Comparative Pharmacology
Head-to-head clinical analysis: SULFAMETHOXAZOLE versus TRIMETHOPRIM SULFAMETHOXAZOLE.
Peer-Reviewed Evidence
Head-to-head clinical analysis: SULFAMETHOXAZOLE versus TRIMETHOPRIM SULFAMETHOXAZOLE.
SULFAMETHOXAZOLE vs Trimethoprim-Sulfamethoxazole
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Displaces dihydropteroate synthetase from its substrate para-aminobenzoic acid (PABA), inhibiting bacterial folate synthesis. Bacteriostatic against susceptible organisms.
Sulfamethoxazole inhibits dihydropteroate synthase, blocking para-aminobenzoic acid incorporation into dihydrofolate; trimethoprim inhibits dihydrofolate reductase, preventing tetrahydrofolate formation. Sequential blockade of folate synthesis.
800 mg sulfamethoxazole with 160 mg trimethoprim (DS tablet) orally 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
9-11 hours in adults with normal renal function. Prolonged in renal impairment: up to 20-30 hours. In neonates, 6-12 hours.
Clinical Note
moderateSulfamethoxazole + Gatifloxacin
"Sulfamethoxazole may increase the hypoglycemic activities of Gatifloxacin."
Clinical Note
moderateSulfamethoxazole + Rosoxacin
"Sulfamethoxazole may increase the hypoglycemic activities of Rosoxacin."
Clinical Note
moderateSulfamethoxazole + Trovafloxacin
"Sulfamethoxazole may increase the hypoglycemic activities of Trovafloxacin."
Clinical Note
moderateSulfamethoxazole + Nalidixic acid
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.
Primarily renal; ~80-90% excreted unchanged in urine, with 15-30% as acetylated metabolite. Biliary/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 D/X
Category C
Sulfonamide Antibiotic
Sulfonamide Antibiotic
"Sulfamethoxazole may increase the hypoglycemic activities of Nalidixic acid."