Genetic variants in the serotonin transporter influence the efficacy of bupropion and nortriptyline in smoking cessation

Authors

  • Marieke Quaak,

    1. Department of Toxicology, Nutrition and Toxicology Research Institute Maastricht (Nutrim), Maastricht University, Maastricht, the Netherlands
    2. Department of General Practice, Care and Public Health Research Institute (CAPHRI), Maastricht University, Maastricht, the Netherlands
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  • Constant P. van Schayck,

    1. Department of General Practice, Care and Public Health Research Institute (CAPHRI), Maastricht University, Maastricht, the Netherlands
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  • Dirkje S. Postma,

    1. Department of Pulmonology, University Medical Center Groningen, Groningen, the Netherlands
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  • Edwin J. Wagena,

    1. Department of General Practice, Care and Public Health Research Institute (CAPHRI), Maastricht University, Maastricht, the Netherlands
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    • Present address: Kiadis Pharma, Amsterdam, the Netherlands.

  • Frederik J. van Schooten

    Corresponding author
    1. Department of Toxicology, Nutrition and Toxicology Research Institute Maastricht (Nutrim), Maastricht University, Maastricht, the Netherlands
      Frederik J. van Schooten, Department of Toxicology, Nutrition and Toxicology Research Institute Maastricht (NUTRIM), Maastricht University, PO Box 616, 6200 MD Maastricht, the Netherlands. E-mail: f.vanschooten@maastrichtuniversity.nl
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Frederik J. van Schooten, Department of Toxicology, Nutrition and Toxicology Research Institute Maastricht (NUTRIM), Maastricht University, PO Box 616, 6200 MD Maastricht, the Netherlands. E-mail: f.vanschooten@maastrichtuniversity.nl

ABSTRACT

Aims  We investigated whether variants in the serotonin transporter gene (SLC6A4) influence smoking cessation rates using antidepressant therapy (i.e. bupropion and nortriptyline).

Design  Pharmacogenetic (secondary) analysis of a randomized, placebo-controlled efficacy trial of bupropion and nortriptyline for smoking cessation.

Setting  Single-centre study, Maastricht University, the Netherlands.

Participants  A total of 214 of 255 (84%) current daily smokers participating in a randomized controlled efficacy trial.

Measurements  Subjects were genotyped for three functional variants in SLC6A4 (5-HTTLPR, STin2, rs25531). Primary outcome measures were prolonged abstinence from weeks 4–12, 4–26 and 4–52. Secondary outcome measures included 7-day point prevalence abstinence at weeks 4, 12, 26 and 52.

Findings  Carriers of the 5-HTTLPR high-activity L-variant had higher prolonged cessation rates with bupropion than placebo [odds ratio (OR) = 1.44, 95% confidence interval (CI) = 1.01–2.05, P = 0.04]. Combining the three variants resulted in increased prolonged cessation rates for both bupropion and nortriptyline among carriers of four to five high-activity variants (bupropion: OR = 2.00, 95% CI = 1.21–3.29, P = 0.01; nortriptyline: OR = 1.91, 95% CI = 1.02–3.56, P = 0.04). Similar results were found for point prevalence abstinence.

Conclusions  Bupropion and nortriptyline seem to be more effective in smoking cessation among SLC6A4 high-activity variant carriers, probably by blocking the increased serotonin transporter activity, thereby increasing serotonin levels. Prospective studies have to assess if this can improve cessation rates when treatment is targeted at individuals based on their genotypes.

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