Comparative Pharmacology
Head-to-head clinical analysis: COTRIM D S versus TRIMETHOPRIM SULFATE AND POLYMYXIN B SULFATE.
Peer-Reviewed Evidence
Head-to-head clinical analysis: COTRIM D S versus TRIMETHOPRIM SULFATE AND POLYMYXIN B SULFATE.
COTRIM D.S. vs TRIMETHOPRIM SULFATE AND POLYMYXIN B SULFATE
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
COTRIM D.S. is a combination of sulfamethoxazole, a competitive inhibitor of dihydropteroate synthase, and trimethoprim, a reversible inhibitor of dihydrofolate reductase. This sequential blockade of folate synthesis leads to bactericidal activity.
Trimethoprim inhibits bacterial dihydrofolate reductase, blocking tetrahydrofolate synthesis and thereby inhibiting thymidine synthesis. Polymyxin B disrupts bacterial cell membrane integrity by binding to lipopolysaccharides in Gram-negative bacteria.
160 mg trimethoprim / 800 mg sulfamethoxazole (one double-strength tablet) orally every 12 hours.
One drop in each affected eye every 2 to 4 hours for 7 to 10 days.
None Documented
None Documented
Sulfamethoxazole: 9-12 hours (normal renal function). Trimethoprim: 8-11 hours. Both are prolonged in renal impairment (e.g., creatinine clearance <30 mL/min: >24 hours). Clinical context: dosing interval is typically 12 hours; dose adjustment required if CrCl <30 mL/min.
Trimethoprim: 8-10 hours (normal renal function); Polymyxin B: 6 hours (prolonged in renal impairment).
Sulfamethoxazole: ~20% unchanged in urine, remainder as acetylated and glucuronide metabolites. Trimethoprim: ~50-80% unchanged in urine, remainder as oxidative metabolites. Both undergo renal excretion via glomerular filtration and tubular secretion. Total renal elimination: 70-90% of dose combined. Biliary/fecal: <10%.
Trimethoprim: renal (80-90% unchanged, 10-20% metabolites); Polymyxin B: renal (60% unchanged, 40% nonrenal).
Category C
Category D/X
Antibiotic
Antibiotic