Brands, Medical Use, Clinical Data
Drug Category
- Antimalarials
- Anti-Infectives
Dosage Forms
Brands / Synonyms
Abacin; Abaprim; Alprim; Apo-Sulfatrim; Bactin; Bactramin; Bactrim; Bactrim DS; Bactrim Pediatric; Baktar; Chemotrim; Co-Trimoxazole; Comox; Cotrim; Cotrim D.S.; Drylin; Eusaprim; Fectrim; Gantaprim; Gantrim; Idotrim; Imexim; Instalac; Ipral; Kepinol; Laratrim; Lidaprim; Linaris; Methoprim; Microtrim; Monoprim; Monotrim; Monotrimin; Nopil; Oraprim; Polymyxin B and Trimethoprim Ophthalmic; Polytrim; Priloprim; Primosept; Primsol; Proloprim; Septra; Septra Ds; Septra Grape; Septrin; Sigaprim; Sulfamethoprim; Sulfamethoprim-Ds; Sulfamethoxazole & Trimethoprim; Sulfamethoxazole and Trimethoprim; Sulfatrim; Sulfatrim Pediatric; Sulfatrim-Ds; Sulfatrim-Ss; Sulfotrim; Sulmeprim; Sulmeprim Pediatric; Sulprim; Sumetrolim; Supracombin; Suprim; Syraprim; Teleprim; Thiocuran; Tiempe; Tmp-Ratiopharm; Trigonyl; Trimanyl; Trimesulf; Trimeth/Sulfa; Trimethioprim; Trimethoprim; Trimethopriom; Trimetoprim; Trimexazole; Trimogal; Trimopan; Trimpex; Trimpex 200; Triprim; Unitrim; Uretrim; Uro-Septra; Uroplus; Uroplus Ds; Uroplus Ss; Veltrim; Wellcoprim
Indications
For the treatment of initial episodes of uncomplicated urinary tract infections
Pharmacology
Trimethoprim, a synthetic antiinfective agent, is used to treat and prevent urinary tract infections, diarrhea, and, when combined with either sulfamethoxazole or dapsone, Pneumocystis carinii infections.
Mechanism of Action
Trimethoprim binds to bacterial dihydrofolate reductase, subsequently interfering with the uptake of p-aminobenzoic acid (PABA) into folic acid. As folic acid is a coenzyme responsible for the transport of one-carbon fragments from one molecule to another, it is an essential component of bacterial development. Sulfonamides inhibit bacterial dihydrofolate synthetase, the enzyme immediately preceding dihydrofolate reductase, and therefore act synergistically with trimethoprim.
Absorption
Not Available
Toxicity
LD50=4850 (orally in mice)
Biotrnasformation / Drug Metabolism
Not Available
Contraindications
Trimethoprim is contraindicated in individuals hypersensitive to trimethoprim and in those with documented
megaloblastic anemia due to folate deficiency.
Drug Interactions
Trimethoprim may inhibit the hepatic metabolism of phenytoin. Trimethoprim, given at a common clinical dosage,
increased the phenytoin half-life by 51% and decreased the phenytoin metabolic clearance rate by 30%. When
administering these drugs concurrently, one should be alert for possible excessive phenytoin effect.
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