Polymer selection in amorphous solid dispersions: From stabilization mechanisms to marketed drug products

Polymers are a central component of amorphous solid dispersions (ASDs), playing a crucial role in maintaining the drug in a high-energy amorphous state. They ensure both physical and chemical stability, inhibit drug crystallization, and sustain supersaturation during dissolution, thereby enabling ASDs to enhance drug dissolution and bioavailability. While ASDs have been extensively studied, the specific role of polymers in governing supersaturation and in vivo performance remains insufficiently addressed. In this review, the fundamental principles governing the selection and performance of polymers in ASD formulations were explored. The classification, molecular interactions, and mechanisms of stabilization were reviewed. Key aspects of polymer physicochemical properties, scalability considerations, and regulatory perspectives are also discussed. Factors influencing the success of ASD products in clinical and commercial settings were also considered. Finally, the review presents an overview of marketed ASD-based formulations and outlines emerging trends in polymer innovation aimed at improving drug solubility and manufacturability. The review concludes that optimal polymer selection is a critical determinant of ASD performance, as it governs both resistance to crystallization and maintenance of supersaturation during dissolution. It highlights the limitations of conventional polymer selection strategies and emphasizes the need for a paradigm shift toward solution-phase stabilization as a primary design criterion.