Comparative Pharmacology
Head-to-head clinical analysis: SULFACETAMIDE SODIUM versus TRIMETH SULFA.
Peer-Reviewed Evidence
Head-to-head clinical analysis: SULFACETAMIDE SODIUM versus TRIMETH SULFA.
SULFACETAMIDE SODIUM vs TRIMETH/SULFA
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Competitively inhibits dihydropteroate synthase, blocking folic acid 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.
1-2 drops of 10-30% solution into the conjunctival sac every 2-3 hours initially, tapering as infection resolves. Ointment: 0.5-inch ribbon into conjunctival sac every 3-4 hours and at bedtime.
1 double-strength tablet (160 mg trimethoprim / 800 mg sulfamethoxazole) orally every 12 hours for 14 days.
None Documented
None Documented
7-12.8 hours (prolonged in renal impairment; requires dosing adjustment in CrCl <50 mL/min).
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: 85-95% unchanged via glomerular filtration and tubular secretion. 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 A/B
Category C
Sulfonamide Antibiotic
Sulfonamide Antibiotic