A PHYSICOCHEMICAL STUDY OF THE INTERACTION OF CIPROFLOXACIN AND OFLOXACIN WITH POLYVALENT CATIONS

The reactions between ciprofloxacin and ofloxacin with different soluble salts of Al3+, Mg2+, Ca2+, and Fe2+ in aqueous medium have been studied; the resulting products have been characterised using different analytical and spectroscopic techniques. Carboxylates are formed with ofloxacin, these salts being more soluble than the quinolone itself, due to its strong ionic character. However, ciprofloxacin does not form salts or non-absorbable complexes with metallic cations, although a crystalline material is formed. Experimental results using infrared and H-1-NMR spectroscopies, mass spectrometry and X-ray diffraction indicate that the carboxylic group is unreacted. This new product, more stable than the corresponding metallic salts, does not contain any metallic atom/cation.