Characterization of azacytidine/poly(L-lactic) acid particles prepared by supercritical antisolvent precipitation

A controlled azacytidine release system based on drug encapsulation with a polymer material has been prepared and characterized. The drug systems were prepared by precipitation from solutions, using supercritical CO2 antisolvent technique operating in a semi-continuous mode. Azacytidine was dissolved in dimethylsulfoxide and poly-lactic acid in methylene chloride. The two solutions were mixed before being sprayed into the supercritical reactor. Experimental conditions were 40 degrees C for temperature, 11 MPa for pressure, and a CO2 flow rate of 30 ml min(-1). The precipitated drug-polymer particles were further characterized to determine the percentage of encapsulated drug and establish the delivery kinetics under various release conditions. A sustained delivery of the drug over a period of various hours was obtained. Besides, an improved stability of the coated drug with respect to the pure azacytidine was found, thus proving the suitability of this approach for dealing with unstable compounds.