THERMODYNAMICS OF LITHIUM DICLOFENAC SALT AQUEOUS SOLUTIONS AT 20-45° С

This work is a continuation of our previous investigations devoted to thermodynamics of aqueous solutions of NSAID of ionic nature [1-2]. Usually these compounds are poorly soluble in aqueous solutions: to improve solubility values and quality control of these drugs we started a study concerning NSAID and their salts crystal structures and behavior in solutions to model intercellular pathway drug delivery. The wide set of thermodynamic parameters thus obtained gives opportunity to characterize the state of the drug molecules in model systems and allows understanding and analyzing the driving forces of passive transport process. We report solution/dilution enthalpies of lithium diclofenac in water at 20, 25, 35 and 45°С obtained using isoperibolic calorimeter: the concentration of the electrolyte was restricted to the solubility value of the salt at various temperatures. The virial coefficients were derived from Pitzer’s model and the excess thermodynamic functions of both the solution and the component of the solution were calculated. The thermodynamic characteristics of the solution from concentration and temperatures are discussed. 1. N.G. Manin, A. Fini, A.N. Manin, G.L. Perlovich. J. Therm. Anal. Calorim., 2007, 90(1), 147-152. 2. N.G. Manin, A. Fini, A.N. Manin, G.L. Perlovich. J. Phys. Chem. (Russ.), 2009, 83(1), 1-10.