LAS VEGAS, NV—Lidocaine patch 5% is effective and well-tolerated if applied to the face, trunk, or extremities, according to the results of a study in patients with postherpetic neuralgia reported during PAINWeek 2012.
Postherpetic neuralgia has the potential to transpire to any bodily location, many times after an acute herpes zoster presence in trigeminal and brachial plexus dermatomes. According to guidelines on postherpetic neuralgia, Lidocaine patch 5% is indicated for as first-line treatment. Compared with systemic therapy, the Lidocaine patch 5% has a low risk of adverse reactions and drug-drug interactions; this may be an advantage when prescribing the agent in complex instances.
Matthew Wieman, MD, from Endo Pharmaceuticals Inc., Chadds Ford, PA, and colleagues conducted a post-hoc analysis to determine whether the anatomic location of Lidocaine patch 5% application is associated with variation in measures of efficacy and tolerability for postherpetic neuralgia pain. Investigators analyzed a 4-week, multicenter, open-label study that enrolled patients of all ages with postherpetic neuralgia of ≥1 month duration after onset. Patients were stratified by bodily location: face (including neck), trunk (consisting of chest, abdomen, back, or hips), and extremities (consisting of arm or leg). Efficacy was measured by the Brief Pain Inventory (BPI) average pain intensity, ranging from 0 (no pain) to 10 (worst pain imaginable).
A total of 332 patients enrolled in the study, of which 203 used the Lidocaine patch 5% for <12 hours daily on a single anatomic site (trunk: n=130; face: n=41; extremities: n=32); their baseline and post-baseline pain score data were then analyzed. BPI average pain significantly improved from baseline in each of the areas (mean score decrease, 1.5–2.04; P<0.004). Patients also reported significant pain relief at all treated anatomic locations (P<0.009). Moreover, there was no significant difference in efficacy between the 3 groups (P≥0.45).
The study investigators concluded that, “Lidocaine 5% patch was effective and well tolerated for each anatomic area compared.” They further noted that fewer adverse events were reported with patch placement on the extremities compared with the head and trunk, possibly because of differences in skin thickness, sensitivity, and sweating in these areas.