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famciclovir (Famvir)

Tradename: Famvir. Indications: - out-patient Herpes simplex virus (HSV) infection - Herpes simplex labialis - treatment of acute Herpes zoster (shingles) or Herpes simplex type-2 (genital Herpes) - not responsive to acyclovir Dosage: Herpes Zoster: 500 mg PO every 8 hours for 7 days. Tabs: 500 mg. Dose adjustment for renal failure: Creatinine clearance dose > 60 mL/min 500 mg every 8 hours 40-59 mL/min 500 mg every 12 hours 10-39 mL/min 500 mg every 24 hours > 10 mL/min 250 mg every 24 hours Pharmacokinetics: 1) food decreased peak & the time to peak concentrations, but overall absorption is the same 2) oral bioavailability is 77% (much better than acyclovir) 3) rapidly deacylated & oxidized to penciclovir 4) 1/2life of penciclovir is 2-3 hours (10-22 hours ESRD) 5) > 90% of penciclovir is eliminated unchanged in the urine Adverse effects: 1) common (> 10%) - headache, nausea 2) less common (1-10%) - fatigue, fever, dizziness, somnolence, diarrhea, vomiting, constipation, anorexia, abdominal pain, rigors, paresthesia 3) other - pruritus Drug interactions: 1) cimetidine 2) digoxin increased by 20% 3) probenecid increases penciclovir concentration Mechanism of action: 1) undergoes rapid bio-transformation to penciclovir 2) penciclovir is converted intracellularly by viral thymidine kinase to penciclovir triphosphate 3) penciclovir triphosphate inhibits viral DNA synthesis

Interactions

drug interactions

Related

penciclovir (Denavir)

General

antiviral agent

Properties

MISC-INFO: elimination route KIDNEY pregnancy-category B safety in lactation ?

Database Correlations

PUBCHEM cid=3324

References

  1. The Pharmacological Basis of Therapeutics, 9th ed. Gilman et al, eds. Permagon Press/McGraw Hill, 1996
  2. Drug Information & Medication Formulary, Veterans Affairs, Central California Health Care System, 1st ed., Ravnan et al eds, 1998
  3. Kaiser Permanente Northern California Regional Drug Formulary, 1998
  4. Sanford Guide to antimicrobial therapy 2001
  5. Mubareka S, Leung V, Aoki FY, Vinh DC. Famciclovir: a focus on efficacy and safety. Expert Opin Drug Saf. 2010 Jul;9(4):643-58 PMID: 20429777
  6. Deprecated Reference