfamide treatment.

• fosphenytoin

  Monitor Closely (1)fosphenytoin increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4/CYP2B6 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• fostamatinib

  Monitor Closely (1)fostamatinib decreases effects of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• ganciclovir

  Monitor Closely (1)ifosfamide, ganciclovir. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Ifosfamide may enhance the toxicities of myelosuppressive agents. Monitor for increased risk of myelosuppression.

• grapefruit

  Monitor Closely (1)grapefruit will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration of CYP3A4 inhibitors may decrease the metabolism of ifosfamide to its active alkylating metabolites and decrease the efficacy of ifosfamide.

• guselkumab

  Monitor Closely (1)ifosfamide, guselkumab. Either increases effects of the other by immunosuppressive effects; risk of infection. Use Caution/Monitor.

• haemophilus influenzae type b vaccine

  Monitor Closely (1)ifosfamide decreases effects of haemophilus influenzae type b vaccine by pharmacodynamic antagonism. Modify Therapy/Monitor Closely. Avoid vaccination during chemotherapy or radiation therapy if possible because antibody response might be suboptimal. Patients vaccinated within a 14-day period before starting or during immunosuppressive therapy should be revaccinated =3 months after therapy is discontinued if immune competence has been restored. .

• haloperidol

  Monitor Closely (1)haloperidol decreases effects of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• hepatitis A vaccine inactivated

  Monitor Closely (1)ifosfamide decreases effects of hepatitis A vaccine inactivated by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• hepatitis a/b vaccine

  Monitor Closely (1)ifosfamide decreases effects of hepatitis a/b vaccine by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• hepatitis b vaccine

  Monitor Closely (1)ifosfamide decreases effects of hepatitis b vaccine by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• HIV vaccine

  Monitor Closely (1)ifosfamide decreases effects of HIV vaccine by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• human papillomavirus vaccine, nonavalent

  Monitor Closely (1)ifosfamide decreases effects of human papillomavirus vaccine, nonavalent by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• human papillomavirus vaccine, quadrivalent

  Monitor Closely (1)ifosfamide decreases effects of human papillomavirus vaccine, quadrivalent by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• hydroxyurea

  Monitor Closely (2)ifosfamide, hydroxyurea. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Coadministration with ifosfamide may increase the risk of immunosuppression and myelosuppression.
  
  ifosfamide, hydroxyurea. Other (see comment). Use Caution/Monitor. Comment: Combination may increase risk of myelosuppression.

• idelalisib

  Monitor Closely (1)idelalisib will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inhibitors may decrease the metabolism of ifosfamide to its active alkylating metabolites, perhaps decreasing the effectiveness of ifosfamide treatment.

• iloperidone

  Monitor Closely (1)iloperidone decreases effects of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Iloperidone is a time-dependent CYP3A inhibitor and may lead to increased plasma levels of drugs predominantly eliminated by CYP3A4.

• imatinib

  Monitor Closely (1)imatinib decreases effects of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• indinavir

  Monitor Closely (1)indinavir will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration of CYP3A4 inhibitors may decrease the metabolism of ifosfamide to its active alkylating metabolites and decrease the efficacy of ifosfamide.

• infliximab

  Monitor Closely (1)ifosfamide, infliximab. Either increases effects of the other by immunosuppressive effects; risk of infection. Use Caution/Monitor.

• influenza A (H5N1) vaccine

  Monitor Closely (2)ifosfamide decreases effects of influenza A (H5N1) vaccine by pharmacodynamic antagonism. Use Caution/Monitor. Immunosuppressive therapies may reduce immune response to H5N1 vaccine.
  
  ifosfamide decreases effects of influenza A (H5N1) vaccine by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• influenza virus vaccine (H5N1), adjuvanted

  Monitor Closely (2)ifosfamide decreases effects of influenza virus vaccine (H5N1), adjuvanted by pharmacodynamic antagonism. Use Caution/Monitor. Immunosuppressive therapies may reduce immune response to H5N1 vaccine.
  
  ifosfamide decreases effects of influenza virus vaccine (H5N1), adjuvanted by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• influenza virus vaccine quadrivalent

  Contraindicated (1)ifosfamide decreases effects of influenza virus vaccine quadrivalent by pharmacodynamic antagonism. Contraindicated. Immunosuppressives may diminish therapeutic effects of vaccines and increase risk of adverse effects (increased risk of infection). Live-attenuated vaccines should be avoided for at least 3 mo. after cessation of immunosuppressive therapy.Monitor Closely (1)ifosfamide decreases effects of influenza virus vaccine quadrivalent by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• influenza virus vaccine quadrivalent, adjuvanted

  Monitor Closely (1)ifosfamide decreases effects of influenza virus vaccine quadrivalent, adjuvanted by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .Serious - Use Alternative (1)ifosfamide decreases effects of influenza virus vaccine quadrivalent, adjuvanted by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Immunosuppressive drugs may reduce the immune response to influenza vaccine.

• influenza virus vaccine quadrivalent, cell-cultured

  Contraindicated (1)ifosfamide decreases effects of influenza virus vaccine quadrivalent, cell-cultured by pharmacodynamic antagonism. Contraindicated. Immunosuppressives may diminish therapeutic effects of vaccines and increase risk of adverse effects (increased risk of infection). Live-attenuated vaccines should be avoided for at least 3 mo. after cessation of immunosuppressive therapy.Monitor Closely (1)ifosfamide decreases effects of influenza virus vaccine quadrivalent, cell-cultured by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• influenza virus vaccine quadrivalent, recombinant

  Monitor Closely (1)ifosfamide decreases effects of influenza virus vaccine quadrivalent, recombinant by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• influenza virus vaccine trivalent

  Monitor Closely (1)ifosfamide decreases effects of influenza virus vaccine trivalent by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• influenza virus vaccine trivalent, adjuvanted

  Monitor Closely (1)ifosfamide decreases effects of influenza virus vaccine trivalent, adjuvanted by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .Serious - Use Alternative (1)ifosfamide decreases effects of influenza virus vaccine trivalent, adjuvanted by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Immunosuppressive drugs may reduce the immune response to influenza vaccine.

• influenza virus vaccine trivalent, recombinant

  Monitor Closely (1)ifosfamide decreases effects of influenza virus vaccine trivalent, recombinant by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• interferon beta 1a

  Monitor Closely (1)ifosfamide, interferon beta 1a. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Ifosfamide may enhance the toxicities of myelosuppressive agents. Monitor for increased risk of myelosuppression.

• interferon beta 1b

  Monitor Closely (1)ifosfamide, interferon beta 1b. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Ifosfamide may enhance the toxicities of myelosuppressive agents. Monitor for increased risk of myelosuppression.

• isavuconazonium sulfate

  Monitor Closely (2)ifosfamide will increase the level or effect of isavuconazonium sulfate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
  
  ifosfamide and isavuconazonium sulfate both decrease immunosuppressive effects; risk of infection. Use Caution/Monitor.

• istradefylline

  Monitor Closely (1)istradefylline will increase the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Istradefylline 40 mg/day increased peak levels and AUC of CYP3A4 substrates in clinical trials. This effect was not observed with istradefylline 20 mg/day. Consider dose reduction of sensitive CYP3A4 substrates.

• itraconazole

  Monitor Closely (1)itraconazole will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration of CYP3A4 inhibitors may decrease the metabolism of ifosfamide to its active alkylating metabolites and decrease the efficacy of ifosfamide.

• ixekizumab

  Monitor Closely (1)ifosfamide, ixekizumab. Either increases effects of the other by immunosuppressive effects; risk of infection. Use Caution/Monitor.

• Japanese encephalitis virus vaccine

  Monitor Closely (1)ifosfamide decreases effects of Japanese encephalitis virus vaccine by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• ketoconazole

  Monitor Closely (1)ketoconazole will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration of CYP3A4 inhibitors may decrease the metabolism of ifosfamide to its active alkylating metabolites and decrease the efficacy of ifosfamide.

• lapatinib

  Monitor Closely (1)lapatinib decreases effects of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• leflunomide

  Monitor Closely (1)ifosfamide increases toxicity of leflunomide by Other (see comment). Use Caution/Monitor. Comment: Consider not using a leflunomide loading dose in patients receiving other immunosuppressants. Monitor for bone marrow suppression at least monthly in patients concomitantly using leflunomide and another immunosuppressant.

• lemborexant

  Monitor Closely (1)ifosfamide will increase the level or effect of lemborexant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Lower nightly dose of lemborexant recommended if coadministered with weak CYP3A4 inhibitors. See drug monograph for specific dosage modification.

• letermovir

  Monitor Closely (1)letermovir decreases effects of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• lomitapide

  Monitor Closely (1)ifosfamide increases levels of lomitapide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Lomitapide dose should not exceed 30 mg/day.

• lomustine

  Monitor Closely (1)ifosfamide, lomustine. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Additive myelosuppression.

• lonafarnib

  Serious - Use Alternative (2)ifosfamide will increase the level or effect of lonafarnib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration of lonafarnib (a sensitive CYP3A substrate) with weak CYP3A inhibitors is unavoidable, reduce to, or continue lonafarnib at starting dose. Closely monitor for arrhythmias and events (eg, syncope, heart palpitations) since lonafarnib effect on QT interval is unknown.
  
  lonafarnib will increase the level or effect of ifosfamide by affecting hepatic enzyme CYP2C19 metabolism. Avoid or Use Alternate Drug. Lonafarnib may increase the AUC and peak concentration of CYP2C19 substrates. If coadministration unavoidable, monitor for adverse reactions and reduce the CYP2C19 substrate dose in accordance with its approved product labeling.

• lopinavir

  Monitor Closely (1)lopinavir will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration of CYP3A4 inhibitors may decrease the metabolism of ifosfamide to its active alkylating metabolites and decrease the efficacy of ifosfamide.

• lorlatinib

  Monitor Closely (1)lorlatinib will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• lumacaftor/ivacaftor

  Monitor Closely (2)lumacaftor/ivacaftor increases effects of ifosfamide by affecting hepatic enzyme CYP2B6 metabolism. Use Caution/Monitor. Coadministration of ifosfamide with CYP2B6 inducers may increase metabolism of ifosfamide to its metabolite. Monitor for increased effects/toxicities if combined with CYP2B6 inducers.
  
  lumacaftor/ivacaftor increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• magnesium citrate

  Monitor Closely (1)ifosfamide, magnesium citrate. Either increases toxicity of the other by nephrotoxicity and/or ototoxicity. Modify Therapy/Monitor Closely. Monitor electrolytes and renal function.

• measles (rubeola) vaccine

  Contraindicated (1)ifosfamide decreases effects of measles (rubeola) vaccine by pharmacodynamic antagonism. Contraindicated. Immunosuppressives may diminish therapeutic effects of vaccines and increase risk of adverse effects (increased risk of infection). Live-attenuated vaccines should be avoided for at least 3 mo. after cessation of immunosuppressive therapy.

• measles mumps and rubella vaccine, live

  Contraindicated (1)ifosfamide decreases effects of measles mumps and rubella vaccine, live by pharmacodynamic antagonism. Contraindicated. Immunosuppressives may diminish therapeutic effects of vaccines and increase risk of adverse effects (increased risk of infection). Live-attenuated vaccines should be avoided for at least 3 mo. after cessation of immunosuppressive therapy.

• measles, mumps, rubella and varicella vaccine, live

  Contraindicated (1)ifosfamide decreases effects of measles, mumps, rubella and varicella vaccine, live by pharmacodynamic antagonism. Contraindicated. Immunosuppressives may diminish therapeutic effects of vaccines and increase risk of adverse effects (increased risk of infection). Live-attenuated vaccines should be avoided for at least 3 mo. after cessation of immunosuppressive therapy.

• mechlorethamine

  Monitor Closely (1)ifosfamide, mechlorethamine. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Coadministration with mechlorethamine may increase the risk of immunosuppression and myelosuppression.

• meningococcal A C Y and W-135 diphtheria conjugate vaccine

  Monitor Closely (1)ifosfamide decreases effects of meningococcal A C Y and W-135 diphtheria conjugate vaccine by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• meningococcal A C Y and W-135 polysaccharide vaccine combined

  Monitor Closely (1)ifosfamide decreases effects of meningococcal A C Y and W-135 polysaccharide vaccine combined by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• meningococcal group B vaccine

  Monitor Closely (2)ifosfamide decreases effects of meningococcal group B vaccine by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .
  
  ifosfamide decreases effects of meningococcal group B vaccine by pharmacodynamic antagonism. Use Caution/Monitor. Individuals with altered immunocompetence may have reduced immune responses to the vaccine.

• methotrexate

  Monitor Closely (1)ifosfamide, methotrexate. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Coadministration with ifosfamide may increase the risk of immunosuppression and myelosuppression.

• metronidazole

  Monitor Closely (1)metronidazole decreases effects of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• miconazole oral

  Monitor Closely (1)miconazole oral will decrease the level or effect of ifosfamide by affecting hepatic enzyme CYP2B6 metabolism. Use Caution/Monitor. Coadministration of ifosfamide with CYP2B6 inhibitors may decrease metabolism of ifosfamide to its metabolite, potentially reducing ifosfamide therapeutic effects.

• midazolam intranasal

  Monitor Closely (1)ifosfamide will increase the level or effect of midazolam intranasal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration of mild CYP3A4 inhibitors with midazolam intranasal may cause higher midazolam systemic exposure, which may prolong sedation.

• mifepristone

  Monitor Closely (2)mifepristone will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration of CYP3A4 inhibitors may decrease the metabolism of ifosfamide to its active alkylating metabolites and decrease the efficacy of ifosfamide.
  
  mifepristone will decrease the level or effect of ifosfamide by affecting hepatic enzyme CYP2B6 metabolism. Use Caution/Monitor. Coadministration of ifosfamide with CYP2B6 inhibitors may decrease metabolism of ifosfamide to its metabolite, potentially reducing ifosfamide therapeutic effects.

• mitotane

  Monitor Closely (1)mitotane increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• modafinil

  Monitor Closely (1)modafinil increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• nafcillin

  Monitor Closely (1)nafcillin increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• natalizumab

  Serious - Use Alternative (1)ifosfamide, natalizumab. Either increases effects of the other by immunosuppressive effects; risk of infection. Avoid or Use Alternate Drug. Concomitant therapy is expected to increase the risk of immunosuppression. Use caution when switching patients from long-acting therapies with immune effects.

• nefazodone

  Monitor Closely (1)nefazodone will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration of CYP3A4 inhibitors may decrease the metabolism of ifosfamide to its active alkylating metabolites and decrease the efficacy of ifosfamide.

• nelfinavir

  Monitor Closely (2)nelfinavir will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration of CYP3A4 inhibitors may decrease the metabolism of ifosfamide to its active alkylating metabolites and decrease the efficacy of ifosfamide.
  
  nelfinavir will decrease the level or effect of ifosfamide by affecting hepatic enzyme CYP2B6 metabolism. Use Caution/Monitor. Coadministration of ifosfamide with CYP2B6 inhibitors may decrease metabolism of ifosfamide to its metabolite, potentially reducing ifosfamide therapeutic effects.

• netupitant/palonosetron

  Monitor Closely (1)netupitant/palonosetron decreases effects of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration .

• nevirapine

  Monitor Closely (2)nevirapine increases effects of ifosfamide by affecting hepatic enzyme CYP2B6 metabolism. Use Caution/Monitor. Coadministration of ifosfamide with CYP2B6 inducers may increase metabolism of ifosfamide to its metabolite. Monitor for increased effects/toxicities if combined with CYP2B6 inducers.
  
  nevirapine increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4/CYP2B6 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• nilotinib

  Monitor Closely (2)nilotinib increases effects of ifosfamide by affecting hepatic enzyme CYP2B6 metabolism. Use Caution/Monitor. Coadministration of ifosfamide with CYP2B6 inducers may increase metabolism of ifosfamide to its metabolite. Monitor for increased effects/toxicities if combined with CYP2B6 inducers.
  
  nilotinib decreases effects of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• nivolumab

  Serious - Use Alternative (1)ifosfamide, nivolumab. Either increases effects of the other by immunosuppressive effects; risk of infection. Avoid or Use Alternate Drug. Avoid use of immunosuppressants (eg, systemic corticosteroids) prior to initiation of nivolumab. Use of immunosuppressants after administration of nivolumab (eg, for treatment of immune-related adverse reactions) is unlikely to affect nivolumab efficacy.

• ocrelizumab

  Serious - Use Alternative (1)ifosfamide, ocrelizumab. Either increases effects of the other by immunosuppressive effects; risk of infection. Avoid or Use Alternate Drug. Concomitant therapy is expected to increase the risk of immunosuppression. Use caution when switching patients from long-acting therapies with immune effects.

• ofatumumab SC

  Monitor Closely (1)ofatumumab SC, ifosfamide. Either increases effects of the other by immunosuppressive effects; risk of infection. Use Caution/Monitor. Consider the risk of additive immune system effects when coadministering immunosuppressive therapies with coadministration. When switching from therapies with immune effects, take into account the duration and mechanism of action of these therapies when initiating ofatumumab SC.

• olaparib

  Monitor Closely (1)ifosfamide and olaparib both increase pharmacodynamic synergism. Use Caution/Monitor. Coadministration with other other myelosuppressive anticancer agents, including DNA damaging agents, may potentiate and prolongate the myelosuppressive toxicity.

• ombitasvir/paritaprevir/ritonavir & dasabuvir

  Monitor Closely (1)ombitasvir/paritaprevir/ritonavir & dasabuvir will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration of CYP3A4 inhibitors may decrease the metabolism of ifosfamide to its active alkylating metabolites and decrease the efficacy of ifosfamide.

• oxaliplatin

  Monitor Closely (1)oxaliplatin, ifosfamide. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Additive myelosuppression.

• oxcarbazepine

  Monitor Closely (1)oxcarbazepine increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• paclitaxel

  Monitor Closely (1)ifosfamide will increase the level or effect of paclitaxel by Other (see comment). Use Caution/Monitor. Paclitaxel levels/toxicity may increase when coadministered with CYP2C8 inhibitors

• paclitaxel protein bound

  Monitor Closely (1)ifosfamide will increase the level or effect of paclitaxel protein bound by Other (see comment). Use Caution/Monitor. Paclitaxel levels/toxicity may increase when coadministered with CYP2C8 inhibitors

• palifermin

  Serious - Use Alternative (1)palifermin increases toxicity of ifosfamide by Other (see comment). Avoid or Use Alternate Drug. Comment: Palifermin should not be administered within 24 hr before, during infusion of, or within 24 hr after administration of antineoplastic agents. Coadministration of palifermin within 24 hr of chemotherapy resulted in increased severity and duration of oral mucositis.

• pegfilgrastim

  Monitor Closely (1)ifosfamide will decrease the level or effect of pegfilgrastim by Other (see comment). Modify Therapy/Monitor Closely. Concomitant use with pegfilgrastim efficacy (antagonistic effects, increased sensitivity of rapidly dividing myeloid cells to cytotoxic chemo)Give pegfilgrastim >14 days before or >24h after cytotoxic chemotherapy.

• peginterferon alfa 2a

  Monitor Closely (1)ifosfamide, peginterferon alfa 2a. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Ifosfamide may enhance the toxicities of myelosuppressive agents. Monitor for increased risk of myelosuppression.

• peginterferon alfa 2b

  Monitor Closely (1)ifosfamide, peginterferon alfa 2b. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Ifosfamide may enhance the toxicities of myelosuppressive agents. Monitor for increased risk of myelosuppression.

• pentamidine

  Monitor Closely (1)ifosfamide, pentamidine. Either increases toxicity of the other by nephrotoxicity and/or ototoxicity. Use Caution/Monitor. Monitor renal function.

• pentobarbital

  Monitor Closely (2)pentobarbital increases effects of ifosfamide by affecting hepatic enzyme CYP2B6 metabolism. Use Caution/Monitor. Coadministration of ifosfamide with CYP2B6 inducers may increase metabolism of ifosfamide to its metabolite. Monitor for increased effects/toxicities if combined with CYP2B6 inducers.
  
  pentobarbital increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• peramivir

  Monitor Closely (1)ifosfamide increases levels of peramivir by decreasing renal clearance. Use Caution/Monitor. Caution when peramivir coadministered with nephrotoxic drugs.

• phenobarbital

  Monitor Closely (2)phenobarbital increases effects of ifosfamide by affecting hepatic enzyme CYP2B6 metabolism. Use Caution/Monitor. Coadministration of ifosfamide with CYP2B6 inducers may increase metabolism of ifosfamide to its metabolite. Monitor for increased effects/toxicities if combined with CYP2B6 inducers.
  
  phenobarbital increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• phenytoin

  Monitor Closely (2)phenytoin increases effects of ifosfamide by affecting hepatic enzyme CYP2B6 metabolism. Use Caution/Monitor. Coadministration of ifosfamide with CYP2B6 inducers may increase metabolism of ifosfamide to its metabolite. Monitor for increased effects/toxicities if combined with CYP2B6 inducers.
  
  phenytoin increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• pimecrolimus

  Serious - Use Alternative (1)ifosfamide, pimecrolimus. Either increases effects of the other by immunosuppressive effects; risk of infection. Avoid or Use Alternate Drug.

• pioglitazone

  Monitor Closely (1)pioglitazone increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• pneumococcal vaccine 13-valent

  Monitor Closely (1)ifosfamide decreases effects of pneumococcal vaccine 13-valent by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• pneumococcal vaccine heptavalent

  Monitor Closely (1)ifosfamide decreases effects of pneumococcal vaccine heptavalent by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• pneumococcal vaccine polyvalent

  Monitor Closely (1)ifosfamide decreases effects of pneumococcal vaccine polyvalent by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• poliovirus vaccine inactivated

  Monitor Closely (1)ifosfamide decreases effects of poliovirus vaccine inactivated by pharmacodynamic antagonism. Modify Therapy/Monitor Closely. Avoid vaccination during chemotherapy or radiation therapy if possible because antibody response might be suboptimal. Patients vaccinated within a 14-day period before starting or during immunosuppressive therapy should be revaccinated =3 months after therapy is discontinued if immune competence has been restored. .

• posaconazole

  Monitor Closely (1)posaconazole will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration of CYP3A4 inhibitors may decrease the metabolism of ifosfamide to its active alkylating metabolites and decrease the efficacy of ifosfamide.

• prednisone

  Monitor Closely (1)ifosfamide, prednisone. Either increases effects of the other by immunosuppressive effects; risk of infection. Use Caution/Monitor.

• primaquine

  Monitor Closely (1)ifosfamide, primaquine. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Ifosfamide may enhance the toxicities of myelosuppressive agents. Monitor for increased risk of myelosuppression.

• primidone

  Monitor Closely (2)primidone increases effects of ifosfamide by affecting hepatic enzyme CYP2B6 metabolism. Use Caution/Monitor. Coadministration of ifosfamide with CYP2B6 inducers may increase metabolism of ifosfamide to its metabolite. Monitor for increased effects/toxicities if combined with CYP2B6 inducers.
  
  primidone increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CCYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• pyrimethamine

  Monitor Closely (1)ifosfamide, pyrimethamine. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Ifosfamide may enhance the toxicities of myelosuppressive agents. Monitor for increased risk of myelosuppression.

• quinupristin/dalfopristin

  Monitor Closely (1)quinupristin/dalfopristin will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• rabies vaccine

  Monitor Closely (1)ifosfamide decreases effects of rabies vaccine by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• rabies vaccine chick embryo cell derived

  Monitor Closely (1)ifosfamide decreases effects of rabies vaccine chick embryo cell derived by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• ribociclib

  Monitor Closely (1)ribociclib decreases effects of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects. .

• rifabutin

  Monitor Closely (1)rifabutin increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• rifampin

  Monitor Closely (2)rifampin increases effects of ifosfamide by affecting hepatic enzyme CYP2B6 metabolism. Use Caution/Monitor. Coadministration of ifosfamide with CYP2B6 inducers may increase metabolism of ifosfamide to its metabolite. Monitor for increased effects/toxicities if combined with CYP2B6 inducers.
  
  rifampin increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• rifapentine

  Monitor Closely (1)rifapentine increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• ritonavir

  Monitor Closely (2)ritonavir will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration of CYP3A4 inhibitors may decrease the metabolism of ifosfamide to its active alkylating metabolites and decrease the efficacy of ifosfamide.
  
  ritonavir increases effects of ifosfamide by affecting hepatic enzyme CYP2B6 metabolism. Use Caution/Monitor. Coadministration of ifosfamide with CYP2B6 inducers may increase metabolism of ifosfamide to its metabolite. Monitor for increased effects/toxicities if combined with CYP2B6 inducers.

• roflumilast

  Monitor Closely (1)roflumilast will increase the level or effect of ifosfamide by immunosuppressive effects; risk of infection. Use Caution/Monitor. Caution should be taken in patients on concomitant immunosuppressants or with impaired immune systems because of increased risk for serious infections.

• rotavirus oral vaccine, live

  Contraindicated (1)ifosfamide decreases effects of rotavirus oral vaccine, live by pharmacodynamic antagonism. Contraindicated. Immunosuppressives may diminish therapeutic effects of vaccines and increase risk of adverse effects (increased risk of infection). Live-attenuated vaccines should be avoided for at least 3 mo. after cessation of immunosuppressive therapy.

• rubella vaccine

  Contraindicated (1)ifosfamide decreases effects of rubella vaccine by pharmacodynamic antagonism. Contraindicated. Immunosuppressives may diminish therapeutic effects of vaccines and increase risk of adverse effects (increased risk of infection). Live-attenuated vaccines should be avoided for at least 3 mo. after cessation of immunosuppressive therapy.

• ruxolitinib

  Minor (1)ifosfamide will increase the level or effect of ruxolitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

• saquinavir

  Monitor Closely (1)saquinavir will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration of CYP3A4 inhibitors may decrease the metabolism of ifosfamide to its active alkylating metabolites and decrease the efficacy of ifosfamide.

• sargramostim

  Monitor Closely (1)ifosfamide will decrease the level or effect of sargramostim by Other (see comment). Modify Therapy/Monitor Closely. Do not administer simultaneously with or within 24 hours preceding/following cytotoxic chemotherapy or radiotherapy (due to the sensitivity of rapidly dividing hematopoietic progenitor cells).

• schisandra

  Monitor Closely (1)schisandra decreases effects of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration .

• secobarbital

  Monitor Closely (1)secobarbital increases effects of ifosfamide by affecting hepatic enzyme CYP2B6 metabolism. Use Caution/Monitor. Coadministration of ifosfamide with CYP2B6 inducers may increase metabolism of ifosfamide to its metabolite. Monitor for increased effects/toxicities if combined with CYP2B6 inducers.

• selexipag

  Monitor Closely (1)ifosfamide will increase the level or effect of selexipag by decreasing metabolism. Modify Therapy/Monitor Closely. Reduce selexipag dose to once daily if coadministered with moderate CYP2C8 inhibitors.

• semaglutide

  Monitor Closely (1)ifosfamide, semaglutide. Either increases toxicity of the other by nephrotoxicity and/or ototoxicity. Use Caution/Monitor. Monitor renal function.

• sertraline

  Monitor Closely (1)sertraline decreases effects of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration .

• siponimod

  Monitor Closely (1)siponimod and ifosfamide both increase immunosuppressive effects; risk of infection. Use Caution/Monitor. Caution if coadministered because of additive immunosuppressive effects during such therapy and in the weeks following administration. When switching from drugs with prolonged immune effects, consider the half-life and mode of action of these drugs to avoid unintended additive immunosuppressive effects.

• sipuleucel-T

  Monitor Closely (2)ifosfamide, sipuleucel-T. Either increases effects of the other by immunosuppressive effects; risk of infection. Use Caution/Monitor. Caution should be taken in patients on concomitant immunosuppressants or with impaired immune systems because of increased risk for serious infections.
  
  ifosfamide decreases effects of sipuleucel-T by pharmacodynamic antagonism. Modify Therapy/Monitor Closely.

• sirolimus

  Monitor Closely (1)ifosfamide, sirolimus. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Coadministration with ifosfamide may increase the risk of immunosuppression and myelosuppression.

• smallpox (vaccinia) vaccine, live

  Contraindicated (1)ifosfamide decreases effects of smallpox (vaccinia) vaccine, live by pharmacodynamic antagonism. Contraindicated. Immunosuppressives may diminish therapeutic effects of vaccines and increase risk of adverse effects (increased risk of infection). Live-attenuated vaccines should be avoided for at least 3 mo. after cessation of immunosuppressive therapy.

• sodium sulfate/?magnesium sulfate/potassium chloride

  Monitor Closely (1)sodium sulfate/?magnesium sulfate/potassium chloride increases toxicity of ifosfamide by Other (see comment). Use Caution/Monitor. Comment: Coadministration with medications that cause fluid and electrolyte abnormalities may increase the risk of adverse events of seizure, arrhythmias, and renal impairment.

• sodium sulfate/potassium sulfate/magnesium sulfate

  Monitor Closely (1)sodium sulfate/potassium sulfate/magnesium sulfate increases toxicity of ifosfamide by Other (see comment). Use Caution/Monitor. Comment: Coadministration with medications that cause fluid and electrolyte abnormalities may increase the risk of adverse events of seizure, arrhythmias, and renal impairment.

• St John's Wort

  Monitor Closely (1)St John's Wort increases toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inducers may increase the metabolism of ifosfamide to its active alkylating metabolites. CYP3A4 inducers may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde. Closely monitor patients taking ifosfamide with CYP3A4 inducers for toxicities and consider dose adjustment.

• stiripentol

  Monitor Closely (2)stiripentol, ifosfamide. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Stiripentol is a CYP3A4 inhibitor and inducer. Monitor CYP3A4 substrates coadministered with stiripentol for increased or decreased effects. CYP3A4 substrates may require dosage adjustment.
  
  stiripentol will increase the level or effect of ifosfamide by affecting hepatic enzyme CYP2C19 metabolism. Modify Therapy/Monitor Closely. Consider reducing the dose of CYP2C19 substrates, if adverse reactions are experienced when administered concomitantly with stiripentol.

• streptozocin

  Monitor Closely (1)ifosfamide, streptozocin. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Additive myelosuppression.

• tacrolimus

  Monitor Closely (1)ifosfamide, tacrolimus. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Ifosfamide may enhance the toxicities of myelosuppressive agents. Monitor for increased risk of myelosuppression.Serious - Use Alternative (1)ifosfamide, tacrolimus. Either increases effects of the other by immunosuppressive effects; risk of infection. Avoid or Use Alternate Drug.

• tacrolimus ointment

  Serious - Use Alternative (1)ifosfamide, tacrolimus ointment. Either increases effects of the other by immunosuppressive effects; risk of infection. Avoid or Use Alternate Drug. Consider avoiding such combinations when clinically appropriate. If such a combination is used, monitor the patient closely for clinical response.

• talimogene laherparepvec

  Contraindicated (1)ifosfamide, talimogene laherparepvec. Either increases effects of the other by immunosuppressive effects; risk of infection. Contraindicated. Patients on concomitant immunosuppressants or with impaired immune systems are contraindicated to receive talimogene laherparepvec because of increased risk for serious infections.

• tazemetostat

  Monitor Closely (2)tazemetostat will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
  
  ifosfamide will increase the level or effect of tazemetostat by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• tecovirimat

  Monitor Closely (2)tecovirimat will increase the level or effect of ifosfamide by affecting hepatic enzyme CYP2C19 metabolism. Use Caution/Monitor. Tecovirimat is a weak inhibitor of CYP2C8 and CYP2C19. Monitor for adverse effects if coadministered with sensitive substrates of these enzymes.
  
  tecovirimat will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Tecovirimat is a weak CYP3A4 inducer. Monitor sensitive CYP3A4 substrates for effectiveness if coadministered.

• tenofovir AF

  Monitor Closely (1)ifosfamide, tenofovir AF. Either increases toxicity of the other by nephrotoxicity and/or ototoxicity. Modify Therapy/Monitor Closely. Monitor electrolytes and renal function.

• teriflunomide

  Monitor Closely (1)ifosfamide, teriflunomide. Either increases effects of the other by immunosuppressive effects; risk of infection. Use Caution/Monitor.

• tetanus & reduced diphtheria toxoids/ acellular pertussis vaccine

  Monitor Closely (1)ifosfamide decreases effects of tetanus & reduced diphtheria toxoids/ acellular pertussis vaccine by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• tetanus toxoid adsorbed or fluid

  Monitor Closely (1)ifosfamide decreases effects of tetanus toxoid adsorbed or fluid by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .

• tetracycline

  Monitor Closely (1)tetracycline decreases effects of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• thiotepa

  Monitor Closely (1)ifosfamide, thiotepa. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Additive myelosuppression.

• tinidazole

  Monitor Closely (1)ifosfamide will increase the level or effect of tinidazole by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• tipranavir

  Monitor Closely (1)tipranavir will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Use alternatives if available. May decrease formation to active metabolite and increase toxicity of active metabolite

• tofacitinib

  Serious - Use Alternative (2)ifosfamide, tofacitinib. Either increases toxicity of the other by immunosuppressive effects; risk of infection. Avoid or Use Alternate Drug. Avoid use in combination with potent immunosuppressants; concurrent use with antirheumatic doses of methotrexate or nonbiologic disease modifying antirheumatic drugs (DMARDs) is permitted. Agents considered as potent immunosuppressants are not specified, but lower corticosteroid doses (ie, equivalent to prednisone 10 mg/day or less), leflunomide, and antirheumatic doses of methotrexate were permitted in clinical studies.
  
  ifosfamide will increase the level or effect of tofacitinib by Other (see comment). Avoid or Use Alternate Drug. Avoid use in combination with potent immunosuppressants; concurrent use with antirheumatic doses of methotrexate or nonbiologic disease modifying antirheumatic drugs (DMARDs) is permitted. Agents considered as potent immunosuppressants are not specified, but lower corticosteroid doses (ie, equivalent to prednisone 10 mg/day or less), leflunomide, and antirheumatic doses of methotrexate were permitted in clinical studies.

• topotecan

  Monitor Closely (1)ifosfamide, topotecan. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Coadministration with ifosfamide may increase the risk of immunosuppression and myelosuppression.

• trabectedin

  Monitor Closely (1)ifosfamide, trabectedin. Other (see comment). Use Caution/Monitor. Comment: Risk of developing cardiotoxic effects increase in patients with prior or concomitant treatment with other cardiotoxic agents.

• trastuzumab

  Monitor Closely (1)trastuzumab, ifosfamide. Either increases toxicity of the other by immunosuppressive effects; risk of infection. Use Caution/Monitor. Neutropenia or febrile neutropenia incidence were increased when trastuzumab was coadministered with myelosuppressive chemotherapy. .

• trastuzumab deruxtecan

  Monitor Closely (3)trastuzumab deruxtecan, ifosfamide. Either increases toxicity of the other by immunosuppressive effects; risk of infection. Use Caution/Monitor. Neutropenia or febrile neutropenia incidence were increased when trastuzumab was coadministered with myelosuppressive chemotherapy. .
  
  ifosfamide, trastuzumab deruxtecan. Other (see comment). Use Caution/Monitor. Comment: Risk of developing cardiotoxic effects increase in patients with prior or concomitant treatment with other cardiotoxic agents.
  
  ifosfamide, trastuzumab deruxtecan. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Ifosfamide may enhance the toxicities of myelosuppressive agents. Monitor for increased risk of myelosuppression.

• triclabendazole

  Monitor Closely (1)triclabendazole will increase the level or effect of ifosfamide by affecting hepatic enzyme CYP2C19 metabolism. Use Caution/Monitor. If plasma concentrations of the CYP2C19 substrates are elevated during triclabendazole, recheck plasma concentration of the CYP2C19 substrates after discontinuation of triclabendazole.

• tucatinib

  Serious - Use Alternative (2)ifosfamide will increase the level or effect of tucatinib by Other (see comment). Avoid or Use Alternate Drug. Coadministration of tucatinib (a CYP2C8 substrate) with a strong or moderate CYP2C8 inhibitors increases tucatinib plasma concentrations and risk of toxicities.
  
  tucatinib will increase the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid concomitant use of tucatinib with CYP3A substrates, where minimal concentration changes may lead to serious or life-threatening toxicities. If unavoidable, reduce CYP3A substrate dose according to product labeling.

• ustekinumab

  Monitor Closely (1)ifosfamide, ustekinumab. Either increases effects of the other by immunosuppressive effects; risk of infection. Use Caution/Monitor.

• vancomycin

  Monitor Closely (1)ifosfamide, vancomycin. Either increases toxicity of the other by nephrotoxicity and/or ototoxicity. Use Caution/Monitor. Monitor renal function.

• varicella virus vaccine live

  Contraindicated (1)ifosfamide decreases effects of varicella virus vaccine live by pharmacodynamic antagonism. Contraindicated. Immunosuppressives may diminish therapeutic effects of vaccines and increase risk of adverse effects (increased risk of infection). Live-attenuated vaccines should be avoided for at least 3 mo. after cessation of immunosuppressive therapy.

• vedolizumab

  Monitor Closely (1)ifosfamide, vedolizumab. Either increases effects of the other by immunosuppressive effects; risk of infection. Use Caution/Monitor.

• verapamil

  Monitor Closely (1)verapamil decreases effects of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• vitamin A

  Minor (1)vitamin A, ifosfamide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Antioxidants such as vitamin A enhance the efficacy, and reduce toxicity, of antineoplastic drugs.

• vitamin E

  Minor (1)vitamin E, ifosfamide. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Antioxidants such as vitamin E enhance the efficacy, and reduce toxicity, of antineoplastic drugs.

• voclosporin

  Monitor Closely (1)voclosporin, ifosfamide. Either increases toxicity of the other by nephrotoxicity and/or ototoxicity. Modify Therapy/Monitor Closely. Coadministration with drugs associated with nephrotoxicity may increase the risk for acute and/or chronic nephrotoxicity.

• voriconazole

  Monitor Closely (1)voriconazole will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration of CYP3A4 inhibitors may decrease the metabolism of ifosfamide to its active alkylating metabolites and decrease the efficacy of ifosfamide.

• voxelotor

  Serious - Use Alternative (1)voxelotor will increase the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Voxelotor increases systemic exposure of sensitive CYP3A4 substrates. Avoid coadministration with sensitive CYP3A4 substrates with a narrow therapeutic index. Consider dose reduction of the sensitive CYP3A4 substrate(s) if unable to avoid.

• warfarin

  Serious - Use Alternative (1)ifosfamide, warfarin. Either increases toxicity of the other by nephrotoxicity and/or ototoxicity. Avoid or Use Alternate Drug. Monitor for increased INR/effects of coumarin derivatives when ifosfamide is initiated/dose increased, and decreased INR/effects when ifosfamide is discontinued/dose decreased.

• yellow fever vaccine

  Contraindicated (1)ifosfamide decreases effects of yellow fever vaccine by pharmacodynamic antagonism. Contraindicated. Immunosuppressives may diminish therapeutic effects of vaccines and increase risk of adverse effects (increased risk of infection). Live-attenuated vaccines should be avoided for at least 3 mo. after cessation of immunosuppressive therapy.

• zidovudine

  Monitor Closely (1)ifosfamide, zidovudine. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Ifosfamide may enhance the toxicities of myelosuppressive agents. Monitor for increased risk of myelosuppression.

• zoster vaccine live

  Contraindicated (1)ifosfamide decreases effects of zoster vaccine live by pharmacodynamic antagonism. Contraindicated. Immunosuppressives may diminish therapeutic effects of vaccines and increase risk of adverse effects (increased risk of infection). Live-attenuated vaccines should be avoided for at least 3 mo. after cessation of immunosuppressive therapy.

• zoster vaccine recombinant

  Monitor Closely (1)ifosfamide decreases effects of zoster vaccine recombinant by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Coadministration with immunosuppressant therapy reduced efficacy of the vaccine may occur. If possible, complete all age-appropriate vaccinations at least 2 weeks prior to initiation of immunosuppressant therapy. Patients vaccinated <14 days before initiation or during immunosuppressive therapy should be revaccinated at least 3 months after therapy is discontinued. .