The roles of cytochrome P450 in nicotine metabolism

The conversion of nicotine to cotinine is a major pathway of nicotine metabolism and cytochrome P450 catalyses the first step of this pathway (Nakayama, 1988). To date, numerous studies have shown that cytochrome P450 is composed of many molecular forms and their expression is regulated by many factors such as drug administration, age, sex and pathophysiological conditions (Ryan and Levin, 1990; Soucek and Gut, 1992; Funae and Imaoka, 1992).