Asthma and chronic obstructive pulmonary disease are among the most prevalent chronic respiratory diseases, representing a significant global health challenge. One of the key treatment strategies is the use of inhalation dosage forms, such as dry powder inhalers, which enable direct delivery of active pharmaceutical ingredients to the respiratory tract. The aim of this master's thesis was to develop and evaluate suitable methods for separating dry powder particles based on their aerodynamic size, and to assess their dissolution performance. The goal was to develop a method capable of discriminating between the investigated samples -by comparing in vitro dissolution profiles with in vivo data and to assess the influence of physicochemical properties of the active pharmaceutical ingredient on the powder and aerosol characteristics, as well as on the efficiency of particle separation, deposition, and dissolution. Different approaches using cascade impactor techniques were applied for the separation of aerosol, including the next generation impactor, the fast-screening impactor and modified next generation impactor with an exhaust cup. Within the dissolution studies, we aimed to identify a method that would be simple to perform; while providing reproducible, representative, and discriminatory results for the investigated samples. Two approaches were tested: the small volume dissolution method and petri dish method. Both dissolution tests revealed differences among the investigated samples, however, a clear in vitro-in vivo correlation could not be established due to the high variability of the results. The experimental work contributes to better understanding of the properties of inhalation formulations and provides a foundation for the further improvement of methods for particle separation, collection and evaluating of drug release performance.
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