Quinupristin/dalfopristin

(Redirected from Synercid)

Quinupristin/dalfopristin, or 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/dalfopristin
Quinupristin (top) and dalfopristin (bottom)
Combination of
QuinupristinStreptogramin antibiotic
DalfopristinStreptogramin antibiotic
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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

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Intravenous, usually 7.5 mg/kg every 8 hours (infections/life threatening VRSA); every 12 hours (skin infections). No renal dosing adjustments, hepatic dosing adjustments are not defined, consider reducing dose.

Mechanism of action

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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

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Clearance by the liver CYP450:3A4 inhibitor, half-life quinupristin 0.8 hours, dalfopristin 0.7 hours (with persistence of effects for 9–10 hours).

Side effects

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[2]

Serious:

  1. C.diff-associated diarrhea
  2. superinfection
  3. anaphylactoid reactions
  4. angioedema

Common:

  1. Joint aches (arthralgia) or muscle aches (myalgia)
  2. Nausea, diarrhea (C. diff associated) or vomiting
  3. Rash or itching
  4. Headache
  5. Hyperbilirubinemia
  6. Anemia
  7. Thrombophlebitis

Drug interactions

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

References

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  1. ^ a b c d Denyer SP, Hodges N, Gorman SP, eds. (2004). Hugo and Russell's Pharmaceutical microbiology (7th ed.). Blackwell Science. p. 212. ISBN 978-0-632-06467-0.
  2. ^ Epocrates v 19.5

Further reading

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