Short communication. The effects of drinking and smoking on the CYP2D6 metabolic capacity.

We studied the influence of drinking and smoking habits on CYP2D6 metabolic capacity measured by the use of debrisoquine as a substance test. We did not find any significant differences in the frequency of subjects with CYP2D6 deficiency (poor metabolizers) among four groups of healthy individuals: nonsmokers/nondrinkers, smokers/drinkers, nondrinkers/smokers, and nonsmokers/drinkers. We demonstrated that, among poor metabolizers, alcohol and tobacco consumption was associated with higher metabolic ratios than it was with the control group, but the differences were not statistically significant. Among extensive metabolizers, the lowest metabolic ratio (highest enzyme activity) was detected for nondrinkers/smokers, intermediate values for smokers/drinkers, and the highest metabolic ratio (lowest enzyme activity) for nonsmokers/drinkers. These variations were slight but statistically significant when logarithmic ratio values were applied. These results show that smoking and drinking habits do not need to be taken into account when humans are phenotyped for CYP2D6.