DepoMed reported negative results from a phase III trial of Gabapentin GR for the treatment of postherpetic neuralgia (PHN). The product is a twice-daily, controlled-release tablet formulation of the anticonvulsant and analgesic gabapentin.

This randomized, double-blind, placebo-controlled trial enrolled 407 subjects who were placed into one of three treatment groups to receive Gabapentin GR once daily, Gabapentin GR twice daily (each 1800 mg/day) or placebo for 10 weeks.

The primary endpoint was the reduction in average daily pain scores from baseline to endpoint with Gabapentin GR compared to placebo. Statistical significance was not reached for either active treatment group. The average daily reductions were 1.83 (once daily), 1.72 (twice daily) and 1.43 (placebo). However, statistical significance was achieved in all the secondary endpoints, including Clinical Global Impression of Change (p less than 0.001) and Patient Global Impression of Change (p=0.009).

DepoMed plans to fully evaluate the data in order to determine a future course of action.