Investigating the Association Behaviour of Cetyltrimethylammonium Bromide as Affected by the Content of Non-steroidal Antiinflammatory Drug and Temperature

Critical micelle concentration of N-cetyl N,N,N-trimethyl ammonium bromide and its mixture with drug naproxen sodium were determined at different temperature by using surface tension technique. Naproxen sodium has been found to exhibit typical amphiphilic behaviour in aqueous solution in that they accumulate at interface, depressing the surface tension and form aggregate in solution at sufficiently high concentration. So critical micelle concentration of cetyltrimethylammonium bromide decreased as the concentration of drug increases and same is the case with temperature. Thermodynamic parameters like Delta G(mic), Delta H-mic and Delta S-mic of micellization of cetyltrimethylammonium bromide were also determined in the presence of naproxen sodium salt at different temperature, which shows that free energy of micellization, is favoured in the presence of drug and become more favourable with the temperature.