Synthesis of γ Phase and Amorphous Solid Dispersion of Glycine from a-Glycine During the Solvent-Free Ball Milling Process

Nano alpha-glycine crystals, gamma-glycine crystals, and amorphous solid dispersion (ASD) of glycine were prepared through solvent-free ball milling of commercial alpha-glycine. The solid-state polymorph conversion of glycine from alpha to gamma was completely realized by ball milling with 0.2 wt.% NaCl for 1 h or by ball milling with 0.02 wt.% NaCl for 1 h with subsequent storage for one week. The ASD of glycine was prepared by ball milling a-glycine with an equal amount of CaCl2 for 1 h. We studied the effect of inorganic salt types and their concentrations on the extent of polymorph conversion and amorphization of glycine in our experiments. This solvent-free ball milling method could be used for the synthesis of polymorphs and amorphous phase of drugs and other organic materials. (C) 2021 American Pharmacists Association. Published by Elsevier Inc. All rights reserved.