Abstract
A method for particle design to prepare a dry powder for inhalation was newly developed by the surface modification of poorly inhaled hydrophobic cohesive drug particles, e. g., pranlukast hydrate (PH, D50=2.1μm) with hydrophilic submicronized particles, e. g., colloidal silica (D50=16nm) and hydroxypropylmethylcellulose phthalate (HP-55) nanospheres (D50=51.6nm) prepared by the authors. The surface modification was carried out by compounding the drug and additive particles under shear with a manually operating mortar, the particle designing equipment (a Theta composer), and by freeze drying the dispersion of the drug and additives. The surface of PH particles were modified with colloidal silica (20%) by the Theta composer and HP-55 nanospheres (2-20%) by a freeze dryer, which dramatically improved the inhalation properties of the original PH particles. In addition, surface modified PH powders with HP-55 nanospheres significantly improved the dispersibility and dissolution rate of the drug in an aqueous media which is preferable for improving the bioavailability of the drug deposited in the bronchi.
