Effect of Temperature on the Supramolecular Behavior of Antidepressant Drug Amitriptyline Hydrochloride in the Presence of Nonionic Surfactants (Tweens and Brijs) as Pharmaceutical Excipients

Abstract

Abstract The aggregational and adsorption behavior of an important antidepressant amphiphilic drug amitriptyline hydrochloride have been studied in the presence of nonionic surfactants at different temperatures by tensiometry. By using regular solution theory and other thermodynamic models, different physicochemical properties such as critical micellar concentration, micellar composition, interfacial adsorption, energetic parameters (free energy, enthalpy, entropy) of micellization are evaluated. The data clearly depict that there is strong interaction between the amitriptyline hydrochloride and nonionic surfactants. Steric factor appears to play an important role during interaction when surfactant molecular structure varies in size of the head group and chain length of the hydrophobic part. The temperature has been observed to be vital in controlling the dehydration and thermal solubility which, in turn, makes environment conducive for aggregational behavior of the drug-surfactant mixtures in aqueous solution.