Glaxo Sues XenoPort Over Contract for Restless-Leg Medicine Horizant

A GlaxoSmithKline Plc (GSK) unit sued XenoPort Inc. in federal court in Delaware, seeking a ruling that it properly promoted the restless-leg medicine Horizant in the U.S.

Glaxo Group of Middlesex, England, and Santa Clara, California-based XenoPort agreed to collaborate on Horizant starting in 2007 and the drug was approved by the U.S. Food and Drug Administration last year, according to court papers.

Last month, XenoPort told Glaxo it wasn’t doing enough “to commercialize and promote Horizant” or reach certain milestones, and said it would terminate the agreement, Glaxo contends in the suit.

The British company asked a federal judge in Wilmington to rule it has complied with XenoPort’s terms and to preserve Glaxo’s “exclusive license rights” to Horizant.

Jackie Cossmon, a XenoPort spokeswoman, didn’t immediately reply to voice and e-mail messages seeking comment on the lawsuit.

Horizant has the potential for $100 million a year in U.S. sales, an analyst said April 7, after the drug was approved.

Shares of XenoPort rose 12 cents or 2.37 percent to $4.32 in Nasdaq stock market trading at 11 a.m. in New York.

The case is Glaxo Group Ltd. v. XenoPort Inc. (XNPT), U.S. District Court, District of Delaware (Wilmington).

To contact the reporter on this story: Phil Milford in Wilmington, Delaware, at

To contact the editor responsible for this story: Michael Hytha at

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