A Study on the Effect of Topical 5% Lidocaine Patches on Postherpetic Neuralgia

ABSTRACT

BACKGROUND: Postherpetic neuralgia (PHN) is the most common and serious complication of herpes zoster and its incidence is increasing in the aging population. Despite the many approaches thath have been proposed to treat postherpetic neuralgia, none of the therapies are satisfactory in their efficacy and safety. OBJECTIVE: Assessment of the effectiveness and safety of the 5% lidocaine patch, a targeted peripheral analgesic, for the treatment of postherpetic neuralgia. METHOD: Fifteen patients with established PHN completed a three-session, random-order, double-blind, vehicle-controlled study. A maximum of three patches were applied to the most painful area for 12 hours, twice in two consecutive days (i.e., 12 hours on followed by 12 hours off). Two sessions were done with the 5% lidocaine patches and one session with a placebo patch. The sessions were conducted at least 7 days apart. RESULTS: The 5% lidocaine patch significantly reduced the mean VAS scores (pain intensity) at the time points from hours 12 to 72 compared with baseline (individual time points p<0.001 to p=0.033) and from hours 12 to 72 compared with the vehicle patch (individual time points p<0.001 to p=0.015). The lidocaine patch also provided significantly greater pain relief on the 6-item scale compared with the vehicle patch (individual time points p<0.001 to p=0.04). The patches were well tolerated by all patients. Neither systemic side effects nor significant skin irritation were noted. CONCLUSION: This study demonstrates that use of the 5% lidocaine patch resulted in statistically significant pain relief. Patients suffering from PHN will find the patches easy to use and there is minimal risk of systemic toxicity