Drug–drug co-amorphous systems: An emerging formulation strategy for poorly water-soluble drugs

Overcoming the poor water solubility of small-molecule drugs is a major challenge in the development of clinical pharmaceuticals. Amorphization of crystalline drugs is a highly effective strategy to improve their aqueous solubility. However, amorphous drugs are thermodynamically unstable and likely to crystallize during manufacturing and storage. Recently, drug–drug co-amorphous systems have emerged as a novel strategy to not only enable enhanced dissolution and physical stability of the individual drugs within the system but also to provide a strategy for combination therapy of the same or different clinical indications. This review serves to highlight advances in the methods used to manufacture and characterize drug–drug co-amorphous systems, summarize drug–drug co-amorphous applications reported in recent decades, and provide an outlook on future possibilities and perspectives. Teaser This review serves to highlight advances in the methods used to manufacture and characterize drug–drug CAM systems, summarize their recently reported applications, and discuss the future perspectives of this strategy.