Astellas Pharma Inc. reached an agreement Thursday with XenoPort Inc., a U.S. pharmaceutical company, giving it exclusive rights to sell in Japan and five other Asian markets a painkiller being developed by the U.S. firm, the two companies said.
Under the licensing agreement, Astellas will pay $85 million to the California-based company to market XenoPort's leading product candidate, Astellas said. It will also pay royalties based on sales volume.
The prospective drug is an improved version of gabapentin, a medication used in the treatment of epileptic seizures and nerve pain.
Astellas plans to begin the first phase of clinical tests on the drug in mid-2006.
The five other Asian markets to which Astellas has acquired exclusive rights to market the product are Indonesia, the Philippines, South Korea, Thailand and Taiwan.