Comparative Pharmacology
Head-to-head clinical analysis: SULFISOXAZOLE versus TRIMETH SULFA.
Peer-Reviewed Evidence
Head-to-head clinical analysis: SULFISOXAZOLE versus TRIMETH SULFA.
SULFISOXAZOLE vs TRIMETH/SULFA
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Sulfisoxazole is a sulfonamide antibiotic that inhibits bacterial dihydropteroate synthase, blocking the synthesis of dihydrofolic acid and ultimately inhibiting bacterial folate synthesis and DNA replication.
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 g orally once, then 500 mg-1 g orally every 4-6 hours; maximum 6 g/day.
1 double-strength tablet (160 mg trimethoprim / 800 mg sulfamethoxazole) orally every 12 hours for 14 days.
None Documented
None Documented
Clinical Note
moderateSulfisoxazole + Gatifloxacin
"Sulfisoxazole may increase the hypoglycemic activities of Gatifloxacin."
Clinical Note
moderateSulfisoxazole + Rosoxacin
"Sulfisoxazole may increase the hypoglycemic activities of Rosoxacin."
Clinical Note
moderateSulfisoxazole + Trovafloxacin
"Sulfisoxazole may increase the hypoglycemic activities of Trovafloxacin."
Clinical Note
moderateSulfisoxazole + Nalidixic acid
Terminal elimination half-life is 5-7 hours in adults with normal renal function; prolonged to 12-20 hours in renal impairment (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 accounts for 70-85% of elimination, predominantly as unchanged drug (30-50%) and the N4-acetyl metabolite (15-30%). Biliary/fecal excretion is minimal (<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
"Sulfisoxazole may increase the hypoglycemic activities of Nalidixic acid."