| Abstract: | A 77-year-old male patient who had been receiving doxifluridine (5'-DFUR) for about a year after surgery for rectal cancer, was newly prescribed TS-1, because tumor markers were elevated and abdominal ultrasonography documented liver metastasis. However, the patient took TS-1 concomitantly with 5'-DFUR, which is contraindicated to TS-1, and experienced a severe drug interaction. This inadvertent drug interaction was caused by a combination of the newly prescribed drug and the unused drug remaining at the patient's home. This type of medication error has not been reported previously. Health professionals should be aware of such drug interactions which may be caused by newly prescribed drugs plus unused drugs remaining in the patient's home. Furthermore, health professionals should instruct patients on the nature of drug interactions as well as explaining their diagnosis and treatment. Although the severity of such drug interaction may vary, health professionals must be alerted to such incidents, which could happen frequently. |
