Solubility of the drugs bisacodyl, methimazole, methylparaben, and Iodoquinol in supercritical carbon dioxide

Fluids have been used before for the extraction and chromatography of drugs, but only a few literature references are available on drug solubility in supercritical fluids. The objective of this work concerned the experimental determination of the equilibrium solubilities of four compounds used as drugs (bisacodyl, methimazole, methylparaben, and iodoquinol) in supercritical carbon dioxide at temperatures ranging from (308 to 348) K and pressures from (122 to 355) bar. The measurements were performed using a simple and reliable static method. Iodoquinol showed solubilities below the range in which reliable data can be obtained with the used method. Bisacodyl, methimazole, and methylparaben solubilities were successfully correlated using a semiempirical model. Correlation of the results shows good self-consistency of the data obtained. Crossover pressures were observed for all compounds.