Investigation of the interaction of promethazine hydrochloride drug with tetradecyltrimethylammonium bromide: Impacts of hydrotropes composition and temperature

Herein, the micellization characteristics of tetradecyltrimethylammonium bromide (TTAB) and promethazine hydrochloride (PMH) mixtures have been explored in the presence of various hydrotropes (HyTs) (sodium salicylate (NaS), sodium benzoate (NaB), and p-amino benzoic acids (4-AmBA)) by applying the conductivity measurement method. The investigation was carried out by varying the composition of HyTs at definite temperature as well as variable temperatures while the composition of HyTs remained unchanged. The influences of hydrotropes and temperatures on the micellization of TTAB and PMH mixture have been examined from the changes in physico-chemical parameters of the respective system with the variation in composition/nature of HyTs and temperatures. A single critical micelle concentration (CMC) was noted for the employed drug + surfactant mixture in the appearance of HyTs. The introduction of NaS disrupted the micelle development whereas the presence of NaB and 4-AmBA promoted micelle formation in TTAB and PMH mixtures. At 6 mmol kg⁻¹ concentration of HyTs, the magnitudes of CMC demonstrated the order of CMC as (aq. NaS) \(> \text{CMC }\left(\text{aq}.\text{ NaB}\right)>\text{ CMC }\left(\text{aq}. 4-\text{AmBA}\right).\) $>\text{CMC}\left(\text{aq},.,,\text{NaB}\right)>\text{CMC}\left(\text{aq},.,4,-,\text{AmBA}\right).$ The CMC values of PMH + TTAB mixtures showed significant changes with the augmentation of temperatures. The appearance of negative \({\Delta G}_{m}^{0}\) ${\mathrm{\Delta }G}_m^0$ apparently indicating the spontaneous nature of aggregation of surfactant species. Other thermodynamic parameters such as enthalpy change ( \({\Delta H}_{m}^{0}\) ${\mathrm{\Delta }H}_m^0$ ), entropy change ( \({\Delta S}_{m}^{0}\) ${\mathrm{\Delta }S}_m^0$ ), molar heat capacity ( \({\Delta C}_{m,P}^{0}\) ${\mathrm{\Delta }C}_{m,P}^0$ )), thermodynamics of transfer and enthalpy-entropy compensation quantities have also been determined and the results were described in detail. The interaction forces among the components within the studied system were found to be electrostatic and hydrophobic in nature.