Micellar behaviour of amphiphilic drug propranolol hydrochloride with cationic surfactant (Hyamine 1622) at different compositions in solution

The micellisation behaviour between an amphiphilic drug propranolol hydrochloride (PPL) and cationic surfactant (Hyamine 1622) has been studied using conductometric technique at different concentrations. The critical micelle concentration (CMC), interaction parameter (beta(m)), mixed micellar composition and, extent of counterion binding(alpha) and thermodynamic parameters for the micellisation process have been computed and discussed. The trend of interaction parameter of the PPL with Hyamine 1622 has been found to be dependent on the CMC values and the composition (more dependent on drug concentration). In an interesting phenomenon, it was observed that in the various compositions of PPL/Hyamine mixture produced two CMC's. Compared to the first micelle, the second micelle condensed more counterions and produced a higher aggregation number. Also, the interaction parameter (beta(m)) is negative at all compositions indicating synergistic interactions between drug-surfactant. Activity coefficients ( and ) are always less than unity suggesting non-ideality in the mixtures.