Quinupristin/dalfopristin

Quinupristin/dalfopristin

Quinupristin (top) and dalfopristin (bottom)
Combination of
Quinupristin	Streptogramin antibiotic
Dalfopristin	Streptogramin antibiotic
Clinical data
Pregnancy category	B (U.S.)
Routes of administration	IV
Legal status	℞-only (U.S.)
Identifiers
CAS Number	126602-89-9
ATC code	J01FG02 (WHO)
PubChem	CID 23724510
ChemSpider	21106373
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Quinupristin/dalfopristin (pronunciation: kwi NYOO pris tin / dal FOE pris tin) (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

The drug inhibits P450 and enhances the effects of terfenadine, astemizole, indinavir, midazolam, calcium channel blockers, warfarin, cisapride and ciclosporin.

References

1. Page 212 in: Title: Hugo and Russell's pharmaceutical microbiology Authors: William Barry Hugo, Stephen P. Denyer, Norman A. Hodges, Sean P. Gorman Edition: 7, illustrated Publisher: Wiley-Blackwell, 2004 ISBN 0-632-06467-6, ISBN 978-0-632-06467-0 Length: 481 pages

Further reading

• Allington DR, Rivey M (Jan 2001). "Quinupristin/dalfopristin: a therapeutic review". Clin Ther. 23 (1): 24–44. doi:10.1016/S0149-2918(01)80028-X. PMID 11219478.
• "Quinupristin/dalfopristin: a review of its use in the management of serious gram-positive infections". Drugs 58 (6): 1061–97. December 1999. doi:10.2165/00003495-199958060-00008. PMID 10651391..
• "Quinupristin-dalfopristin: a new antibiotic for severe gram-positive infections". Am Fam Physician 64 (11): 1863–6. December 2001. PMID 11764864..
• "Antistaphylococcal (MSSA, MRSA, MSSE, MRSE) antibiotics". Med. Clin. North Am. 85 (1): 1–17. January 2001. doi:10.1016/s0025-7125(05)70302-3. PMID 11190346..
• http://www.fda.gov/cder/consumerinfo/druginfo/SYNERCID.HTM