Comparative Pharmacology
Head-to-head clinical analysis: SULFAMETHOXAZOLE versus TRIMETH SULFA.
Peer-Reviewed Evidence
Head-to-head clinical analysis: SULFAMETHOXAZOLE versus TRIMETH SULFA.
SULFAMETHOXAZOLE vs TRIMETH/SULFA
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.
Trimethoprim inhibits bacterial dihydrofolate reductase (DHFR), blocking conversion of dihydrofolate to tetrahydrofolate; sulfamethoxazole inhibits bacterial dihydropteroate synthase, blocking incorporation of para-aminobenzoic acid into folic acid. Sequential blockade of folate synthesis produces synergistic bactericidal effect.
800 mg sulfamethoxazole with 160 mg trimethoprim (DS tablet) orally every 12 hours.
1 double-strength tablet (160 mg trimethoprim / 800 mg sulfamethoxazole) orally every 12 hours for 14 days.
None Documented
None Documented
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
9-11 hours in adults with normal renal function. Prolonged in renal impairment: up to 20-30 hours. In neonates, 6-12 hours.
Trimethoprim: 8-11 hours; Sulfamethoxazole: 9-11 hours. Prolonged in renal impairment (up to 24-30 hours for both). Clinical context: Dosing interval is typically 12 hours in normal renal function; adjust in CrCl <15-30 mL/min.
Primarily renal; ~80-90% excreted unchanged in urine, with 15-30% as acetylated metabolite. Biliary/fecal <5%.
Trimethoprim: 50-60% unchanged in urine; Sulfamethoxazole: 15-30% unchanged in urine, with acetylation and glucuronidation metabolites. Approximately 80-90% of dose recovered in urine within 72 hours; remainder via feces.
Category D/X
Category C
Sulfonamide Antibiotic
Sulfonamide Antibiotic
"Sulfamethoxazole may increase the hypoglycemic activities of Nalidixic acid."