Presented at the 2012 AAPM Annual Meeting « Back

Effectiveness and Safety of Lidocaine 5% Patch as Add-On Treatment in Patients with Allodynia Caused by Postherpetic Neuralgia, Diabetic Neuropathy, or Low Back Pain

Srinivas Nalamachu, MD, nalamachu@yahoo.com¹, Matthew Wieman, MD², Errol M. Gould, PhD², (1) International Clinical Research Institute, Leawood, Kansas, (2) Endo Pharmaceuticals Inc., Chadds Ford, Pennsylvania

Introduction: Patients with neuropathic pain may not respond to pharmaceutical monotherapy. The effectiveness and safety of add-on therapy with a topical lidocaine 5% patch was recently assessed. Materials and Methods: This open-label study included adult patients with postherpetic neuralgia (PHN), diabetic neuropathy (DN), and low back pain (LBP) with a partial response to a gabapentin-containing regimen (pain rating >4; 0 = no pain, 10 = most severe pain). Patients applied ≤4 lidocaine 5% patches (10 x 14 cm) once daily to the area of maximum pain for 14 days without altering their gabapentin regimen. Assessments included Brief Pain Inventory (BPI) scores (0 = no pain, 10 = most severe pain) for worst, least, and average pain. Institutional review board approval and patient informed consent were obtained. Results: Allodynia was present in 57/107 (53%) patients, including 11/11 (100%) with PHN, 27/49 (55%) with DN, and 19/47 (40%) with LBP. The baseline mean pain ratings were 6.7 (PHN), 3.5 (DN), and 2.7 (LBP). Patients with allodynia had greater change from baseline in BPI worst (2.0), average (1.5), and least (1.7) pain scores versus those without allodynia (1.1, 0.9, and 0.8, respectively). The most frequent adverse event (AE) was dermatitis. No serious treatment-related AEs were reported. Conclusions: Addition of topical lidocaine 5% patch to a gabapentin regimen reduced pain intensity in patients with PHN, DN, and LBP. Patients with allodynia obtained greater pain relief than those without allodynia.

Funding: This study was funded by Endo Pharmaceuticals Inc., Chadds Ford, PA.