Occupational exposure to halothane results in enzyme induction in anesthetists.

To determine whether exposure to trace concentrations of halothane resulted in enzyme induction, antipyrine pharmacokinetics were measured in six anesthetists before and after ten days of exposure to waste halothane. Antipyrine clearance increased by 29 per cent, a clinically small but statistically significant (P < 0.025) change, whereas the apparent volume of antipyrine distribution remained unchanged, indicating that halothane induces antipyrine metabolism. The implications of this finding for anesthetists cannot be simply defined. Enzyme induction may be beneficial or harmful, depending on the relative toxicities of the unbiotransformed parent compounds and their metabolites.