Cigarette smoking and drug metabolism

Cigarette smoking appeared to induce total body drug metabolism, as indicated by decreased antipyrine t 1/2 and increased antipyrine clearance. The in vitro parameters of liver drug metabolism used (benzo(a)pyrene hydroxylase and cytochrome P-450 levels), however, were not changed. This implicates induction of drug metabolism in some other organ(s). Serum thiocyanate levels were higher in smokers than in exsmokers and nonsmokers. There was a certain amount of overlap between these groups; whether this reflects unreliability of smoking anamnesis or unspecificity of thiocyanate assay in discriminating between smokers and nonsmokers is not known. There was no significant correlation between serum thiocyanate and the other parameters studied.