Quinupristin and Dalfopristin
Quinupristin and dalfopristin are lincosamide antibiotics (see Lincosamides, Oxazolidinones, and Streptogramins) that are semisynthetic derivatives of pristinamycin, a naturally occurring streptogramin. Quinupristin/dalfopristin (Q/D) is given together in a fixed 30/70 combination; this combination has synergistic bactericidal activity against the following:
Q/D inhibits Enterococcus faecium, including vancomycin-resistant strains. E. faecalis is resistant.
Q/D is given via a central IV catheter because phlebitis frequently occurs when Q/D is given via a peripheral vein. Up to 30% of patients develop significant myalgias.
Dosage reduction is required for severe hepatic insufficiency but not for renal insufficiency.
Q/D may inhibit the metabolism of drugs that are metabolized by the cytochrome P-450 (CYP450) 3A4 isoenzyme system.