Phenytoin intoxication induced by fluvoxamine

Kohsuke Mamiya, Kyoji Kojima, Eiji Yukawa, Shun Higuchi, Ichiro Ieiri, Hideaki Ninomiya, Nobutada Tashiro

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28 Citations (Scopus)


A patient had phenytoin intoxication after administration of fluvoxamine, a selective serotonin reuptake inhibitor. The serum concentration of phenytoin increased dramatically from 16.6 to 49.1 μg/mL when fluvoxamine was coadministered, although the daily dosage of phenytoin and other drugs had not changed. During phenytoin and fluvoxamine treatment, ataxia, a typical side effect of phenytoin, was observed. The genotypes of CYP2C9 and 2C19, the enzymes responsible for phenytoin metabolism, were homozygous for the wild-type alleles (CYP2C9*1/*1 and 2C19*1/*1). The interaction may be a result of inhibition of both CYP2C9 and 2C19 by fluvoxamine.

Original languageEnglish
Pages (from-to)75-77
Number of pages3
JournalTherapeutic drug monitoring
Issue number1
Publication statusPublished - 2001

All Science Journal Classification (ASJC) codes

  • Pharmacology
  • Pharmacology (medical)

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  • Cite this

    Mamiya, K., Kojima, K., Yukawa, E., Higuchi, S., Ieiri, I., Ninomiya, H., & Tashiro, N. (2001). Phenytoin intoxication induced by fluvoxamine. Therapeutic drug monitoring, 23(1), 75-77.