Reduction of Postherpetic Neuralgia in Herpes Zoster

Inclusion Criteria: * Male or female patients of 50 years of age and older. * Patients with a clinical diagnosis of uncomplicated herpes zoster presenting within the first 72 hours of vesicles. * Patients who are willing and able to comply with the requirements of the study. * Patients who are willing and able to give written informed consent. * Average pain score pre-therapy greater or equal than 4 on 10-point Likert scale. Exclusion Criteria: * Sexually-active women of childbearing potential, including postmenopausal women less than 1 year since last menses, not employing adequate contraception (approved oral contraceptive, intrauterine device, barrier methods or total abstinence). * Pregnant females and nursing mothers. * Patients with immune dysfunction including congenital immune deficiency, active malignancy of any type, collagen vascular diseases, organ or bone marrow transplantations, known infection with HIV or severe atopic dermatitis. * Patients who have received cytotoxic drugs or immunosuppressive therapy (e.g., chronic systemic corticosteroids) within the previous 3 months. * Patients with evidence of cutaneous or visceral dissemination of herpes zoster infection (cutaneous dissemination is defined as \> 20 discrete lesions outside adjacent dermatomes). * Patients who have received systemic anti-VZV medications or immunomodulatory medications (including interferon) within the previous 4 weeks. * Patients currently receiving probenecid. * Patients with impaired renal function: calculated creatinine clearance of \<30 mL/min using Cockcroft and Gault formula. * Patients with abnormal liver function (alanine transaminase (ALT) or aspartate;transaminase (AST) levels greater than five times the upper limit of the normal range). * Patients with a history of intolerance or hypersensitivity to acyclovir, penciclovir, valacyclovir, famciclovir or gabapentin. * Patients currently receiving therapy with gabapentin or tricyclic antidepressants. * Patients with clinical evidence of ocular involvement of herpes zoster. Patients with herpes zoster of the ophthalmic branch of the trigeminal nerve without evidence of ocular involvement will be included.