Dry powders for inhalation are typically formulated using a carrier- based approach. However, limitations such as poor drug delivery uniformity are frequently observed. Moreover, since combination therapies are gaining momentum for the treatment of respiratory diseases, the addition of a second API further increases the complexity of the formulation. In order to overcome these challenges, the engineering of carrier free composite particles in which the API is embedded within an excipient matrix is a suitable alternative, with spray drying (SD) being the preferred particle engineering technology.