In pharmaceutical field small particles with a controlled size are required to improve the therapeutic action of several drugs and to increase the bioavailability of the active principle. The use of a supercritical fluid, in particular carbon dioxide, as an antisolvent to cause the precipitation and micronization of drugs initially dissolved in a liquid solvent, has been widely investigated in recent years. In this work, the application of the continuous SAS technique to obtain the micronization of atenolol, a β-blockers drug commonly used in the prevention of heart diseases, has been studied. As first step, the saturation conditions, at 313 and 323 K, of carbon dioxide-atenolol-organic solvents (methanol, ethanol and isopropanol) ternary systems have been determined using a variable volume cell. After the determination of the correct working pressure, the atenolol was precipitated starting from organic solutions at different concentrations at 313 K. The size and morphology of the particles obtained have been observed with an electronic microscopy (SEM). The release profiles of the micronized drug showed a general enhancement of the dissolution rate, compared to the one of the untreated atenolol.
