title: Combination of capecitabine and phenytoin may cause phenytoin intoxication: a case report.
abstract: Capecitabine is an oral antineoplastic agent, and phenytoin is an anticonvulsant drug with a narrow therapeutic index. Although the interaction between capecitabine and phenytoin is rare, it may be potentially fatal. This interaction is thought to be at the level of CYP2C9 isoenzyme system in the liver. Here, we present a patient with metastatic breast cancer who developed phenytoin intoxication when using capecitabine and phenytoin together. Closely monitoring plasma phenytoin levels is essential if capecitabine is used with phenytoin concurrently.
authors.affiliation: 1Department of Medical Oncology, Istanbul University Institute of Oncology, Istanbul, Turkey; and 2Department of Cardiology, Istanbul Bakirköy Dr. Sadi Konuk Training and Research Hospital, Istanbul, Turkey.
authors.forename: Rumeysa
authors.initials: R
authors.lastname: Ciftci
authors.forename: Faruk
authors.initials: F
authors.lastname: Tas
authors.forename: Senem
authors.initials: S
authors.lastname: Karabulut
authors.forename: Serkan
authors.initials: S
authors.lastname: Ciftci
mesh_terms: D000927:Anticonvulsants / Q000009:adverse effects* / Q000493:pharmacokinetics; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology*; D001943:Breast Neoplasms / Q000188:drug therapy / Q000473:pathology; D000069287:Capecitabine; D065729:Cytochrome P-450 CYP2C9 / Q000187:drug effects / Q000378:metabolism; D003841:Deoxycytidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D004347:Drug Interactions; D016903:Drug Monitoring / Q000379:methods; D005260:Female; D005472:Fluorouracil / Q000031:analogs & derivatives* / Q000494:pharmacology; D006801:Humans; D008875:Middle Aged; D010672:Phenytoin / Q000009:adverse effects* / Q000493:pharmacokinetics
chemical_list: D000927:Anticonvulsants; D000964:Antimetabolites, Antineoplastic; D003841:Deoxycytidine; D010672:Phenytoin; D000069287:Capecitabine; D065729:Cytochrome P-450 CYP2C9; D005472:Fluorouracil