Quinupristin/dalfopristin

Quinupristin/dalfopristin

Combination of
Quinupristin	Antibiotic
Dalfopristin	Antibiotic
Clinical data
Pregnancy cat.	B (U.S.)
Legal status	℞-only (U.S.)
Routes	IV
Identifiers
CAS number	126602-89-9 N
ATC code	J01FG02
PubChem	CID 23724510
ChemSpider	21106373 Y
N (what is this?)  (verify)

Quinupristin/dalfopristin (trade name Synercid) is a combination of two antibiotics used to treat infections by staphylococci and by vancomycin-resistant Enterococcus faecium.

Quinupristin and dalfopristin are both streptogramin antibiotics, derived from pristinamycin. Quinupristin is derived from pristinamycin IA; 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

Quinupristin and dalfopristin are protein synthesis inhibitors in a synergistic manner. While each of the two is only a bacteriostatic agent, the combination shows bactericidal activity.

• Dalfopristin binds to the 23S portion of the 50S ribosomal subunit, and changes the conformation of it, enhancing the binding of quinupristin^[1] by a factor of about 100. In addition, it inhibits peptidyl transfer.^[1]
• Quinupristin binds to a nearby site on the 50S ribosomal subunit and prevents elongation of the polypeptide,^[1] as well as causing incomplete chains to be released.^[1]

Pharmacokinetics

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

Side effects

1. Joint aches (arthralgia) or muscle aches (myalgia)
2. Nausea, diarrhea or vomiting
3. Rash or itching
4. Headache
5. Phlebitis
6. Hyperbilirubinemia

Drug interactions

Inhibits P450 and enhances the effects of terfenadine, astemizole, indinavir, midazolam, Ca channel blockers, warfarin, cisapride and cyclosporine.

References

Further reading

• Allington DR, Rivey MP., "Quinupristin/dalfopristin: a therapeutic review.", Clin Ther. 2001 Jan;23(1):24-44. doi:10.1016/S0149-2918(01)80028-X 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