Microspheres as Drug Carriers: Applications and Innovations in Novel Drug Delivery Systems

Abstract

Microspheres are rounded, multi-particulate drug delivery systems between 1μm and 1mm that are used to control drug release. Microspheres are biodegradable polymeric microspheres based on natural or synthetic polymers. They possess merits like superior therapeutic activity, increased bioavailability, lowered toxicity, and decreased drug degradation. Microspheres permit sustained drug release, lowering the frequency of administration, and are suitable for site-specific delivery, for instance, in gastrointestinal tissue. Microspheres have various therapeutic properties such as bioadhesive, floating, radioactive, magnetic, and polymeric functionalities. Bioadhesive microspheres increase drug retention in the mucosal surfaces, while magnetic microspheres enable the delivery of drugs at a localized site through the application of an external magnetic field. The preparation methods differ depending on drug characteristics; solvent evaporation, ionic gelation, and spray drying are the most used. Spray drying is efficient for encapsulating hydrophobic drugs, while double emulsion is appropriate for hydrophilic drugs such as peptides and vaccines. Characterization techniques such as particle size analysis, surface topography, determination of drug content, and evaluation of entrapment efficiency guarantee microsphere optimization. They have uses beyond pharmaceuticals in diagnostics and industrial applications. Microspheres promise new therapeutic approaches with advancement in polymer sciences in the form of vaccines, gene therapy, and anticancer treatments. This review emphasizes the benefits, categorization, preparation, and therapeutic uses of microspheres in contemporary drug delivery systems.