GlaxoSmithKline throws in the towel on $186M Parkinson's pact with Impax

A little more than two years after signing up GlaxoSmithKline as its Big Pharma partner on an extended-release version of a carbidopa-levodopa combo for Parkinson's disease, Impax Laboratories ($IPXL) is headed back to the bargaining table. The FDA rejected the drug based on manufacturing issues a few months ago, and a frustrated Glaxo ($GSK) has now decided to drop out of the game.

Impax says the deal table is now open for new discussions.

GSK gained ex-U.S. rights to Rytary (IPX066) in a $186 million deal inked back in late 2010, paying $11.5 million upfront. The partners trumpeted positive late-stage data just months later, saying that Impax's second try at an extended-release version of carbidopa-levodopa significantly reduced "off-time," the number of minutes each day in which patients' standard treatment wears off and the motor symptoms of the disease return. Researchers said that in Phase III patients given a regimen of carbidopa-levodopa plus entacapone registered 5.2 hours of "off time" compared to a much-improved 3.8 hours for the experimental drug arm.

Getting a sustained-release version of the drug approved, though, has run into a number of problems at the regulatory level. And Impax's release this morning notes that GSK backed out "because of delays in the anticipated regulatory approval and launch dates in countries in which GSK has rights to commercialize the product."

Shares of Hayward, CA-based Impax were down slightly this morning.

- here's the press release