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, [C8mim][Cl], have been investigated using electrical conductivity, at different temperatures. The non-ideal behaviour (i.e., synergistic interaction) of AMT–[C8mim][Cl] binary mixtures, explained by the deviations in critical micelle concentration (cmc) from ideal critical micelle concentration (cmc*) and micellar mole fraction (Xm) from ideal micellar mole fraction (Xideal) values. The values of interaction parameter (β) and activity coefficients (f1 and f2), also confirm the synergistic interaction. The excess free energy (ΔGex) for the AMT–[C8mim][Cl] binary mixtures explains, stability of mixed micelles in comparison to micelles of pure, AMT and [C8mim][Cl]. The calculated thermodynamic parameters (viz., the standard Gibbs energy change, Δ G m ∘ , the standard enthalpy change, Δ H m ∘ , the standard entropy change, Δ S m ∘ ), 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 [C8mim][Cl].