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valacyclovir (Valtrex)

Tradename: Valtrex. Indications: - Herpes simplex - genital Herpes (Herpes simplex labialis) - Herpes zoster, chickenpox - cytomegalovirus [9] Dosage: - Herpes simplex labialis (genital Herpes) - initial occurrence: 1000 mg PO BID for 10 days - recurrence: 500 mg PO BID for 3 days [3] - prevention of transmission: 500 mg PO QD [5,6] - VAMC dose is 500 mg PO BID - Herpes zoster: - 1000 mg PO BID for 7 days Tabs: 500 mg ($3.50 in 2003) Dosage adjustment in renal failure: creatinine clearance dosage > 50-90 mL/min 1.0 mg every BID-TID 10-50 mL/min* 1.0 mg QD-BID < 10 mL/min# 0.5 mg QD * QD dosing for creatinine clearance < 30 mL/min [3] # dose after hemodialysis Pharmacokinetics: 1) prodrug of acyclovir 2) achieves serum levels 4-5 fold greater than acyclovir 3) achieves serum levels comparable to those obtained with intravenous acyclovir 4) elimination 1/2life 2.5 hours (3.3 hours ESRD) Adverse effects: 1) thrombotic thrombocytopenic purpura (TTP) 2) hemolytic uremic syndrome (HUS) 3) nephrotoxicity 4) hepatotoxicity 5) psychomotor disturbances 6) neurotoxity [10] (in order of frequency) - disorientation - diminished level of consciousness - hallucinations - agitation - dysarthria - seizures/myoclonus - coma - tremor - ataxia - aphasia - delirium Mechanism of action: 1) prodrug of acyclovir 2) reduces transmission by 50% [5]

Interactions

drug interactions

Related

acyclovir (ACV, Zovirax, Sitavig)

General

antiviral agent

Properties

MISC-INFO: elimination route KIDNEY 1/2life 2.5 HOURS pregnancy-category B safety in lactation ?

Database Correlations

PUBCHEM correlations

References

  1. The Pharmacological Basis of Therapeutics, 9th ed. Gilman et al, eds. Permagon Press/McGraw Hill, 1996
  2. Medical Knowledge Self Assessment Program (MKSAP) 11, American College of Physicians, Philadelphia 1998
  3. Prescriber's Letter 8(8): 44, 2001
  4. Sanford Guide to antimicrobial therapy 2001
  5. Prescriber's Letter 9(11):62 2002
  6. Prescriber's Letter 10(10):56 2003
  7. Vigil KJ, Chemaly RF. Valacyclovir: approved and off-label uses for the treatment of herpes virus infections in immunocompetent and immunocompromised adults. Expert Opin Pharmacother. 2010 Aug;11(11):1901-13 PMID: 20536295
  8. Leone PA et al, Valacyclovir for episodic treatment of genital herpes: a shorter 3-day treatment course compared with 5-day treatment. Clin Infect Dis 34:958, 2002 PMID: 11880962
  9. Deprecated Reference
  10. Brandariz-Nunez D, Correas-Sanahuja M, Maya-Gallego S, et al. Neurotoxicity associated with acyclovir and valacyclovir: A systematic review of cases. Journal of Clinical Pharmacy and Therapeutics. 2021;46(4):918-926. PMID: 34146428 - Murakami T, Akimoto T, Okada M, et al. Valacyclovir neurotoxicity and nephrotoxicity in an elderly patient complicated by hyponatremia. Drug Target Insights. 2018 Jun 25:12:1177392818782899 PMID: 30013310 PMCID: PMC6043912 Free PMC article
  11. Department of Veterans Affairs, VA National Formulary