New analgesics for neuropathic pain: the lidocaine patch.

Despite the availability of different pharmacologic agents for the treatment of various chronic neuropathic pain syndromes, complete symptom reduction and/or complete functional restoration is rarely achieved. New, safe, and effective treatments for chronic neuropathic pain, therefore, must be developed. One such agent, the lidocaine patch (Lidoderm, Endo Pharmaceuticals, Inc., Chadds Ford, PA), has been approved recently by the US Food and Drug Administration for the treatment of postherpetic neuralgia. Like other local anesthetics, the lidocaine patch results in sodium channel blockade, dampening, both peripheral nociceptor sensitization and, ultimately, central nervous system hyperexcitability. The Lidoderm patch is a topical agent and, consequently, insignificant serum levels are achieved even with chronic use. This fact enhances its safety. Recent studies have suggested that the lidocaine patch may be effective for chronic neuropathic pain conditions other than postherpetic neuralgia as well.