Physicochemical Stability and Compatibility of Revefenacin (LAMA) and Formoterol Fumarate (LABA) Inhalation Solution Admixture.

Revefenacin inhalation solution, a long-acting muscarinic antagonist (LAMA), and formoterol fumarate inhalation solution, a long-acting ß-agonist (LABA), are indicated for the maintenance treatment of patients with chronic obstructive pulmonary disease. LAMA or LABA monotherapy, or a combination of LAMA/LABA for more severe symptoms, is recommended as first-line treatment in this patient population. We conducted a study to test the physicochemical properties of revefenacin and formoterol fumarate inhalation solution admixture in support of a clinical trial evaluating the safety of these nebulized bronchodilators, administered in sequence, and as a combination, in patients with chronic obstructive pulmonary disease (NCT03573817). The admixture of these two products was evaluated for changes in appearance, pH, osmolality, active drug content, purity, and impurity/degradant levels at 25°C for up to 25 hours. No substantial changes were observed in the physicochemical properties of revefenacin inhalation solution and formoterol fumarate inhalation solution admixture, demonstrating the physicochemical compatibility and stability of the two drugs in solution for up to 25 hours at room temperature.