Inhalation Drug Delivery The Impact of Particle Size Reduction

Abstract

API/excipient interactions depend on physicochemical characteristics of the particles, such as morphology, electrostatic charge, contact area, surface energy, carrier surface roughness, and relative humidity. [...]the characterization of the particles' surface properties becomes the key to understanding their surface-based phenomena, offering insights into interactive forces and adhesion affecting the API, carrier and device. The recrystallization of amorphous domains of the particles often leads to particle size growth and agglomeration as a result of molecular rearrangement phenomena occurring at the surface of the particles and, over time, can strongly affect the aerodynamic performance of a pharmaceutical formulation. The following methods were used to evaluate the impact of size reduction techniques on the particles' properties: * Scanning electron microscopy (SEM) was used to study morphological properties * X-ray powder diffraction was used to characterize polymorphic forms * Dynamic vapor sorption (DVS), Brunauer, Emmett and Teller (BET) methods, and PSD were used to study physical properties. PSD was measured using a laser diffraction analyzer (Malvern, Mastersizer 2000); morphology was studied via the scanning electronic microscope (Phenom ProX); specific area was determined using the BET method (Micromeritics, TriStar II 3020); water sorption value was measured using Dynamic Vapor Sorption (Surface Measurement Systems, DVS Intrinsic), and polymorphism was analyzed using a x-ray powder diffraction device (PANalytical, X'Pert PRO).