Microsphere

Microsphere designates spherical microparticles ranging from one to several hundred micrometres in diameter, typically fabricated from biodegradable polymers including poly(lactic-co-glycolic acid) or polylactic acid, serving as drug delivery vehicles that encapsulate or incorporate therapeutic agents within their matrix structure enabling controlled release, protection from degradation, and targeted delivery. The biopharmaceutical industry extensively develops microsphere-based products for applications requiring sustained release reducing dosing frequency or localised delivery.

Depot formulations employ microspheres providing weeks to months of drug release following single administration, with marketed products including Lupron Depot and Risperdal Consta demonstrating commercial success and improving patient adherence compared to frequent injections. Microsphere design variables affecting performance include polymer composition determining degradation rates, particle size influencing tissue distribution, drug loading capacity, and release mechanisms. Protein and peptide delivery via microspheres protects labile molecules while providing sustained therapeutic levels. Cancer therapy employs microspheres for chemoembolisation occluding tumour blood vessels while releasing chemotherapy, and radioactive microspheres delivering localised radiation to liver tumours. Manufacturing employs various techniques balancing scalability, cost, and product attributes, with quality control measuring particle size, drug loading, sterility, and in vitro release kinetics. As polymer science advances and manufacturing technologies improve, microsphere technology continues expanding as a versatile platform enabling sustained-release parenteral formulations.