Comparative Pharmacology
Head-to-head clinical analysis: SULFAMETHOPRIM versus TRIMETHOPRIM SULFAMETHOXAZOLE.
Peer-Reviewed Evidence
Head-to-head clinical analysis: SULFAMETHOPRIM versus TRIMETHOPRIM SULFAMETHOXAZOLE.
SULFAMETHOPRIM vs Trimethoprim-Sulfamethoxazole
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Sulfamethoprim is a combination of sulfamethoxazole and trimethoprim. Sulfamethoxazole inhibits bacterial dihydropteroate synthase, blocking folic acid synthesis; trimethoprim inhibits bacterial dihydrofolate reductase, also blocking folic acid synthesis. This sequential blockade produces bactericidal effects.
Sulfamethoxazole inhibits dihydropteroate synthase, blocking para-aminobenzoic acid incorporation into dihydrofolate; trimethoprim inhibits dihydrofolate reductase, preventing tetrahydrofolate formation. Sequential blockade of folate synthesis.
Oral or intravenous: 800 mg sulfamethoxazole / 160 mg trimethoprim every 12 hours.
Oral: 160 mg TMP/800 mg SMX every 12 hours; IV: 8-10 mg/kg/day (based on TMP) in 2-4 divided doses
None Documented
None Documented
Terminal elimination half-life: 8-12 hours in adults with normal renal function. Prolonged in renal impairment (up to 24-48 hours).
Trimethoprim: 8-10 hours (normal renal function); prolonged to 24-30 hours in severe renal impairment (CrCl <10 mL/min). Sulfamethoxazole: 9-11 hours; prolonged in renal failure. The combination retains a half-life of ~10-12 hours in healthy adults, requiring dose adjustment in renal impairment.
Renal: 60-80% as unchanged drug via glomerular filtration and tubular secretion; biliary: 5-10%; fecal: <5%.
Trimethoprim: 50-60% excreted unchanged in urine via glomerular filtration and tubular secretion; 10-20% as metabolites. Sulfamethoxazole: 20-30% excreted unchanged in urine; 50-70% as N4-acetylated metabolite. Both undergo minimal biliary/fecal elimination (<5% total).
Category C
Category C
Sulfonamide Antibiotic
Sulfonamide Antibiotic