Effects of Cationic Surfactants on Clouding Action of the Drug Amitriptyline Hydrochloride in Ethylene Glycol-Water and Glycerol-Water Mixed Media

The cloud point (CP) and thermodynamic parameters at cloud point viz., Delta(s)G(,)(0) Delta(s)H(0)and T Delta S-s(0) of an amphiphilic drug amitriptyline hydrochloride (AMT) at several compositions of organic solvent-water namely, ethylene glycol (EG) / glycerol (GL) - water (WR) (0%, 5%, 10%, 15%, 20%, 25%, 30%, 35% and 40% w/w) mixed media and the effects of addition of conventional hexadecyltrimethylammonium bromide (CTAB), tetradecyltrimethylammonium bromide (TTAB) and gemini (14-4-14, 14-5-14 and 14-6-14) surfactants at selected compositions of organic solvent-water media (0%, 5%, 10%, 15% and 20%, w/w) have been studied at a pH6.7. Conductivity measurements were done to determine the critical micelle concentration (cmc) and degree of counterion dissociation (-) of AMT in water and different weight% of binary mixture ranging from 0% to 25% of EG/GL at 30 degrees C. It is observed that the micellization of AMT molecules is affected through an indirect, solvent-mediated mechanism with the increase in their binary mixture due to lowering of dielectric constant of the mixed media. As a result, inter / intra electrostatic repulsion in the drug-micellar head groups increases raising the cmc values of AMT. The study reveals that the inclusion of EG and GL to the AMT drug solution with/without additives modifies the interactions of the drug molecules due to a decrease in dielectric constant of resultant mixed media.