Changes in the way new chemical entities are developed and identified have led to a situation where many active pharmaceutical ingredient (API) innovations exhibit poor aqueous solubility. Although numbers deviate (1, 2), there is general agreement that many new drug candidates, especially those coming from synthesis (3), face aqueous solubility challenges. Insufficient solubility may even lead to the abandonment of an otherwise promising new chemical entity. Although no single formulation approach can solve the issue of poor solubility, a recent survey lists solid dispersion as one of the most promising techniques to overcome this challenge (4). In solid dispersions, the poorly soluble API is finely dispersed in a matrix of another solid (5-7). Traditionally, these formulations use organic polymers (e.g., polyacrylates, polyethylene glycols, polyvinyl pyrrolidones, polyvinyl alcohols) or cellulose derivatives as the matrix (8). Solid dispersions are produced either by the co-spray drying of the API and the matrix polymer or through hot-melt extrusion, where the API is incorporated into the polymer matrix at high shear and elevated temperatures. Solid dispersions aim to transform the API into an amorphous, more soluble form. Using this approach makes the stabilization and long-term stability of the amorphous API crucial to prevent recrystallization.

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