erdafitinib (Rx)

Urothelial Carcinoma

Indicated for locally advanced or metastatic urothelial carcinoma that has fibroblast growth factor receptor-2 (FGFR2) or FGFR3 genetic alterations and progressed during or following at least 1 line of prior platinum-containing chemotherapy, including within 12 months of neoadjuvant or adjuvant platinum-containing chemotherapy

8 mg PO qDay initially; increase to 9 mg PO qDay based on serum phosphate (PO4) levels and tolerability at 14-21 days

Continue until disease progression or unacceptable toxicity

Increase dose to 9 mg qDay if serum phosphate level <5.5 mg/dL and there are no ocular disorders or Grade ≥2 adverse reactions

Dosage Modifications

Dose reduction schedule

• 9 mg/day reduction schedule

  • First: 8 mg/day
  • Second: 6 mg/day
  • Third: 5 mg/day
  • Fourth: 4 mg/day
  • Fifth: Stop drug if fifth reduction needed

• 8 mg/day reduction schedule

  • First: 6 mg/day
  • Second: 5 mg/day
  • Third: 4 mg/day
  • Fourth: Stop drug if fourth reduction needed

Hyperphosphatemia

• In all patients, restrict phosphate intake to 600-800 mg/day; if serum phosphate >7 mg/dL, consider adding oral phosphate binder until serum phosphate level returns to <5.5 mg/dL

• Phosphate levels and dosage

  • 5.6-6.9 mg/dL (1.8-2.3 mmol/L): Continue at current dose
  • 7-9 mg/dL (2.3-2.9 mmol/L): Withhold; reassess weekly until phosphate <5.5 mg/dL (or baseline), then resume at same dose level; implement dose reduction if hyperphosphatemia lasts >1 week
  • >9 mg/dL (>2.9 mmol/L): Withhold; reassess weekly until phosphate <5.5 mg/dL (or baseline), then restart at 1 dose level lower
  • >10 mg/dL (>3.2 mmol/L) or significantly altered baseline renal function or Grade 3 hypercalcemia: Withhold; reassess weekly until phosphate <5.5 mg/dL (or baseline), then restart at 2 dose levels lower

Central serous retinopathy or retinal pigment epithelial detachment (CSR/RPED)

• Grade 1

  • Asymptomatic; clinical or diagnostic observations only
  • Withhold drug until resolution
  • If resolves within 4 weeks, resume at the next lower dose level; then, if no recurrence for a month, consider reescalation
  • If stable for 2 consecutive eye examinations, but not resolved, resume at the next lower dose level

• Grade 2

  • Visual acuity 20/40 or better or ≤3 lines of decreased vision from baseline
  • Withhold until resolution
  • If resolves within 4 weeks, may resume at the next lower dose level

• Grade 3

  • Visual acuity worse than 20/40 or >3 lines of decreased vision from baseline
  • Withhold until resolution
  • If resolves within 4 weeks, may resume 2 dose levels lower
  • If recurs, consider permanent discontinuation

• Grade 4

  • Visual acuity 20/200 or worse in affected eye
  • Permanently discontinue

Other adverse reactions

• Grade 3: Withhold drug until resolves to Grade 1 or baseline, then may resume dose 1 level lower
• Grade 4: Permanently discontinue

Renal impairment

• Mild or moderate (eGFR 30-89 mL/min/1.73 m²): No clinically meaningful trends in the pharmacokinetics observed; no dose adjustment recommended
• Severe or dialysis: Unknown

Hepatic impairment

• Mild (TB ≤ULN and AST >ULN or TB >1 to 1.5x ULN and any AST): No clinically meaningful trends in the pharmacokinetics observed; no dose adjustment recommended
• Moderate or severe: Unknown

Dosing Considerations

Patient selection

• Selection based on the presence of susceptible FGFR genetic alterations in tumor specimens as detected by an FDA-approved companion diagnostic
• Information on FDA-approved tests for the detection of FGFR genetic alterations in urothelial cancer is available at: http://www.fda.gov/CompanionDiagnostics

Monitoring

• Assess serum phosphate levels 14-21 days after initiating
• Monitor phosphate levels monthly for hyperphosphatemia

Safety and efficacy not established

Contraindicated (0)

Serious - Use Alternative (167)

• afatinib

  erdafitinib will increase the level or effect of afatinib by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• aliskiren

  erdafitinib will increase the level or effect of aliskiren by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• alpelisib

  alpelisib will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If coadministration of a strong CYP2C9 inhibitors is unavoidable, closely monitor adverse reactions and modify dose of erdafitinib accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• amiodarone

  amiodarone will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP2C9 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.
  
  erdafitinib will increase the level or effect of amiodarone by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• apalutamide

  apalutamide will decrease the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• atazanavir

  atazanavir will increase the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP3A4 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP3A4 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• atorvastatin

  erdafitinib will increase the level or effect of atorvastatin by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• betrixaban

  erdafitinib will increase the level or effect of betrixaban by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• bosentan

  bosentan will decrease the level or effect of erdafitinib by altering metabolism. Avoid or Use Alternate Drug. Avoid coadministration of strong CYP2C9 or CYP3A4 inducers with erdafitinib.

• brentuximab vedotin

  erdafitinib will increase the level or effect of brentuximab vedotin by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• butabarbital

  butabarbital will decrease the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• butalbital

  butalbital will decrease the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• calcium acetate

  calcium acetate, erdafitinib. Other (see comment). Avoid or Use Alternate Drug. Comment: Avoid coadministration during initial dosing adjustment period (ie, first 21 days). Increases in serum phosphate levels are a pharmacodynamic effect of FGFR inhibition. Serum phosphate binders may obscure decisions regarding initial dosage increase.

• calcium carbonate

  calcium carbonate, erdafitinib. Other (see comment). Avoid or Use Alternate Drug. Comment: Avoid coadministration during initial dosing adjustment period (ie, first 21 days). Increases in serum phosphate levels are a pharmacodynamic effect of FGFR inhibition. Serum phosphate binders may obscure decisions regarding initial dosage increase.

• capecitabine

  capecitabine will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP2C9 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• carbamazepine

  carbamazepine will decrease the level or effect of erdafitinib by altering metabolism. Avoid or Use Alternate Drug. Avoid coadministration of strong CYP2C9 or CYP3A4 inducers with erdafitinib.

• carfilzomib

  erdafitinib will increase the level or effect of carfilzomib by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• carvedilol

  erdafitinib will increase the level or effect of carvedilol by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• ceritinib

  erdafitinib will increase the level or effect of ceritinib by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.
  
  ceritinib will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If coadministration of a strong CYP2C9 inhibitors is unavoidable, closely monitor adverse reactions and modify dose of erdafitinib accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• cetirizine

  erdafitinib will increase the level or effect of cetirizine by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• chloramphenicol

  chloramphenicol will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2E1 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP3A4 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP3A4 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• cimetidine

  erdafitinib will increase the level or effect of cimetidine by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• clarithromycin

  clarithromycin will increase the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP3A4 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP3A4 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• cobicistat

  cobicistat will increase the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP3A4 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP3A4 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• colchicine

  erdafitinib will increase the level or effect of colchicine by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• conivaptan

  conivaptan will increase the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP3A4 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP3A4 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• crizotinib

  erdafitinib will increase the level or effect of crizotinib by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• cyclosporine

  erdafitinib will increase the level or effect of cyclosporine by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• dabigatran

  erdafitinib will increase the level or effect of dabigatran by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• dabrafenib

  dabrafenib will decrease the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• darunavir

  darunavir will increase the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP3A4 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP3A4 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• daunorubicin

  erdafitinib will increase the level or effect of daunorubicin by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• desloratadine

  erdafitinib will increase the level or effect of desloratadine by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• dexamethasone

  erdafitinib will increase the level or effect of dexamethasone by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• digoxin

  erdafitinib will increase the level or effect of digoxin by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• diltiazem

  erdafitinib will increase the level or effect of diltiazem by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• docetaxel

  erdafitinib will increase the level or effect of docetaxel by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• doxorubicin

  erdafitinib will increase the level or effect of doxorubicin by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• edoxaban

  erdafitinib will increase the level or effect of edoxaban by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• efavirenz

  efavirenz will decrease the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
  
  efavirenz will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If coadministration of a strong CYP2C9 inhibitors is unavoidable, closely monitor adverse reactions and modify dose of erdafitinib accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• enzalutamide

  enzalutamide will decrease the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• erythromycin base

  erdafitinib will increase the level or effect of erythromycin base by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• erythromycin ethylsuccinate

  erdafitinib will increase the level or effect of erythromycin ethylsuccinate by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• erythromycin lactobionate

  erdafitinib will increase the level or effect of erythromycin lactobionate by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• erythromycin stearate

  erdafitinib will increase the level or effect of erythromycin stearate by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• estradiol

  erdafitinib will increase the level or effect of estradiol by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• etoposide

  erdafitinib will increase the level or effect of etoposide by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• etrasimod

  etrasimod, erdafitinib. Either increases effects of the other by immunosuppressive effects; risk of infection. Avoid or Use Alternate Drug. Risk of additive immune system effects with etrasimod has not been studied in combination with antineoplastic, immune-modulating, or noncorticosteroid immunosuppressive therapies. Avoid coadministration during and in the weeks following administration of etrasimod. .

• etravirine

  etravirine will decrease the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
  
  etravirine will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. Reduce dose of osilodrostat, a CYP3A4 substrate, by half when coadministered with a strong CYP3A4 inhibitor.

• everolimus

  erdafitinib will increase the level or effect of everolimus by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• ferric citrate

  ferric citrate, erdafitinib. Other (see comment). Avoid or Use Alternate Drug. Comment: Avoid coadministration during initial dosing adjustment period (ie, first 21 days). Increases in serum phosphate levels are a pharmacodynamic effect of FGFR inhibition. Serum phosphate binders may obscure decisions regarding initial dosage increase.

• fexofenadine

  erdafitinib will increase the level or effect of fexofenadine by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• fluconazole

  fluconazole will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP2C9 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• fluorouracil

  fluorouracil will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP2C9 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• fluorouracil topical

  fluorouracil topical will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP2C9 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• flurbiprofen

  flurbiprofen will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP2C9 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• fluvastatin

  fluvastatin will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If coadministration of a strong CYP2C9 inhibitors is unavoidable, closely monitor adverse reactions and modify dose of erdafitinib accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• fosamprenavir

  erdafitinib will increase the level or effect of fosamprenavir by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• fosphenytoin

  fosphenytoin will decrease the level or effect of erdafitinib by altering metabolism. Avoid or Use Alternate Drug. Avoid coadministration of strong CYP2C9 or CYP3A4 inducers with erdafitinib.

• gemfibrozil

  gemfibrozil will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP2C9 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• gilteritinib

  erdafitinib will increase the level or effect of gilteritinib by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• grapefruit

  grapefruit will increase the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP3A4 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP3A4 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• hydrocortisone

  erdafitinib will increase the level or effect of hydrocortisone by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• ibuprofen

  ibuprofen will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP2C9 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• idarubicin

  erdafitinib will increase the level or effect of idarubicin by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• idelalisib

  idelalisib will increase the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP3A4 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP3A4 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• imatinib

  erdafitinib will increase the level or effect of imatinib by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• indinavir

  indinavir will increase the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP3A4 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP3A4 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.
  
  erdafitinib will increase the level or effect of indinavir by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• indomethacin

  indomethacin will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP2C9 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• irbesartan

  irbesartan will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If coadministration of a strong CYP2C9 inhibitors is unavoidable, closely monitor adverse reactions and modify dose of erdafitinib accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• irinotecan

  erdafitinib will increase the level or effect of irinotecan by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• irinotecan liposomal

  erdafitinib will increase the level or effect of irinotecan liposomal by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• isoniazid

  isoniazid will increase the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP3A4 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP3A4 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• itraconazole

  itraconazole will increase the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP3A4 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP3A4 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• ivermectin

  erdafitinib will increase the level or effect of ivermectin by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• ivosidenib

  ivosidenib will decrease the level or effect of erdafitinib by altering metabolism. Avoid or Use Alternate Drug. Avoid coadministration of strong CYP2C9 or CYP3A4 inducers with erdafitinib.

• ketoconazole

  ketoconazole will increase the level or effect of erdafitinib by altering metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP3A4/CYP2C9 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP3A4/CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• lanthanum carbonate

  lanthanum carbonate, erdafitinib. Other (see comment). Avoid or Use Alternate Drug. Comment: Avoid coadministration during initial dosing adjustment period (ie, first 21 days). Increases in serum phosphate levels are a pharmacodynamic effect of FGFR inhibition. Serum phosphate binders may obscure decisions regarding initial dosage increase.

• lapatinib

  erdafitinib will increase the level or effect of lapatinib by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• larotrectinib

  erdafitinib will increase the level or effect of larotrectinib by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• ledipasvir/sofosbuvir

  erdafitinib will increase the level or effect of ledipasvir/sofosbuvir by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• levoketoconazole

  levoketoconazole will increase the level or effect of erdafitinib by altering metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP3A4/CYP2C9 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP3A4/CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• loperamide

  erdafitinib will increase the level or effect of loperamide by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• lopinavir

  lopinavir will increase the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP3A4 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP3A4 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• loratadine

  erdafitinib will increase the level or effect of loratadine by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• lorlatinib

  lorlatinib will decrease the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• losartan

  losartan will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If coadministration of a strong CYP2C9 inhibitors is unavoidable, closely monitor adverse reactions and modify dose of erdafitinib accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• lovastatin

  erdafitinib will increase the level or effect of lovastatin by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• lumacaftor/ivacaftor

  lumacaftor/ivacaftor will decrease the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• mefenamic acid

  mefenamic acid will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP2C9 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• methotrexate

  erdafitinib will increase the level or effect of methotrexate by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• miconazole oral

  miconazole oral will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP2C9 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• midazolam

  erdafitinib, midazolam. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with erdafitinib and sensitive CYP3A4 substrates with narrow therapeutic indices. Erdafitinib may altered plasma concentrations of CYP3A4 substrates, leading to either loss of activity or increased toxicity of the substrate.

• mifepristone

  mifepristone will increase the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP3A4 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP3A4 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• mitomycin

  erdafitinib will increase the level or effect of mitomycin by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• mitotane

  mitotane will decrease the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• morphine

  erdafitinib will increase the level or effect of morphine by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• nadolol

  erdafitinib will increase the level or effect of nadolol by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• nafcillin

  nafcillin will decrease the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• naldemedine

  erdafitinib will increase the level or effect of naldemedine by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• nefazodone

  nefazodone will increase the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP3A4 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP3A4 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• nelfinavir

  nelfinavir will increase the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP3A4 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP3A4 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.
  
  erdafitinib will increase the level or effect of nelfinavir by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• nicardipine

  nicardipine will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP2C9 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.
  
  erdafitinib will increase the level or effect of nicardipine by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• nintedanib

  erdafitinib will increase the level or effect of nintedanib by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• nitisinone

  nitisinone will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If coadministration of a strong CYP2C9 inhibitors is unavoidable, closely monitor adverse reactions and modify dose of erdafitinib accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• olanzapine

  olanzapine will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If coadministration of a strong CYP2C9 inhibitors is unavoidable, closely monitor adverse reactions and modify dose of erdafitinib accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• omeprazole

  omeprazole will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If coadministration of a strong CYP2C9 inhibitors is unavoidable, closely monitor adverse reactions and modify dose of erdafitinib accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• ondansetron

  erdafitinib will increase the level or effect of ondansetron by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• paclitaxel

  erdafitinib will increase the level or effect of paclitaxel by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• paclitaxel protein bound

  erdafitinib will increase the level or effect of paclitaxel protein bound by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• paliperidone

  erdafitinib will increase the level or effect of paliperidone by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• pazopanib

  erdafitinib will increase the level or effect of pazopanib by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• pentobarbital

  pentobarbital will decrease the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• phenobarbital

  phenobarbital will decrease the level or effect of erdafitinib by altering metabolism. Avoid or Use Alternate Drug. Avoid coadministration of strong CYP2C9 or CYP3A4 inducers with erdafitinib.

• phenytoin

  phenytoin will decrease the level or effect of erdafitinib by altering metabolism. Avoid or Use Alternate Drug. Avoid coadministration of strong CYP2C9 or CYP3A4 inducers with erdafitinib.

• pimozide

  erdafitinib, pimozide. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with erdafitinib and sensitive CYP3A4 substrates with narrow therapeutic indices. Erdafitinib may altered plasma concentrations of CYP3A4 substrates, leading to either loss of activity or increased toxicity of the substrate.

• piroxicam

  piroxicam will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP2C9 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• posaconazole

  posaconazole will increase the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP3A4 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP3A4 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• potassium acid phosphate

  potassium acid phosphate, erdafitinib. Other (see comment). Avoid or Use Alternate Drug. Comment: Avoid coadministration during initial dosing adjustment period (ie, first 21 days). Increases in serum phosphate levels are a pharmacodynamic effect of FGFR inhibition. Serum phosphate binders may obscure decisions regarding initial dosage increase.

• potassium phosphate

  potassium phosphate, erdafitinib. Other (see comment). Avoid or Use Alternate Drug. Comment: Avoid coadministration during initial dosing adjustment period (ie, first 21 days). Increases in serum phosphate levels are a pharmacodynamic effect of FGFR inhibition. Serum phosphate binders may obscure decisions regarding initial dosage increase.

• primidone

  primidone will decrease the level or effect of erdafitinib by altering metabolism. Avoid or Use Alternate Drug. Avoid coadministration of strong CYP2C9 or CYP3A4 inducers with erdafitinib.

• pyrimethamine

  pyrimethamine will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If coadministration of a strong CYP2C9 inhibitors is unavoidable, closely monitor adverse reactions and modify dose of erdafitinib accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• quinidine

  erdafitinib, quinidine. Other (see comment). Avoid or Use Alternate Drug. Comment: Avoid coadministration during initial dosing adjustment period (ie, first 21 days). Increases in serum phosphate levels are a pharmacodynamic effect of FGFR inhibition. Serum phosphate binders may obscure decisions regarding initial dosage increase.
  
  erdafitinib, quinidine. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with erdafitinib and sensitive CYP3A4 substrates with narrow therapeutic indices. Erdafitinib may altered plasma concentrations of CYP3A4 substrates, leading to either loss of activity or increased toxicity of the substrate.
  
  erdafitinib will increase the level or effect of quinidine by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• quinine

  erdafitinib, quinine. Other (see comment). Avoid or Use Alternate Drug. Comment: Avoid coadministration during initial dosing adjustment period (ie, first 21 days). Increases in serum phosphate levels are a pharmacodynamic effect of FGFR inhibition. Serum phosphate binders may obscure decisions regarding initial dosage increase.
  
  erdafitinib, quinine. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with erdafitinib and sensitive CYP3A4 substrates with narrow therapeutic indices. Erdafitinib may altered plasma concentrations of CYP3A4 substrates, leading to either loss of activity or increased toxicity of the substrate.
  
  erdafitinib will increase the level or effect of quinine by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.
  
  quinine will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If coadministration of a strong CYP2C9 inhibitors is unavoidable, closely monitor adverse reactions and modify dose of erdafitinib accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• ranolazine

  erdafitinib will increase the level or effect of ranolazine by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• repotrectinib

  erdafitinib will increase the level or effect of repotrectinib by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug.

• ribociclib

  ribociclib will increase the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• rifabutin

  rifabutin will decrease the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• rifampin

  rifampin will decrease the level or effect of erdafitinib by altering metabolism. Avoid or Use Alternate Drug. Avoid coadministration of strong CYP2C9 or CYP3A4 inducers with erdafitinib.
  
  erdafitinib will increase the level or effect of rifampin by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• rifapentine

  rifapentine will decrease the level or effect of erdafitinib by altering metabolism. Avoid or Use Alternate Drug. Avoid coadministration of strong CYP2C9 or CYP3A4 inducers with erdafitinib.

• rimegepant

  erdafitinib will increase the level or effect of rimegepant by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug.

• riociguat

  erdafitinib will increase the level or effect of riociguat by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• risperidone

  erdafitinib will increase the level or effect of risperidone by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• ritonavir

  ritonavir will increase the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP3A4 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP3A4 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.
  
  erdafitinib will increase the level or effect of ritonavir by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• romidepsin

  erdafitinib will increase the level or effect of romidepsin by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• saquinavir

  saquinavir will increase the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP3A4 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP3A4 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.
  
  erdafitinib will increase the level or effect of saquinavir by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• saxagliptin

  erdafitinib will increase the level or effect of saxagliptin by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• secobarbital

  secobarbital will decrease the level or effect of erdafitinib by altering metabolism. Avoid or Use Alternate Drug. Avoid coadministration of strong CYP2C9 or CYP3A4 inducers with erdafitinib.

• sevelamer

  sevelamer, erdafitinib. Other (see comment). Avoid or Use Alternate Drug. Comment: Avoid coadministration during initial dosing adjustment period (ie, first 21 days). Increases in serum phosphate levels are a pharmacodynamic effect of FGFR inhibition. Serum phosphate binders may obscure decisions regarding initial dosage increase.

• silodosin

  erdafitinib will increase the level or effect of silodosin by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• sirolimus

  erdafitinib, sirolimus. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with erdafitinib and sensitive CYP3A4 substrates with narrow therapeutic indices. Erdafitinib may altered plasma concentrations of CYP3A4 substrates, leading to either loss of activity or increased toxicity of the substrate.
  
  erdafitinib will increase the level or effect of sirolimus by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• sitagliptin

  erdafitinib will increase the level or effect of sitagliptin by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• sodium phosphates, IV

  sodium phosphates, IV, erdafitinib. Other (see comment). Avoid or Use Alternate Drug. Comment: Avoid coadministration during initial dosing adjustment period (ie, first 21 days). Increases in serum phosphate levels are a pharmacodynamic effect of FGFR inhibition. Serum phosphate binders may obscure decisions regarding initial dosage increase.

• sofosbuvir

  erdafitinib will increase the level or effect of sofosbuvir by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• sorafenib

  sorafenib will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If coadministration of a strong CYP2C9 inhibitors is unavoidable, closely monitor adverse reactions and modify dose of erdafitinib accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• St John's Wort

  St John's Wort will decrease the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• stiripentol

  stiripentol will increase the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP3A4 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP3A4 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• sucroferric oxyhydroxide

  sucroferric oxyhydroxide, erdafitinib. Other (see comment). Avoid or Use Alternate Drug. Comment: Avoid coadministration during initial dosing adjustment period (ie, first 21 days). Increases in serum phosphate levels are a pharmacodynamic effect of FGFR inhibition. Serum phosphate binders may obscure decisions regarding initial dosage increase.

• sulfadiazine

  sulfadiazine will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP2C9 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• sulfamethoxazole

  sulfamethoxazole will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP2C9 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• tacrolimus

  erdafitinib, tacrolimus. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with erdafitinib and sensitive CYP3A4 substrates with narrow therapeutic indices. Erdafitinib may altered plasma concentrations of CYP3A4 substrates, leading to either loss of activity or increased toxicity of the substrate.
  
  erdafitinib will increase the level or effect of tacrolimus by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• temsirolimus

  erdafitinib will increase the level or effect of temsirolimus by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• teniposide

  erdafitinib will increase the level or effect of teniposide by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• tipranavir

  tipranavir will increase the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP3A4 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP3A4 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• tolbutamide

  tolbutamide will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP2C9 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• tolvaptan

  erdafitinib will increase the level or effect of tolvaptan by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• trabectedin

  erdafitinib will increase the level or effect of trabectedin by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• triazolam

  erdafitinib, triazolam. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with erdafitinib and sensitive CYP3A4 substrates with narrow therapeutic indices. Erdafitinib may altered plasma concentrations of CYP3A4 substrates, leading to either loss of activity or increased toxicity of the substrate.

• trimethoprim

  trimethoprim will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If coadministration of a strong CYP2C9 inhibitors is unavoidable, closely monitor adverse reactions and modify dose of erdafitinib accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• vemurafenib

  erdafitinib will increase the level or effect of vemurafenib by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• venetoclax

  erdafitinib will increase the level or effect of venetoclax by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• verapamil

  erdafitinib will increase the level or effect of verapamil by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• vinblastine

  erdafitinib will increase the level or effect of vinblastine by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• vincristine

  erdafitinib will increase the level or effect of vincristine by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• vincristine liposomal

  erdafitinib will increase the level or effect of vincristine liposomal by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• voriconazole

  voriconazole will increase the level or effect of erdafitinib by altering metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP3A4/CYP2C9 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP3A4/CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• zafirlukast

  zafirlukast will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If coadministration of a strong CYP2C9 inhibitors is unavoidable, closely monitor adverse reactions and modify dose of erdafitinib accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

Monitor Closely (30)

• amantadine

  erdafitinib increases levels of amantadine by decreasing renal clearance. Modify Therapy/Monitor Closely. Consider alternatives that are not OCT2 substrates or consider reducing the dose of OCT2 substrates based on tolerability.

• amiloride

  erdafitinib increases levels of amiloride by decreasing renal clearance. Modify Therapy/Monitor Closely. Consider alternatives that are not OCT2 substrates or consider reducing the dose of OCT2 substrates based on tolerability.

• amobarbital

  amobarbital will decrease the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely.

• armodafinil

  armodafinil will decrease the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. If a moderate CYP3A4 inducer must be coadministered, administer 8-mg/day dose initially, with potential to increase to 9 mg/day based on serum phosphate levels on Days 14-21 and tolerability. If a moderate CYP3A4 inducer must be coadministered after the initial dose increase period based on serum phosphate levels and tolerability, increase erdafitinib dose up to 9 mg. When a moderate inducer discontinued, continue erdafitinib at same dose, in absence of drug-related toxicity.

• berotralstat

  erdafitinib increases levels of berotralstat by P-glycoprotein (MDR1) efflux transporter. Modify Therapy/Monitor Closely. Reduced berotralstat dose to 110 mg/day when coadministered with P-gp inhibitors.

• bexarotene

  bexarotene will decrease the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. If a moderate CYP3A4 inducer must be coadministered, administer 8-mg/day dose initially, with potential to increase to 9 mg/day based on serum phosphate levels on Days 14-21 and tolerability. If a moderate CYP3A4 inducer must be coadministered after the initial dose increase period based on serum phosphate levels and tolerability, increase erdafitinib dose up to 9 mg. When a moderate inducer discontinued, continue erdafitinib at same dose, in absence of drug-related toxicity.

• brigatinib

  brigatinib will decrease the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. If a moderate CYP3A4 inducer must be coadministered, administer 8-mg/day dose initially, with potential to increase to 9 mg/day based on serum phosphate levels on Days 14-21 and tolerability. If a moderate CYP3A4 inducer must be coadministered after the initial dose increase period based on serum phosphate levels and tolerability, increase erdafitinib dose up to 9 mg. When a moderate inducer discontinued, continue erdafitinib at same dose, in absence of drug-related toxicity.

• cimetidine

  erdafitinib increases levels of cimetidine by decreasing renal clearance. Modify Therapy/Monitor Closely. Consider alternatives that are not OCT2 substrates or consider reducing the dose of OCT2 substrates based on tolerability.

• cisplatin

  erdafitinib increases levels of cisplatin by decreasing renal clearance. Modify Therapy/Monitor Closely. Consider alternatives that are not OCT2 substrates or consider reducing the dose of OCT2 substrates based on tolerability.

• clobazam

  clobazam will decrease the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. If a moderate CYP3A4 inducer must be coadministered, administer 8-mg/day dose initially, with potential to increase to 9 mg/day based on serum phosphate levels on Days 14-21 and tolerability. If a moderate CYP3A4 inducer must be coadministered after the initial dose increase period based on serum phosphate levels and tolerability, increase erdafitinib dose up to 9 mg. When a moderate inducer discontinued, continue erdafitinib at same dose, in absence of drug-related toxicity.

• dofetilide

  erdafitinib increases levels of dofetilide by decreasing renal clearance. Modify Therapy/Monitor Closely. Consider alternatives that are not OCT2 substrates or consider reducing the dose of OCT2 substrates based on tolerability.

• dopamine

  dopamine increases levels of erdafitinib by decreasing renal clearance. Modify Therapy/Monitor Closely. Consider alternatives that are not OCT2 substrates or consider reducing the dose of OCT2 substrates based on tolerability.

• elvitegravir

  elvitegravir will decrease the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Modify Therapy/Monitor Closely. If a moderate CYP2C9 inducer must be coadministered, administer 8-mg/day dose initially, with potential to increase to 9 mg/day based on serum phosphate levels on Days 14-21 and tolerability. If a moderate CYP2C9 inducer must be coadministered after the initial dose increase period based on serum phosphate levels and tolerability, increase erdafitinib dose up to 9 mg. When a moderate inducer discontinued, continue erdafitinib at same dose, in absence of drug-related toxicity.

• enzalutamide

  enzalutamide will decrease the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Modify Therapy/Monitor Closely. If a moderate CYP2C9 inducer must be coadministered, administer 8-mg/day dose initially, with potential to increase to 9 mg/day based on serum phosphate levels on Days 14-21 and tolerability. If a moderate CYP2C9 inducer must be coadministered after the initial dose increase period based on serum phosphate levels and tolerability, increase erdafitinib dose up to 9 mg. When a moderate inducer discontinued, continue erdafitinib at same dose, in absence of drug-related toxicity.

• eslicarbazepine acetate

  eslicarbazepine acetate will decrease the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. If a moderate CYP3A4 inducer must be coadministered, administer 8-mg/day dose initially, with potential to increase to 9 mg/day based on serum phosphate levels on Days 14-21 and tolerability. If a moderate CYP3A4 inducer must be coadministered after the initial dose increase period based on serum phosphate levels and tolerability, increase erdafitinib dose up to 9 mg. When a moderate inducer discontinued, continue erdafitinib at same dose, in absence of drug-related toxicity.

• famotidine

  famotidine increases levels of erdafitinib by decreasing renal clearance. Modify Therapy/Monitor Closely. Consider alternatives that are not OCT2 substrates or consider reducing the dose of OCT2 substrates based on tolerability.

• lamivudine

  lamivudine increases levels of erdafitinib by decreasing renal clearance. Modify Therapy/Monitor Closely. Consider alternatives that are not OCT2 substrates or consider reducing the dose of OCT2 substrates based on tolerability.

• memantine

  memantine increases levels of erdafitinib by decreasing renal clearance. Modify Therapy/Monitor Closely. Consider alternatives that are not OCT2 substrates or consider reducing the dose of OCT2 substrates based on tolerability.

• metformin

  metformin increases levels of erdafitinib by decreasing renal clearance. Modify Therapy/Monitor Closely. Consider alternatives that are not OCT2 substrates or consider reducing the dose of OCT2 substrates based on tolerability.

• oxaliplatin

  erdafitinib increases levels of oxaliplatin by decreasing renal clearance. Modify Therapy/Monitor Closely. Consider alternatives that are not OCT2 substrates or consider reducing the dose of OCT2 substrates based on tolerability.

• pimozide

  erdafitinib, pimozide. Other (see comment). Modify Therapy/Monitor Closely. Comment: Avoid coadministration during initial dosing adjustment period (ie, first 21 days). Increases in serum phosphate levels are a pharmacodynamic effect of FGFR inhibition. Serum phosphate binders may obscure decisions regarding initial dosage increase.

• pindolol

  erdafitinib increases levels of pindolol by decreasing renal clearance. Modify Therapy/Monitor Closely. Consider alternatives that are not OCT2 substrates or consider reducing the dose of OCT2 substrates based on tolerability.

• pramipexole

  erdafitinib increases levels of pramipexole by decreasing renal clearance. Modify Therapy/Monitor Closely. Consider alternatives that are not OCT2 substrates or consider reducing the dose of OCT2 substrates based on tolerability.

• procainamide

  erdafitinib increases levels of procainamide by decreasing renal clearance. Modify Therapy/Monitor Closely. Consider alternatives that are not OCT2 substrates or consider reducing the dose of OCT2 substrates based on tolerability.

• rucaparib

  rucaparib will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Modify Therapy/Monitor Closely. Adjust dosage of CYP2C9 substrates, if clinically indicated.

• siponimod

  siponimod and erdafitinib 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.

• sparsentan

  sparsentan will decrease the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor. Sparsentan (a CYP2C9 inducer) decreases exposure of CYP2C9 substrates and reduces efficacy related to these substrates.

• telotristat ethyl

  telotristat ethyl will decrease the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. If a moderate CYP3A4 inducer must be coadministered, administer 8-mg/day dose initially, with potential to increase to 9 mg/day based on serum phosphate levels on Days 14-21 and tolerability. If a moderate CYP3A4 inducer must be coadministered after the initial dose increase period based on serum phosphate levels and tolerability, increase erdafitinib dose up to 9 mg. When a moderate inducer discontinued, continue erdafitinib at same dose, in absence of drug-related toxicity.

• trimethoprim

  erdafitinib increases levels of trimethoprim by decreasing renal clearance. Modify Therapy/Monitor Closely. Consider alternatives that are not OCT2 substrates or consider reducing the dose of OCT2 substrates based on tolerability.

• varenicline

  erdafitinib increases levels of varenicline by increasing renal clearance. Modify Therapy/Monitor Closely. Consider alternatives that are not OCT2 substrates or consider reducing the dose of OCT2 substrates based on tolerability.

Minor (1)

• encorafenib

  encorafenib will decrease the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown. If a moderate CYP3A4 inducer must be coadministered, administer 8-mg/day dose initially, with potential to increase to 9 mg/day based on serum phosphate levels on Days 14-21 and tolerability. If a moderate CYP3A4 inducer must be coadministered after the initial dose increase period based on serum phosphate levels and tolerability, increase erdafitinib dose up to 9 mg. When a moderate inducer discontinued, continue erdafitinib at same dose, in absence of drug-related toxicity.

• afatinib

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of afatinib by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• aliskiren

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of aliskiren by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• alpelisib

  Serious - Use Alternative (1)alpelisib will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If coadministration of a strong CYP2C9 inhibitors is unavoidable, closely monitor adverse reactions and modify dose of erdafitinib accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• amantadine

  Monitor Closely (1)erdafitinib increases levels of amantadine by decreasing renal clearance. Modify Therapy/Monitor Closely. Consider alternatives that are not OCT2 substrates or consider reducing the dose of OCT2 substrates based on tolerability.

• amiloride

  Monitor Closely (1)erdafitinib increases levels of amiloride by decreasing renal clearance. Modify Therapy/Monitor Closely. Consider alternatives that are not OCT2 substrates or consider reducing the dose of OCT2 substrates based on tolerability.

• amiodarone

  Serious - Use Alternative (2)amiodarone will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP2C9 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.
  
  erdafitinib will increase the level or effect of amiodarone by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• amobarbital

  Monitor Closely (1)amobarbital will decrease the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely.

• apalutamide

  Serious - Use Alternative (1)apalutamide will decrease the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• armodafinil

  Monitor Closely (1)armodafinil will decrease the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. If a moderate CYP3A4 inducer must be coadministered, administer 8-mg/day dose initially, with potential to increase to 9 mg/day based on serum phosphate levels on Days 14-21 and tolerability. If a moderate CYP3A4 inducer must be coadministered after the initial dose increase period based on serum phosphate levels and tolerability, increase erdafitinib dose up to 9 mg. When a moderate inducer discontinued, continue erdafitinib at same dose, in absence of drug-related toxicity.

• atazanavir

  Serious - Use Alternative (1)atazanavir will increase the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP3A4 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP3A4 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• atorvastatin

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of atorvastatin by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• berotralstat

  Monitor Closely (1)erdafitinib increases levels of berotralstat by P-glycoprotein (MDR1) efflux transporter. Modify Therapy/Monitor Closely. Reduced berotralstat dose to 110 mg/day when coadministered with P-gp inhibitors.

• betrixaban

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of betrixaban by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• bexarotene

  Monitor Closely (1)bexarotene will decrease the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. If a moderate CYP3A4 inducer must be coadministered, administer 8-mg/day dose initially, with potential to increase to 9 mg/day based on serum phosphate levels on Days 14-21 and tolerability. If a moderate CYP3A4 inducer must be coadministered after the initial dose increase period based on serum phosphate levels and tolerability, increase erdafitinib dose up to 9 mg. When a moderate inducer discontinued, continue erdafitinib at same dose, in absence of drug-related toxicity.

• bosentan

  Serious - Use Alternative (1)bosentan will decrease the level or effect of erdafitinib by altering metabolism. Avoid or Use Alternate Drug. Avoid coadministration of strong CYP2C9 or CYP3A4 inducers with erdafitinib.

• brentuximab vedotin

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of brentuximab vedotin by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• brigatinib

  Monitor Closely (1)brigatinib will decrease the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. If a moderate CYP3A4 inducer must be coadministered, administer 8-mg/day dose initially, with potential to increase to 9 mg/day based on serum phosphate levels on Days 14-21 and tolerability. If a moderate CYP3A4 inducer must be coadministered after the initial dose increase period based on serum phosphate levels and tolerability, increase erdafitinib dose up to 9 mg. When a moderate inducer discontinued, continue erdafitinib at same dose, in absence of drug-related toxicity.

• butabarbital

  Serious - Use Alternative (1)butabarbital will decrease the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• butalbital

  Serious - Use Alternative (1)butalbital will decrease the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• calcium acetate

  Serious - Use Alternative (1)calcium acetate, erdafitinib. Other (see comment). Avoid or Use Alternate Drug. Comment: Avoid coadministration during initial dosing adjustment period (ie, first 21 days). Increases in serum phosphate levels are a pharmacodynamic effect of FGFR inhibition. Serum phosphate binders may obscure decisions regarding initial dosage increase.

• calcium carbonate

  Serious - Use Alternative (1)calcium carbonate, erdafitinib. Other (see comment). Avoid or Use Alternate Drug. Comment: Avoid coadministration during initial dosing adjustment period (ie, first 21 days). Increases in serum phosphate levels are a pharmacodynamic effect of FGFR inhibition. Serum phosphate binders may obscure decisions regarding initial dosage increase.

• capecitabine

  Serious - Use Alternative (1)capecitabine will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP2C9 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• carbamazepine

  Serious - Use Alternative (1)carbamazepine will decrease the level or effect of erdafitinib by altering metabolism. Avoid or Use Alternate Drug. Avoid coadministration of strong CYP2C9 or CYP3A4 inducers with erdafitinib.

• carfilzomib

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of carfilzomib by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• carvedilol

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of carvedilol by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• ceritinib

  Serious - Use Alternative (2)erdafitinib will increase the level or effect of ceritinib by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.
  
  ceritinib will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If coadministration of a strong CYP2C9 inhibitors is unavoidable, closely monitor adverse reactions and modify dose of erdafitinib accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• cetirizine

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of cetirizine by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• chloramphenicol

  Serious - Use Alternative (1)chloramphenicol will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2E1 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP3A4 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP3A4 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• cimetidine

  Monitor Closely (1)erdafitinib increases levels of cimetidine by decreasing renal clearance. Modify Therapy/Monitor Closely. Consider alternatives that are not OCT2 substrates or consider reducing the dose of OCT2 substrates based on tolerability.Serious - Use Alternative (1)erdafitinib will increase the level or effect of cimetidine by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• cisplatin

  Monitor Closely (1)erdafitinib increases levels of cisplatin by decreasing renal clearance. Modify Therapy/Monitor Closely. Consider alternatives that are not OCT2 substrates or consider reducing the dose of OCT2 substrates based on tolerability.

• clarithromycin

  Serious - Use Alternative (1)clarithromycin will increase the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP3A4 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP3A4 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• clobazam

  Monitor Closely (1)clobazam will decrease the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. If a moderate CYP3A4 inducer must be coadministered, administer 8-mg/day dose initially, with potential to increase to 9 mg/day based on serum phosphate levels on Days 14-21 and tolerability. If a moderate CYP3A4 inducer must be coadministered after the initial dose increase period based on serum phosphate levels and tolerability, increase erdafitinib dose up to 9 mg. When a moderate inducer discontinued, continue erdafitinib at same dose, in absence of drug-related toxicity.

• cobicistat

  Serious - Use Alternative (1)cobicistat will increase the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP3A4 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP3A4 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• colchicine

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of colchicine by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• conivaptan

  Serious - Use Alternative (1)conivaptan will increase the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP3A4 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP3A4 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• crizotinib

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of crizotinib by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• cyclosporine

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of cyclosporine by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• dabigatran

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of dabigatran by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• dabrafenib

  Serious - Use Alternative (1)dabrafenib will decrease the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• darunavir

  Serious - Use Alternative (1)darunavir will increase the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP3A4 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP3A4 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• daunorubicin

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of daunorubicin by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• desloratadine

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of desloratadine by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• dexamethasone

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of dexamethasone by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• digoxin

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of digoxin by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• diltiazem

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of diltiazem by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• docetaxel

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of docetaxel by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• dofetilide

  Monitor Closely (1)erdafitinib increases levels of dofetilide by decreasing renal clearance. Modify Therapy/Monitor Closely. Consider alternatives that are not OCT2 substrates or consider reducing the dose of OCT2 substrates based on tolerability.

• dopamine

  Monitor Closely (1)dopamine increases levels of erdafitinib by decreasing renal clearance. Modify Therapy/Monitor Closely. Consider alternatives that are not OCT2 substrates or consider reducing the dose of OCT2 substrates based on tolerability.

• doxorubicin

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of doxorubicin by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• edoxaban

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of edoxaban by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• efavirenz

  Serious - Use Alternative (2)efavirenz will decrease the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
  
  efavirenz will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If coadministration of a strong CYP2C9 inhibitors is unavoidable, closely monitor adverse reactions and modify dose of erdafitinib accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• elvitegravir

  Monitor Closely (1)elvitegravir will decrease the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Modify Therapy/Monitor Closely. If a moderate CYP2C9 inducer must be coadministered, administer 8-mg/day dose initially, with potential to increase to 9 mg/day based on serum phosphate levels on Days 14-21 and tolerability. If a moderate CYP2C9 inducer must be coadministered after the initial dose increase period based on serum phosphate levels and tolerability, increase erdafitinib dose up to 9 mg. When a moderate inducer discontinued, continue erdafitinib at same dose, in absence of drug-related toxicity.

• encorafenib

  Minor (1)encorafenib will decrease the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown. If a moderate CYP3A4 inducer must be coadministered, administer 8-mg/day dose initially, with potential to increase to 9 mg/day based on serum phosphate levels on Days 14-21 and tolerability. If a moderate CYP3A4 inducer must be coadministered after the initial dose increase period based on serum phosphate levels and tolerability, increase erdafitinib dose up to 9 mg. When a moderate inducer discontinued, continue erdafitinib at same dose, in absence of drug-related toxicity.

• enzalutamide

  Monitor Closely (1)enzalutamide will decrease the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Modify Therapy/Monitor Closely. If a moderate CYP2C9 inducer must be coadministered, administer 8-mg/day dose initially, with potential to increase to 9 mg/day based on serum phosphate levels on Days 14-21 and tolerability. If a moderate CYP2C9 inducer must be coadministered after the initial dose increase period based on serum phosphate levels and tolerability, increase erdafitinib dose up to 9 mg. When a moderate inducer discontinued, continue erdafitinib at same dose, in absence of drug-related toxicity.Serious - Use Alternative (1)enzalutamide will decrease the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• erythromycin base

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of erythromycin base by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• erythromycin ethylsuccinate

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of erythromycin ethylsuccinate by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• erythromycin lactobionate

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of erythromycin lactobionate by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• erythromycin stearate

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of erythromycin stearate by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• eslicarbazepine acetate

  Monitor Closely (1)eslicarbazepine acetate will decrease the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. If a moderate CYP3A4 inducer must be coadministered, administer 8-mg/day dose initially, with potential to increase to 9 mg/day based on serum phosphate levels on Days 14-21 and tolerability. If a moderate CYP3A4 inducer must be coadministered after the initial dose increase period based on serum phosphate levels and tolerability, increase erdafitinib dose up to 9 mg. When a moderate inducer discontinued, continue erdafitinib at same dose, in absence of drug-related toxicity.

• estradiol

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of estradiol by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• etoposide

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of etoposide by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• etrasimod

  Serious - Use Alternative (1)etrasimod, erdafitinib. Either increases effects of the other by immunosuppressive effects; risk of infection. Avoid or Use Alternate Drug. Risk of additive immune system effects with etrasimod has not been studied in combination with antineoplastic, immune-modulating, or noncorticosteroid immunosuppressive therapies. Avoid coadministration during and in the weeks following administration of etrasimod. .

• etravirine

  Serious - Use Alternative (2)etravirine will decrease the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
  
  etravirine will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. Reduce dose of osilodrostat, a CYP3A4 substrate, by half when coadministered with a strong CYP3A4 inhibitor.

• everolimus

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of everolimus by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• famotidine

  Monitor Closely (1)famotidine increases levels of erdafitinib by decreasing renal clearance. Modify Therapy/Monitor Closely. Consider alternatives that are not OCT2 substrates or consider reducing the dose of OCT2 substrates based on tolerability.

• ferric citrate

  Serious - Use Alternative (1)ferric citrate, erdafitinib. Other (see comment). Avoid or Use Alternate Drug. Comment: Avoid coadministration during initial dosing adjustment period (ie, first 21 days). Increases in serum phosphate levels are a pharmacodynamic effect of FGFR inhibition. Serum phosphate binders may obscure decisions regarding initial dosage increase.

• fexofenadine

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of fexofenadine by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• fluconazole

  Serious - Use Alternative (1)fluconazole will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP2C9 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• fluorouracil

  Serious - Use Alternative (1)fluorouracil will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP2C9 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• fluorouracil topical

  Serious - Use Alternative (1)fluorouracil topical will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP2C9 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• flurbiprofen

  Serious - Use Alternative (1)flurbiprofen will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP2C9 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• fluvastatin

  Serious - Use Alternative (1)fluvastatin will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If coadministration of a strong CYP2C9 inhibitors is unavoidable, closely monitor adverse reactions and modify dose of erdafitinib accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• fosamprenavir

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of fosamprenavir by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• fosphenytoin

  Serious - Use Alternative (1)fosphenytoin will decrease the level or effect of erdafitinib by altering metabolism. Avoid or Use Alternate Drug. Avoid coadministration of strong CYP2C9 or CYP3A4 inducers with erdafitinib.

• gemfibrozil

  Serious - Use Alternative (1)gemfibrozil will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP2C9 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• gilteritinib

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of gilteritinib by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• grapefruit

  Serious - Use Alternative (1)grapefruit will increase the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP3A4 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP3A4 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• hydrocortisone

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of hydrocortisone by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• ibuprofen

  Serious - Use Alternative (1)ibuprofen will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP2C9 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• idarubicin

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of idarubicin by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• idelalisib

  Serious - Use Alternative (1)idelalisib will increase the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP3A4 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP3A4 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• imatinib

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of imatinib by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• indinavir

  Serious - Use Alternative (2)indinavir will increase the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP3A4 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP3A4 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.
  
  erdafitinib will increase the level or effect of indinavir by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• indomethacin

  Serious - Use Alternative (1)indomethacin will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP2C9 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• irbesartan

  Serious - Use Alternative (1)irbesartan will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If coadministration of a strong CYP2C9 inhibitors is unavoidable, closely monitor adverse reactions and modify dose of erdafitinib accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• irinotecan

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of irinotecan by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• irinotecan liposomal

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of irinotecan liposomal by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• isoniazid

  Serious - Use Alternative (1)isoniazid will increase the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP3A4 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP3A4 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• itraconazole

  Serious - Use Alternative (1)itraconazole will increase the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP3A4 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP3A4 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• ivermectin

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of ivermectin by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• ivosidenib

  Serious - Use Alternative (1)ivosidenib will decrease the level or effect of erdafitinib by altering metabolism. Avoid or Use Alternate Drug. Avoid coadministration of strong CYP2C9 or CYP3A4 inducers with erdafitinib.

• ketoconazole

  Serious - Use Alternative (1)ketoconazole will increase the level or effect of erdafitinib by altering metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP3A4/CYP2C9 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP3A4/CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• lamivudine

  Monitor Closely (1)lamivudine increases levels of erdafitinib by decreasing renal clearance. Modify Therapy/Monitor Closely. Consider alternatives that are not OCT2 substrates or consider reducing the dose of OCT2 substrates based on tolerability.

• lanthanum carbonate

  Serious - Use Alternative (1)lanthanum carbonate, erdafitinib. Other (see comment). Avoid or Use Alternate Drug. Comment: Avoid coadministration during initial dosing adjustment period (ie, first 21 days). Increases in serum phosphate levels are a pharmacodynamic effect of FGFR inhibition. Serum phosphate binders may obscure decisions regarding initial dosage increase.

• lapatinib

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of lapatinib by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• larotrectinib

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of larotrectinib by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• ledipasvir/sofosbuvir

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of ledipasvir/sofosbuvir by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• levoketoconazole

  Serious - Use Alternative (1)levoketoconazole will increase the level or effect of erdafitinib by altering metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP3A4/CYP2C9 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP3A4/CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• loperamide

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of loperamide by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• lopinavir

  Serious - Use Alternative (1)lopinavir will increase the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP3A4 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP3A4 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• loratadine

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of loratadine by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• lorlatinib

  Serious - Use Alternative (1)lorlatinib will decrease the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• losartan

  Serious - Use Alternative (1)losartan will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If coadministration of a strong CYP2C9 inhibitors is unavoidable, closely monitor adverse reactions and modify dose of erdafitinib accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• lovastatin

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of lovastatin by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• lumacaftor/ivacaftor

  Serious - Use Alternative (1)lumacaftor/ivacaftor will decrease the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• mefenamic acid

  Serious - Use Alternative (1)mefenamic acid will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP2C9 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• memantine

  Monitor Closely (1)memantine increases levels of erdafitinib by decreasing renal clearance. Modify Therapy/Monitor Closely. Consider alternatives that are not OCT2 substrates or consider reducing the dose of OCT2 substrates based on tolerability.

• metformin

  Monitor Closely (1)metformin increases levels of erdafitinib by decreasing renal clearance. Modify Therapy/Monitor Closely. Consider alternatives that are not OCT2 substrates or consider reducing the dose of OCT2 substrates based on tolerability.

• methotrexate

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of methotrexate by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• miconazole oral

  Serious - Use Alternative (1)miconazole oral will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP2C9 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• midazolam

  Serious - Use Alternative (1)erdafitinib, midazolam. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with erdafitinib and sensitive CYP3A4 substrates with narrow therapeutic indices. Erdafitinib may altered plasma concentrations of CYP3A4 substrates, leading to either loss of activity or increased toxicity of the substrate.

• mifepristone

  Serious - Use Alternative (1)mifepristone will increase the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP3A4 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP3A4 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• mitomycin

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of mitomycin by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• mitotane

  Serious - Use Alternative (1)mitotane will decrease the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• morphine

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of morphine by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• nadolol

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of nadolol by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• nafcillin

  Serious - Use Alternative (1)nafcillin will decrease the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• naldemedine

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of naldemedine by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• nefazodone

  Serious - Use Alternative (1)nefazodone will increase the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP3A4 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP3A4 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• nelfinavir

  Serious - Use Alternative (2)nelfinavir will increase the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP3A4 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP3A4 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.
  
  erdafitinib will increase the level or effect of nelfinavir by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• nicardipine

  Serious - Use Alternative (2)nicardipine will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP2C9 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.
  
  erdafitinib will increase the level or effect of nicardipine by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• nintedanib

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of nintedanib by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• nitisinone

  Serious - Use Alternative (1)nitisinone will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If coadministration of a strong CYP2C9 inhibitors is unavoidable, closely monitor adverse reactions and modify dose of erdafitinib accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• olanzapine

  Serious - Use Alternative (1)olanzapine will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If coadministration of a strong CYP2C9 inhibitors is unavoidable, closely monitor adverse reactions and modify dose of erdafitinib accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• omeprazole

  Serious - Use Alternative (1)omeprazole will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If coadministration of a strong CYP2C9 inhibitors is unavoidable, closely monitor adverse reactions and modify dose of erdafitinib accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• ondansetron

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of ondansetron by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• oxaliplatin

  Monitor Closely (1)erdafitinib increases levels of oxaliplatin by decreasing renal clearance. Modify Therapy/Monitor Closely. Consider alternatives that are not OCT2 substrates or consider reducing the dose of OCT2 substrates based on tolerability.

• paclitaxel

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of paclitaxel by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• paclitaxel protein bound

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of paclitaxel protein bound by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• paliperidone

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of paliperidone by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• pazopanib

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of pazopanib by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• pentobarbital

  Serious - Use Alternative (1)pentobarbital will decrease the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• phenobarbital

  Serious - Use Alternative (1)phenobarbital will decrease the level or effect of erdafitinib by altering metabolism. Avoid or Use Alternate Drug. Avoid coadministration of strong CYP2C9 or CYP3A4 inducers with erdafitinib.

• phenytoin

  Serious - Use Alternative (1)phenytoin will decrease the level or effect of erdafitinib by altering metabolism. Avoid or Use Alternate Drug. Avoid coadministration of strong CYP2C9 or CYP3A4 inducers with erdafitinib.

• pimozide

  Monitor Closely (1)erdafitinib, pimozide. Other (see comment). Modify Therapy/Monitor Closely. Comment: Avoid coadministration during initial dosing adjustment period (ie, first 21 days). Increases in serum phosphate levels are a pharmacodynamic effect of FGFR inhibition. Serum phosphate binders may obscure decisions regarding initial dosage increase.Serious - Use Alternative (1)erdafitinib, pimozide. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with erdafitinib and sensitive CYP3A4 substrates with narrow therapeutic indices. Erdafitinib may altered plasma concentrations of CYP3A4 substrates, leading to either loss of activity or increased toxicity of the substrate.

• pindolol

  Monitor Closely (1)erdafitinib increases levels of pindolol by decreasing renal clearance. Modify Therapy/Monitor Closely. Consider alternatives that are not OCT2 substrates or consider reducing the dose of OCT2 substrates based on tolerability.

• piroxicam

  Serious - Use Alternative (1)piroxicam will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP2C9 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• posaconazole

  Serious - Use Alternative (1)posaconazole will increase the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP3A4 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP3A4 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• potassium acid phosphate

  Serious - Use Alternative (1)potassium acid phosphate, erdafitinib. Other (see comment). Avoid or Use Alternate Drug. Comment: Avoid coadministration during initial dosing adjustment period (ie, first 21 days). Increases in serum phosphate levels are a pharmacodynamic effect of FGFR inhibition. Serum phosphate binders may obscure decisions regarding initial dosage increase.

• potassium phosphate

  Serious - Use Alternative (1)potassium phosphate, erdafitinib. Other (see comment). Avoid or Use Alternate Drug. Comment: Avoid coadministration during initial dosing adjustment period (ie, first 21 days). Increases in serum phosphate levels are a pharmacodynamic effect of FGFR inhibition. Serum phosphate binders may obscure decisions regarding initial dosage increase.

• pramipexole

  Monitor Closely (1)erdafitinib increases levels of pramipexole by decreasing renal clearance. Modify Therapy/Monitor Closely. Consider alternatives that are not OCT2 substrates or consider reducing the dose of OCT2 substrates based on tolerability.

• primidone

  Serious - Use Alternative (1)primidone will decrease the level or effect of erdafitinib by altering metabolism. Avoid or Use Alternate Drug. Avoid coadministration of strong CYP2C9 or CYP3A4 inducers with erdafitinib.

• procainamide

  Monitor Closely (1)erdafitinib increases levels of procainamide by decreasing renal clearance. Modify Therapy/Monitor Closely. Consider alternatives that are not OCT2 substrates or consider reducing the dose of OCT2 substrates based on tolerability.

• pyrimethamine

  Serious - Use Alternative (1)pyrimethamine will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If coadministration of a strong CYP2C9 inhibitors is unavoidable, closely monitor adverse reactions and modify dose of erdafitinib accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• quinidine

  Serious - Use Alternative (3)erdafitinib, quinidine. Other (see comment). Avoid or Use Alternate Drug. Comment: Avoid coadministration during initial dosing adjustment period (ie, first 21 days). Increases in serum phosphate levels are a pharmacodynamic effect of FGFR inhibition. Serum phosphate binders may obscure decisions regarding initial dosage increase.
  
  erdafitinib, quinidine. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with erdafitinib and sensitive CYP3A4 substrates with narrow therapeutic indices. Erdafitinib may altered plasma concentrations of CYP3A4 substrates, leading to either loss of activity or increased toxicity of the substrate.
  
  erdafitinib will increase the level or effect of quinidine by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• quinine

  Serious - Use Alternative (4)erdafitinib, quinine. Other (see comment). Avoid or Use Alternate Drug. Comment: Avoid coadministration during initial dosing adjustment period (ie, first 21 days). Increases in serum phosphate levels are a pharmacodynamic effect of FGFR inhibition. Serum phosphate binders may obscure decisions regarding initial dosage increase.
  
  erdafitinib, quinine. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with erdafitinib and sensitive CYP3A4 substrates with narrow therapeutic indices. Erdafitinib may altered plasma concentrations of CYP3A4 substrates, leading to either loss of activity or increased toxicity of the substrate.
  
  erdafitinib will increase the level or effect of quinine by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.
  
  quinine will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If coadministration of a strong CYP2C9 inhibitors is unavoidable, closely monitor adverse reactions and modify dose of erdafitinib accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• ranolazine

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of ranolazine by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• repotrectinib

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of repotrectinib by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug.

• ribociclib

  Serious - Use Alternative (1)ribociclib will increase the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• rifabutin

  Serious - Use Alternative (1)rifabutin will decrease the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• rifampin

  Serious - Use Alternative (2)rifampin will decrease the level or effect of erdafitinib by altering metabolism. Avoid or Use Alternate Drug. Avoid coadministration of strong CYP2C9 or CYP3A4 inducers with erdafitinib.
  
  erdafitinib will increase the level or effect of rifampin by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• rifapentine

  Serious - Use Alternative (1)rifapentine will decrease the level or effect of erdafitinib by altering metabolism. Avoid or Use Alternate Drug. Avoid coadministration of strong CYP2C9 or CYP3A4 inducers with erdafitinib.

• rimegepant

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of rimegepant by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug.

• riociguat

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of riociguat by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• risperidone

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of risperidone by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• ritonavir

  Serious - Use Alternative (2)ritonavir will increase the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP3A4 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP3A4 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.
  
  erdafitinib will increase the level or effect of ritonavir by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• romidepsin

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of romidepsin by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• rucaparib

  Monitor Closely (1)rucaparib will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Modify Therapy/Monitor Closely. Adjust dosage of CYP2C9 substrates, if clinically indicated.

• saquinavir

  Serious - Use Alternative (2)saquinavir will increase the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP3A4 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP3A4 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.
  
  erdafitinib will increase the level or effect of saquinavir by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• saxagliptin

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of saxagliptin by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• secobarbital

  Serious - Use Alternative (1)secobarbital will decrease the level or effect of erdafitinib by altering metabolism. Avoid or Use Alternate Drug. Avoid coadministration of strong CYP2C9 or CYP3A4 inducers with erdafitinib.

• sevelamer

  Serious - Use Alternative (1)sevelamer, erdafitinib. Other (see comment). Avoid or Use Alternate Drug. Comment: Avoid coadministration during initial dosing adjustment period (ie, first 21 days). Increases in serum phosphate levels are a pharmacodynamic effect of FGFR inhibition. Serum phosphate binders may obscure decisions regarding initial dosage increase.

• silodosin

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of silodosin by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• siponimod

  Monitor Closely (1)siponimod and erdafitinib 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.

• sirolimus

  Serious - Use Alternative (2)erdafitinib, sirolimus. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with erdafitinib and sensitive CYP3A4 substrates with narrow therapeutic indices. Erdafitinib may altered plasma concentrations of CYP3A4 substrates, leading to either loss of activity or increased toxicity of the substrate.
  
  erdafitinib will increase the level or effect of sirolimus by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• sitagliptin

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of sitagliptin by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• sodium phosphates, IV

  Serious - Use Alternative (1)sodium phosphates, IV, erdafitinib. Other (see comment). Avoid or Use Alternate Drug. Comment: Avoid coadministration during initial dosing adjustment period (ie, first 21 days). Increases in serum phosphate levels are a pharmacodynamic effect of FGFR inhibition. Serum phosphate binders may obscure decisions regarding initial dosage increase.

• sofosbuvir

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of sofosbuvir by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• sorafenib

  Serious - Use Alternative (1)sorafenib will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If coadministration of a strong CYP2C9 inhibitors is unavoidable, closely monitor adverse reactions and modify dose of erdafitinib accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• sparsentan

  Monitor Closely (1)sparsentan will decrease the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor. Sparsentan (a CYP2C9 inducer) decreases exposure of CYP2C9 substrates and reduces efficacy related to these substrates.

• St John's Wort

  Serious - Use Alternative (1)St John's Wort will decrease the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• stiripentol

  Serious - Use Alternative (1)stiripentol will increase the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP3A4 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP3A4 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• sucroferric oxyhydroxide

  Serious - Use Alternative (1)sucroferric oxyhydroxide, erdafitinib. Other (see comment). Avoid or Use Alternate Drug. Comment: Avoid coadministration during initial dosing adjustment period (ie, first 21 days). Increases in serum phosphate levels are a pharmacodynamic effect of FGFR inhibition. Serum phosphate binders may obscure decisions regarding initial dosage increase.

• sulfadiazine

  Serious - Use Alternative (1)sulfadiazine will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP2C9 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• sulfamethoxazole

  Serious - Use Alternative (1)sulfamethoxazole will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP2C9 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• tacrolimus

  Serious - Use Alternative (2)erdafitinib, tacrolimus. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with erdafitinib and sensitive CYP3A4 substrates with narrow therapeutic indices. Erdafitinib may altered plasma concentrations of CYP3A4 substrates, leading to either loss of activity or increased toxicity of the substrate.
  
  erdafitinib will increase the level or effect of tacrolimus by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• telotristat ethyl

  Monitor Closely (1)telotristat ethyl will decrease the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. If a moderate CYP3A4 inducer must be coadministered, administer 8-mg/day dose initially, with potential to increase to 9 mg/day based on serum phosphate levels on Days 14-21 and tolerability. If a moderate CYP3A4 inducer must be coadministered after the initial dose increase period based on serum phosphate levels and tolerability, increase erdafitinib dose up to 9 mg. When a moderate inducer discontinued, continue erdafitinib at same dose, in absence of drug-related toxicity.

• temsirolimus

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of temsirolimus by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• teniposide

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of teniposide by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• tipranavir

  Serious - Use Alternative (1)tipranavir will increase the level or effect of erdafitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP3A4 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP3A4 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• tolbutamide

  Serious - Use Alternative (1)tolbutamide will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP2C9 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• tolvaptan

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of tolvaptan by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• trabectedin

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of trabectedin by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• triazolam

  Serious - Use Alternative (1)erdafitinib, triazolam. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with erdafitinib and sensitive CYP3A4 substrates with narrow therapeutic indices. Erdafitinib may altered plasma concentrations of CYP3A4 substrates, leading to either loss of activity or increased toxicity of the substrate.

• trimethoprim

  Monitor Closely (1)erdafitinib increases levels of trimethoprim by decreasing renal clearance. Modify Therapy/Monitor Closely. Consider alternatives that are not OCT2 substrates or consider reducing the dose of OCT2 substrates based on tolerability.Serious - Use Alternative (1)trimethoprim will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If coadministration of a strong CYP2C9 inhibitors is unavoidable, closely monitor adverse reactions and modify dose of erdafitinib accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• varenicline

  Monitor Closely (1)erdafitinib increases levels of varenicline by increasing renal clearance. Modify Therapy/Monitor Closely. Consider alternatives that are not OCT2 substrates or consider reducing the dose of OCT2 substrates based on tolerability.

• vemurafenib

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of vemurafenib by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• venetoclax

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of venetoclax by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• verapamil

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of verapamil by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• vinblastine

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of vinblastine by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• vincristine

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of vincristine by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• vincristine liposomal

  Serious - Use Alternative (1)erdafitinib will increase the level or effect of vincristine liposomal by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug. If coadministration unavoidable, separate administration by at least 6 hr before or after administration of P-gp substrates with narrow therapeutic index.

• voriconazole

  Serious - Use Alternative (1)voriconazole will increase the level or effect of erdafitinib by altering metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with strong CYP3A4/CYP2C9 inhibitors, monitor closely for adverse reactions and consider decreasing dose accordingly. If strong CYP3A4/CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.

• zafirlukast

  Serious - Use Alternative (1)zafirlukast will increase the level or effect of erdafitinib by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. If coadministration of a strong CYP2C9 inhibitors is unavoidable, closely monitor adverse reactions and modify dose of erdafitinib accordingly. If strong CYP2C9 inhibitor is discontinued, consider increasing erdafitinib dose in the absence of any drug-related toxicities.