Comparative Pharmacology
Head-to-head clinical analysis: SYNERCID versus TRIMETHOPRIM SULFATE AND POLYMYXIN B SULFATE.
Peer-Reviewed Evidence
Head-to-head clinical analysis: SYNERCID versus TRIMETHOPRIM SULFATE AND POLYMYXIN B SULFATE.
SYNERCID vs TRIMETHOPRIM SULFATE AND POLYMYXIN B SULFATE
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
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.
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.
7.5 mg/kg IV every 8 hours, administered as a 60-minute infusion.
One drop in each affected eye every 2 to 4 hours for 7 to 10 days.
None Documented
None Documented
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.
Trimethoprim: 8-10 hours (normal renal function); Polymyxin B: 6 hours (prolonged in renal impairment).
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).
Trimethoprim: renal (80-90% unchanged, 10-20% metabolites); Polymyxin B: renal (60% unchanged, 40% nonrenal).
Category C
Category D/X
Antibiotic
Antibiotic