THE CHARACTERISTICS OF PHOTOLYTIC REACTIONS OF QUINOLONE ANTIBIOTICS

AIM: To understand the characteristics of photolytic reactions of quinolone antibiotics. METHODS: A differential photo calorimetric technique, together with HPLC and other analytical methods, was used. The rates of photolytic reactions of sparfloxacin, pefloxacin, ciprofloxacin, levofloxacin and enoxacin were compared and the order of the impurities produced in irradiation were analyzed. RESULTS: The photolytic reaction was an exothermic one. In solution circumstance, the photolytic reaction could be auto inhibited and be inhibited by histidine as well. An irradiation could not only induce quinolone antibiotics to degrade, but to polymerize as well. Photodegradation might occur at primary periods of irradiation and the degradation site might be on the piperazine group of quinolone antibiotics at the 7-site. However, the photo polymerization reaction might occur at the late periods of irradiation. The photolytic reaction might be a step reaction. CONCLUSION: The structures of the drugs influenced greatly on the rates of photolytic reaction. Either in the degradation or in the polymerization, the rate of photolytic reactions of the drugs with a 1,8-naphthyridine structure was faster than the drugs with a quinolone structure.