Comparative Pharmacology
Head-to-head clinical analysis: SULFAMETHOPRIM DS versus TRIMETH SULFA.
Peer-Reviewed Evidence
Head-to-head clinical analysis: SULFAMETHOPRIM DS versus TRIMETH SULFA.
SULFAMETHOPRIM-DS vs TRIMETH/SULFA
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Sulfamethoprim-DS is a combination of sulfamethoxazole, a dihydropteroate synthase inhibitor, and trimethoprim, a dihydrofolate reductase inhibitor. The sequential inhibition of folate synthesis leads to bactericidal activity.
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.
Sulfamethoprim-DS (trimethoprim 160 mg-sulfamethoxazole 800 mg) orally every 12 hours for 10-14 days for uncomplicated UTI; for Pneumocystis jirovecii pneumonia: 3-5 mg/kg/day (based on TMP) orally or IV divided every 6-8 hours for 21 days.
1 double-strength tablet (160 mg trimethoprim / 800 mg sulfamethoxazole) orally every 12 hours for 14 days.
None Documented
None Documented
Terminal elimination half-life of sulfamethoxazole is 9-11 hours (prolonged to 20-50 hours in severe renal impairment). Clinically, this supports twice-daily dosing in normal renal function; dose adjustment required for CrCl <30 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 excretion of unchanged drug (50-70%) and metabolites (primarily N4-acetylated form, 15-30%); biliary/fecal excretion accounts for <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