Study to Assess the Effect of Gabapentin Enacarbil on Simulated Driving in Healthy Subjects

proportional systemic gabapentin exposure over a wide dose range. This is a double-blind, placebo-and active-controlled 3-period crossover study designed to assess the effect of GEn 600 mg on simulated driving performance. Subjects will receive each of 3 treatments in a randomized order: GEn 600 mg, placebo and placebo/diphenhydramine 50 mg. Each treatment period will consist of 6 days, with subjects being dosed at approximately 5 pm on each dosing day. The placebo /diphenhydramine treatment will consist of placebo on Days 1-4 and 6 and 50 mg diphenhydramine on Day 5. Placebo will be administered on Day 6 in all treatment periods to ensure washout of drug prior to the start of the next treatment period. Simulated driving performance will be assessed at baseline (prior to randomization) and on Day 5 in the evening (7-9 pm) and on Day 6 between7-9 am and between 11am-1pm for each treatment period.