Halothane inhalation inhibits the metabolism of chlorzoxazone, a substrate for CYP2E1, in rabbits

Tomonori Tateishi, Minoru Watanabe, Hironori Nakura, Masami Tanaka, Toshio Kumai, Tadashi Aoki, Shinichi Kobayashi

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3 Citations (Scopus)


We demonstrated the inhibitory effect of halothane (HAL) inhalation on the metabolism of chlorzoxazone (CZZ), a substrate for CYP2E1, in a bolus and a continuous injection study in rabbits receiving artificial ventilation. In a bolus injection study, the inhalation of 1.0% HAL significantly increased the half-line and the area under the curve and decreased the clearance of CZZ compared with those variables in midazolam administration. In a continuous injection study, the effect of various concentrations of inhaled HAL on plasma CZZ concentration at steady state was compared. Systolic and diastolic arterial blood pressure were decreased dose-dependently after 0.5%, 1.0%, or 2.0% HAL was inhaled. Although the plasma concentration of CZZ was increased 2.5-fold later 3 h of HAL inhalation, there was no significant difference in mean plasma concentrations among the groups treated with 0.5%, 1.0%, or 2.0% HAL. In contrast, the plasma concentration of lidocaine, a substrate for CYP3A, remained unchanged after 1.0% HAL was inhaled. These results suggest that general anesthesia obtained with HAL inhalation will affect the metabolism of drugs administered concomitantly when the drug is a substrate for CYP2E1.

Original languageEnglish
Pages (from-to)199-203
Number of pages5
JournalAnesthesia and Analgesia
Issue number1
Publication statusPublished - Aug 26 1997
Externally publishedYes

ASJC Scopus subject areas

  • Anesthesiology and Pain Medicine


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