Depomed has announced that its new pain drug DM-1796 (gabapentin ER) has met the primary target of reducing pain associated with postherpetic neuralgia (PHN) during late-stage drug trials.

The drug, which Depomed has licensed to Solvay Pharmaceuticals, achieved a statistically significant reduction in pain versus placebo in 452 PHN patients treated over a ten-week period.

Depomed vice-president, research and development Dr Michael Sweeney said that gabapentin has proven efficacy, and the study data suggest that the new extended-release formulation may offer a favourable side-effect profile and added convenience.

“DM-1796 has shown good potential as an important new option for patients with postherpetic neuralgia who often struggle to find effective pain relief treatments,” Sweeney said.

PHN, or pain after shingles, is a persistent neuropathic pain condition caused either by nerve damage or the viral infection herpes zoster, which effects approximately one in five patients diagnosed with shingles.

Following the announcement Depomed shares soared as much as 41% to trade up $1.23 at $5.64.

A New Drug Application for DM-1796 is expected to be submitted to the US Food and Drug Administration (FDA) by the end of the first quarter of 2010.

Depomed stands to receive about $70m in milestone payments from Solvay if DM-1796 achieves FDA approval.