Lunesta Data to Be Presented at American Psychiatric Association Annual Meeting

Business Wire, May 19, 2005

MARLBOROUGH, Mass. -- Sepracor Inc. (Nasdaq: SEPR) today announced that Phase III/IV clinical data for LUNESTA(TM) brand eszopiclone for the treatment of insomnia will be presented at the American Psychiatric Association (APA) annual meeting in Atlanta.

Posters will be presented on May 25, 2005 in the Georgia World Congress Center, Level 3, Rooms B302-B305 between 12:00 pm and 2:00 pm. The posters are entitled:

--Adjunctive Eszopiclone and Fluoxetine in Major Depressive Disorder (MDD) and Insomnia: Depression Effects

--Adjunctive Eszopiclone With Fluoxetine for MDD and Insomnia: Sleep Effects

--Effect of Eszopiclone on Sleep Parameters That Affect Next-Day Function

--A Crossover Study of Eszopiclone Treatment of Primary Insomnia

Sepracor will also have a LUNESTA Booth (booth #2742) at APA from May 22 to 25, 2005.

On April 4, 2005, Sepracor began full-scale commercial launch of LUNESTA. LUNESTA, which is indicated for the treatment of insomnia in patients who experience difficulty falling asleep as well as for the treatment of patients who are unable to sleep through the night (sleep maintenance difficulty), is now available by prescription in 1 mg, 2 mg and 3 mg tablets.

Insomnia can include difficulty falling asleep as well as difficulty maintaining sleep through the night. The recommended dosing for LUNESTA to improve sleep onset and/or maintenance is 2 mg or 3 mg for adult patients (ages 18 to 64). In older adult patients (ages 65 and older), 2 mg is recommended for improving sleep onset and/or maintenance, while the 1 mg dose is recommended for improving sleep onset in older adult patients whose primary complaint is difficulty falling asleep.

An estimated 100 million adult Americans suffer from either chronic or occasional insomnia.(1) Symptoms of insomnia include difficulty falling asleep, awakening frequently during the night, waking up too early, an inability to fall back to sleep or awakening feeling unrefreshed.

The U.S. market for prescription sleep products was approximately $2.1 billion in 2004, excluding products not indicated for the treatment of insomnia that are nonetheless used in its treatment. This represents nearly a 19 percent increase over the previous year, according to IMS Health information.

Important Safety Information

LUNESTA works quickly and should only be taken immediately before bedtime. Be sure you have at least eight hours to devote to sleep before becoming active. You should not engage in any activity after taking LUNESTA that requires complete alertness, such as driving a car or operating machinery. You should use extreme care when engaging in these activities the morning after taking LUNESTA. Do not use alcohol while taking any sleep medicine. All sleep medicines carry some risk of dependency. Do not use sleep medicines for extended periods without first talking to your doctor. Side effects may include unpleasant taste, headache, drowsiness and dizziness.

Please visit http://www.sepracor.com or http://www.lunesta.com to access the FDA-approved labeling text for LUNESTA.

About Sepracor

Sepracor Inc. is a research-based pharmaceutical company dedicated to treating and preventing human disease through the discovery, development and commercialization of innovative pharmaceutical products that are directed toward serving unmet medical needs. Sepracor's drug development program has yielded an extensive portfolio of pharmaceutical compound candidates with a focus on respiratory and central nervous system disorders. The company's commercialization efforts are carried out by its U.S.-based, 1,250-person, primary care and specialty-oriented sales force. Sepracor's corporate headquarters are located in Marlborough, Massachusetts.

This news release contains forward-looking statements that involve risks and uncertainties, including statements with respect to the commercial launch and availability of LUNESTA brand eszopiclone, as well as the safety, efficacy and potential benefits of LUNESTA. Among the factors that could cause actual results to differ materially from those indicated by such forward-looking statements are: unexpected interruptions in commercial distribution of LUNESTA; Sepracor's ability to fund, and the results of, further clinical trials; the timing and success of submission, acceptance and approval of additional regulatory filings; the scope of Sepracor's patents and the patents of others; the commercial success of LUNESTA; the ability of the company to attract and retain qualified personnel; and certain other factors that are detailed in the company's quarterly report on Form 10-Q for the quarter ended March 31, 2005 filed with the Securities and Exchange Commission.

In addition, the statements in this press release represent Sepracor's expectations and beliefs as of the date of this press release. Sepracor anticipates that subsequent events and developments may cause these expectations and beliefs to change. However, while Sepracor may elect to update these forward-looking statements at some point in the future, it specifically disclaims any obligation to do so. These forward-looking statements should not be relied upon as representing Sepracor's expectations or beliefs as of any date subsequent to the date of this press release.