Insight into intermolecular interactions and hydration properties of biologically active amino acids in aqueous solutions of cefepime: volumetric, compressibility and viscometric studies

The measurement of density, speed of sound and viscosity of an amino acid and its dipeptide i.e., glycine and glycylglycine in aqueous solution of antibiotic drug cefepime has been carried out at various temperatures. The density and speed of sound data has been used to obtain partial molar volume(Vφo), partial molar expansion coefficient(∂Vφo∂T)p, second derivative(∂2Vφo∂T2)p, hydration number (ηH), isentropic compressibility(κs), partial molar isentropic compressibility(κφ,so), partial molar volume of transfer(ΔtrVφo) and partial molar isentropic compressibility of transfer(Δtrκφ,so). The viscosity data have been used to calculate the viscosity B–coefficients, its temperature derivative dB/dT, viscosity B–coefficient of transfer (ΔtrB) and various thermodynamic parameters of activation of viscous flow i.e.,Δμ1o*,Δμ2o*, ΔS2o* and ΔH2o* for amino acid/peptide in cefepime solutions. The dependence of these parameters upon concentration and temperature clearly suggests the role of amino acid/peptide and cefepime in solute-solvent interactions. The obtained results have been explained on the basis of competing pattern of interactions between the co-solute and solute in the studied ternary system in order to deduce important information regarding drug-amino acid/peptide interactions.