ABSTRACT

Poly(lactic-co-glycolic acid) microspheres have increasingly become the focus of research efforts in the scientific community and pharmaceutical industry. Their application as drug delivery vehicles has risen in line with the expanding biotechnology sector and the promise of new drugs discovered in the wake of the human genome project and proteomics. Many polymers have been utilized for the encapsulation and controlled release of various drugs. The stabilizer polyvinyl alcohol is most commonly used, although nonionic surfactants and triblock copolymers may be more useful for certain protein formulations. A nonsolvent such as silicone oil is then added to extract the dichloromethane from the polymer phase, causing precipitation of the polymer. The nonsolvent is then removed by addition of a second volatile solvent such as heptane or petroleum ether, which facilitates microsphere hardening. Spray-drying requires fine control of air flow and inlet and outlet air temperatures.