VALACYCLOVIR

OBJECTIVE: To discuss the clinical pharmacology, antiviral activity, c linical efficacy, and other therapeutic issues associated with valacyc lovir use for the treatment of herpesvirus infections. DATA SOURCE: Li terature searches using MEDLINE were prospectively designed to include relevant articles and abstracts between January 1982 and March 1996. The searches focused on valacyclovir pharmacology, clinical efficacy, and issues associated with herpesvirus infections. STUDY SELECTION: Se lection of clinical and basic science studies were limited to those fo cusing on valacyclovir. All articles with pertinent information releva nt to the scope of this article were reviewed. DATA SYNTHESIS: Valacyc lovir is an amino acid ester prodrug of acyclovir. It is currently app roved for die treatment of herpes tester infections in immunocompetent adults (1 g po tid for 7 d) and recurrent episodes of genital herpes in immunocompetent adults (500 mg bid for 5 d), Valacyclovir is rapidl y and almost completely hydrolyzed to acyclovir prior to systemic expo sure. The bioavailability of valacyclovir is 54% compared to approxima tely 20% for oral acyclovir. At higher dosages (2 g qid), the plasma A UC of acyclovir following oral valacyclovir administration approximate s that seen after intravenous administration of 10 mg/kg every 8 hours , Clinical data indicate that valacyclovir is at least as effective as acyclovir in decreasing the duration of pain associated with postherp etic neuralgia, and in reducing time to genital lesion healing and the length of the episode. CONCLUSIONS: Valacyclovir has improved bioavai lability over acyclovir and is at least as efficacious. The favorable safety profile of acyclovir and increased systemic exposure make it a particularly ideal candidate for further studies of herpes group viral infections in immunocompromised patients.