Solubility and Dissolution Considerations for Amorphous Solid Dispersions

This chapter presents differences between dispersions, amorphous materials, and crystalline forms, and discusses the impact of excipient selection, especially polymers. It provides guidance for solubility and dissolution testing of amorphous dispersions. Crystalline solids are mostly used in pharmaceutical drug formulations because of their physical and chemical stabilities. Amorphous solids are commonly described as condensed phases that lack the long‐range translational order typical of a crystalline solid, although the molecules may have short‐range order. The success of amorphous solids as a supersaturating dosage form depends on the choice of processing conditions to yield a pure amorphous solid with no or minimal crystallization of the amorphous drug during storage and upon dosing. The use of amorphous solid dispersions has become a well‐known strategy for inhibiting crystallization, as the amorphous solid dispersions can have increased physical stability over neat amorphous material.