Effect of carbon monoxide inhalation exposure in mice on drug metabolism in vivo.

Experiments were undertaken to evaluate the action of carbon monoxide (CO) on the mixed-function oxidase (MFO) system in vivo. Mice were exposed to 500 ppm CO for 8 h per day in an inhalation chamber under dynamic airflow conditions. Hexobarbital (150 mg/kg, i.p.), zoxazolamine (150 mg/kg, i.p.) or ethanol (2 mg/g, i.p.) was given to each group of mice during CO exposure and disappearance of the drug from blood or brain was determined while CO exposure continued. The experiments were repeated with different groups of animals which were exposed to CO for 3 or 5 days. Hexobarbital and ethanol metabolism were not affected by CO following either one day exposure or repeated exposure. There was no statistically significant difference in the brain level of zoxazolamine in animals exposed to CO when compared to control. These studies indicate that in vivo metabolism of hexobarbital, zoxazolamine and ethanol in mice is not affected by exposure to 500 ppm CO under the conditions employed in the present study.