Antidepressant drug amitriptyline hydrochloride (AMT) interaction with anionic surfactant sodium dodecyl sulfate in aqueous/brine/urea solutions at different temperatures

Abstract

Conductivity method was carried out at various temperatures ranging from 293.15K to 313.15K to examine the monomeric as well as micellar phases of aqueous/brine/urea solutions of mixed systems composed of anionic surfactant sodium dodecyl sulfate (SDS) and cationic drug amitriptyline hydrochloride (AMT). AMT is used to treat mental/mood problems such as depression. NaCl decreases critical micelles concentration (cmc) of pure components as well as their mixed systems may be mainly ascribed to the salting-out effect of the hydrophobic moiety of components while urea increases the cmc value because of enhancement in the surface charge of the micelles/mixed micelles. The interaction among the monomers in the micelles/mixed micelles in the urea solution is slightly less than the NaCl and aqueous solutions. Synergism is modeled by employing the regular solution theory (RST) with a negative interaction parameter and nonideal behavior. Molecular thermodynamic models of Rubingh, Rodens and Motomura allow the calculation of the total excess free energy of micellization (ΔGex) with negative values in all the three situations. The aggregation number, micropolarity, and apparent dielectric constant of solution mixtures were evaluated and discussed in detail by fluorescence measurement in three different media.