Molnupiravir is an antiviral drug used to treat the novel coronavirus infection, COVID-19, caused by the SARS-CoV-2 virus. Currently, it is available only in oral form. Developing an alternative inhalation dosage form could increase the drug's bioavailability through targeted action on the organs most affected by the infection, while simultaneously reducing the dosage of the active ingredient and minimizing the risk of systemic side effects. The aim of this study is to evaluate the influence of L-leucine and lactose monohydrate on the particle size distribution and key aerodynamic characteristics of the resulting inhalation powder prototypes, and to select the leading formulation for the current development stage. Spray drying was chosen as the primary technology for obtaining the samples. The paper presents a spray-drying technique that ensures the necessary dispersion and uniformity of the product. Following this method, two samples were prepared containing a model substance and excipients (Sample 1: Poloxamer 188 and Hypromellose; Sample 2: Poloxamer 188, Hypromellose, and L-leucine). Additionally, a portion of Sample 1 underwent mechanical blending with a carrier (lactose monohydrate). The particle size distribution of the powder compositions was studied using an optical microscope (granulometric analysis) and a Next Generation Cascade Impactor (aerodynamic characterization). The effects of the amino acid (L-leucine) and the carrier (lactose monohydrate) on the formulation characteristics were evaluated. Based on the comparative analysis, an intermediate leading formulation was selected (Sample 1 with the addition of lactose monohydrate), and a plan for further development was established (incorporating lactose monohydrate at various weight percentages and exploring a combination of leucine and lactose monohydrate).

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