Estimation of the critical micelle concentration of sodium taurocholate inintestine-relevant conditions using complimentary techniques

Abstract

Bile salts such as sodium taurocholate (NaTc) play an important role in drugs’ bioavailability due to their capacityto form micelles. These aggregates can host a wide range of drugs and enhance their solubility in biologicalfluids. The micellization process and the types of micelles formed not only depend on the surfactant, butalso on the environment (solvent, temperature, presence of other compounds, etc.). Therefore, when solubilityassays are performed it is key to ensure that micelles are present. In this work, the critical micelle concentration(CMC) of NaTc has been evaluated using three different techniques (conductometry, fluorescence and calorimetry)in water and in different biorelevant conditions (intestinal biorelevant aqueous buffers, FaSSIF-v2 andFeSSIF-v2). While conductometry is not adequate for CMC determination of bile salts, fluorescence and calorimetryoffer complementary information. CMC experiments have shown that ion strength and the presence ofmixed micelles (formed by NaTc, phosphatidylcholine and lipids) favor the micellization process and wouldimpact on the drugs bioavailability.