Solubility of Anti-Inflammatory, Anti-Cancer, and Anti-HIV Drugs in Supercritical Carbon Dioxide

This paper focuses on the collection of solubility data for pharmaceutical drugs in supercritical carbon dioxide. The experimental techniques used to obtain the data include a supercritical fluid chromatographic technique and a conventional dynamic solubility apparatus. The chromatographic method provided the retention times of the solutes of interest and those of an un-retained substance, which were used to obtain equilibrium partition coefficients. The partition coefficients were subsequently used to obtain solubilities at various temperatures and pressures. The conventional dynamic solubility apparatus was used to provide a calibration parameter for the chromatographic method. The coupling of these two techniques allowed for the fast and accurate determination of the solubility data. Both techniques were validated by measuring the solubility of naphthalene and phenanthrene in carbon dioxide at temperatures between (35 and 55) °C and pressures between (100 and 300) bar. The results agreed within ±10 %, a reasonable experimental uncertainty, to those of other investigators, thus confirming the reliability of the techniques. Additionally, the solubility of anti-inflammatory drugs (naproxen, ibuprofen, and acetaminophen), anti-cancer drugs (paclitaxel, 5-fluorouracil, and thymidine), and anti-HIV drugs (azodicarbonamide and 2-phenyl-4 H -1,3-benzoxazin-4-one) were measured in supercritical carbon dioxide for the same range of temperatures and pressures. The results are explained in terms of solute volatility and specific interactions as the most significant factors influencing solubility of pharmaceutical drugs in pure carbon dioxide.