The protective effects of null or reduced activity CYP2A6 alleles on both nicotine dependence and lung cancer suggests that inhibition of CYP2A6 may be a useful therapeutic strategy (Sellers et al., 2003b). Methoxsalen, a medication that is approved for the treatment of psoriasis, is a potent inhibitor of CYP2A6 (Damaj et al., 2007; Sellers & Tyndale, 2000; Zhang et al., 2001). In pharmacokinetic assessments, methoxsalen, at doses of 10 and 30 mg administered to overnight abstinent smokers, doubled plasma nicotine levels from 4 mg of oral nicotine and decreased the self-rated desire to smoke (Sellers et al., 2000). When smokers were allowed to smoke ad libitum after the administration of 30 mg of methoxsalen along with 4 mg of oral nicotine, there was a decrease in expired breath CO by 47%, cigarettes smoked by 24%, total numbers of puffs taken, and an increase in the latency to light a cigarette, compared to smokers who received placebo plus 4 mg of oral nicotine (Sellers et al., 2000). Methoxsalen (10 mg) administered to smokers who were asked to maintain their smoking habit
