RESUMEN
In this research article, we have described to establish a comparison between the solubility of the hydrochloride and non-hydrochlorideforms of ciprofloxacin and tetracycline in relevant solvents. For that purpose the solubility ofciprofloxacin and tetracycline were measured in water, methanol, propanol,and acetone, in the temperature range between 293.20 and 323.20 K for ciprofloxacin and between 288.20and 303.20 K for tetracycline. The solubility of the hydrochloride form in water is about 2 orders of magnitude higherthan those of the respective base forms. In acetone, we see the opposite effect. For methanol and propanolthe influence of the hydrochloride group of the antibiotic on the solubility in the alcohol is much smaller thanfor water and acetone. The experimental data was correlated with good results using two different activitycoefficient models, NRTL and UNIQUAC, with UNIQUAC giving better results, particularly for ciprofloxacin.The performance of COSMO-RS model to describe the studied systems was also evaluated.The dependence of these properties with temperature are shown. Theresults are interpreted in terms of solute-solvent interaction.