Role of 1-methyl-3-octylimidazolium chloride in the micellization behavior of amphiphilic drug amitriptyline hydrochloride

The mixed micellization behaviour of amitriptyline hydrochloride (AMT) with ionic liquid (IL) 1-methyl-3-octylimidazolium hydrochloride, [C(8)mim][Cl], have been investigated using electrical conductivity, at different temperatures. The non-ideal behaviour (i.e., synergistic interaction) of AMT-[C(8)mim][Cl] binary mixtures, explained by the deviations in critical micelle concentration (cmc) from ideal critical micelle concentration (cmc*) and micellar mole fraction (X-m) from ideal micellar mole fraction (X-ideal) values. The values of interaction parameter (beta) and activity coefficients (f(1) and f(2)), also confirm the synergistic interaction. The excess free energy (Delta G(ex)) for the AMT-[C(8)mitn][Cl] binary mixtures explains, stability of mixed micelles in comparison to micelles of pure, AMT and [C(8)mim][Cl]. The calculated thermodynamic parameters (viz., the standard Gibbs energy change, Delta G(m)degrees the standard enthalpy change, Delta H-m degrees the standard entropy change, Delta S-m degrees), suggest the dehydration of hydrophobic part of the drug at higher temperatures (>313 K), not only in case of AMT but also in the presence of [C(8)mitn][Cl]. (C) 2013 Elsevier B.V. All rights reserved.