LAUSR

Abstract Micelles are well established solubilizing agents which can solubilize poorly soluble drug moieties. For choosing the optimum solubilizing medium for levofloxacin (LEVO) solubilization, studies were carried out using various surfactants viz., tyloxapol, tween 80, tween 20, sodium cholate, (NaC), sodium dodecyl sulphate (SDS), dodecyl ethyl dimethyl ammonium bromide (DDAB), dodecyl trimethyl ammonium bromide (DTAB), cetyl trimethyl ammonium bromide (CTAB). UV–Visible and fluorescence spectroscopy studies were used to evaluate the binding constants (Kb) and quenching constants (Ksv) which were found to be highest for CTAB based systems. Variation in thermodynamic parameters viz., free energy (∆G0m), enthalpy (∆H0m) and entropy (∆S0m) of drug-surfactant associations were estimated via conductivity measurements. Changes in enthalpy and entropy for LEVO-CTAB systems suggested increase in partitioning of drug in CTAB micelles. Solubility of LEVO showed a linear increase with increasing CTAB concentrations. Interactions of LEVO with serum protein (bovine serum albumin; BSA) were investigated in presence of surfactants using UV–Visible and fluorescence studies. Long term biocompatibility of LEVO-CTAB formulation was observed in association with structural (collagen) and transport proteins (BSA, human serum albumin; HSA) via circular dichroism studies.