Sepracor Presents Arformoterol Data at American Thoracic Society International Conference.

MARLBOROUGH, Mass. -- Sepracor Inc. (Nasdaq: SEPR) today announced that it presented two arformoterol tartrate inhalation solution posters at the International Conference of the American Thoracic Society (ATS) in San Diego.

Arformoterol tartrate inhalation solution is a long-acting beta-agonist formulation for long-term maintenance treatment of chronic obstructive pulmonary disease (COPD), including chronic bronchitis and emphysema. A New Drug Application (NDA) for arformoterol tartrate inhalation solution is currently under U.S. Food and Drug Administration (FDA) review. The Prescription Drug User Fee Act (PDUFA) date for arformoterol is October 12, 2006. A PDUFA date is the date by which the FDA is expected to review and act on an NDA submission.

Arformoterol, a single isomer of formoterol, is the first long-acting bronchodilator to be developed in an inhalation solution for use with a nebulizer, which is a machine that converts liquid medication into a fine mist that is inhaled through a mask; other long-acting bronchodilators currently available in the U.S. are formulated in dry-powder inhalers.

Nebulized Arformoterol in COPD: A Prospective Phase III Clinical Trial 

This multicenter, double-blind, double-dummy, randomized Phase III study of 717 patients evaluated airway function improvement in patients with COPD who were treated with either arformoterol 50 micrograms, or (mu)g once daily, arformoterol 25 (mu)g twice daily, arformoterol 15 (mu)g twice daily, salmeterol metered-dose inhaler (SEREVENT(R)) 42 (mu)g twice daily, or placebo. Both an albuterol metered-dose inhaler (MDI) as rescue therapy and an ipratropium bromide MDI as supplemental medication for COPD were provided to all patients in this study to be used on an as-needed basis. In this study, patients treated with arformoterol by nebulizer demonstrated significant and sustained improvement in airway function over 12 weeks of treatment versus patients administered placebo.

In this study, patients treated with arformoterol (p<0.001) and salmeterol (p<0.001) demonstrated a clinically meaningful and significant improvement in morning trough FEV1 over 12 weeks, versus patients administered placebo. FEV1 refers to the amount of air forcefully exhaled in one second and is a test of lung function. Patients in each arformoterol treatment group (p<0.001) demonstrated significantly greater improvement than those patients administered placebo, in the percent change from pre-dose in the 12-hour FEV1 area under the curve (AUC) throughout the study. Patients treated with salmeterol (p<0.001) also demonstrated significant improvement versus placebo in percent change from pre-dose in 12-hour FEV1 AUC in this study. Percent change in the area under the curve is one important measure of the magnitude of effect in lung function improvement.

The results also demonstrated that the percentage of patients who were treated with arformoterol who achieved a greater than or equal to 10 percent improvement in FEV1 from pre-dose levels ranged from 93.7 percent to 95.7 percent at Week 0 and 77.1 percent to 87.5 percent at Week 12 versus patients administered placebo, who achieved 55.2 percent at Week 0 and 47.6 percent at Week 12. The percentage of patients treated with salmeterol who achieved greater than or equal to 10 percent improvement in FEV1 from pre-dose levels was 85.1 percent at Week 0 and 58.4 percent at Week 12. Both arformoterol and salmeterol demonstrated adequate time to onset for maintenance treatment of COPD: at Week 12, the time to achieve a 10 percent improvement in FEV1 was 4 to 14 minutes for those patients treated with arformoterol and was 132.3 minutes for patients treated with salmeterol. Overall, arformoterol was well tolerated in this study.

"I believe that these results offer evidence of the potential medical benefit of arformoterol," said James Donohue, M.D., Professor of Medicine and Division Chief of Pulmonary Diseases and Critical Care Medicine, University of North Carolina, School of Medicine, Department of Medicine at Chapel Hill. "Many patients with COPD already use nebulizers for their respiratory medications, and they may prefer nebulization to metered-dose or dry-powder inhaler therapy. I expect that these patients would benefit from having the option of a nebulized long-acting bronchodilator for the treatment of their COPD."

A Crossover Dose-Ranging Study of Nebulized Arformoterol in Patients with COPD

Also presented were results of a 62-patient, 5-way crossover study in patients with COPD. This study evaluated bronchodilation produced by arformoterol 9.6 (mu)g once daily, 24 (mu)g twice daily, 48 (mu)g once daily and 96 (mu)g once daily, and salmeterol 42 (mu)g twice daily, versus placebo. Both an albuterol MDI as rescue therapy and an ipratropium bromide MDI as supplemental medication for COPD were provided to all patients in this study to be used on an as-needed basis.

Patients treated with arformoterol (p<0.001) showed significant improvement in bronchodilation as measured by change in FEV1 AUC, versus patients administered placebo. Mean percent change in FEV1 AUC from pre-dose was 13.8 percent for the 9.6 (mu)g dose of arformoterol, 22.4 percent for the 24 (mu)g twice daily dose, 23.14 percent for the 48 (mu)g dose, and 23.14 percent for the 96 (mu)g dose. Arformoterol was well tolerated in this study.

About Arformoterol

Sepracor completed more than 100 preclinical and 16 clinical studies of arformoterol involving more than 2,000 patients. Among the clinical studies conducted were two 12-week pivotal studies, each with more than 700 patients, as well as a large-scale, 12-month safety study. In Phase III studies, patients treated with arformoterol demonstrated a statistically significant improvement in FEV1 versus those patients administered placebo.

About COPD

According to the National Center for Health Statistics, COPD is the fourth leading cause of death in the U.S., and in 2003, an estimated 11 million adults in the U.S. had COPD. Approximately 24 million adults have evidence of impaired lung function, which may indicate that COPD is under-diagnosed, according to the National Heart, Lung, and Blood Institute (NHLBI). COPD is a slowly progressive disease of the airways that is characterized by a gradual loss of lung function. According to the NHLBI, COPD includes chronic bronchitis, chronic obstructive bronchitis and emphysema, or combinations of these conditions. Bronchodilator medications are used to improve airflow and COPD symptoms, and to reduce the occurrence and/or severity of exacerbations in patients affected by COPD.

About Sepracor

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

Forward Looking Statement

This news release contains forward-looking statements that involve risks and uncertainties, including statements with respect to the safety, efficacy and potential benefits of arformoterol, the date by which the FDA is expected to complete its review of the arformoterol NDA and the successful development, regulatory approval and expected commercial launch of arformoterol. Among the factors that could cause actual results to differ materially from those indicated by such forward-looking statements are: Sepracor's ability to fund, and the results of, further clinical trials; the timing and outcome of the FDA's review of the arformoterol NDA and other regulatory filings; and certain other factors that are detailed in the company's quarterly report on Form 10-Q for the quarter ended March 31, 2006 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.

Serevent is a registered trademark of Glaxo Group Limited Corporation.

For a copy of this release or any recent release, visit Sepracor's web site at www.sepracor.com.