Determination of osmotic coefficients and activity coefficients of calcium D-pantothenate, cefazolin sodium, and ceftriaxone sodium drugs in aqueous solutions of amino acids by using vapor pressure osmometry at 310.15 K

Fundamental and serious efforts have been made over the past years to improve the drug acts, which leads to the discovery of novel drug preparations and delivery systems. The optimal design of such processes requires a molecular-level understanding of the interactions between drug molecules and biomolecules such as proteins. The thermodynamic investigation provides deep insight and knowledge of solute-solvent interactions and selection of appropriate production compounds in pharmaceutical fields. Particularly, the study of drug + biomolecule in aqueous media is the central issue in many types of research. The osmotic coefficient data for aqueous solutions containing the drugs (calcium D-pantothenate (CDP), cefazolin sodium (CFZ.Na), ceftriaxone sodium (CFT.Na)) with simple amino acid, L-alanine, glycine and L-leucine are obtained at 310.15 K using vapor pressure osmometry. Activity coefficients of both components in mixture were estimated using experimental osmotic coefficients. According to the results, the values of osmotic coefficients for the ternary system (drug + water + L-leucine) with a concentration of 0.04 mol.kg(-1) are higher than those values in other systems. The concentration dependence of osmotic coefficients indicates ion-pair formation between the ions of the drugs. Finally, Lin et al. and ECA models were used to correlate the water activity data in the presence of the amino acids obtained for the aqueous solution (drug + water + amino acid).