Nicotine is a major addictive compound in tobacco cigarette smoke. After being absorbed by the lung nicotine is rapidly metabolized and mainly inactivated to cotinine by hepatic cytochrome P450 2A6 (CYP2A6) enzyme. Genetic polymorphisrns in CYP2A6 may play a role in smoking behavior and nicotine dependence. CYP2A6* I A is the wild type of the CYP2A6 gene which is associated with normal or exten…