BACKGROUND: Genital herpes and herpes labialis are prevalent, physically and 
psychologically painful, and often disabling. Herpes zoster is often very 
painful and may result in months or years of postherpetic neuralgia (PHN). Over 
the past two decades, the treatment of these conditions has been transformed by 
guanosine nucleoside antivirals such as valacyclovir (Valtrex, a highly 
bioavailable prodrug of acyclovir (Zovirax, and famciclovir (Famvir), a highly 
bioavailable prodrug of penciclovir (Denavir).
OBJECTIVE: We describe the pharmacology, pharmacokinetics, and clinical efficacy 
of valacyclovir for the treatment of herpes simplex, herpes zoster, and other 
viral infections. Valacyclovir is also compared with acyclovir and famciclovir.
METHODS: All published literature containing the word "valacyclovir" was 
reviewed and summarized.
RESULTS: Valacyclovir is the only oral antiviral agent approved for therapy of 
herpes labialis, the only antiviral drug approved for a 3-day course in the 
episodic treatment of recurrent genital herpes, as well as the only antiviral 
drug approved for once daily dosing for suppressive therapy. In herpes zoster, 
valacyclovir is more effective than acyclovir and equally effective as 
famciclovir at hastening the healing of zoster-associated pain and PHN.
CONCLUSION: Valacyclovir is safe and effective in the therapy of patients with 
herpes simplex and herpes zoster and may be useful in other viral infections.