Quinupristin + Dalfopristin are marketed under which brand name?

• A. Synercid
• B. Zosyn
• C. Primaxin
• D. Unasyn

Answer: (A)

Quinupristin and dalfopristin form a streptogramin antibiotic combination that is marketed under the brand name Synercid. The two components work together to shut down bacterial protein synthesis: dalfopristin binds to the 50S ribosomal subunit and changes its structure in a way that enhances the binding of quinupristin, which then blocks peptide elongation. This synergy makes the combination effective against certain resistant Gram-positive infections (notably some MRSA and Enterococcus strains) and it must be given intravenously because it has poor oral bioavailability.

The other names listed are different antibiotic combos: Zosyn is piperacillin/tazobactam, Primaxin is imipenem/cilastatin, and Unasyn is ampicillin/sulbactam. They are not quinupristin/dalfopristin, which is specifically Synercid.