Long Term Safety Study of Levalbuterol and Racemic Albuterol in Subjects Twelve Years of Age and Older With Asthma

Inclusion Criteria * Willing and able to comply with study procedures and visit schedules * Females 12-60 yrs must have a negative serum pregnancy test at study start * Women of child bearing potential must use acceptable method of birth control throughout study * Confirmed diagnosis of asthma minimum of 6 mos. prior to study start * Have stable baseline asthma and have been using B-adrenergic agonist, and/or anti-asthma anti-inflammatory meds, and/or OTC asthma meds. \>6 mos. prior to study start * In good health with exception of reversible airways disease and not suffering from any chronic condition that might affect their respiratory function * Had chest X-ray w/in 12 mos. prior to randomization that is not diagnostic of pneumonia, atelectasis, pulmonary fibrotic disease, pneumothorax, chronic obstructive pulmonary disease etc. * Subject rolling over from either Sepracor study 051-353 or 051-355 must have successfully completed the study * Subject who is not immediately rolled over from Sepracor study 051-353 or 051-355 must wait \>30 days and will be regarded as a de novo subject * Able to complete daily diary cards and medical event calendars reliably, understand dosing instructions, demonstrate how to use the MiniWright PEF meter. Minor subjects must have a parent/legal guardian assist them during the study with these activities Exclusion Criteria * Female who is pregnant or lactating * Participated in investigational drug study w/in 30 days prior to study start, or currently participating in another clinical trial, other than Sepracor studies 051-353 or 051-355 * Subject who early terminated from Sepracor study 051-353 or 051-355 * Subject whose schedule prevents him or her from taking the first daily dose of study medication and/or starting study visits before 10 AM * Have travel commitments during the study that would interfere with trial measurements and/or compliance * History of hospitalization for asthma w/in 45 days prior to study start, or scheduled for in-patient hospitalization, including elective surgery during the trial * Subject with a known sensitivity to levalbuterol or racemic albuterol, or any of the excipients contained in any of these formulations * Subject using any prescription drug with which albuterol sulfate is contraindicated * Subject with currently diagnosed life-threatening asthma * History of cancer (exception: basal cell carcinoma in remission) * Subject with hyperthyroidism, diabetes, hypertension, cardiac diseases or seizure disorders that currently are not well controlled by medication or may interfere with the successful completion of this protocol * History of substance abuse or drug abuse within 12 months preceding V1 * Subject with \>10 pack/yr history of cigarette smoking or use of any tobacco products within 6 months of study start * Documented history of bronchopulmonary aspergillosis or any form of allergic alveolitis * Have suffered from a clinically significant upper or lower respiratory tract infection in the 2 weeks prior to study start * Subject who is a staff member or relative of a staff member