Nano spray-dried pyrazinamide-L-leucine dry powders, physical properties and feasibility used as dry powder aerosols

Abstract

Objective: The aim of this study was to investigate the effect of adding L-leucine and using an ethanolic solvent on the physicochemical properties and aerodynamic behavior of nano spray-dried pyrazinamide (PZA)-L-leucine powders.

Materials and methods: A nano spray dryer was employed to prepare PZA-L-leucine powders. The physicochemical properties were evaluated using a scanning electron microscope (SEM), differential scanning calorimetry and X-ray diffraction. The Andersen cascade impactor was used to evaluate the in vitro aerosolization performance of the sprayed powders.

Results and discussion: The incorporation of L-leucine at 10% improved the percentage fine particle fraction (%FPF) in all ethanolic solvent formulations by up to nearly twofold (20.0-23.4%) compared to the normal spray-dried PZA of (8.8-13.0%). Changes in the particle density and morphology were also observed. The dense solid particles of PZA were completely converted to bulk hollow particles with a thin shell by increasing the L-leucine content up to 50%. Higher ethanol concentration resulted in larger dimensions of the hollow particle but did not directly affect the aerosolization performance. The co-spray dried PZA with 20% L-leucine in a 10% ethanol feed solvent gave the best aerosolization performance (FPF = 33.0%).

Conclusions: The co-spray dried PZA with a suitable L-leucine content using a nano spray drying technique could be applied to formulate the PZA DPI.

Keywords: Andersen cascade impactor; dry powder inhaler; lung delivery; nano spray dryer; tuberculosis.