ABSTRACT
The consequences of tobacco dependence are both health related and economic. Novel treatment approaches are needed to offer alternatives to patients and to improve treatment outcomes. We review concepts and selected recent discoveries in the area of treatment, with a specific orientation towards drug development. Current treatments are outlined and we highlight new strategies that are based on the manipulation of cytochrome P450 2A6 (CYP2A6) activity, which is responsible for the metabolism of nicotine. The clinical implications of CYP2A6 polymorphisms have been linked to a decreased risk of tobacco dependence, a decrease in number of cigarettes smoked and reduced risk of tobacco-related cancers. Further, we discuss a range of models for proof-of-concept studies for new treatments to alleviate tobacco dependence
Subject(s)
Aryl Hydrocarbon Hydroxylases/antagonists & inhibitors , Mixed Function Oxygenases/antagonists & inhibitors , Nicotine , Tobacco Use Disorder/drug therapy , Aryl Hydrocarbon Hydroxylases/genetics , Cytochrome P-450 CYP2A6 , Humans , Methoxsalen/therapeutic use , Mixed Function Oxygenases/genetics , Nicotine/administration & dosage , Nicotine/metabolism , Nicotine/therapeutic use , Polymorphism, Genetic , Prevalence , Tobacco Use Disorder/enzymology , Tobacco Use Disorder/epidemiologyABSTRACT
Codeine is O-demethylated by cytochrome P450 2D6 (CYP2D6) to form the more potent drug morphine, accounting for much of codeine's analgesic and dependence-producing properties. Because morphine production can be decreased by inhibition of CYP2D6, the authors hypothesized that CYP2D6 inhibition could be used to treat codeine dependence. A randomized, double-blind, placebo-controlled trial was conducted. All patients received brief behavioral therapy. Two weeks of baseline monitoring were followed by 8 weeks of daily treatment with fluoxetine or quinidine (two potent CYP2D6 inhibitors) or placebo. Thirty patients were assessed (all white, age 40 + 12 years using 127 + 79 mg/day of codeine [mean + SD]), and 17 entered treatment. Eight patients remained in the study by treatment week 8. Quinidine > fluoxetine > placebo inhibited CYP2D6 as reflected in the change of the O-demethylation of dextromethorphan, a specific CYP2D6 probe. At treatment week 8, placebo, quinidine, and fluoxetine reduced mean daily codeine intake by 57%, 56%, and 51% of baseline intake respectively; there was no difference among treatment groups. In this small sample, CYP2D6 inhibitors did not appear to have a useful role in the treatment of codeine dependence.
