Stability of Levalbuterol in a Mixture of Levalbuterol and Ipratropium Nebulizer Solution

Levalbuterol hydrochloride (Xopenex) inhalation solution is a short-acting bronchodilator, which was approved by the United States Food and Drug Administration for the treatment or prevention of bron-chospasm in adults and children 6 years of age and older. Levalbuterol is also a (R)-enantiomer of racemic albuterol. Because of the lesser dose required for bronchodilatory effect, levalbuterol may cause less cardiovascular adverse effects, such as tachycardia, than racemic albuterol.

The stability of levalbuterol in the mixture of levalbuterol and ipratropium nebulizer solution was studied. At 0, 1, 2, 6, 24, 48 hours and 5, 7, 14, and 28 days, 150 mcL of this mixture was combined with 1.5 mcL of internal standard solution (mepivacaine 5 mg in 1 mL of distilled water) and injected into the high-performance liquid chromatography (HPLC) system. Injections were done in triplicate and the concentrations for levalbuterol and ipratropium calculated using a calibration curve. The concentration of each drug was found to be within the acceptable limit (± 10% of the initial concentration) in all test samples. The levalbuterol and ipratropium mixture was stored at room temperature during the study period. Over the time period of 28 days at room temperature, no significant decrease in concentrations could be detected for levalbuterol or ipratropium.