Dosing & Uses
Dosage Forms & Strengths
trimethoprim/sulfamethoxazole
injected solution
- (16mg/80mg)/mL
oral suspension
- (40mg/200mg)/5mL
tablet
- 80mg/400mg
- 160mg/800mg
Dosing Guidelines for Infections
1-2 DS tablets PO q12-24hr
Chronic Bronchitis
Acute exacerbations of chronic bronchitis due to susceptible strains of Streptococcus pneumoniae or Haemophilus influenzae
DS tablet: 1 PO q12h for 10-14 days
Meningitis, Bacterial
10-20 mg TMP/kg/day IV divided q6-12hr
Pneumocystis (Carinii) Jiroveci Pneumonia
Documented Pneumocystis jiroveci pneumonia (PCP); also, prophylaxis against PCP in individuals who are immunosuppressed
Prophylaxis
- Tablet: 80-160 mg TMP PO qDay or 160 mg TMP 3 times/week on consecutive or alternate days
Treatment
Sepsis
20 mg TMP/kg/day IV divided q6hr
Shigellosis
Enteritis caused by susceptible strains of Shigella flexneri and S sonnei
DS tablet: 1 tab PO q12hr for 5 days
Alternatively, 8-10 mg TMP/kg/day IV divided q6-12hr for up to 5 days
Traveler's Diarrhea
Traveler's diarrhea due to susceptible strains of enterotoxigenic Escherichia coli
DS tablet: 1 tab PO q12hr for 5 days
Urinary Tract Infections
UTIs caused by susceptible strains of Escherichia coli, Klebsiella species, Enterobacter species, Morganella morganii, Proteus mirabilis, and Proteus vulgaris
Pyelonephritis: 1 DS tab or 2 regular-strength tabs PO q12hr x 14 days
Prostatitis: 1 DS tab or 2 regular-strength tabs PO q12hr x 14 days or 2-3 months if chronic infection
A 3 to 5 day course may be used for acute, uncomplicated cystitis
Prophylaxis (off-label): Various regimens exist; may use regular-strength tablet once/twice per week
Acne Vulgaris (Off-label)
1 DS tab or 1 regular-strength tab PO qDay or q12hr for up to 18 weeks
Community Acquired Pneumonia (Off-label)
1 DS tab PO q12hr for 10-14 days
Dosage Modifications
Renal impairment
- CrCl >30 mL/min: Dose adjustment not necessary
- CrCl 15-30 mL/min: Decrease dose by 50%
- CrCl <15 mL/min: Do not use
Renal impairment, off-label
- Administer doses PO/IV
- Dosing (Dose based on Total Body Weight(TBW) and trimethoprim component; use TBW in obese patients)
Pneumocystis jjirovecii pneumonia (PJP) prophylaxis
- CrCl < 30mL/min: 160 mg (1DS) q24hr or 80 mg (1 SS) q24hr or 160 mg (1DS) 3x week
- Hemodialysis (HD): 80 mg (1 SS) q24 hr or 160 mg (1DS) 3 x week; on hemodialysis days, administer dose post-HD
- Continuous renal replacement therapy (CRRT): 160 mg (1 DS) q24hr or 80 mg (1SS) q24hr or 160 mg (1DS) 3x week
Pneumocystis jjirovecii pneumonia (PJP) treatment
- CrCl < 30mL/min: 5 mg/kg q12hr
- HD: 10 mg/kg post-HD
- CRRT: 5 mg/kg q12hr
- Total daily dose: 15-20 mg/kg/day for Pneumocystis treatment
Skin and soft tissue infection
- CrCl < 30mL/min: 80-160 mg (1-2 SS) q12hr
- HD: 80 mg (1SS) q24hr; on hemodialysis days, administer dose post-HD
- CRRT: 80-160 mg (1-2SS) q12hr
Stenotrophomonas treatment
- CrCl<30mL/min: 4 mg/kg q12hr
- HD: 8 mg/kg post-HD
- CRRT: 4 mg/kg q12hr
- Total daily dose: 12-15 mg/kg/day for Stenotrophomonas treatment
Urinary tract infection
- CrCl < 30mL/min: 80 mg (1SS) q12hr
- HD: 80 mg (1SS) q12hr; on hemodialysis days, administer dose post-HD
- CRRT: 160 mg (1DS) q12hr
Other Infections
- CrCl < 30mL/min: 3 mg/kg q12hr
- HD: 6 mg/kg post-HD
- CRRT: 3 mg/kg q12hr
- Total daily dose: 8-12 mg/kg/day
Dosing Considerations
Susceptible organisms
- Acinetobacter baumannii, Actinobacillus actinomycetemcomitans, Aeromonas hydrophila, Alcaligenes xylosoxidans, Bartonella henselae, Bordetella pertussis, Brucella spp, Burkholderia pseudomallei, Burkholderia cepacia, Chryseobacterium meningosepticum, Enterobacter aerogenes, Enterobacter cloacae, Escherichia coli, Haemophilus aphrophilus, Haemophilus influenzae, Hafnia alvei, Kingella spp, Klebsiella pneumoniae, Klebsiella granulomatis, Legionella spp, Listeria monocytogenes, Moraxella catarrhalis, Morganella morganii, MRSA, MSSA, Nocardia asteroides, Plesiomonas shigelloides, Pneumocystis jiroveci (PCP), Proteus mirabilis, Proteus vulgaris, Providencia rettgeri, Providencia stuartii, Salmonella typhi, Serratia spp, Shigella spp, Staphylococcus saprophyticus, Stenotrophomonas maltophilia, Streptococcus pneumoniae, Tropheryma whippelii, Vibrio cholerae, Yersinia enterocolitica, Yersinia pseudotuberculosis, various Mycobacteria
Dosage Forms & Strengths
trimethoprim/sulfamethoxazole
injected solution
- (16mg/80mg)/mL
oral solution
- (40mg/200mg)/5mL
tablet
- 80mg/400mg
- 160mg/800mg
Mild to Moderate Infections
<2 months: Contraindicated
>2 months
Serious Infections
<2 months: Contraindicated
>2 months
Acute Otitis Media
Acute otitis media in pediatric patients due to susceptible strains of Streptococcus pneumoniae or Haemophilus influenzae
<2 months: Contraindicated
>2 months: 6-10 mg TMP/kg/day PO divided q12hr for 10 days
Pneumocystis (Carinii) Jiroveci Pneumonia
<2 months: Contraindicated
>2 months
- Treatment: 15-20 mg TMP/kg/day PO/IV divided q6-8hr for 21 days
- Prophylaxis: 150 mg TMP/m²/day PO divided q12 hr for 3 days/week on consecutive or alternate days
Shigellosis
<2 months: Contraindicated
>2 months
Urinary Tract Infection
<2 months: Contraindicated
>2 months
- 8 mg TMP/kg/day PO divided q12hr for 7-14 days if serious infection
- 8-10 mg TMP/kg/day IV divided q6-12hr for 14 days if serious infection
- Prophylaxis: 2 mg TMP/kg/dose PO qDay or 5 mg TMP/kg/dose twice weekly
Skin/soft Tissue Infection Due to Community Acquired MRSA (Off-label)
8-12 mg TMP/kg/day PO divided q12hr for 5-10 days; add beta-lactam antibiotic to regimen if beta-hemolytic Streptococcus spp also suspected
Interactions
Interaction Checker
No Results

Contraindicated
Serious - Use Alternative
Significant - Monitor Closely
Minor

Contraindicated (0)
Serious - Use Alternative (56)
- abametapir
abametapir will increase the level or effect of trimethoprim by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. For 2 weeks after abametapir application, avoid taking drugs that are CYP3A4 substrates. If not feasible, avoid use of abametapir.
- aminobenzoate potassium
aminobenzoate potassium decreases effects of sulfamethoxazole by pharmacodynamic antagonism. Avoid or Use Alternate Drug.
- aminolevulinic acid oral
aminolevulinic acid oral, sulfamethoxazole. Either increases toxicity of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Avoid administering other phototoxic drugs with aminolevulinic acid oral for 24 hr during perioperative period.
- aminolevulinic acid topical
sulfamethoxazole, aminolevulinic acid topical. Either increases toxicity of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Each drug may increase the photosensitizing effect of the other.
- amiodarone
amiodarone and sulfamethoxazole both increase QTc interval. Avoid or Use Alternate Drug.
amiodarone and trimethoprim both increase QTc interval. Avoid or Use Alternate Drug. - antithrombin alfa
sulfamethoxazole increases effects of antithrombin alfa by decreasing metabolism. Avoid or Use Alternate Drug.
sulfamethoxazole increases effects of antithrombin alfa by plasma protein binding competition. Avoid or Use Alternate Drug. - BCG vaccine live
trimethoprim decreases effects of BCG vaccine live by pharmacodynamic antagonism. Contraindicated. Wait until Abx Tx complete to administer live bacterial vaccine.
- apalutamide
apalutamide will decrease the level or effect of trimethoprim by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration of apalutamide, a strong CYP3A4 inducer, with drugs that are CYP3A4 substrates can result in lower exposure to these medications. Avoid or substitute another drug for these medications when possible. Evaluate for loss of therapeutic effect if medication must be coadministered. Adjust dose according to prescribing information if needed.
- antithrombin III
sulfamethoxazole increases effects of antithrombin III by decreasing metabolism. Avoid or Use Alternate Drug.
sulfamethoxazole increases effects of antithrombin III by plasma protein binding competition. Avoid or Use Alternate Drug. - argatroban
sulfamethoxazole increases effects of argatroban by decreasing metabolism. Avoid or Use Alternate Drug.
sulfamethoxazole increases effects of argatroban by plasma protein binding competition. Avoid or Use Alternate Drug. - BCG vaccine live
sulfamethoxazole decreases effects of BCG vaccine live by pharmacodynamic antagonism. Contraindicated. Wait until Abx Tx complete to administer live bacterial vaccine.
- bemiparin
sulfamethoxazole increases effects of bemiparin by decreasing metabolism. Avoid or Use Alternate Drug.
sulfamethoxazole increases effects of bemiparin by plasma protein binding competition. Avoid or Use Alternate Drug. - bivalirudin
sulfamethoxazole increases effects of bivalirudin by decreasing metabolism. Avoid or Use Alternate Drug.
sulfamethoxazole increases effects of bivalirudin by plasma protein binding competition. Avoid or Use Alternate Drug. - cholera vaccine
trimethoprim, cholera vaccine. pharmacodynamic antagonism. Avoid or Use Alternate Drug. Avoid coadministration of cholera vaccine with systemic antibiotics since these agents may be active against the vaccine strain. Do not administer cholera vaccine to patients who have received oral or parenteral antibiotics within 14 days prior to vaccination.
- dalteparin
sulfamethoxazole increases effects of dalteparin by decreasing metabolism. Avoid or Use Alternate Drug.
sulfamethoxazole increases effects of dalteparin by plasma protein binding competition. Avoid or Use Alternate Drug. - disopyramide
disopyramide and trimethoprim both increase QTc interval. Avoid or Use Alternate Drug.
sulfamethoxazole and disopyramide both increase QTc interval. Avoid or Use Alternate Drug. - enoxaparin
sulfamethoxazole increases effects of enoxaparin by decreasing metabolism. Avoid or Use Alternate Drug.
sulfamethoxazole increases effects of enoxaparin by plasma protein binding competition. Avoid or Use Alternate Drug. - erdafitinib
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.
- erdafitinib
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.
- fexinidazole
fexinidazole will increase the level or effect of trimethoprim by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Fexinidazole inhibits CYP3A4. Coadministration may increase risk for adverse effects of CYP3A4 substrates.
- fondaparinux
sulfamethoxazole increases effects of fondaparinux by decreasing metabolism. Avoid or Use Alternate Drug.
sulfamethoxazole increases effects of fondaparinux by plasma protein binding competition. Avoid or Use Alternate Drug. - heparin
sulfamethoxazole increases effects of heparin by decreasing metabolism. Avoid or Use Alternate Drug.
sulfamethoxazole increases effects of heparin by plasma protein binding competition. Avoid or Use Alternate Drug. - ibutilide
ibutilide and trimethoprim both increase QTc interval. Avoid or Use Alternate Drug.
sulfamethoxazole and ibutilide both increase QTc interval. Avoid or Use Alternate Drug. - idelalisib
idelalisib will increase the level or effect of trimethoprim by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Idelalisib is a strong CYP3A inhibitor; avoid coadministration with sensitive CYP3A substrates
- indapamide
sulfamethoxazole and indapamide both increase QTc interval. Avoid or Use Alternate Drug.
- indapamide
indapamide and trimethoprim both increase QTc interval. Avoid or Use Alternate Drug.
- ivosidenib
ivosidenib will decrease the level or effect of trimethoprim by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of sensitive CYP3A4 substrates with ivosidenib or replace with alternative therapies. If coadministration is unavoidable, monitor patients for loss of therapeutic effect of these drugs.
ivosidenib will decrease the level or effect of trimethoprim by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of sensitive CYP2C9 substrates with ivosidenib or replace with alternate therapies. If coadministration is unavoidable, monitor patients for loss of therapeutic effect of these drugs. - leucovorin
leucovorin decreases effects of trimethoprim by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Monitor for trimethoprim treatment failure or decreased efficacy when coadministered with leucovorin, especially when used with sulfamethoxazole for Pneumocystis jiroveci pneumonia in patients who are HIV positive .
- levoleucovorin
levoleucovorin decreases effects of trimethoprim by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Monitor for trimethoprim treatment failure or decreased efficacy when coadministered with levoleucovorin, especially when used with sulfamethoxazole for Pneumocystis jiroveci pneumonia in patients who are HIV positive .
- lonafarnib
lonafarnib will increase the level or effect of trimethoprim by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with sensitive CYP3A substrates. If coadministration unavoidable, monitor for adverse reactions and reduce CYP3A substrate dose in accordance with product labeling.
- lopinavir
lopinavir will increase the level or effect of trimethoprim by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
- mefloquine
mefloquine increases toxicity of trimethoprim by QTc interval. Avoid or Use Alternate Drug. Mefloquine may enhance the QTc prolonging effect of high risk QTc prolonging agents.
mefloquine increases toxicity of sulfamethoxazole by QTc interval. Avoid or Use Alternate Drug. Mefloquine may enhance the QTc prolonging effect of high risk QTc prolonging agents. - methenamine
methenamine, sulfamethoxazole. Other (see comment). Contraindicated. Comment: This combination may form an insoluble precipitate in the urine, decreasing the effects of both agents.
- methotrexate
trimethoprim, methotrexate. Either increases toxicity of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Due to an additive antifolate effect, trimethoprim has been shown to rarely increase bone marrow suppression in patients receiving methotrexate.
- methotrexate
sulfamethoxazole increases toxicity of methotrexate by plasma protein binding competition. Avoid or Use Alternate Drug. Methotrexate concentrations may be elevated, increasing the risk of toxicity (eg, bone marrow suppression).
- methyl aminolevulinate
sulfamethoxazole, methyl aminolevulinate. Either increases toxicity of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Each drug may increase the photosensitizing effect of the other.
- microbiota oral
trimethoprim decreases effects of microbiota oral by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Microbiota oral contains bacterial spores. Antibacterial agents may decrease efficacy if coadministered. Complete antibiotic regimens 2-4 days before initiating microbiota oral. .
- pentamidine
sulfamethoxazole and pentamidine both increase QTc interval. Avoid or Use Alternate Drug.
pentamidine and trimethoprim both increase QTc interval. Avoid or Use Alternate Drug. - pexidartinib
sulfamethoxazole and pexidartinib both increase inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug. Pexidartinib can cause hepatotoxicity. Avoid coadministration of pexidartinib with other products know to cause hepatoxicity.
- pimozide
pimozide and trimethoprim both increase QTc interval. Avoid or Use Alternate Drug.
- phenindione
sulfamethoxazole increases effects of phenindione by decreasing metabolism. Avoid or Use Alternate Drug.
sulfamethoxazole increases effects of phenindione by plasma protein binding competition. Avoid or Use Alternate Drug. - pimozide
sulfamethoxazole and pimozide both increase QTc interval. Avoid or Use Alternate Drug.
- pretomanid
sulfamethoxazole, pretomanid. Either increases toxicity of the other by Other (see comment). Avoid or Use Alternate Drug. Comment: Pretomanid regimen associated with hepatotoxicity. Avoid alcohol and hepatotoxic agents, including herbal supplements and drugs other than bedaquiline and linezolid.
- procainamide
sulfamethoxazole and procainamide both increase QTc interval. Avoid or Use Alternate Drug.
procainamide and trimethoprim both increase QTc interval. Avoid or Use Alternate Drug. - protamine
sulfamethoxazole increases effects of protamine by decreasing metabolism. Avoid or Use Alternate Drug.
sulfamethoxazole increases effects of protamine by plasma protein binding competition. Avoid or Use Alternate Drug. - quinidine
quinidine and trimethoprim both increase QTc interval. Avoid or Use Alternate Drug.
- quinidine
quinidine and sulfamethoxazole both increase QTc interval. Avoid or Use Alternate Drug.
- siponimod
trimethoprim will increase the level or effect of siponimod by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. Coadministration of siponimod with drugs that cause moderate CYP2C9 AND a moderate or strong CYP3A4 inhibition is not recommended. Caution if siponimod coadministered with moderate CYP2C9 inhibitors alone.
sulfamethoxazole will increase the level or effect of siponimod by affecting hepatic enzyme CYP2C9/10 metabolism. Avoid or Use Alternate Drug. Coadministration of siponimod with drugs that cause moderate CYP2C9 AND a moderate or strong CYP3A4 inhibition is not recommended. Caution if siponimod coadministered with moderate CYP2C9 inhibitors alone. - sotalol
sulfamethoxazole and sotalol both increase QTc interval. Avoid or Use Alternate Drug.
sotalol and trimethoprim both increase QTc interval. Avoid or Use Alternate Drug. - tafenoquine
tafenoquine will increase the level or effect of trimethoprim by Other (see comment). Avoid or Use Alternate Drug. Tafenoquine inhibits organic cation transporter-2 (OCT2) and multidrug and toxin extrusion (MATE) transporters in vitro. Avoid coadministration with OCT2 or MATE substrates. If coadministration cannot be avoided, monitor for substrate-related toxicities and consider dosage reduction if needed based on product labeling of the coadministered drug.
- tretinoin
sulfamethoxazole, tretinoin. Mechanism: pharmacodynamic synergism. Avoid or Use Alternate Drug. Increased phototoxicity.
- tretinoin topical
sulfamethoxazole, tretinoin topical. Mechanism: pharmacodynamic synergism. Avoid or Use Alternate Drug. Increased phototoxicity.
- trilaciclib
trilaciclib will decrease the level or effect of trimethoprim by Other (see comment). Avoid or Use Alternate Drug. Avoid coadministration of trilaciclib (OCT2, MATE1, and MATE-2K inhibitor) with substrates where minimal increased concentration in kidney or blood may lead to serious or life-threatening toxicities.
- tucatinib
trimethoprim will increase the level or effect of tucatinib by Other (see comment). Avoid or Use Alternate Drug. Coadministration of tucatinib (a CYP2C8 substrate) with a strong or moderate CYP2C8 inhibitors increases tucatinib plasma concentrations and risk of toxicities.
tucatinib will increase the level or effect of trimethoprim by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid concomitant use of tucatinib with CYP3A substrates, where minimal concentration changes may lead to serious or life-threatening toxicities. If unavoidable, reduce CYP3A substrate dose according to product labeling. - typhoid vaccine live
sulfamethoxazole decreases effects of typhoid vaccine live by pharmacodynamic antagonism. Contraindicated. Wait until Abx Tx complete to administer live bacterial vaccine.
trimethoprim decreases effects of typhoid vaccine live by pharmacodynamic antagonism. Contraindicated. Wait until Abx Tx complete to administer live bacterial vaccine. - voxelotor
voxelotor will increase the level or effect of trimethoprim by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Voxelotor increases systemic exposure of sensitive CYP3A4 substrates. Avoid coadministration with sensitive CYP3A4 substrates with a narrow therapeutic index. Consider dose reduction of the sensitive CYP3A4 substrate(s) if unable to avoid.
Monitor Closely (192)
- aliskiren
trimethoprim and aliskiren both increase serum potassium. Use Caution/Monitor. Trimethoprim decreases urinary potassium excretion. May cause hyperkalemia, particularly with high doses, renal insufficiency, or when combined with other drugs that cause hyperkalemia.
- alpelisib
alpelisib will decrease the level or effect of trimethoprim by affecting hepatic enzyme CYP2C9/10 metabolism. Modify Therapy/Monitor Closely.
- amantadine
trimethoprim increases levels of amantadine by decreasing elimination. Use Caution/Monitor. Coadministration may impair renal clearance of amantadine, resulting in higher plasma concentrations.
sulfamethoxazole increases levels of amantadine by decreasing elimination. Use Caution/Monitor. Coadministration may impair renal clearance of amantadine, resulting in higher plasma concentrations. - amiloride
trimethoprim and amiloride both increase serum potassium. Use Caution/Monitor. Trimethoprim decreases urinary potassium excretion. May cause hyperkalemia, particularly with high doses, renal insufficiency, or when combined with other drugs that cause hyperkalemia.
- amiodarone
amiodarone will increase the level or effect of sulfamethoxazole by basic (cationic) drug competition for renal tubular clearance. Use Caution/Monitor.
- amiodarone
amiodarone will increase the level or effect of trimethoprim by basic (cationic) drug competition for renal tubular clearance. Use Caution/Monitor.
- amitriptyline
amitriptyline and sulfamethoxazole both increase QTc interval. Modify Therapy/Monitor Closely.
amitriptyline and trimethoprim both increase QTc interval. Modify Therapy/Monitor Closely. - amoxapine
amoxapine and trimethoprim both increase QTc interval. Modify Therapy/Monitor Closely.
amoxapine and sulfamethoxazole both increase QTc interval. Modify Therapy/Monitor Closely. - apalutamide
apalutamide will decrease the level or effect of trimethoprim by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor. Coadministration of apalutamide, a weak CYP2C9 inducer, with drugs that are CYP2C9 substrates can result in lower exposure to these medications. Evaluate for loss of therapeutic effect if medication must be coadministered.
- artemether/lumefantrine
sulfamethoxazole and artemether/lumefantrine both increase QTc interval. Modify Therapy/Monitor Closely.
- artemether/lumefantrine
artemether/lumefantrine and trimethoprim both increase QTc interval. Modify Therapy/Monitor Closely.
- aspirin
aspirin, sulfamethoxazole. Either increases effects of the other by plasma protein binding competition. Use Caution/Monitor. Due to high protein binding capacity of both drugs, one may displace the other when coadministered leading to an enhanced effect of the displaced drug; risk is low with low dose aspirin.
- aspirin/citric acid/sodium bicarbonate
aspirin/citric acid/sodium bicarbonate, sulfamethoxazole. Either increases effects of the other by plasma protein binding competition. Use Caution/Monitor. Due to high protein binding capacity of both drugs, one may displace the other when coadministered leading to an enhanced effect of the displaced drug; risk is low with low dose aspirin.
- bazedoxifene/conjugated estrogens
sulfamethoxazole will decrease the level or effect of bazedoxifene/conjugated estrogens by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
trimethoprim will decrease the level or effect of bazedoxifene/conjugated estrogens by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor. - benazepril
trimethoprim and benazepril both increase serum potassium. Use Caution/Monitor. Trimethoprim decreases urinary potassium excretion. May cause hyperkalemia, particularly with high doses, renal insufficiency, or when combined with other drugs that cause hyperkalemia.
- carvedilol
sulfamethoxazole will increase the level or effect of carvedilol by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.
- canagliflozin
trimethoprim and canagliflozin both increase serum potassium. Use Caution/Monitor.
- candesartan
trimethoprim and candesartan both increase serum potassium. Use Caution/Monitor. Trimethoprim decreases urinary potassium excretion. May cause hyperkalemia, particularly with high doses, renal insufficiency, or when combined with other drugs that cause hyperkalemia.
- cannabidiol
cannabidiol will increase the level or effect of trimethoprim by decreasing metabolism. Modify Therapy/Monitor Closely. Cannabidiol may potentially inhibit CYP2C9 activity. Consider reducing the dose when concomitantly using CYP2C9 substrates.
- captopril
trimethoprim and captopril both increase serum potassium. Use Caution/Monitor. Trimethoprim decreases urinary potassium excretion. May cause hyperkalemia, particularly with high doses, renal insufficiency, or when combined with other drugs that cause hyperkalemia.
- chlorpromazine
chlorpromazine and sulfamethoxazole both increase QTc interval. Modify Therapy/Monitor Closely.
chlorpromazine and trimethoprim both increase QTc interval. Modify Therapy/Monitor Closely. - chlorpropamide
sulfamethoxazole increases levels of chlorpropamide by plasma protein binding competition. Use Caution/Monitor.
- cimetidine
cimetidine will increase the level or effect of trimethoprim by basic (cationic) drug competition for renal tubular clearance. Use Caution/Monitor.
- cimetidine
cimetidine will increase the level or effect of sulfamethoxazole by basic (cationic) drug competition for renal tubular clearance. Use Caution/Monitor.
- clarithromycin
clarithromycin and trimethoprim both increase QTc interval. Modify Therapy/Monitor Closely.
clarithromycin and sulfamethoxazole both increase QTc interval. Modify Therapy/Monitor Closely. - clomipramine
clomipramine and sulfamethoxazole both increase QTc interval. Modify Therapy/Monitor Closely.
clomipramine and trimethoprim both increase QTc interval. Modify Therapy/Monitor Closely. - conjugated estrogens
trimethoprim will decrease the level or effect of conjugated estrogens by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
sulfamethoxazole will decrease the level or effect of conjugated estrogens by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor. - crofelemer
crofelemer increases levels of trimethoprim by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Crofelemer has the potential to inhibit CYP3A4 at concentrations expected in the gut; unlikely to inhibit systemically because minimally absorbed.
- cyclosporine
sulfamethoxazole, cyclosporine. Either increases effects of the other by nephrotoxicity and/or ototoxicity. Use Caution/Monitor.
- cyclosporine
trimethoprim and cyclosporine both increase serum potassium. Use Caution/Monitor. Trimethoprim decreases urinary potassium excretion. May cause hyperkalemia, particularly with high doses, renal insufficiency, or when combined with other drugs that cause hyperkalemia.
- dabrafenib
dabrafenib will decrease the level or effect of trimethoprim by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely.
- dapsone topical
trimethoprim increases toxicity of dapsone topical by decreasing metabolism. Modify Therapy/Monitor Closely. Coadministration increases systemic exposure of dapsone and its metabolites (N-acetyl-dapsone, dapsone hydroxylamine). May induce methemoglobinemia.
sulfamethoxazole increases toxicity of dapsone topical by decreasing metabolism. Modify Therapy/Monitor Closely. Coadministration increases systemic exposure of dapsone and its metabolites (N-acetyl-dapsone, dapsone hydroxylamine). May induce methemoglobinemia. - desipramine
desipramine and sulfamethoxazole both increase QTc interval. Modify Therapy/Monitor Closely.
desipramine and trimethoprim both increase QTc interval. Modify Therapy/Monitor Closely. - digoxin
digoxin will increase the level or effect of trimethoprim by basic (cationic) drug competition for renal tubular clearance. Use Caution/Monitor.
sulfamethoxazole will increase the level or effect of digoxin by basic (cationic) drug competition for renal tubular clearance. Use Caution/Monitor.
trimethoprim will increase the level or effect of digoxin by altering intestinal flora. Applies only to oral form of both agents. Use Caution/Monitor.
sulfamethoxazole will increase the level or effect of digoxin by altering intestinal flora. Applies only to oral form of both agents. Use Caution/Monitor. - dofetilide
dofetilide and trimethoprim both increase QTc interval. Modify Therapy/Monitor Closely.
sulfamethoxazole will increase the level or effect of dofetilide by basic (cationic) drug competition for renal tubular clearance. Use Caution/Monitor.
dofetilide will increase the level or effect of trimethoprim by basic (cationic) drug competition for renal tubular clearance. Use Caution/Monitor.
sulfamethoxazole and dofetilide both increase QTc interval. Modify Therapy/Monitor Closely. - dolasetron
sulfamethoxazole and dolasetron both increase QTc interval. Use Caution/Monitor.
dolasetron and trimethoprim both increase QTc interval. Use Caution/Monitor. - doxepin
doxepin and trimethoprim both increase QTc interval. Modify Therapy/Monitor Closely.
doxepin and sulfamethoxazole both increase QTc interval. Modify Therapy/Monitor Closely. - dronabinol
sulfamethoxazole will increase the level or effect of dronabinol by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor. Dronabinol is a CYP2C9 substrate.
- dronedarone
dronedarone and trimethoprim both increase QTc interval. Modify Therapy/Monitor Closely.
- dronedarone
sulfamethoxazole and dronedarone both increase QTc interval. Modify Therapy/Monitor Closely.
- droperidol
droperidol and trimethoprim both increase QTc interval. Modify Therapy/Monitor Closely.
sulfamethoxazole and droperidol both increase QTc interval. Modify Therapy/Monitor Closely. - efavirenz
efavirenz will increase the level or effect of sulfamethoxazole by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.
- elagolix
elagolix decreases levels of trimethoprim by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Elagolix is a weak-to-moderate CYP3A4 inducer. Monitor CYP3A substrates if coadministered. Consider increasing CYP3A substrate dose if needed.
- eltrombopag
sulfamethoxazole will increase the level or effect of eltrombopag by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.
- eluxadoline
sulfamethoxazole increases levels of eluxadoline by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor. As a precautionary measure due to incomplete information on the metabolism of eluxadoline, use caution when coadministered with strong CYP2C9/10 inhibitors.
- elvitegravir/cobicistat/emtricitabine/tenofovir DF
elvitegravir/cobicistat/emtricitabine/tenofovir DF increases levels of trimethoprim by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Cobicistat is a CYP3A4 inhibitor; contraindicated with CYP3A4 substrates for which elevated plasma concentrations are associated with serious and/or life-threatening events.
elvitegravir/cobicistat/emtricitabine/tenofovir DF decreases levels of trimethoprim by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor. Elvitegravir is a moderate CYP2C9 inducer. - enalapril
trimethoprim and enalapril both increase serum potassium. Use Caution/Monitor. Trimethoprim decreases urinary potassium excretion. May cause hyperkalemia, particularly with high doses, renal insufficiency, or when combined with other drugs that cause hyperkalemia.
- encorafenib
encorafenib, trimethoprim. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Encorafenib both inhibits and induces CYP3A4 at clinically relevant plasma concentrations. Coadministration of encorafenib with sensitive CYP3A4 substrates may result in increased toxicity or decreased efficacy of these agents.
- epinephrine
epinephrine and trimethoprim both increase QTc interval. Modify Therapy/Monitor Closely.
epinephrine and sulfamethoxazole both increase QTc interval. Modify Therapy/Monitor Closely. - epinephrine racemic
epinephrine racemic and sulfamethoxazole both increase QTc interval. Modify Therapy/Monitor Closely.
epinephrine racemic and trimethoprim both increase QTc interval. Modify Therapy/Monitor Closely. - eplerenone
trimethoprim and eplerenone both increase serum potassium. Use Caution/Monitor. Trimethoprim decreases urinary potassium excretion. May cause hyperkalemia, particularly with high doses, renal insufficiency, or when combined with other drugs that cause hyperkalemia.
- erythromycin base
sulfamethoxazole and erythromycin base both increase QTc interval. Modify Therapy/Monitor Closely.
- eprosartan
trimethoprim and eprosartan both increase serum potassium. Use Caution/Monitor. Trimethoprim decreases urinary potassium excretion. May cause hyperkalemia, particularly with high doses, renal insufficiency, or when combined with other drugs that cause hyperkalemia.
- erdafitinib
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.
- erythromycin base
erythromycin base and trimethoprim both increase QTc interval. Modify Therapy/Monitor Closely.
- erythromycin ethylsuccinate
sulfamethoxazole and erythromycin ethylsuccinate both increase QTc interval. Modify Therapy/Monitor Closely.
erythromycin ethylsuccinate and trimethoprim both increase QTc interval. Modify Therapy/Monitor Closely. - erythromycin lactobionate
erythromycin lactobionate and trimethoprim both increase QTc interval. Modify Therapy/Monitor Closely.
sulfamethoxazole and erythromycin lactobionate both increase QTc interval. Modify Therapy/Monitor Closely. - erythromycin stearate
sulfamethoxazole and erythromycin stearate both increase QTc interval. Modify Therapy/Monitor Closely.
erythromycin stearate and trimethoprim both increase QTc interval. Modify Therapy/Monitor Closely. - estradiol
trimethoprim will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
sulfamethoxazole will decrease the level or effect of estradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor. - estrogens conjugated synthetic
trimethoprim will decrease the level or effect of estrogens conjugated synthetic by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
sulfamethoxazole will decrease the level or effect of estrogens conjugated synthetic by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor. - estropipate
trimethoprim will decrease the level or effect of estropipate by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
sulfamethoxazole will decrease the level or effect of estropipate by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor. - ethinylestradiol
trimethoprim will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
sulfamethoxazole will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor. - ethotoin
sulfamethoxazole will increase the level or effect of ethotoin by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.
- fedratinib
fedratinib will increase the level or effect of trimethoprim by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Adjust dose of drugs that are CYP3A4 substrates as necessary.
- etravirine
sulfamethoxazole will increase the level or effect of etravirine by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.
- finerenone
trimethoprim and finerenone both increase serum potassium. Modify Therapy/Monitor Closely. Finerenone dose adjustment based on current serum potassium concentration. Monitor serum potassium and adjust finerenone dose as described in the prescribing information as necessary.
- flecainide
sulfamethoxazole and flecainide both increase QTc interval. Use Caution/Monitor.
flecainide and trimethoprim both increase QTc interval. Use Caution/Monitor. - fluconazole
fluconazole and trimethoprim both increase QTc interval. Modify Therapy/Monitor Closely.
sulfamethoxazole and fluconazole both increase QTc interval. Modify Therapy/Monitor Closely. - fluoxetine
fluoxetine and trimethoprim both increase QTc interval. Use Caution/Monitor.
fluoxetine will increase the level or effect of sulfamethoxazole by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor. - fluphenazine
fluphenazine and trimethoprim both increase QTc interval. Modify Therapy/Monitor Closely.
fluphenazine and sulfamethoxazole both increase QTc interval. Modify Therapy/Monitor Closely. - fluvoxamine
fluvoxamine and trimethoprim both increase QTc interval. Use Caution/Monitor.
fluvoxamine and sulfamethoxazole both increase QTc interval. Use Caution/Monitor. - formoterol
sulfamethoxazole and formoterol both increase QTc interval. Modify Therapy/Monitor Closely.
formoterol and trimethoprim both increase QTc interval. Modify Therapy/Monitor Closely. - foscarnet
sulfamethoxazole and foscarnet both increase QTc interval. Use Caution/Monitor.
foscarnet and trimethoprim both increase QTc interval. Use Caution/Monitor. - fosinopril
trimethoprim and fosinopril both increase serum potassium. Use Caution/Monitor. Trimethoprim decreases urinary potassium excretion. May cause hyperkalemia, particularly with high doses, renal insufficiency, or when combined with other drugs that cause hyperkalemia.
- fosphenytoin
sulfamethoxazole will increase the level or effect of fosphenytoin by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.
- fosphenytoin
fosphenytoin will decrease the level or effect of trimethoprim by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- glimepiride
sulfamethoxazole increases levels of glimepiride by plasma protein binding competition. Use Caution/Monitor.
- glipizide
sulfamethoxazole increases levels of glipizide by plasma protein binding competition. Use Caution/Monitor.
- glucarpidase
glucarpidase will decrease the level or effect of sulfamethoxazole by increasing metabolism. Modify Therapy/Monitor Closely. Leucorvorin, reduced folates, and folate antimetabolites are substrates for glucarpidase (hydrolyzes glutamate residue from folic acid and antifolates)
glucarpidase will decrease the level or effect of trimethoprim by increasing metabolism. Modify Therapy/Monitor Closely. Leucorvorin, reduced folates, and folate antimetabolites are substrates for glucarpidase (hydrolyzes glutamate residue from folic acid and antifolates) - glyburide
sulfamethoxazole increases levels of glyburide by plasma protein binding competition. Use Caution/Monitor.
sulfamethoxazole increases levels of glyburide by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor. Strong CYP2C9 inhibitors may decrease glyburide metabolism. - haloperidol
haloperidol and trimethoprim both increase QTc interval. Modify Therapy/Monitor Closely.
- haloperidol
sulfamethoxazole and haloperidol both increase QTc interval. Modify Therapy/Monitor Closely.
- iloperidone
sulfamethoxazole and iloperidone both increase QTc interval. Use Caution/Monitor.
iloperidone and trimethoprim both increase QTc interval. Use Caution/Monitor.
iloperidone increases levels of trimethoprim by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Iloperidone is a time-dependent CYP3A inhibitor and may lead to increased plasma levels of drugs predominantly eliminated by CYP3A4. - imatinib
imatinib will increase the level or effect of sulfamethoxazole by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.
- imipramine
imipramine and trimethoprim both increase QTc interval. Modify Therapy/Monitor Closely.
- imidapril
sulfamethoxazole, imidapril. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Risk of hyperkalemia.
- imipramine
imipramine and sulfamethoxazole both increase QTc interval. Modify Therapy/Monitor Closely.
- indinavir
indinavir will increase the level or effect of trimethoprim by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- irbesartan
trimethoprim and irbesartan both increase serum potassium. Use Caution/Monitor. Trimethoprim decreases urinary potassium excretion. May cause hyperkalemia, particularly with high doses, renal insufficiency, or when combined with other drugs that cause hyperkalemia.
- istradefylline
istradefylline will increase the level or effect of trimethoprim by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Istradefylline 40 mg/day increased peak levels and AUC of CYP3A4 substrates in clinical trials. This effect was not observed with istradefylline 20 mg/day. Consider dose reduction of sensitive CYP3A4 substrates.
- itraconazole
sulfamethoxazole and itraconazole both increase QTc interval. Modify Therapy/Monitor Closely.
itraconazole and trimethoprim both increase QTc interval. Modify Therapy/Monitor Closely. - ketoconazole
ketoconazole and trimethoprim both increase QTc interval. Modify Therapy/Monitor Closely.
sulfamethoxazole and ketoconazole both increase QTc interval. Modify Therapy/Monitor Closely. - L-methylfolate
trimethoprim decreases effects of L-methylfolate by Mechanism: pharmacodynamic antagonism. Use Caution/Monitor. Folic acid antagonists may interfere with folic acid utilization.
- lacosamide
sulfamethoxazole increases levels of lacosamide by affecting hepatic enzyme CYP2C9/10 metabolism. Modify Therapy/Monitor Closely. Consider decreasing lacosamide dose when coadministered with strong CYP2C9 inhibitors.
- lamivudine
trimethoprim increases effects of lamivudine by basic (cationic) drug competition for renal tubular clearance. Use Caution/Monitor. Potential for increased toxicity.
- lapatinib
sulfamethoxazole and lapatinib both increase QTc interval. Use Caution/Monitor.
- lenacapavir
lenacapavir will increase the level or effect of trimethoprim by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Lencapavir may increase CYP3A4 substrates initiated within 9 months after last SC dose of lenacapavir, which may increase potential risk of adverse reactions of CYP3A4 substrates.
- lesinurad
sulfamethoxazole will increase the level or effect of lesinurad by affecting hepatic enzyme CYP2C9/10 metabolism. Modify Therapy/Monitor Closely.
- levofloxacin
sulfamethoxazole and levofloxacin both increase QTc interval. Use Caution/Monitor.
levofloxacin and trimethoprim both increase QTc interval. Use Caution/Monitor. - levoketoconazole
levoketoconazole and trimethoprim both increase QTc interval. Modify Therapy/Monitor Closely.
sulfamethoxazole and levoketoconazole both increase QTc interval. Modify Therapy/Monitor Closely. - levonorgestrel oral/ethinylestradiol/ferrous bisglycinate
trimethoprim will decrease the level or effect of levonorgestrel oral/ethinylestradiol/ferrous bisglycinate by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor. Antibiotics may decrease hormonal contraceptive efficacy.
sulfamethoxazole will decrease the level or effect of levonorgestrel oral/ethinylestradiol/ferrous bisglycinate by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor. Antibiotics may decrease hormonal contraceptive efficacy. - lisinopril
trimethoprim and lisinopril both increase serum potassium. Use Caution/Monitor. Trimethoprim decreases urinary potassium excretion. May cause hyperkalemia, particularly with high doses, renal insufficiency, or when combined with other drugs that cause hyperkalemia.
- lofepramine
lofepramine and sulfamethoxazole both increase QTc interval. Modify Therapy/Monitor Closely.
- lofepramine
lofepramine and trimethoprim both increase QTc interval. Modify Therapy/Monitor Closely.
- losartan
sulfamethoxazole will increase the level or effect of losartan by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor. May inhibit the conversion of losartan to its active metabolite E-3174. Importance of interaction not established; monitor individual therapeutic response to determine losartan dosage.
trimethoprim and losartan both increase serum potassium. Use Caution/Monitor. Trimethoprim decreases urinary potassium excretion. May cause hyperkalemia, particularly with high doses, renal insufficiency, or when combined with other drugs that cause hyperkalemia. - lumacaftor/ivacaftor
lumacaftor/ivacaftor, trimethoprim. affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor. In vitro studies suggest that lumacaftor may induce and ivacaftor may inhibit CYP2C9 substrates. .
- lumefantrine
sulfamethoxazole and lumefantrine both increase QTc interval. Modify Therapy/Monitor Closely.
- lumefantrine
lumefantrine and trimethoprim both increase QTc interval. Modify Therapy/Monitor Closely.
- maprotiline
maprotiline and sulfamethoxazole both increase QTc interval. Modify Therapy/Monitor Closely.
maprotiline and trimethoprim both increase QTc interval. Modify Therapy/Monitor Closely. - mestranol
trimethoprim will decrease the level or effect of mestranol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.
sulfamethoxazole will decrease the level or effect of mestranol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor. - metformin
trimethoprim increases levels of metformin by Other (see comment). Use Caution/Monitor. Comment: Trimethoprim may inhibit active renal tubular secretion of metformin (eg, via OCT2, MATE1); dose adjustments may be necessary.
- methadone
sulfamethoxazole and methadone both increase QTc interval. Use Caution/Monitor.
- methadone
methadone and trimethoprim both increase QTc interval. Use Caution/Monitor.
- methotrexate
trimethoprim increases toxicity of methotrexate by Other (see comment). Use Caution/Monitor. Comment: Trimethoprim may increase risk of methotrexate-induced bone marrow suppression and megaloblastic anemia. If this drug combination cannot be avoided, closely monitor for signs of hematologic toxicity.
- methoxsalen
methoxsalen, sulfamethoxazole. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Additive photosensitizing effects.
- metronidazole
metronidazole, sulfamethoxazole. Mechanism: decreasing metabolism. Use Caution/Monitor. Disulfiram like reaction.
- mipomersen
mipomersen, sulfamethoxazole. Either increases toxicity of the other by Other (see comment). Use Caution/Monitor. Comment: Both drugs have potential to increase hepatic enzymes; monitor LFTs.
- mitotane
mitotane decreases levels of trimethoprim by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Mitotane is a strong inducer of cytochrome P-4503A4; monitor when coadministered with CYP3A4 substrates for possible dosage adjustments.
- moexipril
trimethoprim and moexipril both increase serum potassium. Use Caution/Monitor. Trimethoprim decreases urinary potassium excretion. May cause hyperkalemia, particularly with high doses, renal insufficiency, or when combined with other drugs that cause hyperkalemia.
- moxifloxacin
sulfamethoxazole and moxifloxacin both increase QTc interval. Modify Therapy/Monitor Closely.
moxifloxacin and trimethoprim both increase QTc interval. Modify Therapy/Monitor Closely. - nateglinide
sulfamethoxazole will increase the level or effect of nateglinide by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.
sulfamethoxazole increases levels of nateglinide by plasma protein binding competition. Use Caution/Monitor. - nitisinone
nitisinone will increase the level or effect of trimethoprim by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor. Nitisinone inhibits CYP2C9. Caution if CYP2C9 substrate coadministered, particularly those with a narrow therapeutic index.
- nilotinib
sulfamethoxazole and nilotinib both increase QTc interval. Modify Therapy/Monitor Closely.
- nortriptyline
nortriptyline and sulfamethoxazole both increase QTc interval. Modify Therapy/Monitor Closely.
nortriptyline and trimethoprim both increase QTc interval. Modify Therapy/Monitor Closely. - octreotide
octreotide and trimethoprim both increase QTc interval. Modify Therapy/Monitor Closely.
sulfamethoxazole and octreotide both increase QTc interval. Modify Therapy/Monitor Closely. - octreotide (Antidote)
octreotide (Antidote) and trimethoprim both increase QTc interval. Modify Therapy/Monitor Closely.
sulfamethoxazole and octreotide (Antidote) both increase QTc interval. Modify Therapy/Monitor Closely. - ofloxacin
sulfamethoxazole and ofloxacin both increase QTc interval. Use Caution/Monitor.
ofloxacin and trimethoprim both increase QTc interval. Use Caution/Monitor. - olmesartan
trimethoprim and olmesartan both increase serum potassium. Use Caution/Monitor. Trimethoprim decreases urinary potassium excretion. May cause hyperkalemia, particularly with high doses, renal insufficiency, or when combined with other drugs that cause hyperkalemia.
- ospemifene
sulfamethoxazole increases levels of ospemifene by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.
sulfamethoxazole, ospemifene. Either increases levels of the other by plasma protein binding competition. Modify Therapy/Monitor Closely. - paclitaxel
trimethoprim will increase the level or effect of paclitaxel by Other (see comment). Use Caution/Monitor. Paclitaxel levels/toxicity may increase when coadministered with CYP2C8 inhibitors
- paclitaxel protein bound
trimethoprim will increase the level or effect of paclitaxel protein bound by Other (see comment). Use Caution/Monitor. Paclitaxel levels/toxicity may increase when coadministered with CYP2C8 inhibitors
- paliperidone
sulfamethoxazole and paliperidone both increase QTc interval. Use Caution/Monitor.
paliperidone and trimethoprim both increase QTc interval. Use Caution/Monitor. - parecoxib
sulfamethoxazole will increase the level or effect of parecoxib by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.
- paroxetine
paroxetine and trimethoprim both increase QTc interval. Use Caution/Monitor.
- paroxetine
sulfamethoxazole and paroxetine both increase QTc interval. Use Caution/Monitor.
- pentamidine
trimethoprim and pentamidine both increase serum potassium. Use Caution/Monitor. Trimethoprim decreases urinary potassium excretion. May cause hyperkalemia, particularly with high doses, renal insufficiency, or when combined with other drugs that cause hyperkalemia.
- perindopril
trimethoprim and perindopril both increase serum potassium. Use Caution/Monitor. Trimethoprim decreases urinary potassium excretion. May cause hyperkalemia, particularly with high doses, renal insufficiency, or when combined with other drugs that cause hyperkalemia.
- perphenazine
perphenazine and trimethoprim both increase QTc interval. Modify Therapy/Monitor Closely.
perphenazine and sulfamethoxazole both increase QTc interval. Modify Therapy/Monitor Closely. - phenytoin
sulfamethoxazole will increase the level or effect of phenytoin by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.
- posaconazole
posaconazole and trimethoprim both increase QTc interval. Use Caution/Monitor.
- porfimer
sulfamethoxazole, porfimer. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Enhanced photosensitivity.
- posaconazole
sulfamethoxazole and posaconazole both increase QTc interval. Use Caution/Monitor.
- potassium acid phosphate
trimethoprim and potassium acid phosphate both increase serum potassium. Use Caution/Monitor. Trimethoprim decreases urinary potassium excretion. May cause hyperkalemia, particularly with high doses, renal insufficiency, or when combined with other drugs that cause hyperkalemia.
- potassium chloride
trimethoprim and potassium chloride both increase serum potassium. Use Caution/Monitor. Trimethoprim decreases urinary potassium excretion. May cause hyperkalemia, particularly with high doses, renal insufficiency, or when combined with other drugs that cause hyperkalemia.
- potassium citrate
trimethoprim and potassium citrate both increase serum potassium. Use Caution/Monitor. Trimethoprim decreases urinary potassium excretion. May cause hyperkalemia, particularly with high doses, renal insufficiency, or when combined with other drugs that cause hyperkalemia.
- potassium citrate/citric acid
trimethoprim and potassium citrate/citric acid both increase serum potassium. Use Caution/Monitor.
- pralatrexate
sulfamethoxazole increases levels of pralatrexate by decreasing renal clearance. Use Caution/Monitor.
- procainamide
sulfamethoxazole will increase the level or effect of procainamide by basic (cationic) drug competition for renal tubular clearance. Use Caution/Monitor.
procainamide will increase the level or effect of trimethoprim by basic (cationic) drug competition for renal tubular clearance. Use Caution/Monitor. - prochlorperazine
prochlorperazine and sulfamethoxazole both increase QTc interval. Modify Therapy/Monitor Closely.
prochlorperazine and trimethoprim both increase QTc interval. Modify Therapy/Monitor Closely. - promazine
promazine and sulfamethoxazole both increase QTc interval. Modify Therapy/Monitor Closely.
promazine and trimethoprim both increase QTc interval. Modify Therapy/Monitor Closely.
promazine increases toxicity of sulfamethoxazole by unspecified interaction mechanism. Use Caution/Monitor. Enhanced myelosuppression. - promethazine
promethazine and trimethoprim both increase QTc interval. Modify Therapy/Monitor Closely.
promethazine and sulfamethoxazole both increase QTc interval. Modify Therapy/Monitor Closely. - protriptyline
protriptyline and sulfamethoxazole both increase QTc interval. Modify Therapy/Monitor Closely.
protriptyline and trimethoprim both increase QTc interval. Modify Therapy/Monitor Closely. - quinapril
trimethoprim and quinapril both increase serum potassium. Use Caution/Monitor. Trimethoprim decreases urinary potassium excretion. May cause hyperkalemia, particularly with high doses, renal insufficiency, or when combined with other drugs that cause hyperkalemia.
- quinidine
quinidine will increase the level or effect of sulfamethoxazole by basic (cationic) drug competition for renal tubular clearance. Use Caution/Monitor.
- quinidine
quinidine will increase the level or effect of trimethoprim by basic (cationic) drug competition for renal tubular clearance. Use Caution/Monitor.
- ramipril
trimethoprim and ramipril both increase serum potassium. Use Caution/Monitor. Trimethoprim decreases urinary potassium excretion. May cause hyperkalemia, particularly with high doses, renal insufficiency, or when combined with other drugs that cause hyperkalemia.
- ranolazine
sulfamethoxazole and ranolazine both increase QTc interval. Use Caution/Monitor.
ranolazine and trimethoprim both increase QTc interval. Use Caution/Monitor. - repaglinide
trimethoprim increases levels of repaglinide by decreasing metabolism. Use Caution/Monitor. Hepatic cytochrome P450 2C8.
sulfamethoxazole increases levels of repaglinide by plasma protein binding competition. Use Caution/Monitor. - rifabutin
rifabutin will decrease the level or effect of trimethoprim by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- risperidone
sulfamethoxazole and risperidone both increase QTc interval. Use Caution/Monitor.
- rifampin
rifampin will decrease the level or effect of trimethoprim by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- risperidone
risperidone and trimethoprim both increase QTc interval. Use Caution/Monitor.
- sacubitril/valsartan
sacubitril/valsartan and trimethoprim both increase serum potassium. Use Caution/Monitor. Trimethoprim decreases urinary potassium excretion. May cause hyperkalemia, particularly with high doses, renal insufficiency, or when combined with other drugs that cause hyperkalemia.
- selexipag
trimethoprim will increase the level or effect of selexipag by decreasing metabolism. Modify Therapy/Monitor Closely. Reduce selexipag dose to once daily if coadministered with moderate CYP2C8 inhibitors.
- sodium picosulfate/magnesium oxide/anhydrous citric acid
trimethoprim decreases effects of sodium picosulfate/magnesium oxide/anhydrous citric acid by altering metabolism. Use Caution/Monitor. Coadministration with antibiotics decreases efficacy by altering colonic bacterial flora needed to convert sodium picosulfate to active drug.
sulfamethoxazole decreases effects of sodium picosulfate/magnesium oxide/anhydrous citric acid by altering metabolism. Use Caution/Monitor. Coadministration with antibiotics decreases efficacy by altering colonic bacterial flora needed to convert sodium picosulfate to active drug. - sparsentan
sparsentan will decrease the level or effect of trimethoprim 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.
- tamoxifen
sulfamethoxazole, tamoxifen. affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor. CYP2C9/10 inhibition decreases tamoxifen metabolism to active metabolites.
- spironolactone
trimethoprim and spironolactone both increase serum potassium. Use Caution/Monitor. Trimethoprim decreases urinary potassium excretion. May cause hyperkalemia, particularly with high doses, renal insufficiency, or when combined with other drugs that cause hyperkalemia.
- sulfamethoxazole
sulfamethoxazole and trimethoprim both increase QTc interval. Use Caution/Monitor.
- tecovirimat
tecovirimat will decrease the level or effect of trimethoprim by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Tecovirimat is a weak CYP3A4 inducer. Monitor sensitive CYP3A4 substrates for effectiveness if coadministered.
- telavancin
telavancin and trimethoprim both increase QTc interval. Use Caution/Monitor.
sulfamethoxazole and telavancin both increase QTc interval. Use Caution/Monitor. - telmisartan
trimethoprim and telmisartan both increase serum potassium. Use Caution/Monitor. Trimethoprim decreases urinary potassium excretion. May cause hyperkalemia, particularly with high doses, renal insufficiency, or when combined with other drugs that cause hyperkalemia.
- terbinafine
sulfamethoxazole will increase the level or effect of terbinafine by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.
- thioridazine
thioridazine and sulfamethoxazole both increase QTc interval. Modify Therapy/Monitor Closely.
thioridazine and trimethoprim both increase QTc interval. Modify Therapy/Monitor Closely. - tolazamide
sulfamethoxazole increases levels of tolazamide by plasma protein binding competition. Use Caution/Monitor.
- trandolapril
trimethoprim and trandolapril both increase serum potassium. Use Caution/Monitor. Trimethoprim decreases urinary potassium excretion. May cause hyperkalemia, particularly with high doses, renal insufficiency, or when combined with other drugs that cause hyperkalemia.
- tolbutamide
sulfamethoxazole increases levels of tolbutamide by plasma protein binding competition. Use Caution/Monitor.
- trazodone
trazodone and sulfamethoxazole both increase QTc interval. Modify Therapy/Monitor Closely.
trazodone and trimethoprim both increase QTc interval. Modify Therapy/Monitor Closely. - triamterene
trimethoprim and triamterene both increase serum potassium. Use Caution/Monitor. Trimethoprim decreases urinary potassium excretion. May cause hyperkalemia, particularly with high doses, renal insufficiency, or when combined with other drugs that cause hyperkalemia.
- trifluoperazine
trifluoperazine and sulfamethoxazole both increase QTc interval. Modify Therapy/Monitor Closely.
- trifluoperazine
trifluoperazine and trimethoprim both increase QTc interval. Modify Therapy/Monitor Closely.
- trimethoprim
sulfamethoxazole and trimethoprim both increase QTc interval. Use Caution/Monitor.
- trimipramine
trimipramine and trimethoprim both increase QTc interval. Modify Therapy/Monitor Closely.
trimipramine and sulfamethoxazole both increase QTc interval. Modify Therapy/Monitor Closely. - tropisetron
trimethoprim and tropisetron both increase QTc interval. Use Caution/Monitor.
sulfamethoxazole and tropisetron both increase QTc interval. Use Caution/Monitor. - valsartan
valsartan and trimethoprim both increase serum potassium. Use Caution/Monitor. Trimethoprim decreases urinary potassium excretion. May cause hyperkalemia, particularly with high doses, renal insufficiency, or when combined with other drugs that cause hyperkalemia.
- venlafaxine
sulfamethoxazole and venlafaxine both increase QTc interval. Use Caution/Monitor.
- venlafaxine
trimethoprim and venlafaxine both increase QTc interval. Use Caution/Monitor.
- voclosporin
voclosporin and trimethoprim both decrease serum potassium. Use Caution/Monitor.
- voriconazole
trimethoprim and voriconazole both increase QTc interval. Use Caution/Monitor.
sulfamethoxazole and voriconazole both increase QTc interval. Use Caution/Monitor. - warfarin
sulfamethoxazole will increase the level or effect of warfarin by affecting hepatic enzyme CYP2C9/10 metabolism. Modify Therapy/Monitor Closely. Mechanism of interaction may be caused by CYP2C9 inhibition and protein-binding displacement. If coadministered, consider decreasing warfarin dose by 10-20%.
- zidovudine
trimethoprim increases levels of zidovudine by decreasing renal clearance. Use Caution/Monitor. Potential for increased toxicity. .
- ziprasidone
sulfamethoxazole and ziprasidone both increase QTc interval. Modify Therapy/Monitor Closely.
trimethoprim and ziprasidone both increase QTc interval. Modify Therapy/Monitor Closely.
Minor (137)
- acetazolamide
acetazolamide will increase the level or effect of trimethoprim by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.
- alosetron
sulfamethoxazole will increase the level or effect of alosetron by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.
- amiloride
amiloride, trimethoprim. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Hyperkalemia.
amiloride, sulfamethoxazole. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Hyperkalemia.
amiloride increases levels of sulfamethoxazole by unspecified interaction mechanism. Minor/Significance Unknown. - aminohippurate sodium
sulfamethoxazole, aminohippurate sodium. Other (see comment). Minor/Significance Unknown. Comment: This substance interferes with chemical color development of aminohippurate (PAH) essential to accurate renal clearance analysis.
- anastrozole
anastrozole will increase the level or effect of trimethoprim by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.
- amiodarone
amiodarone will increase the level or effect of sulfamethoxazole by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.
- amitriptyline
sulfamethoxazole decreases levels of amitriptyline by unspecified interaction mechanism. Minor/Significance Unknown.
- amobarbital
amobarbital will decrease the level or effect of sulfamethoxazole by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.
- amoxapine
sulfamethoxazole decreases levels of amoxapine by unspecified interaction mechanism. Minor/Significance Unknown.
- aspirin rectal
aspirin rectal increases levels of sulfamethoxazole by unspecified interaction mechanism. Minor/Significance Unknown.
- aspirin/citric acid/sodium bicarbonate
aspirin/citric acid/sodium bicarbonate increases levels of sulfamethoxazole by unspecified interaction mechanism. Minor/Significance Unknown.
- azathioprine
sulfamethoxazole, azathioprine. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Leukopenia due to additive myelosuppression.
- azithromycin
azithromycin and sulfamethoxazole both increase QTc interval. Minor/Significance Unknown.
azithromycin and trimethoprim both increase QTc interval. Minor/Significance Unknown. - balsalazide
trimethoprim will decrease the level or effect of balsalazide by altering intestinal flora. Applies only to oral form of both agents. Minor/Significance Unknown.
sulfamethoxazole will decrease the level or effect of balsalazide by altering intestinal flora. Applies only to oral form of both agents. Minor/Significance Unknown.
balsalazide increases levels of sulfamethoxazole by unspecified interaction mechanism. Minor/Significance Unknown. - bendroflumethiazide
bendroflumethiazide, trimethoprim. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Risk of hyponatremia.
bendroflumethiazide, sulfamethoxazole. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Risk of hyponatremia.
bendroflumethiazide increases levels of sulfamethoxazole by unspecified interaction mechanism. Minor/Significance Unknown. - biotin
trimethoprim will decrease the level or effect of biotin by altering intestinal flora. Applies only to oral form of both agents. Minor/Significance Unknown.
sulfamethoxazole will decrease the level or effect of biotin by altering intestinal flora. Applies only to oral form of both agents. Minor/Significance Unknown. - bosentan
sulfamethoxazole will increase the level or effect of bosentan by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.
- chlorothiazide
chlorothiazide, trimethoprim. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Risk of hyponatremia.
- bumetanide
bumetanide increases levels of sulfamethoxazole by unspecified interaction mechanism. Minor/Significance Unknown.
- butabarbital
butabarbital will decrease the level or effect of sulfamethoxazole by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.
- butalbital
butalbital will decrease the level or effect of sulfamethoxazole by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.
- carbamazepine
carbamazepine will decrease the level or effect of sulfamethoxazole by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.
- celecoxib
sulfamethoxazole will increase the level or effect of celecoxib by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.
- chlorothiazide
chlorothiazide increases levels of sulfamethoxazole by unspecified interaction mechanism. Minor/Significance Unknown.
chlorothiazide, sulfamethoxazole. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Risk of hyponatremia. - chlorthalidone
chlorthalidone increases levels of sulfamethoxazole by unspecified interaction mechanism. Minor/Significance Unknown.
chlorthalidone, trimethoprim. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Risk of hyponatremia.
chlorthalidone, sulfamethoxazole. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Risk of hyponatremia. - choline magnesium trisalicylate
choline magnesium trisalicylate increases levels of sulfamethoxazole by unspecified interaction mechanism. Minor/Significance Unknown.
- cyclopenthiazide
cyclopenthiazide, trimethoprim. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Risk of hyponatremia.
- cimetidine
cimetidine will increase the level or effect of sulfamethoxazole by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.
- clomipramine
sulfamethoxazole decreases levels of clomipramine by unspecified interaction mechanism. Minor/Significance Unknown.
- cyclopenthiazide
cyclopenthiazide increases levels of sulfamethoxazole by unspecified interaction mechanism. Minor/Significance Unknown.
cyclopenthiazide, sulfamethoxazole. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Risk of hyponatremia. - cyclophosphamide
cyclophosphamide will increase the level or effect of trimethoprim by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.
- dapsone
sulfamethoxazole, dapsone. Either increases levels of the other by decreasing elimination. Minor/Significance Unknown.
trimethoprim, dapsone. Either increases levels of the other by decreasing elimination. Minor/Significance Unknown. - desipramine
sulfamethoxazole decreases levels of desipramine by unspecified interaction mechanism. Minor/Significance Unknown.
- drospirenone
drospirenone, trimethoprim. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Hyperkalemia.
- diclofenac
sulfamethoxazole will increase the level or effect of diclofenac by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.
- diflunisal
diflunisal increases levels of sulfamethoxazole by unspecified interaction mechanism. Minor/Significance Unknown.
- diltiazem
sulfamethoxazole will increase the level or effect of diltiazem by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown.
- disulfiram
disulfiram will increase the level or effect of sulfamethoxazole by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.
- dosulepin
sulfamethoxazole decreases levels of dosulepin by unspecified interaction mechanism. Minor/Significance Unknown.
- doxepin
sulfamethoxazole decreases levels of doxepin by unspecified interaction mechanism. Minor/Significance Unknown.
- drospirenone
drospirenone, sulfamethoxazole. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Hyperkalemia.
drospirenone increases levels of sulfamethoxazole by unspecified interaction mechanism. Minor/Significance Unknown. - ethacrynic acid
ethacrynic acid increases levels of sulfamethoxazole by unspecified interaction mechanism. Minor/Significance Unknown.
- ethotoin
sulfamethoxazole increases levels of ethotoin by decreasing metabolism. Minor/Significance Unknown.
- etravirine
etravirine will increase the level or effect of sulfamethoxazole by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.
- felbamate
felbamate will increase the level or effect of sulfamethoxazole by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.
- fluconazole
fluconazole will increase the level or effect of sulfamethoxazole by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.
- flurbiprofen
sulfamethoxazole will increase the level or effect of flurbiprofen by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.
- fluvastatin
sulfamethoxazole will increase the level or effect of fluvastatin by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.
- folic acid
sulfamethoxazole decreases levels of folic acid by inhibition of GI absorption. Applies only to oral form of both agents. Minor/Significance Unknown.
- fosphenytoin
sulfamethoxazole increases levels of fosphenytoin by decreasing metabolism. Minor/Significance Unknown.
- furosemide
furosemide increases levels of sulfamethoxazole by unspecified interaction mechanism. Minor/Significance Unknown.
- ganciclovir
ganciclovir increases toxicity of sulfamethoxazole by pharmacodynamic synergism. Minor/Significance Unknown.
- hydrochlorothiazide
hydrochlorothiazide will increase the level or effect of trimethoprim by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown.
hydrochlorothiazide, sulfamethoxazole. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Risk of hyponatremia.
hydrochlorothiazide, trimethoprim. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Risk of hyponatremia.
hydrochlorothiazide increases levels of sulfamethoxazole by unspecified interaction mechanism. Minor/Significance Unknown.
sulfamethoxazole will increase the level or effect of hydrochlorothiazide by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown. - ibuprofen
sulfamethoxazole will increase the level or effect of ibuprofen by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.
- indapamide
indapamide, trimethoprim. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Risk of hyponatremia.
- ibuprofen IV
sulfamethoxazole will increase the level or effect of ibuprofen IV by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.
- imipramine
sulfamethoxazole decreases levels of imipramine by unspecified interaction mechanism. Minor/Significance Unknown.
- indapamide
indapamide increases levels of sulfamethoxazole by unspecified interaction mechanism. Minor/Significance Unknown.
indapamide, sulfamethoxazole. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Risk of hyponatremia. - indomethacin
indomethacin increases levels of sulfamethoxazole by unspecified interaction mechanism. Minor/Significance Unknown.
- isavuconazonium sulfate
isavuconazonium sulfate will increase the level or effect of trimethoprim by Other (see comment). Minor/Significance Unknown. Isavuconazonium sulfate, an OCT2 inhibitor, may increase the effects or levels of OCT2 substrates.
- isocarboxazid
isocarboxazid increases levels of sulfamethoxazole by unspecified interaction mechanism. Minor/Significance Unknown.
- ketoconazole
ketoconazole will increase the level or effect of sulfamethoxazole by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.
- L-methylfolate
sulfamethoxazole decreases levels of L-methylfolate by inhibition of GI absorption. Applies only to oral form of both agents. Minor/Significance Unknown.
- lamivudine
sulfamethoxazole increases levels of lamivudine by decreasing renal clearance. Minor/Significance Unknown.
- larotrectinib
larotrectinib will increase the level or effect of trimethoprim by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.
- leflunomide
leflunomide will increase the level or effect of sulfamethoxazole by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.
- levoketoconazole
levoketoconazole will increase the level or effect of sulfamethoxazole by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.
levoketoconazole will increase the level or effect of trimethoprim by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown. - linezolid
linezolid increases levels of sulfamethoxazole by unspecified interaction mechanism. Minor/Significance Unknown.
- memantine
memantine will increase the level or effect of trimethoprim by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown.
- lofepramine
sulfamethoxazole decreases levels of lofepramine by unspecified interaction mechanism. Minor/Significance Unknown.
- losartan
sulfamethoxazole decreases effects of losartan by decreasing metabolism. Minor/Significance Unknown. May inhibit the conversion of losartan to its active metabolite E-3174. Importance of interaction not established; monitor individual therapeutic response to determine losartan dosage.
- maprotiline
sulfamethoxazole decreases levels of maprotiline by unspecified interaction mechanism. Minor/Significance Unknown.
- meloxicam
sulfamethoxazole will increase the level or effect of meloxicam by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.
- memantine
sulfamethoxazole will increase the level or effect of memantine by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown.
- mesalamine
mesalamine increases levels of sulfamethoxazole by unspecified interaction mechanism. Minor/Significance Unknown.
- metformin
sulfamethoxazole will increase the level or effect of metformin by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown.
metformin will increase the level or effect of trimethoprim by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown. - methyclothiazide
methyclothiazide, sulfamethoxazole. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Risk of hyponatremia.
methyclothiazide will increase the level or effect of trimethoprim by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown.
methyclothiazide, trimethoprim. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Risk of hyponatremia.
sulfamethoxazole will increase the level or effect of methyclothiazide by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown. - metolazone
metolazone, trimethoprim. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Risk of hyponatremia.
metolazone, sulfamethoxazole. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Risk of hyponatremia.
metolazone increases levels of sulfamethoxazole by unspecified interaction mechanism. Minor/Significance Unknown. - metronidazole
metronidazole will increase the level or effect of sulfamethoxazole by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.
- midodrine
midodrine will increase the level or effect of trimethoprim by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown.
- miconazole vaginal
miconazole vaginal will increase the level or effect of sulfamethoxazole by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.
- midodrine
sulfamethoxazole will increase the level or effect of midodrine by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown.
- mineral oil
mineral oil decreases levels of sulfamethoxazole by inhibition of GI absorption. Applies only to oral form of both agents. Minor/Significance Unknown.
- nateglinide
nateglinide will increase the level or effect of sulfamethoxazole by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.
- nilotinib
nilotinib will increase the level or effect of sulfamethoxazole by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.
- nitazoxanide
nitazoxanide, sulfamethoxazole. Either increases levels of the other by Mechanism: plasma protein binding competition. Minor/Significance Unknown.
- nortriptyline
sulfamethoxazole decreases levels of nortriptyline by unspecified interaction mechanism. Minor/Significance Unknown.
- ofloxacin
ofloxacin will increase the level or effect of trimethoprim by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown.
sulfamethoxazole will increase the level or effect of ofloxacin by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown. - omeprazole
omeprazole will increase the level or effect of sulfamethoxazole by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.
- pantothenic acid
trimethoprim will decrease the level or effect of pantothenic acid by altering intestinal flora. Applies only to oral form of both agents. Minor/Significance Unknown.
- pantothenic acid
sulfamethoxazole will decrease the level or effect of pantothenic acid by altering intestinal flora. Applies only to oral form of both agents. Minor/Significance Unknown.
- patiromer
patiromer, trimethoprim. cation binding in GI tract. Minor/Significance Unknown. No observed clinically important interaction. No separation of dosing required.
- pazopanib
sulfamethoxazole and pazopanib both increase QTc interval. Minor/Significance Unknown.
- pentobarbital
pentobarbital will decrease the level or effect of sulfamethoxazole by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.
- phenelzine
phenelzine increases levels of sulfamethoxazole by unspecified interaction mechanism. Minor/Significance Unknown.
- phenobarbital
phenobarbital will decrease the level or effect of sulfamethoxazole by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.
- phenytoin
sulfamethoxazole increases levels of phenytoin by decreasing metabolism. Minor/Significance Unknown.
- pimozide
sulfamethoxazole decreases levels of pimozide by unspecified interaction mechanism. Minor/Significance Unknown.
- piroxicam
sulfamethoxazole will increase the level or effect of piroxicam by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.
- primaquine
primaquine, sulfamethoxazole. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Risk of hemolysis in G6PD deficient pts.
- primidone
primidone will decrease the level or effect of sulfamethoxazole by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.
- probenecid
probenecid increases levels of sulfamethoxazole by unspecified interaction mechanism. Minor/Significance Unknown.
- protriptyline
sulfamethoxazole decreases levels of protriptyline by unspecified interaction mechanism. Minor/Significance Unknown.
- pyridoxine
sulfamethoxazole will decrease the level or effect of pyridoxine by altering intestinal flora. Applies only to oral form of both agents. Minor/Significance Unknown.
trimethoprim will decrease the level or effect of pyridoxine by altering intestinal flora. Applies only to oral form of both agents. Minor/Significance Unknown. - pyridoxine (Antidote)
sulfamethoxazole will decrease the level or effect of pyridoxine (Antidote) by altering intestinal flora. Applies only to oral form of both agents. Minor/Significance Unknown.
trimethoprim will decrease the level or effect of pyridoxine (Antidote) by altering intestinal flora. Applies only to oral form of both agents. Minor/Significance Unknown. - pyrimethamine
sulfamethoxazole, pyrimethamine. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Increased bone marrow toxicity.
- quinine
quinine will increase the level or effect of trimethoprim by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown.
- quinine
sulfamethoxazole will increase the level or effect of quinine by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown.
- ramelteon
sulfamethoxazole will increase the level or effect of ramelteon by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.
- ribociclib
ribociclib will increase the level or effect of trimethoprim by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.
- rifampin
rifampin will decrease the level or effect of sulfamethoxazole by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.
- rifapentine
rifapentine will decrease the level or effect of sulfamethoxazole by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.
- salicylates (non-asa)
salicylates (non-asa) increases levels of sulfamethoxazole by unspecified interaction mechanism. Minor/Significance Unknown.
- salsalate
salsalate increases levels of sulfamethoxazole by unspecified interaction mechanism. Minor/Significance Unknown.
- secobarbital
secobarbital will decrease the level or effect of sulfamethoxazole by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.
- selegiline transdermal
selegiline transdermal increases levels of sulfamethoxazole by unspecified interaction mechanism. Minor/Significance Unknown.
- spironolactone
spironolactone, sulfamethoxazole. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Hyperkalemia.
spironolactone, trimethoprim. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Hyperkalemia.
spironolactone increases levels of sulfamethoxazole by unspecified interaction mechanism. Minor/Significance Unknown. - sulfamethoxazole
sulfamethoxazole will increase the level or effect of trimethoprim by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown.
- sulfasalazine
sulfasalazine increases levels of sulfamethoxazole by unspecified interaction mechanism. Minor/Significance Unknown.
- thiamine
sulfamethoxazole will decrease the level or effect of thiamine by altering intestinal flora. Applies only to oral form of both agents. Minor/Significance Unknown.
trimethoprim will decrease the level or effect of thiamine by altering intestinal flora. Applies only to oral form of both agents. Minor/Significance Unknown. - ticlopidine
ticlopidine will increase the level or effect of sulfamethoxazole by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.
- triamterene
triamterene will increase the level or effect of trimethoprim by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown.
triamterene, trimethoprim. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Hyperkalemia. - tolbutamide
sulfamethoxazole will increase the level or effect of tolbutamide by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.
- torsemide
torsemide increases levels of sulfamethoxazole by unspecified interaction mechanism. Minor/Significance Unknown.
- tranylcypromine
tranylcypromine increases levels of sulfamethoxazole by unspecified interaction mechanism. Minor/Significance Unknown.
- trazodone
sulfamethoxazole decreases levels of trazodone by unspecified interaction mechanism. Minor/Significance Unknown.
- triamterene
sulfamethoxazole will increase the level or effect of triamterene by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown.
triamterene, sulfamethoxazole. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Hyperkalemia.
triamterene increases levels of sulfamethoxazole by unspecified interaction mechanism. Minor/Significance Unknown. - trimethoprim
sulfamethoxazole will increase the level or effect of trimethoprim by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown.
- trimipramine
sulfamethoxazole decreases levels of trimipramine by unspecified interaction mechanism. Minor/Significance Unknown.
- valganciclovir
valganciclovir increases toxicity of sulfamethoxazole by pharmacodynamic synergism. Minor/Significance Unknown.
- valproic acid
valproic acid will increase the level or effect of sulfamethoxazole by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.
- verapamil
sulfamethoxazole will increase the level or effect of verapamil by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown.
trimethoprim will increase the level or effect of verapamil by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown. - verteporfin
sulfamethoxazole, verteporfin. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Increased phototoxicity.
- voriconazole
sulfamethoxazole will increase the level or effect of voriconazole by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.
voriconazole will increase the level or effect of sulfamethoxazole by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown. - willow bark
willow bark increases levels of sulfamethoxazole by unspecified interaction mechanism. Minor/Significance Unknown.
- zafirlukast
zafirlukast will increase the level or effect of sulfamethoxazole by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.
- zidovudine
zidovudine increases toxicity of sulfamethoxazole by pharmacodynamic synergism. Minor/Significance Unknown.
sulfamethoxazole increases levels of zidovudine by decreasing renal clearance. Minor/Significance Unknown.
Adverse Effects
Frequency Not Defined
Anorexia
Nausea
Vomiting
Vertigo
Seizure
Peripheral neuritis
Erythema multiforme
Hyperkalemia
Rash
Urticaria
Immune hypersensitivity reaction
Stevens-Johnson syndrome
Toxic epidermal necrolysis
Agranulocytosis
Aplastic anemia
Hyponatremia
Disorder of hematopoietic structure
Fulminant hepatic necrosis
Postmarketing Reports
Thrombotic thrombocytopenia purpura
Idiopathic thrombocytopenic purpura
QT prolongation resulting in ventricular tachycardia and torsade de pointes
Embryo-fetal toxicity
Hypersensitivity and other fatal reactions
Thrombocytopenia
Clostridium difficile-associated diarrhea
Sulfite sensitivity
Risk associated with concurrent use of leucovorin for
Pneumocystis jirovecii
Pneumonia
Infusion reactions
Hypoglycemia
Electrolyte abnormalities
Thrombophlebitis
Propylene glycol Toxicity
Metabolic acidosis
Drug reaction with eosinophilia and systemic symptoms (DRESS)
Acute generalized exanthematous pustulosis (AGEP)
Acute febrile neutrophilic dermatosis (AFND)
Circulatory shock
Acute and delayed lung injury
Interstitial lung disease
Acute respiratory failure
Renal failure, interstitial nephritis, BUN and serum creatinine elevation, renal insufficiency, oliguria and anuria, crystalluria, and nephrotoxicity in association with cyclosporine
Warnings
Contraindications
Known hypersensitivity
Age <2 months
CrCl <15 mL/min when renal function status cannot be monitored
Documented megaloblastic or folate deficiency anemia
Significan hepatic impairment
Contraindicated in pregnant patients at term and in nursing mothers, because antimicrobials#sulfonamides, which pass the placenta and are excreted in the milk, may cause kernicterus
History of drug-induced immune thrombocytopenia with use of trimethoprim and/or antimicrobials#sulfonamides
Concomitant administration with dofetilide
Cautions
Not for use in areas with resistance rates >10%
Severe and symptomatic hyponatremia can occur in patients receiving sulfamethoxazole/ trimethoprim, particularly for treatment of P. jirovecii pneumonia; evaluation for hyponatremia and appropriate correction is necessary in symptomatic patients to prevent life-threatening complications
If patient treated for Pneumocystis jirovecii develops skin rash, fever, leukopenia, or any other sign of adverse reaction, therapy or re-challenge should be re-evaluated
Circulatory shock with fever, severe hypotension, and confusion requiring intravenous fluid resuscitation and vasopressors has occurred within minutes to hours of re-challenge with trimethoprim-sulfamethoxazole in patients with history of recent (days to weeks) exposure to sulfamethoxazole-trimethoprim
Fatalities associated with the administration of antimicrobials#sulfonamides, although rare, have occurred due to severe reactions, including severe cutaneous adverse reactions (SCARs), including Stevens-Johnson Syndrome, toxic epidermal necrolysis, drug reaction with eosinophilia and systemic symptoms (DRESS), acute generalized exanthematous pustulosis (AGEP) and acute febrile neutrophilic dermatosis (AFND), fulminant hepatic necrosis, agranulocytosis, aplastic anemia and other blood dyscrasias; clinical signs, such as rash, sore throat, fever, arthralgia, pallor, purpura or jaundice may be early indications of serious reactions; discontinue therapy at first appearance of skin rash or any sign of serious adverse reaction
Acute and delayed lung injury; anaphylaxis and circulatory shock have occurred with administration of sulfamethoxazole and trimethoprim products
Cough, shortness of breath and pulmonary infiltrates potentially representing hypersensitivity reactions of the respiratory tract reported in association with sulfamethoxazole and trimethoprim treatment
Severe pulmonary adverse reactions occurring within days to week of initiation of treatment and resulting in prolonged respiratory failure requiring mechanical ventilation or extracorporeal membrane oxygenation (ECMO), lung transplantation or death also reported in patients and otherwise healthy individuals treated with sulfamethoxazole and trimethoprim products
Caution when used in elderly individuals; risk of bone marrow suppression
PCP prophylaxis with AIDS: Rash, fever, leukopenia, and elevated transaminase values reported; hyperkalemia and hyponatremia also appear to be increased
Severe cases (including fatalities) of immune-mediated thrombocytopenia reported; monitor patients for hematologic toxicity; resolves within a week upon discontinuation of therapy
Sulfonamides should not be used to treat group A beta-hemolytic streptococcal infections; they will not eradicate streptococcus or prevent rheumatic fever
Clostridium difficile-associated diarrhea reported
Coadministration with leucovorin for the treatment of HIV-positive patients with PCP resulted in treatment failure and excess mortality in a randomized, placebo-controlled trial; avoid coadministration
Development of drug-resistant bacteria may occur when prescribed in absence of strongly suspected bacterial infection or prophylactic indication
Prolonged use may result in fungal or bacterial superinfection
Caution with impaired renal or hepatic function, patients with possible folate deficiency (eg, the elderly, chronic alcoholics, patients receiving anticonvulsant therapy, patients with malabsorption syndrome, and patients in malnutrition states), and patients with severe allergies or bronchial asthma
Hematological changes indicative of folic acid deficiency may occur in elderly patients or in patients with preexisting folic acid deficiency or kidney failure; effects are reversible by folinic acid therapy
Hemolysis may occur if administered to patients with G6PD deficiency
Hypoglycemia (rare) reported in nondiabetic patients; patients with renal dysfunction, liver disease, or malnutrition or those receiving high doses at particular risk
Trimethoprim may impair phenylalanine metabolism but may have no significance in phenylketonuric patients on appropriate dietary restriction
Caution with porphyria or thyroid dysfunction; antimicrobials#sulfonamides can precipitate porphyria crisis and hypothyroidism; avoid use in patients with porphyria or thyroid dysfunction
Complete blood counts should be done frequently in patients receiving therapy; discontinue therapy if a significant reduction in count of any formed blood element is noted’ perform urinalyses with careful microscopic examination and renal function tests during therapy, particularly for those patients with impaired renal function
When administered at high doses as for the treatment of P. jirovecii pneumonia, monitor for total daily intake of propylene glycol from all sources and for acid-base disturbances; discontinue therapy if propylene glycol toxicity suspected
Treatment failure and excess mortality were observed when trimethoprim-sulfamethoxazole was used concomitantly with leucovorin for treatment of HIV positive patients with Pneumocystis jirovecii pneumonia; co-administration of trimethoprim-sulfamethoxazole and leucovorin during treatment of Pneumocystis jirovecii pneumonia should be avoided
During treatment, adequate fluid intake and urinary output should be ensured to prevent crystalluria; patients who are “slow acetylators” may be more prone to idiosyncratic reactions to antimicrobials#sulfonamides
Hyperkalemia
- High dosage of trimethoprim, as used in patients with P. jirovecii pneumonia, induces a progressive but reversible increase of serum potassium concentrations in a substantial number of patients
- Treatment with recommended doses may cause hyperkalemia when trimethoprim is administered to patients with underlying disorders of potassium metabolism, with renal insufficiency, or if drugs known to induce hyperkalemia are given concomitantly; close monitoring of serum potassium recommended
Risk in treatment of Pneumocystis jirovecy pneumonia
- AIDS patients may not tolerate or respond to sulfamethoxazole/ trimethoprim in same manner as non-AIDS patients
- Incidence of adverse reactions, particularly rash, fever, leukopenia and elevated aminotransferase (transaminase) values, with therapy in AIDS patients who are being treated for P. jirovecii pneumonia reported to be increased compared with incidence normally associated with use of drug in non-AIDS patients
- If a patient develops skin rash, fever, leukopenia or any sign of adverse reaction, reevaluate benefit-risk of continuing therapy or re-challenge with drug
Pregnancy & Lactation
Pregnancy
Therapy may cause fetal harm if administered to pregnant woman; some epidemiologic studies suggest that exposure to drug during pregnancy may be associated with increased risk of congenital malformations, particularly neural tube defects, cardiovascular abnormalities, urinary tract defects, oral clefts, and club foot
Urinary tract infection in pregnancy is associated with adverse perinatal outcomes such as preterm birth, low birth weight, and pre-eclampsia, and increased mortality to pregnant woman
P. jirovecii pneumonia in pregnancy is associated with preterm birth and increased morbidity and mortality for the pregnant woman
Use during pregnancy only if potential benefit justifies potential risk to fetus
Lactation
Levels of drug in breast milk are approximately 2 to 5% of recommended daily dose for pediatric patients over two months of age; there is no information regarding effect of therapy on breastfed infant or effect on milk production; because of potential risk of bilirubin displacement and kernicterus on breastfed child, advise women to avoid breastfeeding during therapy
Pregnancy Categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk. C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done. D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk. X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist. NA: Information not available.Pharmacology
Mechanism of Action
Blocks 2 consecutive steps in the biosynthesis of nucleic acids and proteins essential to many bacteria
Trimethoprim: Inhibits dihydrofolate reductase, thereby blocking production of tetrahydrofolic acid from dihydrofolic acid
Sulfamethoxazole: Inhibits bacterial synthesis of dihydrofolic acid by competing with para-aminobenzoic acid
Absorption
Time to peak: 1-4 hours
Distribution
Protein bound: TMP (44%); SMX (70%)
Metabolism
Hepatic
Enzymes inhibited: Hepatic CYP2C9
Elimination
Half-life: TMP (8-10 hr); SMX (10 hr)
Excretion: Urine (as unchanged drug)
Administration
IV Incompatibilities
Additive: Fluconazole, linezolid, verapamil
Y-site: Cisatracurium (incompatible at 2 mg/mL cisatra; may be compatible at much lower concs), fluconazole, foscarnet (may be compatible at very low TMP/SMX concs), midazolam, vinorelbine
IV Preparation
Do not use NS as diluent
Injection vehicle contains benzyl alcohol and sodium metabisulfite
Stability of parenteral admixture at room temperature (25°C)
- 5 mL/125 mL D5W: 6 hr
- 5 mL/100 mL D5W: 4 hr
- 5 mL/75 mL D5W: 2 hr
IV Administration
Infuse over 60-90 min; give q6hr, 8hr, or 12hr
Must be diluted well
May be given less diluted in a central line
Not for IM
Maintain adequate fluid intake to prevent crystalluria
Storage
Do not refrigerate injection
Less soluble in more alkaline pH
Protect from light
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Formulary
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