Life Science Encyclopedia

Quinupristin/dalfopristin (Synercid®) 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

References

• Allington DR, Rivey MP., "Quinupristin/dalfopristin: a therapeutic review.", Clin Ther. 2001 Jan;23(1):24-44. PMID 11219478.
• Lamb HM, Figgitt DP, Faulds D., "Quinupristin/dalfopristin: a review of its use in the management of serious gram-positive infections.", Drugs. 1999 Dec;58(6):1061-97. PMID 10651391.
• Manzella JP., "Quinupristin-dalfopristin: a new antibiotic for severe gram-positive infections.", Am Fam Physician. 2001 Dec 1;64(11):1863-6. PMID 11764864.
• Paradisi F, Corti G, Messeri D., "Antistaphylococcal (MSSA, MRSA, MSSE, MRSE) antibiotics.", Med Clin North Am. 2001 Jan;85(1):1-17. PMID 11190346.
• http://www.fda.gov/cder/consumerinfo/druginfo/SYNERCID.HTM