Stability of co-Amorphous Solid Dispersions: Physical and Chemical Aspects

Drug amorphization is one of the major approaches in pharmaceutical sciences to improve the solubility and dissolution rate of poorly water-soluble drugs. Amorphous solid dispersions are widely discussed approach to convert the drug into an amorphous state but due to its high energy state, the system tends to recrystallize upon storage. Co-amorphous system is a single-phase low energy system that falls under the glass solution, a type of solid dispersion. Being low-energy state and single-phase, co-amorphous dispersions are more stable than amorphous solid dispersions. In co-amorphous dispersions, the homogeneous single phase is formed only with low molecular weight co-formers, so the amount of co-former required is relatively low and this reduces the bulk of the system. This aspect of co-amorphous dispersions makes it popular over the amorphous solid dispersions in the area of solid dispersion researchers. This review provides an overview of co-amorphous dispersions and their recent advances. Particularly, this review will discuss various factors (physical and chemical) that affect and provide the stability of the co-amorphous dispersions formulation.