The photodegradation rate of histidine increased with the increase of UVA dosage and drug concentration.Conclusion Both pipemidic acid and norfloxacin cause photooxidation of histidine.

• 结论吡哌酸和诺氟沙星均引起组氨酸光氧化分解，UVA剂量增加和药物浓度增加都导致光敏反应增强。