Solubilization thermodynamics of ibuprofen in modified and classical FeSSIF biorelevant media

Abstract

Abstract Some thermodynamic information related to the transfer of ibuprofen (IBP) between aqueous systems at pH 5.0 and micellar systems, in some biorelevant media, is reported. For this purpose, the apparent solubility of IBP at different temperatures, in the modified and classical Fed State Simulated Intestinal Fluid (FeSSIF) media, at different concentrations of sodium taurocholate and phosphatidylcholine, was studied. It is observed that temperature and surfactant concentration affected the apparent solubility of this drug in these aqueous media. The solubility results were used to determine the micelle partition coefficients expressed in mole fraction ( K m/w X ) in both media. For modified FeSSIF, K m/w X values varied from 8102 at 293.15 to 5987 at 313.15 K, whereas for classical FeSSIF, this property varied from 11,551 to 8540, considering the same temperatures. The temperature dependence of solubility and micelle partition coefficient allowed the calculation of the respective thermodynamic quantities of transfer of IBP from the aqueous media to the micellar pseudo-phases. Gibbs energies and enthalpies were negative, whereas entropies were positive, in a different way to the IBP solubilization behavior in the modified and classical Fasted State Simulated Intestinal Fluid (FaSSIF) biorelevant media. These results indicate spontaneous processes of transfer, and driven by enthalpy and entropy in both FeSSIF media. The thermodynamic quantities were interpreted in terms of solute–micellar interactions, especially hydrogen bonding and electrostatics interactions. Also, the critical micelle concentrations (CMC) of surfactants in each medium were determined, obtaining values of 6.7 and 3.4 mmol L − 1 , for modified and classical FeSSIF at 293.15 K, respectively.