Depomed Inc. has completed patient enrolment in the pivotal registration phase 3 clinical trial designed to evaluate the safety and efficacy of Gabapentin GR for the treatment of postherpetic neuralgia (PHN). The company expects to announce results from this trial mid-year.

The randomised, double-blind, placebo-controlled phase 3 clinical trial is being conducted at 110 sites in the US and has enrolled 407 patients with PHN. Patients have been randomised 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-daily and twice-daily (1800 mg total daily-dose) for eight weeks compared to placebo in reducing average daily pain scores from baseline to endpoint. Secondary objectives include generating data on safety, sleep interference and general impressions of changes in pain.

Gabapentin GR is an investigational extended release formulation of gabapentin, an FDA-approved product for the treatment of PHN. 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. In 2006, 16.3 million prescriptions for gabapentin were dispensed.

Neuropathic pain affects approximately 2.6 million individuals in the United States. Postherpetic neuralgia (PHN) is a persistent neuropathic pain condition caused by nerve damage after a shingles, or herpes zoster, viral infection.