Trimethoprim + DofetilideContraindicated
Trimethoprim 160 mg BID increases dofetilide AUC by 103% and Cmax by 93%. Concomitant use is contraindicated.
Source: NLP:dofetilide
Trimethoprim Interactions
Brand names: Trimethoprim
Dihydrofolate Reductase Inhibitor Antibacterial · Dihydrofolate Reductase Inhibitors · Cytochrome P450 2C8 Inhibitors · Organic Cation Transporter 2 Inhibitors
Route: Oral
Contraindications
CONTRAINDICATIONS Trimethoprim is contraindicated in individuals hypersensitive to trimethoprim and in those with documented megaloblastic anemia due to folate deficiency.
Pregnancy & Breastfeeding
Pregnancy Teratogenic Effects Pregnancy category C Trimethoprim has been shown to be teratogenic in the rat when given in doses 40 times the human dose. In some rabbit studies, the overall increase in fetal loss (dead and resorbed and malformed conceptuses) was associated with doses six times the human therapeutic dose. While there are no large, well-controlled studies on the use of trimethoprim in pregnant women, Brumfitt and Pursell, 3 in a retrospective study, reported the outcome of 186 pregnancies during which the mother received either placebo or trimethoprim in combination with sulfamethoxazole. The incidence of congenital abnormalities was 4.5% (3 of 66) in those who received placebo and 3.3% (4 of 120) in those receiving trimethoprim and sulfamethoxazole. There were no abnormalities in the 10 children whose mothers received the drug during the first trimester. In a separate survey, Brumfitt and Pursell also found no congenital abnormalities in 35 children whose mothers had received trimethoprim and sulfamethoxazole at the time of conception or shortly thereafter. Because trimethoprim may interfere with folic acid metabolism, trimethoprim should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. Nonteratogenic Effects The oral administration of trimethoprim to rats at a dose of 70 mg/kg/day commencing with the last third of gestation and continuing through parturition and lactation caused no deleterious effects on gestation or pup growth and survival.
17 interactions on record
Trimethoprim + SepiapterinContraindicated
DHFR inhibitor that may reduce sepiapterin metabolism to tetrahydrobiopterin (BH4). Avoid concomitant use.
Source: NLP:sepiapterin
Trimethoprim may increase serum potassium, leading to severe hyperkalemia when used with CAROSPIR.
Source: NLP:carospir
Antifolate agent that directly inhibits dihydrofolate reductase, decreasing formation of active folate derivatives.
Source: NLP:folic acid
Trimethoprim can increase serum potassium; concomitant use with spironolactone may lead to severe hyperkalemia.
Source: NLP:spironolactone
Trimethoprim + CyclosporineModerate
May potentiate renal dysfunction when used with sulfamethoxazole and cyclosporine. Close monitoring required.
Source: NLP:cyclosporine
Trimethoprim + DapsoneModerate
Mutual interaction where Dapsone and trimethoprim each raise the level of the other approximately 1.5 times; interaction severity varies with trimethoprim dosing regimens.
Source: NLP:dapsone
Trimethoprim + DigoxinModerate
Increases digoxin serum concentration by 22-28%. Requires monitoring and dose adjustment.
Source: NLP:digoxin
Trimethoprim + Lamivudine OralModerate
Potential interaction possible due to similar renal elimination pathways via organic cationic transport system. Monitor for interactions.
Source: NLP:lamivudine
Cationic drug eliminated by renal tubular secretion with potential for interaction with metformin by competing for common renal tubular transport systems.
Source: NLP:metformin hcl
Trimethoprim + PhenytoinModerate
Trimethoprim inhibits hepatic metabolism of phenytoin, increasing phenytoin half-life by 51% and decreasing metabolic clearance by 30%. Monitor for excessive phenytoin effect.
Source: NLP:trimethoprim
Trimethoprim + Phenytoin SodiumModerate
May increase phenytoin serum levels; monitoring of phenytoin levels recommended when interaction is suspected.
Source: NLP:phenytoin sodium
May decrease plasma folate levels.
Source: NLP:prenatal multivitamin tablet and combination omega-3 softgel/mineral capsule
Trimethoprim + RepaglinideModerate
CYP2C8 inhibitor. Repaglinide dose reductions and increased glucose monitoring may be required.
Source: NLP:repaglinide
May decrease endogenous BH4 levels by inhibiting dihydrofolate reductase, potentially increasing phenylalanine levels.
Source: NLP:sapropterin dihydrochloride
Terazosin has been used concomitantly with trimethoprim in at least 50 patients with no interactions observed.
Source: NLP:terazosin
Used concomitantly with terazosin in at least 50 patients with no interactions observed.
Source: NLP:terazosin hydrochloride