Efficacy and Safety of Lacosamide in Painful Diabetic Neuropathy

OBJECTIVE To evaluate efficacy and safety of lacosamide compared with placebo in painful diabetic polyneuropathy. RESEARCH DESIGN AND METHODS Diabetic patients with at least moderate neuropathic pain were randomized to placebo or lacosamide 400 (in a slow or standard titration) or 600 mg/day over 6-week titration and 12-week maintenance periods. Primary efficacy criterion was intra-individual change in average daily Numeric Pain Rating Scale score from baseline to the last 4 weeks. RESULTS For the primary end point, pain reduction was numerically but not statistically greater with lacosamide compared with placebo (400 mg/day, P = 0.12; 600 mg/day, P = 0.18). Both doses were significantly more effective compared with placebo over the titration (P = 0.03, P = 0.006), maintenance (P = 0.01, P = 0.005), and entire treatment periods (P = 0.03, P = 0.02). Safety profiles between titration schemes were similar. CONCLUSIONS Lacosamide reduced neuropathic pain and was well tolerated in diabetic patients, but the primary efficacy criterion was not met, possibly due to an increased placebo response over the last 4 weeks.