Clinical trials for Valeant's shingles pain drug show no conclusive benefit

Announcing the preliminary results from its Phase IIa proof-of-concept clinical trial of retigabine, which it was hoping to bring to the market as a cure for the treatment of pain associated with postherpetic neuralgia (PHN), a painful and common complication of shingles, drug maker Valeant Pharmaceuticals International, today said while retigabine was generally well tolerated, the study did not meet its pre-specified primary efficacy endpoint.

Further detailed analyses are warranted and are ongoing, Valeant said in a statement.

"As is typical in many proof-of-concept studies, these results are inconclusive at this time with regard to the potential utility of retigabine in PHN patients," Valeant chairman and CEO J Michael Pearson, said.

Retigabine has not been found by the Food and Drug Administration (FDA) or any other regulatory agency to be safe or effective in the diagnosis, mitigation, treatment or cure of any disease or illness. It is not permitted for sale or promoted in the United States as the FDA has not yet approved a NDA. Similar restrictions apply in other countries.

The study was a randomised, double-blind, placebo-controlled Phase IIa proof-of-concept study with 187 patients randomised 2:1 of retigabine versus placebo for a treatment period of up to 10 weeks.

Valeant said the study was conducted in approximately 50 trial locations. Study patients were titrated to their individually determined maximum tolerated dose within the range of 300mg to 900mg per day. The primary outcome assessment was the comparison of the average pain intensity over the last seven days of maintenance therapy with retigabine versus placebo. Pain intensity was measured on a standard 0 - 10 numerical rating scale.