Valacyclovir

General
  • Type: Antiviral, inhibits DNA polymerase
  • Dosage Forms: 500, 1000
  • Common Trade Names: Valtrex

Adult Dosing

HSV-1
  • Acute episode: 2000mg PO BID x 1 day
  • Suppression: 500mg PO Qday

Genital HSV
  • 1st episode: 1000mg PO BID x 7-10 days, start within 48-72 hour of symptoms
  • recurrence: 500mg PO BID x 3 days, alternative: 1000mg PO qday x 5 days

Shingles
  • 1000mg PO TID x 7 days

Pediatric Dosing

Genital HSV
  • ≥12 yrs same as adult dosing for adolescents

Special Populations
  • Pregnancy Rating: B
  • Lactation: Excreted in breastmilk
  • Renal Dosing
    • CrCl <10 mL/min: 500 mg/day PO
  • Hepatic Dosing: not defined

Contraindications
  • Allergy to class/drug

Adverse Reactions

Serious
  • TTP, HUS (reported in advanced HIV and transplant patients)
  • Acute renal failure (especially if elderly or underlying renal disease)
  • Agitation, hallucinations, encephalopathy (higher risk in elderly)

Common
  • Headache, dizziness
  • Nausea/vomiting, abdominal pain
  • Neutropenia, thrombocytopenia, leukopenia
  • Elevated LFTs
  • Nasopharyngitis
  • Dysmenorrhea
  • Depression
  • Rash
  • Alopecia
  • EM
  • Hypertension
  • Tachycardia
  • Tremor
  • Visual disturbance

Pharmacology
  • Half-life: 2-3.3hr
  • Metabolism: Hepatic
  • Excretion: Urinary
  • Mechanism of Action: converted to acyclovir, which competes with deoxyguanosine triphosphate for viral DNA polymerase to inhibit DNA synthesis and viral replication

See Also


References
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