Pulmonary drug administration has long been used for local or systemic treatment due to several advantages. Dry powder inhalers emerge as the most promising due to efficiency, ecologic, and drug stability concerns. Coarse lactose-carrier is still the gold standard when inhalation powders are developed. Despite some efforts to produce new types of powders, the lung drug deposition is still poorly controlled, which will ultimately impact therapeutic effectiveness. In this study, we developed "engineered-inhalation powders" using the spray-drying technique. Multiple carbohydrates excipients were binary mixed and combined with two active pharmaceutical ingredients for asthma therapy (budesonide and formoterol). Particle morphology, from spherical to deflated shapes, was characterized by the number and the depth of dimples measured from SEM images. We define a new characteristic deflation ratio ξ as the product between the number of dimples and their depth. Six different powders having opposite morphologies have been selected and we have demonstrated a linear correlation between the fine particle fraction and the deflation ratio of produced powders. Overall, we showed first that the morphology of inhalable powder can be finely tuned by spray-drying technique when excipients varied. Secondly, we developed stable inhalation powders that simultaneously induced high fine particle fractions (>40%) for two drugs due to their deflated surface. The stability has been evaluated for up to 2 months at room temperature.
Keywords: Carbohydrates; DPI; Inhalation; Morphology; Powder; Spray-drying.
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