Drug-excipient behavior in polymeric amorphous solid dispersions

Amorphous drug delivery systems are increasingly utilized to enhance aqueous solubility and oral bioavailability. However, they lack physical and/or chemical stability. One of the most common ways of stabilizing an amorphous form is by formulating it as an amorphous solid dispersion. This review focuses on polymeric amorphous solid dispersions wherein polymers are used as excipients to stabilize the amorphous form. A brief introduction to the basic concepts of amorphous systems such as glass transition temperature and the solubility advantage of amorphous systems is provided. Additionally, information on types of polymers used for the development of amorphous solid dispersions, their structural attributes and mechanisms of stabilization are presented here. Molecular aspects of drug-polymer miscibility and drugpolymer interactions are also discussed.