In-Depth Comparison of Dry Particle Coating Processes Used in DPI Particle Engineering

Abstract

High-shear mixer coatings as well as mechanofusion processes are used in the particle-engineering of dry powder inhalation carrier systems. The aim of coating the carrier particle is usually to decrease carrier–drug adhesion. This study comprises the in-depth comparison of two established dry particle coating options. Both processes were conducted with and without a model additive (magnesium stearate). In doing so, changes in the behaviour of the processed particles can be traced back to either the process or the additive. It can be stated that the coarse model carrier showed no significant changes when processed without additives. By coating the particles with magnesium stearate, the surface energy decreased significantly. This leads to a significant enhancement of the aerodynamic performance of the respective carrier-based blends. Comparing the engineered carriers with each other, the high-shear mixer coating shows significant benefits, namely, lower drug–carrier adhesion and the higher efficiency of the coating process.

Dry-Coating of Powder Particles is Current Trend in Pharmaceutical Field

“…Underlying principle of the process is bringing forth a chemical-mechanical-reaction among two or more powder materials, to produce new material having differing properties 24,[49][50][51][52][53] . The process employs a batch operated specifically designed device for fusing particle-to-particle at high compressive and shear forces thus resulting controlled particle shape 4,24 .…”

“…The process employs a batch operated specifically designed device for fusing particle-to-particle at high compressive and shear forces thus resulting controlled particle shape 4,24 . The device comprises of outer vessel (rotating), inner piece (stationary), and scraper (stationary) as its key parts [50][51][52][53] .…”

“…Processing involves placing of aliquot amount of HPs and GPs into rotating vessel [2][3][4]24 . As vessel rotates at speed between 200 to 1600 rpm, powders are forced outwardly towards vessel [50][51][52][53] . Gap between inner stationary piece and rotating vessel is controlled; result is the powder particles passing thru gap are subjecting for intense compressive and shearing forces [50][51][52][53] .…”

“…As vessel rotates at speed between 200 to 1600 rpm, powders are forced outwardly towards vessel [50][51][52][53] . Gap between inner stationary piece and rotating vessel is controlled; result is the powder particles passing thru gap are subjecting for intense compressive and shearing forces [50][51][52][53] . Combination of these forces acting on particles builds-up local temperature.…”

“…Combination of these forces acting on particles builds-up local temperature. The generated thermal energy is sufficient to fuse GPs onto surface of HPs [50][51][52][53] .…”