Antipyrine and metronidazole metabolism during occupational exposure to gasoline

Summary Antipyrine and metronidazole clearance was measured in 18 fuel-filling attendants by the single-sample method while the attendants were being exposed occupationally to gasoline; the measurements were repeated after 2–4 weeks with no exposure. Eighteen office workers were investigated simultaneously. The median concentration of gasoline in the breathing zone of the fuel-filling attendants during filling and cleaning operations was 270mgm^–3 (range 18–1758mgm^–3). Antipyrine clearance was 18% higher during exposure to gasoline than after 2–4 weeks of vacation (P<0.01), while antipyrine clearance was unchanged in the office workers. No change was found in metronidazole clearance in either group. Antipyrine clearance was on average 26% higher in the smokers than in the nonsmokers (P<0.05), while metronidazole clearance was similar in smokers and nonsmokers. We conclude that gasoline is an inducer of antipyrine elimination, with no impact on metronidazole elimination. This indicates that gasoline has a differential inducing effect on the hepatic drug metabolizing enzymes of man.