Thermodynamic solution properties of pefloxacin mesylate and its interactions with organized assemblies of anionic surfactant, sodium dodecyl sulphate

• Free energy of adsorption is more negative than free energy of micellization.
• Micellization becomes more spontaneous at high temperature.
• There is strong interaction between PFM and SDS.

This manuscript reports the physicochemical behavior of antibiotic amphiphilic drug pefloxacin mesylate (PFM) and its interaction with anionic surfactant, sodium dodecyl sulfate (SDS). The data of surface tension and electrical conductivity are helpful to detect the CMC as well as to calculate surface parameters, i.e. surface pressure, π, surface excess concentration, Γ, area per molecule of drug and standard Gibbs free energy of adsorption, ΔGads and thermodynamic parameters like standard free energy of micellization, ΔGm, standard enthalpy of micellization, ΔHm and standard entropy of micellization, ΔSm. The interaction of this drug with anionic surfactant, sodium dodecyl sulfate (SDS) was studied by electrical conductivity and UV/visible spectroscopy. This enabled us to compute the values of partition coefficient (Kx), free energy of partition, ΔGp, binding constant, Kb, free energy of binding, ΔGb, number of drug molecules per micelle, n, and thermodynamic parameters of drug–surfactant interaction.

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