LAUSR

Abstract Rational drug design is undoubtedly an extremely important objective for chemists and biologists. As a step in this direction, quantitative understanding of physical chemistry underlying partitioning of drugs in drug delivery vehicles such as micelles provides guidelines to meet such an objective. Interactions of tryptophan (chosen as a model drug) and diclofenac sodium (nonsteroidal anti-inflammatory drug) have been studied with the micelles and monomers of cationic surfactant hexadecyoltrimethylammonium bromide (HTAB), non-ionic surfactant triton X-100 (TX-100), and their mixture. This has been addressed in terms of changes in physicochemical properties such as standard molar enthalpy, entropy and Gibbs free energy of partitioning in combination with pyrene fluorescence emission and dynamic light scattering measurements. The mechanism of partitioning of the drugs in individual micelles, micellar mixture, and interaction behavior with the monomers has been discussed. The energetics of interaction of partitioning, correlated with the functional groups on a wide range of drugs can be very important in deriving guidelines for target oriented synthesis. The effect of drugs on micellization properties of HTAB, TX-100 and their mixture has also been addressed.