A new method for preparing biodegradable microparticles and entrapment of hydrocortisone in dl-PLG microparticles using supercritical fluids

An improved process for the production of polymeric microparticles, based on solution-enhanced dispersion by supercritical fluids (SEDS) using a combination of supercritical N 2 and CO 2, was evaluated. The biodegradable polymers, poly( d,l-lactide-co-glycolide): copolymer composition 50:50 ( dl-PLG), poly( l-lactide) ( l-PLA), poly( d,l-lactide) ( dl–PLA) and polycaprolactone, were used for preparation of microparticles by a modified SEDS process. Solutions of the polymers in organic solvents were dispersed and the solvent was extracted with supercritical CO 2 and N 2. The morphology, the size distributions and degree of hydrocortisone entrapment were determined. The combination of supercritical N 2 and CO 2 led to a more efficient dispersion of the polymer solutions than CO 2 alone. This resulted in a reduction of particle size of the microparticles produced from all of the amorphous polymers. Discrete spherical microparticles with a mean volumetric diameter of less than 10 μm were produced from dl-PLG, dl–PLA and L–PLA. Hydrocortisone was successfully entrapped within the dl-PLG microparticles. The modified SEDS process improved the dispersion of amorphous polymer solutions resulting in formation of small spherical microparticles. The SEDS process can be used for incorporation of drugs into the dl-PLG microparticles.