title: Phenytoin toxicity in a patient receiving concomitant use of phenytoin and S-1 plus cisplatin chemotherapy for advanced gastric cancer.
abstract: A 61-year-old man had been receiving phenytoin(225mg/day)and valproate(600mg/day)for several years as the treatment for seizures. He was diagnosed with advanced gastric cancer,and S-1 plus cisplatin treatment was administered as neoadjuvant chemotherapy because bulky lymph node metastases were found at the time of the initial diagnosis. He complained of weakness of the lower extremities,light -headedness,and trembling of the upper extremities 2 months after the start of concomitant treatment with S-1 plus cisplatin. The serum phenytoin concentration increased to 21. 2mg/mL. Head computed tomography and magnetic resonance imaging did not reveal any intracranial lesion such as brain metastasis. Therefore, we diagnosed phenytoin toxicity due to concomitant use of S-1 and phenytoin,and the dose of phenytoin was then decreased to 150 mg. Although the weakness of the lower extremities improved,light -headedness remained. Phenytoin and valproate treatments were stopped,and he was able to walk 7 days after the termination of therapy. It is important to predict the timing of phenytoin toxicity due to S-1,and therapeutic drug monitoring should be performed in patients receiving S-1 plus cisplatin and phenytoin.
authors.affiliation: Dept. of Surgery, Social Insurance Yokohama Central Hospital.
authors.forename: Kenji
authors.initials: K
authors.lastname: Mimatsu
authors.forename: Takatsugu
authors.initials: T
authors.lastname: Oida
authors.forename: Atsushi
authors.initials: A
authors.lastname: Kawasaki
authors.forename: Kazutoshi
authors.initials: K
authors.lastname: Kida
authors.forename: Nobutada
authors.initials: N
authors.lastname: Fukino
authors.forename: Youichi
authors.initials: Y
authors.lastname: Kuboi
authors.forename: Hisao
authors.initials: H
authors.lastname: Kano
authors.forename: Sadao
authors.initials: S
authors.lastname: Amano
mesh_terms: D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D002945:Cisplatin / Q000008:administration & dosage / Q000627:therapeutic use*; D004338:Drug Combinations; D017809:Fatal Outcome; D006801:Humans; D008297:Male; D008875:Middle Aged; D010094:Oxonic Acid / Q000008:administration & dosage / Q000627:therapeutic use*; D010672:Phenytoin / Q000008:administration & dosage / Q000009:adverse effects* / Q000627:therapeutic use; D013274:Stomach Neoplasms / Q000188:drug therapy*; D005641:Tegafur / Q000008:administration & dosage / Q000627:therapeutic use*
chemical_list: D004338:Drug Combinations; C079198:S 1 (combination); D005641:Tegafur; D010094:Oxonic Acid; D010672:Phenytoin; D002945:Cisplatin