Interaction of an Amphiphilic Drug and Sodium Bis(2-ethylhexyl)sulfosuccinate at Low Concentrations in the Absence and Presence of Sodium Chloride

In the present study mixed micelles of the amphiphilic phenothiazine drug promazine hydrochloride (PMZ) and the anionic surfactant sodium bis(2-ethylhexyl)sulfosuccinate (AOT) have been studied using conductometry at different compositions and temperatures in aqueous as well as aqueous electrolyte (25 mmol center dot kg(-1) NaCl) solutions to determine various physicochemical properties of the solutions. The experimental and ideal critical micelle concentration (CMC and CMC (id)) values suggest attractive interactions in PMZ-AOT mixed systems. The negative values of interaction parameter (beta) obtained from regular solution theory indicate synergistic interactions; the negative values of beta decrease further with the addition of salt. From the CMC values obtained as a function of temperature, various other thermodynamic properties have been evaluated.