Depomed, Inc. has initiated a Phase II clinical trial to evaluate the safety and efficacy of its Gabapentin extended release tablets to treat patients with postherpetic neuralgia, a long-lasting pain condition associated with nerve damage from herpes zoster, or shingles, infection.

The randomized, double-blind, placebo controlled trial is expected to include approximately 25 US sites and 150 postherpetic neuralgia patients. The primary objective is to assess the efficacy of Gabapentin ER twice daily compared to placebo in reducing mean daily pain scores. In addition, the trial will evaluate other safety and efficacy parameters, including sleep interference, a common problem of patients in pain.

"From this trial, we will gather data on Gabapentin ER's ability to provide extended pain relief, with less frequent dosing, to patients suffering from this chronic pain condition," Bret Berner, vice president, Product Development said adding, "This is particularly important to provide a more patient-friendly regimen that allows patients to stay ahead of the pain."

In a Phase I trial involving 15 healthy volunteers, pharmacokinetic properties of Gabapentin ER were compared to Neurontin, Pfizer's brand of gabapentin. The data showed that Gabapentin ER has an extended, sustained release plasma profile that is appropriate for administration twice daily compared to the most commonly prescribed three times daily dosing with Neurontin.

Postherpetic neuralgia (PHN) is a persistent pain condition caused by nerve damage during a shingles, or herpes zoster, viral infection. PHN afflicts approximately one in five patients diagnosed with shingles. The incidence increases in elderly patients with 75 per cent of those over 70 years old developing PHN. Since there is no cure for PHN, treatments are focused on relieving pain.