Physico-chemical investigation of the assembly and clouding development nature of the mixture of metformin hydrochloride and ionic/nonionic surfactants: Influences of hydrotropes

The clouding development and the association of the mixture of surfactant and antidiabetic drug metformin hydrochloride (MNH) have been investigated in aq. solutions of two anionic hydrotropes (sodium salicylate (NaSal) and sodium benzoate (NaBenz)) and an uncharged hydrotrope (4-amino benzoic acid (4-ABA)) (HDTs) media. In the present study, nonionic (triton X-100 (TX-100)) and cationic (tetradecyltrimethylammonium bromide (TTAB)) surfactants were employed. The cloud point (CP) of TX-100 + MNH system has been reduced with the enhancing contents of HDTs. The micellar variables (critical micelle concentration (CMC) and extent of ionization (a) of TTAB + MNH system have been assessed while the parameters are dependent on the HDT contents and changes of study temperature. The free energy of clouding (AG0c) and assembly (AGc0) processes have been detected as positive and negative respectively which indicated that the respective processes are non-spontaneous and spontaneous in nature. For the clouding and assembly processes, the standard enthalpy (AHc0/AH0m), and standard entropy (AS0c/AS0m) were also determined and discussed. The AHc0 and AS0c recommend that the core forces between TX-100 and MNH in presence of 4-ABA are H-bonding and electrostatic interactions but hydrophobic interaction is suggested as main force amid the employed components in aq. NaBenz and NaSal media. The AH0m and AS0m values of TTAB + MNH assembly reveal the occurrence of electrostatic interaction and hydrophobic forces amid the components inspected.(c) 2022 Elsevier B.V. All rights reserved.