Gunnar Wasner, MD, a consultant neurologist at the Department of Neurology and the Division of Neurological Pain Research and Therapy, Christian-Albrechts-University, Kiel, Germany discussed at the 14th World Congress on Pain the mechanism of action of lidocaine 5% plaster in the management of postherpetic neuralgia (PHN) and new safety data available.

The lidocaine contained in the plaster diffuses continuously into the skin, providing a cumulative local analgesic effect. Lidocaine is a voltage-gated sodium channel antagonist which inhibits the generation and conduction of nerve impulses. The hydrogel plaster acts specifically on abnormally excitable, damaged A- and C-fibers by blocking the sodium channels that they express in high number. This leads to a stabilization of the neuronal membrane potential, resulting in a reduction of ectopic discharges.

The responder rate of 62% is comparable to systemic treatments, and more than 80% of responding patients experience pain relief within the first two weeks. All adverse reactions were predominantly of mild and moderate intensity. Up to four-year clinical data demonstrated sustained long-term efficacy with minimal risk of systemic side effects and minimal risk of drug-drug interactions.