Furosemide–Cetyltrimethylammonium Bromide Interactions in Aqueous Dimethylsulfoxide Solutions: Physico–Chemical Studies

Interaction of a cardiovascular drug, Furosemide with cetyltrimethylammonium bromide (CTAB) has been studied in aqueous solutions of Dimethylsulfoxide (DMSO) with the help of density, speed of sound and conductivity measurements over a range of temperatures 293.15–313.15 K at interval of 5 K. The interaction parameters viz. apparent molar volume, Vϕ and apparent molar isentropic compression, κs,ϕ have been enumerated from density and speed of sound data. Also, variation in the micellization behavior has been explored by calculating critical micelle concentration, CMC. It has been observed that micellization tendency of the surfactant decreases in the presence of DMSO as compared to pure aqueous system. Moreover, the CMC values shift toward lower concentration with increase in Furosemide content because of increase in hydrophobic hydration which may be to hydrophobicity of drug molecule. The dependence of CMC in mole fraction (Xcmc) values on the temperature has been analyzed in terms of thermodynamics of the system by reporting the standard thermodynamic parameters i.e. standard Gibb’s free energy $(\Delta G_m^o),$ enthalpy $(\Delta H_m^o)$ and entropy $(\Delta S_m^o)$ of micellization for CTAB in mixed solvent systems. The entropies of micellization are all positive, and they compensate the enthalpies of the process. Compensation temperature, Tc has also been evaluated from enthalpy–entropy compensation whose values lies in Lumrys range (270–300 K).