Effect of S‐1 on blood levels of phenobarbital and phenytoin: A case report

Abstract

Abstract Drug‐drug interaction of fluorinated pyrimidine anticancer agents with phenytoin is well known, but interaction with phenobarbital is limited. We describe a case showing increases in plasma phenobarbital as well as phenytoin concentrations during preoperative S‐1 (tegafur/gimeracil/oteracil) and radiation therapy for rectal cancer.

Keywords

• drug‐drug interaction
• phenobarbital
• phenytoin
• S‐1
• therapeutic drug monitoring