Systemic absorption of topical lidocaine in normal volunteers, patients with post-herpetic neuralgia, and patients with acute herpes zoster.

Topical lidocaine has been recently marketed as a new treatment for post-herpetic neuralgia. The aim of our study was to characterize the absorption profile of and systemic exposure to lidocaine from patch and gel formulations in normal volunteers, patients with post-herpetic neuralgia, and patients with acute herpes zoster. The bioavailability of lidocaine from the patch formulation averaged 3%, and was similar after single and repeated doses. Systemic exposure to lidocaine and monoethylglycinexylidide (MEGX), the primary active metabolite of lidocaine, after application of lidocaine gel or patches was minimal in normal volunteers, patients with post-herpetic neuralgia, and patients with acute herpes zoster. Considering the benefit versus risk of topical lidocaine, systemic absorption and toxicity of lidocaine seems not to be a significant risk. Copyright 2002 Wiley-Liss, Inc. and the American Pharmaceutical Association