Impax Pharmaceuticals, the brand products division of Impax Laboratories, and GlaxoSmithKline (GSK) are terminating their collaboration for the development and commercialization of IPX066 outside the U.S. and Taiwan.

In the December 2010 agreement, GSK's right to develop and commercialize IPX066 outside the U.S. and Taiwan will transfer back to Impax effective at the end of July 2013. The decision has been reached because of delays in the anticipated regulatory approval and launch dates in countries in which GSK has rights to commercialize the product.

Impax intends to initiate activities to find a partner or partners for markets outside the U.S. looking to grow their non-U.S. neurology franchise.

IPX066 (known as Rytary in the U.S.) is an investigational extended-release capsule formulation of carbidopa-levodopa being developed for the symptomatic treatment of adult patients with idiopathic Parkinson's disease and is not approved anywhere in the world.