Comparative Pharmacology
Head-to-head clinical analysis: SULFONAMIDES DUPLEX versus TRIMETH SULFA.
Peer-Reviewed Evidence
Head-to-head clinical analysis: SULFONAMIDES DUPLEX versus TRIMETH SULFA.
SULFONAMIDES DUPLEX vs TRIMETH/SULFA
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Sulfonamides are competitive antagonists of para-aminobenzoic acid (PABA) and inhibit dihydropteroate synthase, blocking folate synthesis in susceptible bacteria.
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.
Oral: 500-1000 mg twice daily; maximum 2000 mg/day.
1 double-strength tablet (160 mg trimethoprim / 800 mg sulfamethoxazole) orally every 12 hours for 14 days.
None Documented
None Documented
Terminal half-life: 7-12 hours in patients with normal renal function; prolonged to 24-50 hours in renal impairment (CrCl <30 mL/min) due to reduced elimination.
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.
Renal: 70-100% unchanged drug via glomerular filtration and tubular secretion; fecal/biliary: <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 C
Category C
Sulfonamide Antibiotic
Sulfonamide Antibiotic