Comparative Pharmacology
Head-to-head clinical analysis: TRIMETHOPRIM SULFAMETHOXAZOLE versus TRIPLE SULFAS.
Peer-Reviewed Evidence
Head-to-head clinical analysis: TRIMETHOPRIM SULFAMETHOXAZOLE versus TRIPLE SULFAS.
Trimethoprim-Sulfamethoxazole vs TRIPLE SULFAS
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Sulfamethoxazole inhibits dihydropteroate synthase, blocking para-aminobenzoic acid incorporation into dihydrofolate; trimethoprim inhibits dihydrofolate reductase, preventing tetrahydrofolate formation. Sequential blockade of folate synthesis.
Competitive inhibition of dihydropteroate synthase, thereby blocking folate synthesis and bacterial DNA replication. Triple sulfas (sulfadiazine, sulfamerazine, sulfamethazine) act synergistically to inhibit folic acid synthesis.
Oral: 160 mg TMP/800 mg SMX every 12 hours; IV: 8-10 mg/kg/day (based on TMP) in 2-4 divided doses
1 to 2 tablets (each containing sulfadiazine 167 mg, sulfamerazine 167 mg, sulfamethazine 167 mg) orally every 4 hours initially, then 2 tablets every 6 hours. Maximum daily dose: 6 grams of total sulfonamide.
None Documented
None Documented
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.
Terminal elimination half-life ranges from 10-12 hours in adults with normal renal function. Prolonged in renal impairment (up to 24-48 hours) and neonates (40-120 hours).
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).
Primarily renal; approximately 70-100% excreted unchanged in urine via glomerular filtration and tubular secretion. Minor biliary/fecal elimination (<5%) with enterohepatic circulation possible.
Category C
Category C
Sulfonamide Antibiotic
Sulfonamide Antibiotic