Melt Extruded Amorphous Solid Dispersions
Combinatory chemistry and high throughput screening are the principal components in new drug discovery. They reveal that more than 50% of newly identified active pharmaceutical ingredients (APIs) show superior lipophilicity and higher melting point. Hot-melt extrusion (HME) is being used as a preferred option in the development of solid dispersions as it offers various advantages over the other techniques, including solvent-free processing, suitability for continuous processing, no requirement of major downstream processing, and ease of scale-up. This chapter discusses processing conditions and excipient selection criteria for HME technology. For several decades, atomic force microscopy (AFM) has been used to study the growth rates of a drug crystal within different polymer combinations in amorphous pharmaceutical formulations. Polymers used in the HME process are thermoplastic in nature and form a polymeric binder. The properties of the polymer influence the processing conditions and the characteristics of the extruded dosage form, which can include dispersibility of the active ingredient, its stability, and release rate.