Comparative Pharmacology
Head-to-head clinical analysis: ILOSONE SULFA versus SULFAMETHOPRIM DS.
Peer-Reviewed Evidence
Head-to-head clinical analysis: ILOSONE SULFA versus SULFAMETHOPRIM DS.
ILOSONE SULFA vs SULFAMETHOPRIM-DS
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Ilosone (erythromycin) is a macrolide antibiotic that inhibits bacterial protein synthesis by binding to the 50S ribosomal subunit. Sulfa (sulfisoxazole) is a sulfonamide that inhibits dihydropteroate synthase, blocking folate synthesis. The combination provides synergistic bacteriostatic activity.
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.
Each 5 mL suspension contains 250 mg erythromycin base and 600 mg sulfisoxazole; typical adult dose is 10 mL (2 tsp) every 6 hours, not to exceed 40 mL/day.
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.
None Documented
None Documented
Erythromycin: 1.5-2 hours; Sulfisoxazole: 4-7 hours; clinical context: dose adjustment in renal impairment (CrCl <50 mL/min) needed for sulfisoxazole
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.
Renal: 70-80% as unchanged drug and active metabolite (sulfisoxazole); Biliary: 10-15% as metabolites; Fecal: <5%
Renal excretion of unchanged drug (50-70%) and metabolites (primarily N4-acetylated form, 15-30%); biliary/fecal excretion accounts for <5%.
Category C
Category C
Macrolide and Sulfonamide Antibiotic
Sulfonamide Antibiotic