Abstract
The micellization behavior of an amphiphilic drug (promethazine hydrochloride (PMT)) in the presence of cationic surfactants (conventional as well as gemini) has been investigated conductometrically at different concentrations and temperatures. The micellar mole fractions of the surfactant (X1Rub, X1M, X1Rod, and X1id), calculated by different proposed models, show greater contribution of surfactant in mixed micelle and increases with the increase in concentration of the surfactant. Although α1 (mole fraction of surfactant) is higher for DTAB than that of 12-4-12, the contribution of 12-4-12 is almost equal to that of DTAB. The interaction parameter (β) is negative at all temperatures and at all compositions indicating attractive interactions. Activity coefficients (f1 and f2) are always less than unity suggesting nonideality in the systems. Thermodynamic parameters suggest dehydration of the hydrophobic part of the drug at or above a certain temperature.
► Micellization behaviors of amphiphilic drug–cationic surfactant combinations have been investigated. ► The negative β values suggest attractive interactions between the components. ► Temperature helps in tuning the aggregational behavior of a drug and its mixtures. ► For PMT/PMT–surfactant systems, ∆Hom values change from negative to positive with temperature.