Depomed is regaining the rights to its recently-approved shingles drug Gralise from Abbott Laboratories.

In a regulatory filing to the US Securities and Exchange Commission, the Menlo Park, California-based firm revealed that it has entered into a settlement with Abbott over Gralise (extended-release gabapentin) tablets  which was approved by the US Food and Drug Administration for once-daily treatment of post-herpetic neuralgia, ie pain following healing of the rash associated with shingles, in January. However news of that green light was spoilt for Depomed somewhat by Abbott saying it was not particularly keen on continuing the firms' pact.

Gralise was licensed to Solvay Pharmaceuticals in November 2008, which was then acquired by the US major in February 2010. The original deal, in addition to the $48 million for approval, called for royalties of 14%-20% on product sales, and milestone payments of up to $300 million.

Abbott declared it did not believe it was "obligated to launch and commercialise" Gralise but Depomed disagreed, though the firms have now settled their differences. Depomed is getting the rights back to the treatment and will also receive a $40 million payment.

The company currently plans to launch Gralise by the end of 2011, and direct its sales and marketing efforts at neurologists "and other postherpetic neuralgia thought leaders". It will also look for a co-promotion partner to address the primary care segment.

However last month, despite the approval of Gralise, the FDA asked Depomed for additional evidence to prove the clinical superiority of the drug - based on its improved safety profile - before it will grant the seven years of marketing exclusivity associated with orphan drug status.