Cannabidiol in a DPI – maximising the spray drying yield of HPMC matrix particles
Tobias Gutowski & Regina Scherließ
Department of Pharmaceutics and Biopharmaceutics, Kiel University, Grasweg 9a, 24118 Kiel, Germany
The purpose of this study was the evaluation of the ability of hydroxypropyl methylcellulose (HPMC) to form solid cannabidiol dispersions at 25 % drug load with high loading efficiency and maximised yield in the inhalable range (< 5 µm). Cannabidiol (94 % purity) was chosen as model drug for highly lipophilic, resinous materials. A preliminary experiment showed that a loading efficiency of > 85 % is feasible. To maximise the yield, a software supported experimental design (3³) was carried out for pure HPMC. The results of the Design of Experiments (DoE) show that the best yields are achieved with a high solid content and aspirator setting and a low inlet temperature. Since the aerodynamic behaviour could not be evaluated without the active pharmaceutical ingredient (API), two parameter settings, which initially showed promising results, were selected in addition to the theoretical optimum to evaluate the loading efficiency of the optimised spray drying process. All three parameter settings were suitable to achieve the targeted loading dose (25 %) with an efficiency of > 95 %. Powders were dispersible from a DPI device; aerodynamic assessment is still ongoing.