Physicochemical study on the effect of urea and sodium chloride on the binding of cetylpyridinium chloride with antihistamines

The effects of urea and sodium chloride (NaCl) on the binding behavior of the surfactant cetylpyridinium chloride (CPC) with the antihistamine drugs diphenhydramine hydrochloride (DPH) and cetirizine hydrochloride (CTZ) were investigated using conductivity measurement. The critical micelle concentration (CMC) values were determined by measuring conductivity changes in surfactant solutions and surfactant-antihistamine mixed systems at varying concentrations of urea and NaCl. To elucidate the mechanism by which urea and NaCl affect surfactant-antihistamine interactions, key parameters such as the slope of the conductivity curve and ion migration behavior were analyzed. The feasibility and driving force of micelle formation were evaluated by analyzing standard thermodynamic parameters. The negative value of <m:math xmlns:m="http://www.w3.org/1998/Math/MathML"> <m:mrow> <m:mo>Δ</m:mo> <m:msubsup> <m:mi>G</m:mi> <m:mi>m</m:mi> <m:mi>θ</m:mi> </m:msubsup> </m:mrow> </m:math> Δ Gₘθ indicate that micelle formation in the studied system is spontaneous. Furthermore, the transfer thermodynamic parameters for CPC micelles in the presence of the drugs were calculated and discussed. This study holds significance for the design of drug formulations and for industrial processes involving surfactants and additives.