Sepracor sues to suppress generic copies of Lunesta

WASHINGTON - Sepracor Inc. said it filed a lawsuit to prevent companies from selling generic versions of its top-selling sleep drug, Lunesta.

Among the dozen companies sued were Teva Pharmaceutical Industries Ltd., the world's biggest generic-drug maker, and Mylan Inc., the biggest in the United States. Each is applying to sell low-cost versions of the drug, whose chemical name is eszopiclone. The suit claims copies would infringe four patents and seeks to block regulatory approval until all four expire in 2012.

Lunesta generated $600.3 million in sales last year for Marlborough, Mass.-based Sepracor, or 46 percent of all revenue.

The lawsuit against the generic-drug makers was filed yesterday in federal court in New Jersey. Under federal drug law, the Food and Drug Administration can't approve their applications until June 2012 unless a court rules in their favor before then.