-- Submission includes data from three Phase III studies in more than 1,000 patients from 23 countries

-- More than 3 million people in the U.S. are afflicted with epilepsy and seizures¹

-- U.S. epilepsy treatment market estimated to be $3.5 billion²

Sepracor Inc. (Nasdaq: SEPR) today announced that it has been notified by the U.S. Food and Drug Administration (FDA) that the New Drug Application (NDA) for STEDESA^™ (eslicarbazepine acetate) has been accepted for filing and is now under formal review. As previously announced, the NDA for STEDESA was submitted to the FDA on March 31, 2009 for adjunctive therapy in the treatment of partial-onset seizures in adults with epilepsy. The acceptance of the filing means that the FDA has made a threshold determination that the NDA is sufficiently complete to permit a substantive review.

The Prescription Drug User Fee Act (PDUFA) date for STEDESA is expected to be January 30, 2010, subject to written confirmation. A PDUFA date is the date by which the FDA is expected to review and act on an NDA submission.

“We are very pleased to continue the advancement of STEDESA as a potential new adjunctive treatment for partial-onset epilepsy,” said Adrian Adams, President and Chief Executive Officer of Sepracor. “STEDESA represents a significant and near-term opportunity for Sepracor, and the FDA acceptance of the NDA is yet another step forward in one of our near- and mid-term corporate objectives of expanding and advancing our pharmaceutical product pipeline.”

STEDESA, a new chemical entity, is a novel voltage-gated sodium channel blocker. STEDESA has been studied in three Phase III, multi-center, randomized, placebo-controlled trials, which involved more than 1,000 patients from 23 countries. Patients involved in the trials had a history of at least four partial-onset seizures per month despite treatment with one to three concomitant antiepileptic drugs. During the trials, patients were randomized to eslicarbazepine acetate or placebo, and after a 2-week titration period, were assessed over a 12-week maintenance period with continued follow-up over a one-year, open-label period.

BIAL-Portela & C^a, S.A. (BIAL), a privately held Portuguese pharmaceutical company, was responsible for the research and development of eslicarbazepine acetate. Sepracor acquired the rights to commercialize eslicarbazepine acetate in the U.S. and Canadian markets from BIAL in late 2007.

Sepracor is seeking approval of STEDESA for adjunctive therapy with once-daily doses of 800 mg and 1200 mg in the treatment of partial-onset seizures in adults with epilepsy.

About partial-onset seizures and their treatment

Epilepsy is one of the most common neurological diseases that, according to the Epilepsy Foundation, afflicts more than 3 million people in the United States.