Comparative Pharmacology
Head-to-head clinical analysis: SEPTRA DS versus SULFAMETHOXAZOLE AND TRIMETHOPRIM DOUBLE STRENGTH.
Peer-Reviewed Evidence
Head-to-head clinical analysis: SEPTRA DS versus SULFAMETHOXAZOLE AND TRIMETHOPRIM DOUBLE STRENGTH.
SEPTRA DS vs SULFAMETHOXAZOLE AND TRIMETHOPRIM DOUBLE STRENGTH
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
SEPTRA DS is a combination of trimethoprim and sulfamethoxazole. Trimethoprim inhibits bacterial dihydrofolate reductase, while sulfamethoxazole inhibits dihydropteroate synthase, sequentially blocking folate synthesis and ultimately DNA synthesis in susceptible bacteria.
Sulfamethoxazole inhibits bacterial dihydropteroate synthase, blocking folic acid synthesis. Trimethoprim inhibits bacterial dihydrofolate reductase, blocking reduction of dihydrofolate to tetrahydrofolate. Sequential blockade produces bactericidal effect.
One DS tablet (800 mg sulfamethoxazole/160 mg trimethoprim) orally every 12 hours for 10-14 days.
One double-strength tablet (160 mg trimethoprim/800 mg sulfamethoxazole) orally every 12 hours.
None Documented
None Documented
Trimethoprim: 8-10 hours; sulfamethoxazole: 10-12 hours (prolonged in renal impairment, e.g., creatinine clearance <30 mL/min increases half-life to >20 hours).
Sulfamethoxazole: 9-11 hours; trimethoprim: 8-11 hours. In severe renal impairment (CrCl <15 mL/min), half-life prolongs significantly (up to 30 hours for trimethoprim).
Renal excretion of unchanged drugs accounts for 50-70% of trimethoprim and 20-30% of sulfamethoxazole; biliary excretion is minor (<10% total).
Both sulfamethoxazole and trimethoprim are primarily excreted via the kidneys. Sulfamethoxazole: ~30% as unchanged drug, ~50% as N4-acetyl metabolite; trimethoprim: ~80% as unchanged drug. Fecal elimination is minimal (<5%).
Category C
Category D/X
Antibiotic
Antibiotic