Solubilities of the drugs benzocaine, metronidazole benzoate, and naproxen in supercritical carbon dioxide

The solubilities of the drugs benzocaine, metronidazole benzoate, and naproxen in supercritical carbon dioxide were measured at pressures ranging from (122 to 355) bar and temperatures ranging from (308 to 348) K. These drugs have mole fraction solubilies between 1.0 x 10(-5) and 1.2 x 10(-2), which are high enough to make the supercritical impregnation process a feasible alternative to impregnation employing organic solvents. Crossover pressures of (150, 180, and 150) bar were found for benzocaine, metronidazole benzoate, and naproxen, respectively. The solubility data were correlated with a semiempirical model.