Supercritical carbon dioxide (scCO(2)) 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 P-estradiol in scCO(2), for impregnation into the glassy polymer polyvinylpyrrolidone (PVPP), leading to more efficient polymer impregnation. Experimental conditions cover a range of temperatures from 40 degrees C to 50 degrees 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. (C) 2006 Elsevier B.V. All rights reserved.