Physico-chemical characterization of drug-bio-surfactant micellar system: A road for developing better pharmaceutical formulations

The knowledge about the characteristics of drug - bio-surfactants system is crucial in pharmacology which helps to design better pharmaceutical formulations. The descriptions of the modulation in drug (metformin hydrochloride) - bio-surfactants (sodium cholate and sodium deoxycholate) mixture, in solution micellar phase has been accessed by means of critical micelle concentration (CMC) determination and thermodynamic approach through conductometric and spectroscopic techniques. The conductivity, kappa data have been employed to determine critical micelle concentration, CMC i.e. point of aggregation and results have been discussed in terms of hydrophobic and electrostatic interactions present in the system. The obtained CMC values reveal the fact that the micellization tendency of studied bio-surfactant increases in the presence of drug. The conductivity study (CMC determination) has also been found to corroborate the results obtained from UV-visible (absorption spectra) and fluorescence (emission spectra) studies. Moreover, the temperature dependence of CMC values (typical U-shaped profile) has been explained in terms of various interactions present around the hydrophobic part of bile salts. Furthermore, charged pseudo-phase separation model of micellization has also been applied to grasp information on the intermolecular interactions existing in the present ternary system. The work may be considered a step towards making use of bile salts as a promising approach in drug delivery and increasing their bioavailability. (C) 2018 Elsevier B.V. All rights reserved.