The oral route remains the most preferred and widely accepted route of drug administration because of its convenience, patient compliance, and economic advantages. However, the therapeutic effectiveness of numerous active pharmaceutical ingredients is limited by poor aqueous solubility and low dissolution rates. Biopharmaceutics Classification System (BCS) Class II drugs are characterized by high permeability but poor solubility, making dissolution the rate-limiting step in drug absorption. Over the past few decades, solid dispersion technology has emerged as one of the most promising strategies for improving the solubility, dissolution rate, and oral bioavailability of poorly water-soluble drugs. This review comprehensively examines the advances in solid dispersion approaches for BCS Class II drugs, with particular emphasis on formulation strategies, preparation techniques, carrier systems, characterization methods, and industrial applications. The review discusses conventional and advanced solid dispersion systems including eutectic mixtures, amorphous dispersions, solid solutions, glass solutions, lipid-based dispersions, and supersaturating formulations. Various preparation methods such as solvent evaporation, hot-melt extrusion, spray drying, freeze drying, electrospinning, and supercritical fluid technology are critically analyzed. Furthermore, the review highlights the mechanisms responsible for solubility enhancement, including particle size reduction, amorphization, wettability improvement, and inhibition of drug recrystallization. Current challenges related to scale-up, stability, regulatory compliance, and commercialization are discussed alongside future opportunities involving nanotechnology, machine learning-assisted formulation development, and continuous manufacturing.

BCS Class II drugs, solid dispersion, solubility enhancement, amorphous solid dispersion, hot-melt extrusion, spray drying, dissolution rate, bioavailability

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