About the trial designThe Phase 1b trial design involved baseline safety and lung function testing on Day One followed by a one-hour intravenous infusion of placebo or 1200 micrograms MN-221. Safety, pharmacokinetic, and respiratory performance measurements were taken for the remainder of the day. Following a clinical investigator's evaluation early on Day Two, subjects received a treatment infusion every 12 hours through the morning of Day Four. Subjects were monitored until discharge on the morning of Day Five following a clinical investigator's examination. Clinical trial subjects received six treatment infusions over four days. There were no additional safety concerns with repeat dosing. Two MN-221 recipients with pre-existing heart disorders were terminated from the study on the first day of dosing due to transient arrhythmias identified by electrocardiograph monitoring that did not have clinical symptoms or consequences and resolved spontaneously. About MN-221 MN-221 is a novel, highly selective beta(2)-adrenergic receptor agonist in development for the treatment of acute exacerbations of asthma and COPD. An acute asthma or COPD exacerbation is defined as a long-lasting and severe episode that is not responsive to the standard bronchodilator or corticosteroid therapy. Patients with an asthma/COPD exacerbation typically go to the emergency room (ER) for treatment. If treatment in the ER is not successful, the patient may be admitted to the hospital. Current inhaled beta-agonist treatments for asthma and COPD exacerbations are limited by bronchoconstriction or insufficient airflow due to inflammation and airway constriction, reducing the amount of inhaled drug that can get into the lungs. In addition, the amount of inhaled treatments a patient can tolerate is limited due to the potential for cardiovascular side effects, such as increased heart rate. MN-221 is designed to treat acute exacerbations via intravenous infusion, bypassing constricted airways to deliver the drug directly to the lungs. Preclinical studies showed MN-221 to have a high affinity for the beta(2)-adrenergic receptor, found primarily in the lungs, and a much lower affinity for the beta(1)-adrenergic receptor found primarily in cardiac tissue. These studies showed no worrisome increase in heart rate when MN-221 was administered.