Comparative Pharmacology
Head-to-head clinical analysis: SULFAMETHOXAZOLE AND TRIMETHOPRIM DOUBLE STRENGTH versus SYNERCID.
Peer-Reviewed Evidence
Head-to-head clinical analysis: SULFAMETHOXAZOLE AND TRIMETHOPRIM DOUBLE STRENGTH versus SYNERCID.
SULFAMETHOXAZOLE AND TRIMETHOPRIM DOUBLE STRENGTH vs SYNERCID
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
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.
Synercid is a combination of two streptogramin antibiotics, quinupristin and dalfopristin, which bind to the 50S bacterial ribosome and inhibit protein synthesis. Quinupristin binds to the 23S rRNA near the peptidyl transferase center, while dalfopristin binds to a nearby site and enhances quinupristin's binding. The synergistic effect results in irreversible inhibition of bacterial protein synthesis.
One double-strength tablet (160 mg trimethoprim/800 mg sulfamethoxazole) orally every 12 hours.
7.5 mg/kg IV every 8 hours, administered as a 60-minute infusion.
None Documented
None Documented
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).
The terminal elimination half-life is approximately 0.85 hours for dalfopristin and 1.3 hours for quinupristin; however, the active metabolite of quinupristin has a half-life of about 3.5 hours, supporting twice-daily dosing.
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%).
Primarily hepatic metabolism with biliary excretion; approximately 15% of the dalfopristin dose and 32% of the quinupristin dose are excreted unchanged in feces; renal excretion is minor (<5% for both components).
Category D/X
Category C
Antibiotic
Antibiotic