Quinupristin/dalfopristin

Quinupristin/dalfopristin (Synercid&reg;) is a combination of two antibiotics used to treat infections by staphylococci and by vancomycin-resistant Enterococcus faecium. It is not effective against Enterococcus faecalis infections.

Quinupristin and dalfopristin are both streptogramin antibiotics, derived from pristinamycin. Quinupristin is derived from pristinamycin I; dalfopristin from pristinamycin IIA. They are combined in a weight-to-weight ratio of 30% quinupristin to 70% dalfopristin.

Administration
Intravenous, usually 7.5 mg/kg every 8-12 hours

Mechanism of action
Dalfopristin inhibits the early phase of protein synthesis in the bacterial ribosome and quinupristin inhibits the late phase of protein synthesis. The combination of the two components acts synergistically and is more effective in vitro than each component alone.

Pharmacokinetics
Clearance by the liver, half-life 1-3 hours (with persistence of effects for 9-10 hours).

Side effects

 * 1) Joint or muscle aches
 * 2) Nausea, diarrhea or vomiting
 * 3) Rash or itching
 * 4) Headache