HOT MELT EXTRUSION FOR AMORPHOUS SOLID DISPERSIONS: THE ROLE OF RHEOLOGY AND POLYMERS IN ENHANCING DRUG SOLUBILITY AND DELIVERY

Abstract

Polymer-based drug delivery systems are essential to improve the effectiveness of poorly soluble drugs. This review was prepared as a Narrative Review of recent and previous studies on the use of hot-melt extrusion (HME) technology to produce amorphous solid dispersions (ASDs). The research focuses on the HME technique in detail, as well as on the importance of selecting a polymer based on its properties, such as molecular weight, heat transfer, melting point, and biocompatibility with the drug, which is poorly soluble or requires controlled release. It also highlights the role of rheological properties, such as viscosity and shear behavior, in controlling formulation stability, drug-polymer compatibility, and processing performance during extrusion. The review covers the most popular polymers and associated poorly soluble drugs, emphasizing their effect on melt viscosity, ease of processing, and prevention of drug recrystallization. It also discusses the effects of screw speed, thermal, and shear parameters on drug bioavailability and product quality. The main findings show that rheology control is very important for selecting HME extrusion conditions to protect heat-sensitive drugs, choosing optimal polymers, and improving the bioavailability of poorly soluble drugs. This review provides clear recommendations for identifying suitable polymers and optimum processing conditions to enhance solubility and pharmacological performance using HME.