Abstract: The invention relates to methods and compositions for regulating nicotine metabolism. Also provided are methods for screening and assessing substances for regulating nicotine metabolism. Methods are provided for assessing nicotine metabolism.

Abstract: A method of regulating the activity of human cytochrome P450 isozyme CYP2A6 to control nicotine metabolism or decrease to production of carcinogens from procarcinogens, such as those present in tobacco smoke, in an individual by selectively inhibiting CYP2A6. Various prophylactic (i.e., prevention and treatment) compositions and methods are also described, including an improved oral nicotine composition and method comprising the use of nicotine together with an inhibitor of the CYP2A6 enzyme. Furthermore, it has been discovered that the presence in an individual of a mutant allele of human cytochrome P450 enzyme CYP2A6 (referred to throughout this specification as “CYP2A6” for brevity) is predictive of an individual who: (i) has a decreased risk of becoming a smoker, (ii) will smoke less if he/she becomes dependent, and/or (iii) may be at relatively lower risk for cancer due to both decreased smoke exposure and decreased CYP2A6-mediated activation of tobacco smoke and other procarcinogenic substrates.

Abstract: Various compounds that can inhibit the enzyme CYP2D6 are disclosed. The compounds are useful in increasing the effectiveness and reducing the abuse potential of drugs that are metabolised by CYP2D6.