Valtrex

Key Benefits of Valtrex

Valtrex demonstrates superior bioavailability (54% vs acyclovirs 15-30%), allowing for less frequent dosing with equal or better efficacy. Clinical trials show Valtrex reduces genital herpes transmission risk by 48% among heterosexual couples when taken daily as suppressive therapy. For cold sores, a 2-day course (2 grams 12 hours apart) can shorten healing time by 1-2 days when initiated at prodrome.

Mechanism of Action

After oral administration, Valtrex rapidly converts to acyclovir via first-pass intestinal/hepatic metabolism. The active form then competitively inhibits viral DNA polymerase, incorporating into viral DNA to terminate chain elongation. This selective action requires viral thymidine kinase for activation, making it particularly targeted to infected cells.

FDA-Approved Uses

Valtrex is indicated for: treatment of initial/recurrent genital herpes (HSV-2) suppression of recurrent genital herpes treatment of cold sores (HSV-1) treatment of shingles (herpes zoster) and chickenpox in pediatric patients. Off-label uses include HSV prophylaxis in immunocompromised patients.

Dosing Guidelines

Standard Valtrex dosing includes: 1g twice daily for 10 days (initial genital herpes) 500mg twice daily for 3 days (recurrent genital herpes) 500mg-1g daily (suppression) 2g twice daily for 1 day (cold sores) and 1g three times daily for 7 days (shingles). Renal dosing adjustments required for CrCl <50mL/min.

Safety Information

Most common adverse reactions (=10%): headache (35%), nausea (14%), abdominal pain (11%). Serious but rare risks include thrombotic thrombocytopenic purpura/hemolytic uremic syndrome (TTP/HUS) in advanced HIV patients and acute renal failure with aggressive IV hydration. Contraindicated in patients with hypersensitivity to valacyclovir or acyclovir.