The role of surfactants in preserving the stability of amorphous solid dispersions: A review

In recent years among various formulation strategies, amorphous solid dispersions (ASDs) has gained tremendous recognition for improving the solubility of poorly soluble drug substances. Among various manufacturing strategies, hot melt extrusion (HME), spray drying, kinetisol, and electrospinning are the most widely employed for developing ASDs. Despite the improving solubility and bioavailability, the stability of ASDs is the major problem haunting the pharmaceutical industries. Various factors, such as miscibility, the solubility of the drug in polymer, drug-polymer interactions, glass transition temperature, hygroscopicity, and storage conditions, determine the stability of ASDs. The poor stability of amorphous drugs also limits the drug loading capacity, resulting in an increased volume of the dosage form affecting patient compliance. Apart from the physical stability of ASDs, solution-mediated recrystallization of the drug when present in a supersaturated state is another factor affecting the quality and performance of the formulations. In recent years incorporation of surfactants to hinder solution-mediated recrystallization of drugs, thereby improving the stability and performance of ASD formulations, is being most widely investigated. The incorporation of surfactant in the HME process will also act as a plasticizer, thereby allowing the process to be carried at lower temperatures. This review article mainly focuses on the role of surfactants in ASD systems and recent advancements. Still, research is warranted to understand the mechanism of surfactants and to establish screening criteria.