Microporous Drug Delivery Systems: A Literature-Based Analysis of Formulation, Development, and In Vitro Evaluation

Traditional methods of delivering drugs are usually constrained by low solubility, absence of targeted delivery to specific sites, uncontrolled release of the drug, and largely varying plasma drug concentrations, in particular with Biopharmaceutics Classification System (BCS) Class II drugs. Such limitations contribute to the decrease in the therapeutic efficacy and the increase in the adverse effects. In this review, the discussed solution to these difficulties is a type of drug delivery system, known as microsponges, which are drug-loaded microporous systems. Microsponges are porous microspheres made of a polymer that can entrap hydrophilic and lipophilic drugs and allow controlled and sustained drug delivery. This is a systematic review of the literature on formulation methodologies, polymers employed, and ways of preparation and in vitro characterization of the polymers. The results of the significant findings are high solubility, stabilization, lower dosing, and decreased plasma variability. They are also flexible systems in terms of oral, topical, and controlled-release. Although the benefits are there, issues like scalability, reproducibility, and lack of in vivo validation still exist. The review covers recent achievements, outlines research gaps, and proposes further directions for the development of microporous drug delivery systems.