C&EN, 21 November 2021
Within the past few years, much has been learned about characterizing the particles used in inhalation therapies, with the goal of improving drug delivery to the lungs.
Optimizing the manufacturing of these therapies requires avoiding particle interactions during size reducing, blending, and capsule filling, because these can affect the final product’s quality.
In an inhalation formulation, the physicochemical properties of size-reduced drug particles strongly affect the end product’s stability and performance. Previous studies reported that size-reduced APIs that had been milled using different techniques may present significant differences in terms of morphological and interfacial properties (1,2). Characterizing the particles’ surface properties is key to understanding API/excipient interactions and their impact on the final formulation performance.
Selecting the micronization technique is crucial for particles that are to be used in inhalation therapies, because it will determine the API’s properties. For inhalation delivery, a narrow and controlled particle size distribution (PSD) is key to improving and consistently delivering the aerodynamic performance. With a narrow PSD and Dv90<5µm, the fraction of particles that reach the lungs (FPF) will be higher.