Valacyclovir indications and dosage in dermatology

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Valacyclovir indications and dosage in dermatology

Indications

  • Episodic herpes labialis.
  • Herpes labialis suppression.
  • Herpes simplex prophylaxis after laser resurfacing.
  • Varicella.
  • Herpes zoster.
  • Herpes zoster ophthalmicus.
  • Primary and recurrent herpes simplex.
  • Recurrent erythema multiforme.
  • Suppression and episodic treatment for herpes simplex or varicella-zoster infections in HIV.
  • Other subsets of herpes simplex infections.

Dosage

  • Episodic herpes labialis: 2 g po bid for 1 day.
  • Herpes labialis suppression: 500 mg po qd.
  • Prophylaxis of Herpes simplex after laser resurfacing: 500 mg PO bid for 14 days ( starting one day before the procedure or on the same day)
  • Herpes zoster: 1000 mg po q8h for 7 days.
  • Herpes zoster ophthalmicus: 1 g po tid for 7 days.
  • Primary genital herpes: 1000 mg po q12h for 10 days.
  • Recurrent genital herpes: 500 mg po q12h for 5 days.
  • Suppression and episodic treatment for herpes simplex in hiv: 500 mg po bid, 1000 mg po bid for 5 days.
  • Suppressive genital herpes: 500–1000 mg po q12h.
  • Varicella: 1 g po tid for 7 days.

Renal dosing :

•Creatinine clearance (crcl) 50–90 ml/min: 1 g po q8h.

•Crcl 10–50 ml/min: 1 g po q12h–q24h.

•Crcl < 10 ml/min: 500 mg po q24h.

•Hemodialysis: 500 mg po q24h after dialysis.

•Continuous ambulatory peritoneal dialysis: 500 mg po q24h.

•Continuous arteriovenous hemofiltration: 1g po q12h–q24h

The efficacy of Valacyclovir in children below the age of 12 years has not been evaluated.

Mechanism of action

  • Valacyclovir is converted into acyclovir, with increased bioavailability.
  • It requires phosphorylation by viral thymidine kinase to be activated.
  • The active triphosphate metabolite of acyclovir inhibits viral DNA polymerase and thus DNA synthesis.

Side effects

Common :

  • Nausea, vomiting, diarrhea and headache.
  • Agitation, vertigo, confusion, dizziness, edema, arthralgia, sore throat, constipation, abdominal pain, rash, weakness and/or renal impairment (infrequent).

Rare :

  • Coma, seizures, neutropenia, leukopenia, tremor, ataxia, encephalopathy, psychotic symptoms, crystalluria, anorexia, fatigue, hepatitis, Stevens–Johnson syndrome, toxic epidermal necrolysis and/or anaphylaxis.

Contraindications

  • Hypersensitivity to drug/class or acyclovir

Interactions

  • Decreased rate of conversion of drug to acyclovir: cimetidine, probenecid.

Pregnancy &Lactation

  • Pregnancy category: B.
  • Lactation: Drug excreted in breast milk; use with caution.

Precautions

  • Use with caution in patients with renal impairment, the elderly, and/or patients receiving nephrotoxic drugs.
  • Central nervous system (CNS) effects may occur ; risk is higher in elderly patients.
  • Thrombotic thrombocytopenic purpura (TTP)/hemolytic uremic syndrome (HUS) reported in patients with advanced HIV disease.
  • Adequately hydrate patient; decreased precipitation in renal tubules may occur.
  • Low dose (1000 mg/day) valacyclovir therapy may cause thrombotic thrombocytopenic purpura in an immunocompetent patient. 

Drug Info

  • Valacyclovir is an oral prodrug of acyclovir.
  • In the oral form it is nearly as potent as intravenous Acyclovir.
Acyclovir in dermatology

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