XOPENEX HFA(R) Data Presented at American College of Allergy, Asthma and Immunology Annual Meeting.

MARLBOROUGH, Mass. -- Sepracor Inc. (Nasdaq: SEPR) today announced that clinical data for XOPENEX HFA([R]) (levalbuterol tartrate) Inhalation Aerosol were presented at the American College of Allergy, Asthma and Immunology annual meeting in Philadelphia. This study compared safety and tolerability of cumulative doses of XOPENEX HFA (hydrofluoroalkane) MDI (metered-dose inhaler) with those from a racemic albuterol HFA MDI in a group of asthmatic subjects.

The results demonstrated that both ( R )-albuterol systemic exposure and consequent beta-mediated adverse events were less following cumulative dosing with XOPENEX HFA when compared to cumulative dosing with racemic albuterol HFA MDI. Racemic albuterol HFA MDI contains both ( R )- and ( S )-albuterol, while XOPENEX HFA contains only ( R )-albuterol.

This study was designed to look at safety parameters associated with overdosing. Patients received excessive doses under medical supervision to evaluate these effects. The safety and efficacy results of this study do not support a comparison of the two products when used at recommended doses.

After completing screening and single-blind placebo run-in periods, asthmatic patients who met randomization criteria were administered either 16 cumulative puffs of XOPENEX HFA (45 mcg) (n=22) or racemic albuterol HFA MDI (90 mcg) (n=27) during the first dosing visit (Visit 4). Following a seven-day washout period, they were crossed-over and received a total of 16 puffs of the other treatment. Measures of heart rate, blood pressure, serum potassium and glucose concentrations were obtained pre-dose, after each dose, and up to eight hours after the final dose.

Changes in mean heart rate following one and two cumulative puffs did not differ significantly between the XOPENEX HFA and racemic albuterol HFA groups. However, changes in mean heart rate after 4, 8, and 16 cumulative puffs were significantly higher for racemic albuterol compared to XOPENEX HFA. Median ( R )-albuterol concentrations appeared to increase proportionally with dose for both treatments. Median plasma concentrations of ( R )-albuterol following each dose of racemic albuterol HFA were approximately 10% to 28% higher than those observed following the corresponding doses of XOPENEX HFA, and this difference in ( R )-albuterol levels became more pronounced with increased doses. When subjects received racemic albuterol HFA, median ( S )-albuterol concentrations were consistently two- to five-times higher than ( R )-albuterol concentrations.

Improvement in FEV1, which is a test of lung function that measures the amount of air forcefully exhaled in one second, was comparable between treatment groups, as were changes in serum potassium, glucose concentrations and blood pressure.

About XOPENEX HFA Inhalation Aerosol

XOPENEX HFA is a hydrofluoroalkane MDI, which is a portable, hand-held device consisting of a pressurized canister containing medication and a mouthpiece through which the medication is inhaled. XOPENEX HFA is indicated for treatment or prevention of bronchospasm in adults, adolescents and children 4 years of age and older with reversible obstructive airway disease.

About Asthma

Asthma is a chronic lung disorder characterized by reversible airway obstruction and a 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 is contraindicated in patients with a history of hypersensitivity to levalbuterol, racemic albuterol or any other component of XOPENEX HFA. XOPENEX HFA 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.

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 a portfolio of pharmaceutical products and candidates with a focus on respiratory and central nervous system disorders. 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 XOPENEX HFA Inhalation Aerosol. 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 further clinical trials; the results of any further clinical trials; the commercial success of XOPENEX HFA; any changes in the use and/or label of XOPENEX HFA; 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 September 30, 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.

XOPENEX HFA is a registered trademark of Sepracor Inc.

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