A Randomized, Double-Blind, Placebo- and Active-Controlled Study of Carisbamate in the Treatment of Neuropathic Pain in Diabetic Peripheral Neuropathy Followed by a Blinded Extension Phase

INTERVENTION: Product Name: Carisbamate Product Code: RWJ‐333369 Pharmaceutical Form: Tablet Current Sponsor code: RWJ‐333369 Other descriptive name: Casrisbamate Concentration unit: mg milligram(s) Concentration type: equal Concentration number: 200‐ Pharmaceutical form of the placebo: Tablet Route of administration of the placebo: Oral use Product Name: Carisbamate Product Code: RWJ‐333369 Pharmaceutical Form: Tablet Current Sponsor code: RWJ‐333369 Other descriptive name: Casrisbamate Concentration unit: mg milligram(s) Concentration type: equal Concentration number: 400‐ Pharmaceutical form of the placebo: Tablet Route of administration of the placebo: Oral use Trade Name: Lyrica Product Name: Pregabalin Pharmaceutical Form: Capsule* Concentration unit: mg milligram(s) Concentration type: equal Concentration number: 75‐ Pharmaceutical form of the placebo: Capsule* Route of administration of the placebo: Oral use Trade Name: Lyrica Product Name: Pregabalin Pharmaceutical Form: Capsule* Concentration unit: mg milligram(s) Concentration type: equal Concentration number: 150‐ Pharmaceutical form of the placebo: Capsule* Route of administration of the placebo: Oral use CONDITION: Neuropathic Pain in Diabetic Peripheral Neuropathy ; MedDRA version: 9.1 Level: LLT Classification code 10054095 Term: Neuropathic pain PRIMARY OUTCOME: Main Objective: The primary objective is to evaluate the efficacy, safety, and tolerability of 800 and 1,200 mg/day of carisbamate compared with placebo in reducing the average daily pain in subjects with diabetic peripheral neuropathy (DPN). Primary end point(s): The primary efficacy endpoint is the mean of the last 7 Daily Average DPN Pain scores; of the double‐blind treatment phase on days study drug is taken. Secondary Objective: • To evaluate the impact of 800 and 1,200 mg/day of carisbamate on:; – Pain symptoms; – Functional health status (including physical and social functioning) and well‐being; – Rescue medication use; – Sleep interference; • To evaluate global assessments of improvement and severity from subject perspective; • To characterize the population pharmacokinetics of carisbamate in subjects with DPN; • To evaluate long‐term safety of carisbamate in subjects with DPN INCLUSION CRITERIA: • Men or women between 18 and 75 years of age, inclusive • Have diabetes mellitus (Type 1 or Type 2) • Subjects must meet the following criteria at the end of the baseline period to be randomly assigned into the double‐blind treatment phase of the study: – Documented daily average DPN pain assessments (ie, evening ratings for pain over the past 24 hours) for at least 5 days in the baseline period – Mean Daily Average DPN Pain score of at least 4 on an 11‐point scale during the baseline period • Have symptoms of diabetes‐related painful peripheral neuropathy in the distal extremities for at least 6 months prior to study entry. The pain symptoms must be attributable to DPN confirmed by history and findings on neurologic examination. • Experienced lower extremity pain due to diabetic neuropathy on a nearly daily basis for the previous 3 months • Have hemoglobin A1c (HbA1c) levels =11% • Have a stable diabetic treatment regi