Effect of various cationic hydrotropes on association behaviour of imipramine hydrochloride at different temperatures

Abstract

The micellization phenomena in the mixed system of the amphiphilic antidepressant drug imipramine hydrochloride (IPH) and cationic hydrotropes - aniline hydrochloride (AnH), ortho-toluidine hydrochloride (o-ToH), as well as para-toluidine hydrochloride (p-ToH)- in a water solution at a range of temperatures (288.15, 293.15, 298.15, and 303.15 K) was investigated using the conductometry method. In accordance with the regular solution theory (RST), along with other models, such as Rubingh's model, Rodenas's model, and so forth, various parameters were determined to attain a complete picture of the association behaviours of IPH and the hydrotrope mixtures. For every IPH-hydrotrope mixture, the critical micelle concentration (cmc) of the mixture along with the composition of the hydrotropes in the mixed micelle diverged from what they would have been in an ideal system, demonstrating non-ideal behaviour. The divergence amongst evaluated cmc and ideal cmc (cmcid) values viewing interaction amid studied constituents. The effects of the hydrotropes on the cmc of IPH (drug) were found to occur in the following order: p-ToH > AnH > o-ToH. The interaction parameters (β) were also evaluated to obtain detailed insights into the interactions amongst the studied constituents by applying a theoretical model introduced by Rubingh. The β values were negative, showing the presence of interactions between the binary mixtures of IPH and the hydrotropes. Micellar mole fraction (X1) data estimated via the applied models in present system showed the attractive interactions between the IPH and hydrotropes as well as the intercalation of hydrotrope monomers between the drug IPH monomers constituting the micelle. Through the achieved thermodynamic parameters of the micellization of IPH under different conditions, the effects of temperature and the cationic hydrotropes, along with the impact of their concentrations on their association behaviours, were deduced.