Depomed announced that it has completed patient enrollment in a pivotal registration Phase III clinical trial designed to evaluate the safety and efficacy of Gabapentin GR for the treatment of postherpetic neuralgia. The company expects to announce results from this trial sometime in mid-2007.

The randomized, double-blind, placebo-controlled study is being conducted at 110 sites in the U.S. and has enrolled 407 patients with postherpetic neuralgia. Patients have been randomized into one of three treatment groups: Gabapentin GR once daily, Gabapentin GR twice daily and placebo. The primary objective of the study is to assess the efficacy of Gabapentin GR administered once and twice daily (with a total daily dose of 1,800 mg) for eight weeks in reducing average daily pain scores, compared with placebo. Secondary objectives include generating data on the drug's safety and interference with sleep, as well as patients' general impressions of changes in pain.

Gabapentin GR is an investigational extended-release formulation of gabapentin, an FDA-approved product for the treatment of postherpetic neuralgia. Formulated with Depomed's proprietary AcuForm drug-delivery technology, Gabapentin GR holds the potential to offer patients the pain-relief benefits provided by immediate-release formulations of gabapentin, with fewer side effects and a more convenient once- or twice-daily dosing regimen, the company said. Depomed is also developing the drug for treating diabetic peripheral neuropathy.

Last year 16.3 million prescriptions for gabapentin were dispensed, according to Depomed.