Synthesis of controlled release device with supercritical CO2 and co-solvent

Supercritical carbon dioxide (scCO2) has found use as a replacement for organic solvents in the creation of controlled release drug devices. This study uses supercritical carbon dioxide with ethanol as a co-solvent. Ethanol increases the solubility of β-estradiol in scCO2 for impregnation into the glassy polymer polyvinylpyrrolidone (PVPP), leading to more efficient polymer impregnation. Experimental conditions cover a range of temperatures from 40 °C to 50 °C and pressures up to 2500 psi. The effect of polymer swelling time on the sorption process also is studied. A dual mode sorption model describes the sorption of drug into the glassy polymer. The determined sorption parameters allow analysis of polymer conformation and suggest optimum impregnation conditions.