Patient description: A 66yo female with significant smoking history and chronic cough for the past two years presents with recent, progressive shortness of breath. She is in moderate respiratory distress after walking from the waiting room to the examination room. Physical exam reveals mildly distended neck veins, a barrel-shaped chest, and moderate inspiratory and expiratory wheezes. She has smoked 1 to 2 packs per days for the past 47 years.

Clinical trial eligibility criteria: eligible ages (years): 0.0-4.0,  Asthma Subject's parent/legal guardian must give written informed consent, including privacy authorization, prior to study participation. Complete documentation regarding the consent process must be recorded in the case report form (CRF) and source documentation Subject's parent/legal guardian must be willing and able to comply with the study procedures and visit schedules Subject, male or female, must be between the ages of birth and <48 months, exclusive, at the time of consent Subjects 24 to <48 months of age must have a history of physician-diagnosed asthma (defined as at least 3 episodes of respiratory symptoms consistent with asthma symptoms including, but not limited to, cough, wheeze, or dyspnea) Subjects 0 to <24 months of age must have a history of 3 episodes of respiratory symptoms that in the judgement of the investigator could be consistent with asthma or reactive airways disease Subject must be in good health and not affected by any other chronic conditions, including respiratory disorders other than asthma In subjects with a chest radiograph (taken 12 months prior to screening visit), no evidence of any chronic cardiopulmonary condition other than asthma should be present as discerned by the Investigator Subject's parent/legal guardian must be able to complete the diary cards and medical event calendars (MEC) reliably on a daily basis and understand dosing instructions and questionnaire completion  Subject who requires or is expected to require any disallowed medications Subject who has participated in an investigational drug study within 30 days prior to screening, or who is currently participating in another clinical trial Subject or parent/legal guardian who has daily commitments during the study that would interfere with trial measurements, compliance, or both Subject who has a history of hospitalization for asthma, reactive airways disease, or bronchospasm within 4 weeks prior to screening or who is scheduled for in-patient hospitalization, including elective surgery during the course of the trial Subject who has experienced significant blood loss within 60 days of study drug Subject with a clinical diagnosis of cystic fibrosis Subject who was born prematurely, defined as less than 38 weeks gestational age at birth, and is <1 year of age at screening Subject whose body weight is less than 7.0 kg at screening. This minimum weight requirement is based upon standard pediatric growth charts [CDC 2000] 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 levalbuterol or racemic albuterol sulfate administration is contraindicated