Solubility Enhancement of BCS Class 2 Drugs by Solid Dispersion Technique

Abstract

Oral drug delivery is the primary choice for pharmaceuticals due to convenience and maximal surface area for drug administration. However, challenges like poor solubility hinder absorption and bioavailability in humans. Nearly 40% of approved drugs and 90% in development face solubility issues. The Biopharmaceutical Classification System (BCS) divides medications into groups based on how soluble and permeable they are, impacting their absorption from oral forms. Strategies for enhancing solubility involve physical and chemical modifications, nanotechnology-based approaches, and solid dispersion technology Solid dispersion increases the stability, bioavailability allows the active ingredients to disperse in an inert matrix in a solid form, hence increasing the rate of dissolution of medications that are poorly soluble in water. There are numerous technologies available for creating solid dispersions, including melting techniques like melt agglomeration and hot-melt extrusion, as well as solvent-based techniques including solvent evaporation, spray drying, freeze-drying, and supercritical fluid technology. BCS class 2 drugs, like Ibuprofen and Ketoconazole, possess high permeability but low solubility, impacting absorption and bioavailability. Solid dispersions offer advantages like enhanced dissolution and reduced pre-systemic metabolism but come with challenges like crystallization, aging-related issues, and stability concerns in moisture or temperature variations. Applications of solid dispersions range from homogeneous drug distribution and stabilization of unstable drugs to sustained release formulations. However, challenges like understanding structure-release relations and residual solvents persist.