Optimization of an In Vitro Dissolution Test Method for Inhalation Formulations

The aim of this research project was to investigate a potential standardized test method to characterize the dissolution properties of numerous formulation types available for pulmonary delivery. A commercially available dissolution tester was adapted for use as a testing apparatus by the incorporation of a membrane-containing holder. The holder was designed to enclose previously air-classified formulations so that they could be uniformly tested in the dissolution apparatus. Dissolution procedures, the apparatus, dose collection, medium, and test conditions were developed relying on USP General Chapter . To collect an active pharmaceutical ingredient (API) fraction from the devices for subsequent dissolution studies, aerodynamic particle separation on the membrane holder was achieved using the Next Generation Impactor (NGI) for two commercially available products, Ventolin HFA and Pulmicort Flexhaler. The dissolution profiles of budesonide (BD) and albuterol sulfate (AS) were successfully estimated by analyzing the amount of drug released from the membrane holder. This dissolution method may be applied to quality control studies for various inhalation products. In particular, the in vitro dissolution profiles of the drugs may provide an estimate of their dispersion characteristics, which directly relate to the device or aerosol performances.