XOPENEX HFA(TM) Pediatric Data Presented at American College of Asthma Allergy & Immunology; Study Shows Improvement in FEV(1) in Asthma Patients Treated With XOPENEX HFA.

MARLBOROUGH, Mass. -- Sepracor Inc. (Nasdaq: SEPR) today announced the presentation of results of a four-week, multicenter, randomized, double-blind, placebo-controlled, parallel-group study assessing treatment with XOPENEX HFA(TM) (levalbuterol tartrate) Inhalation Aerosol metered-dose inhaler (MDI), a hydrofluoroalkane (HFA) MDI, versus placebo in pediatric patients 4 to 11 years of age who experience bronchospasm associated with asthma. XOPENEX HFA is a single-isomer short-acting bronchodilator that is indicated for the treatment or prevention of bronchospasm in patients 4 years and older with reversible obstructive airway disease. An MDI is a portable, hand-held device consisting of a pressurized canister containing medication and a mouthpiece through which the medicine is inhaled. The results of this 150-patient study were presented at the annual meeting of the American College of Allergy, Asthma & Immunology in Anaheim, Calif.

Patients in this study who were administered the short-acting bronchodilator, XOPENEX HFA, demonstrated a statistically significantly greater mean peak percent change in FEV(1) from pre-dose levels (p<0.001) versus placebo. FEV(1) refers to forced expiratory volume in one second, which is a test of lung function. These changes in FEV(1) from pre-dose levels were also significantly greater (p<0.05) than placebo at first dose and at week four. Mean peak percent change in FEV(1) area under the curve from pre-dose, which is a measure of both the degree and duration of change in lung function, was significantly greater (p<0.05) for the XOPENEX HFA treatment group versus the placebo group. Treatment with XOPENEX HFA was also associated with significantly less rescue medication use in terms of both days used per week (p<0.001) and the number of treatments per day (p<0.01) as compared to placebo. XOPENEX HFA was well tolerated during the treatment period; the incidence of asthma adverse events, including asthma attacks, and beta-mediated side effects were low and comparable to placebo.

"This study supported the pediatric portion of the New Drug Application for FDA approval of XOPENEX HFA in patients 4 years of age and older," said Henry Milgrom, M.D., Director of the Ambulatory Pediatric Allergy Program at National Jewish Medical and Research Center, Denver. "I am looking forward to prescribing XOPENEX HFA for my patients who are already on XOPENEX delivered by nebulizer. The new preparation will be easier and more convenient to administer. Further, XOPENEX HFA will provide a new and effective treatment alternative for patients using albuterol."

Sepracor is targeting commercial launch by the end of 2005 for XOPENEX HFA, which is indicated for the treatment or prevention of bronchospasm in patients 4 years of age and older with reversible obstructive airway disease.

"We have been eagerly awaiting the arrival of this new treatment option," said Nancy Sander, founder and President of Allergy and Asthma Network Mothers of Asthmatics. "Children with asthma will now have access to a new medication to treat their asthma symptoms whether they are at school or at home."

"The variability and frequency of asthma symptoms are often unpredictable and treating them effectively is the primary goal of short-acting beta-agonists," said William E. Berger, M.D., Clinical Professor, Department of Pediatrics, Division of Allergy and Immunology, University of California, Irvine. "XOPENEX HFA will provide doctors and patients with an effective new choice to treat these symptoms."

The XOPENEX HFA development program included approximately 1,870 pediatric and adult subjects and 54 studies (preclinical and clinical). In each of the three, large-scale, pivotal Phase III trials that Sepracor conducted, XOPENEX HFA was well tolerated and met the targeted efficacy endpoints in both adults and children with asthma. In the primary airway function measure, FEV(1), XOPENEX HFA produced statistically and clinically significant improvements relative to placebo.

Sepracor and 3M Drug Delivery Systems Division are collaborating under an agreement that includes scale-up, manufacturing and supply of XOPENEX HFA. Each XOPENEX HFA canister provides 200 actuations (or inhalations).

Approximately 96 percent of the short-acting beta-agonist inhalers sold in 2004 contained chlorofluorocarbon (CFC) propellants, according to IMS Health information. Under provisions in the Montreal Protocol on Substances that Deplete the Ozone Layer, an international agreement that requires the phase-out of substances that deplete the ozone layer, MDIs containing CFC propellants would qualify for removal from the marketplace. In March 2005, the FDA issued its final rule for the removal of the essential use exemption for albuterol, which currently permits the use of CFC-containing albuterol inhalers despite environmental concerns. Under the rule, all production and sales of albuterol CFC MDIs in the U.S. are required to cease by the end of 2008. XOPENEX HFA uses HFA technology and does not contain a CFC propellant.

Sepracor currently markets XOPENEX Inhalation Solution for use with a nebulizer. XOPENEX Inhalation Solution is indicated for the treatment or prevention of bronchospasm in patients 6 years of age and older with reversible obstructive airway disease. XOPENEX Inhalation Solution is available for use in a nebulizer at 0.31 mg and 0.63 mg dosage strengths for treatment of children 6 to 11 years old, and in 0.63 mg and 1.25 mg dosage strengths for patients 12 years of age and older.

Asthma is a chronic lung disorder characterized by reversible airway obstruction and the pathologic finding of airway inflammation. According to the 2002 National Health Interview Survey conducted by the Centers for Disease Control and Prevention, nearly 31 million Americans have been diagnosed with asthma in their lifetime. It is the most common childhood illness and affects nearly 9 million children in the U.S. under the age of 18. Short-acting bronchodilators are the most-prescribed asthma therapy among primary care physicians and pediatricians in the U.S., according to IMS Health information.

Important Safety Information

XOPENEX HFA and XOPENEX Inhalation Solution are contraindicated in patients with a history of hypersensitivity to levalbuterol, racemic albuterol or any other component of XOPENEX HFA or XOPENEX Inhalation Solution. XOPENEX HFA and XOPENEX Inhalation Solution and other beta-agonists can produce paradoxical bronchospasm, which may be life threatening. If additional adrenergic drugs, including other short-acting sympathomimetic bronchodilators or epinephrine, are to be administered by any route, they should be used with caution to avoid deleterious cardiovascular effects. Due to the cardiovascular side effects associated with beta-agonists, caution is generally recommended for patients with cardiovascular disorders (especially coronary insufficiency, cardiac arrhythmias and hypertension), diabetes, hyperthyroidism, or convulsive disorders. Also, see the complete prescribing information regarding potential drug interactions with beta-blockers, diuretics, digoxin, or MAOI and tricyclic antidepressants.

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, primary care and specialty-oriented sales force, which is comprised of more than 1,400 sales professionals. 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 safety, efficacy and potential benefits of XOPENEX HFA and XOPENEX Inhalation Solution and successful development and expected commercial launch of XOPENEX HFA. 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 success of submission, acceptance and approval of additional regulatory filings; label/use changes or concerns of XOPENEX HFA or XOPENEX Inhalation Solution prescribers or patients; and certain other factors that are detailed in the company's quarterly report on Form 10-Q for the quarter ended June 30, 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.

Xopenex HFA is a trademark and Xopenex is a registered trademark of Sepracor Inc.

For a copy of this release or any recent release, visit www.sepracor.com.