Lidocaine patch: double-blind controlled study of a new treatment method for post-herpetic neuralgia

TLDR

Post‑herpetic neuralgia is a common, often intractable neuropathic pain syndrome in the elderly, and topical local anesthetics have shown promise in treating it. In a double‑blind, vehicle‑controlled study, 35 PHN patients received up to three 5 % lidocaine patches applied in two of four 12‑hour sessions, with vehicle and no‑treatment sessions as controls. Lidocaine patches significantly reduced pain intensity at all measured time points versus vehicle and no‑treatment, were superior in average pain relief, had minimal systemic absorption (0.1 µg/mL), and were well tolerated, demonstrating ease of use and efficacy for PHN.

Abstract

Post-herpetic neuralgia (PHN) is a common and often intractable neuropathic pain syndrome predominantly affecting the elderly. Topical local anesthetics have shown promise in both uncontrolled and controlled studies. Thirty-five subjects with established PHN affecting the torso or extremities completed a four-session, random order, double-blind, vehicle-controlled study of the analgesic effects of topically applied 5% lidocaine in the form of a non-woven polyethylene adhesive patch. All subjects had allodynia on examination. Up to 3 patches, covering a maximum of 420 cm2, were applied to cover the area of greatest pain as fully as possible. Lidocaine containing patches were applied in two of the four 12-h-long sessions, in one session vehicle patches were applied, and one session was a no-treatment observation session. Lidocaine containing patches significantly reduced pain intensity at all time points 30 min to 12 h compared to no-treatment observation, and at all time points 4–12 h compared to vehicle patches. Lidocaine patches were superior to both no-treatment observation and vehicle patches in averaged category pain relief scores. The highest blood Lidocaine level measured was 0.1 μg/ ml, indicating minimal systemic absorption of Lidocaine. Patch application was without systemic side effects and well tolerated when applied on allodynic skin for 12 h. This study demonstrates that topical 5% Lidocaine in patch form is easy to use and relieves post-herpetic neuralgia.