Effect of high-dose aspirin on CYP2E1 activity in healthy subjects measured using chlorzoxazone as a probe

Ji-Young Park, Kyoung Ah Kim, Pil Whan Park, Jong Myung Ha

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8 Citations (Scopus)


The authors evaluated the effect of high-dose aspirin at a therapeutic dose, using chlorzoxazone as a probe for CYP2E1 enzyme activity. In a randomized, open-label, 2-way crossover study, 10 healthy men were treated 3 times daily for 6 days with 1 g aspirin or placebo. On day 7, 1 dose of 400 mg chlorzoxazone was administered orally. Plasma concentrations of chlorzoxazone and its metabolite, 6-hydroxychlorzoxazone, were measured. During the aspirin phase, the area under the time-concentration curve (AUC) and peak plasma concentration of chlorzoxazone were 95% (90% confidence interval [CI], 87%-103%) and 90% (90% CI, 80%-101%) of the values during the placebo phase, respectively. High-dose aspirin did not affect the oral clearance of chlorzoxazone significantly (90% CI, 98%-120%; P = .24). The AUC ratio and plasma concentration ratios of 6-hydroxychlorzoxazone/chlorzoxazone were not changed significantly by high-dose aspirin. High-dose aspirin at a therapeutic dose does not affect CYP2E1 activity in humans.

Original languageEnglish
Pages (from-to)109-114
Number of pages6
JournalJournal of Clinical Pharmacology
Issue number1
Publication statusPublished - 2006 Jan 1
Externally publishedYes



  • Aspirin
  • Chlorzoxazone, 6-hydroxychlorzoxazone
  • Cytochrome P450 2E1 (CYP2E1)
  • Drug interaction

ASJC Scopus subject areas

  • Pharmacology
  • Pharmacology (medical)

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