Role of Fine Silica as Amorphous Solid Dispersion Carriers for Enhancing Drug Load and Preventing Recrystallization- A Comprehensive Review.

Amorphous solid dispersion (ASD) is a popular concept for improving the dissolution and oral bioavailability of poorly water-soluble drugs. ASD faces two primary challenges of low drug loading and recrystallization upon storage. Several polymeric carriers are used to fabricate a stable ASD formulation with a high drug load. The role of silica in this context has been proven significant. Different types of silica, porous and nonporous, have been used to develop ASD. Amorphous drugs get entrapped into silica pores or adsorbed on their surface. Due to high porosity and wide surface area, silica provides better drug dissolution and high drug loading. Recrystallization of amorphous drugs is inhibited by limited molecular ability inside the delicate pores due to hydrogen bonding with the surface silanol groups. A handful of researches have been published on silica-based ASD, where versatile types of silica have been used. However, the effect of different kinds of silica on product stability and drug loading has been rarely addressed. The present study analyzes multiple porous and nonporous silica types and their distinct role in developing a stable ASD. Emphasis has been given to various types of silica which are commonly used in the pharmaceutical industry.