Surface modification of pollen-shape carriers for dry powder inhalation through surface etching

Surface modification of pollen-shape hydroxyapatite (HA) carriers is achieved using surface etching technique. Characterization of HA carriers before and after etching are performed by scanning electron microscopy (SEM), Carrs compressibility index (CI), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). Four surface etching temperatures are tested but only the particles etched at 40 and 50 °C are found satisfactory. Proper surface etching allows a reduction of the petal-like structure on the particle surface and improves the crystallinity of the particles. While the reduction of petal-like structure decreases the emitted dose (ED) of the drug particles, an increase in fine particle fraction (FPF) can be attained owing to the improvement in drug liberation. An increase in the air flow rate, however, decreases the significance of particle surface morphology and the difference in FPF among the use of different carrier particles diminishes. Surface etching technique is found to have good potential as an economical process to improve dry powder inhalation efficiency through surface modification.