A series of impac ul studies in the last few years, in par cular by the research groups of Taylor and Sadowksi and their collaborators, has revealed the cri cally important role of AAPS of ASDs in aqueous media can play in media ng drug release, par cularly as a func on of drug loading . The studies have shown that below a threshold drug loading value, typically between 5 and 40% (depending on the drug, polymer and drug release condi ons), the dissolu on of the ASD is driven by the polymer solubility in the aqueous media and drug and polymer release is congruent (i.e. the drug and polymer release concurrently at the same rate). In this scenario, the film may remain as a single phase during drug release, or, waterdriven AAPS may occur faster than dissolu on of the ASD, but with the result of the drug-rich phase being disperse (i.e. the drug rich phase exists as droplets/par cles within the con nuous polymer-rich phase). However, at higher drug loadings, AAPS can occur within and at the surface of the ASD faster than dissolu on of the ASD, in which the drug-rich phase becomes the con nuous (percola ng) phase and the polymer-rich phase is discrete. In this scenario, the much lower solubility of the amorphous drug itself then dictates release, and to a greater or lesser extent, also the polymer. The consequence of such phase separa on can be drama c, with the drug (and polymer) release o en dropping to negligible levels. This has been described as the 'falling-off-the-cliff' effect .