Lidocaine medicated plaster, an additional potential treatment option for localized post-surgical neuropathic pain: efficacy and safety results of a randomized, placebo-controlled trial

Objective: To assess the efficacy and safety of lidocaine 700 mg medicated plaster (lidocaine plaster) compared to placebo in patients with moderate to severe chronic post-surgical neuropathic pain (PSNP). Methods: Patients (n = 363) with a diagnosis of PSNP for a minimum of 3 months to 36 months were randomized (1:1) to lidocaine plaster or placebo for a 12 week double-blind treatment period. Randomization was stratified as plaster-only (no concomitant medication for PSNP) or as add-on (stable systemic medication for PSNP). The primary efficacy endpoint was the change from baseline in 24 hour average pain intensity at Week 12, assessed by 11 point numerical rating scale (NRS). The trial was registered in ClinicalTrials.gov (NCT01752322) and EudraCT (2012-000347-28). Results: Treatment with lidocaine or placebo plaster led to a clinically relevant reduction in average pain intensity. Pain reduction (least squares mean [LS mean] standard error [SE], [95% confidence interval, CI]) with lidocaine plaster (-1.70 [0.16], [-2.03, -1.38]) was numerically higher than with placebo (-1.47 [0.16], [-1.78, -1.15]) but the difference was not statistically significant (-0.23 [0.23], [-0.69, 0.22]). Pre-specified exploratory subgroup analyses showed the largest differentiation between lidocaine and placebo in patients without concomitant pain medication, and in patients with more than 1 year between surgery and enrollment. Many secondary outcomes showed a numerically larger improvement in favor of lidocaine. The most commonly reported adverse events were administration site reactions linked to topical administration. Conclusions: A clinically relevant pain reduction was observed with lidocaine plaster in patients with PSNP. The safety and tolerability profile is consistent with current knowledge.