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Smoking cessation pharmacogenetics: analysis of varenicline and bupropion in placebo-controlled clinical trials.

ABSTRACT: Despite effective therapies for smoking cessation, most smokers find quitting difficult and most successful quitters relapse. Considerable evidence supports a genetic risk for nicotine dependence; however, less is known about the pharmacogenetics of smoking cessation. In the first pharmacogenetic investigation of the efficacy of varenicline and bupropion, we examined whether genes important in the pharmacodynamics and pharmacokinetics of these drugs and nicotine predict medication efficacy and adverse events. Subjects participated in randomized, double-blind, placebo-controlled smoking cessation clinical trials, comparing varenicline, a nicotinic acetylcholine receptor (nAChR) partial agonist, with bupropion, a norepinephrine/dopamine reuptake inhibitor, and placebo. Primary analysis included 1175 smokers of European ancestry, and 785 single nucleotide polymorphisms from 24 genes, representing 254 linkage disequilibrium (LD) bins (genes included nAChR subunits, additional varenicline-specific genes, and genes involved in nicotine or bupropion metabolism). For varenicline, continuous abstinence (weeks 9-12) was associated with multiple nAChR subunit genes (including CHRNB2, CHRNA5, and CHRNA4) (OR=1.76; 95% CI: 1.23-2.52) (p<0.005); for bupropion, abstinence was associated with CYP2B6 (OR=1.78; 95% CI: 1.27-2.50) (p<0.001). Incidence of nausea was associated with several nAChR subunit genes (OR=0.50; 95% CI: 0.36-0.70) (p<0.0001) and time to relapse after quitting was associated with HTR3B (HR=1.97; 95% CI: 1.45-2.68) (p<0.0001). These data provide evidence for multiple genetic loci contributing to smoking cessation and therapeutic response. Different loci are associated with varenicline vs bupropion response, suggesting that additional research may identify clinically useful markers to guide treatment decisions.

SUBMITTER: King DP

PROVIDER: S-EPMC3260990 | biostudies-literature | 2012 Feb

REPOSITORIES: biostudies-literature

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Smoking cessation pharmacogenetics: analysis of varenicline and bupropion in placebo-controlled clinical trials.

King David P DP Paciga Sara S Pickering Eve E Benowitz Neal L NL Bierut Laura J LJ Conti David V DV Kaprio Jaakko J Lerman Caryn C Park Peter W PW

Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology 20111102 3

Despite effective therapies for smoking cessation, most smokers find quitting difficult and most successful quitters relapse. Considerable evidence supports a genetic risk for nicotine dependence; however, less is known about the pharmacogenetics of smoking cessation. In the first pharmacogenetic investigation of the efficacy of varenicline and bupropion, we examined whether genes important in the pharmacodynamics and pharmacokinetics of these drugs and nicotine predict medication efficacy and a ...[more]

PMID: 22048466

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Project description:BackgroundAlthough a relatively small proportion of women who become pregnant continue to smoke cigarettes, no smoking cessation medication has been shown to be effective for this subgroup of smokers. Bupropion, a nonnicotine-based medication, is approved for the promotion of smoking cessation in nonpregnant individuals. We chose to study it in pregnant smokers because, although pregnancy increases nicotine metabolism, it does not affect the metabolism of bupropion.ObjectiveWe evaluated the efficacy and safety of sustained-release bupropion for smoking cessation among pregnant women.Study designWe conducted a multiple site, placebo-controlled, randomized clinical trial of bupropion for tobacco use among pregnant women (N=129) (clinical trial number NCT02188459). We enrolled women during the second trimester and randomly assigned them to receive 10 weeks of treatment with either bupropion or placebo, accompanied by a total of 6 smoking cessation counseling sessions (4 during treatment and 2 postpartum). The primary outcome was 7-day point prevalence smoking abstinence, confirmed with breath carbon monoxide measurements, at the end of treatment (week 10) and at week 24. Group differences were assessed as a binary abstinence outcome using a repeated measure generalized estimating equations model with a logit link. Prolonged abstinence and smoking rates were secondary outcomes. Safety measures included maternal treatment-related adverse events, gestational age, the rate of overall and spontaneous preterm births and infant birthweight and size for gestational age, head circumference, and 5-minute Apgar scores.ResultsThere were no significant differences in the safety measures across the treatment arms and bupropion was not efficacious in promoting smoking cessation at the end of treatment (7-day point prevalence quit rates: bupropion, 11.0%; placebo, 18.5%) or week 24 (7-day point prevalence quit rates: bupropion, 9.4%; placebo, 21.5%) (P>.05). African American women and women with a lower severity of nicotine dependence had significantly higher quit rates overall and women with an opioid use disorder who were being treated with opioid agonist therapy had significantly lower quit rates overall, irrespective of the treatment group (all P values <.05).ConclusionAlthough bupropion use was not associated with an elevated risk for pregnancy complications when initiated in the second trimester, it did not increase the likelihood of smoking cessation in this cohort of pregnant women. Because smoking is the major preventable source of poor pregnancy outcomes and psychosocial interventions have only modest beneficial effects, additional studies are needed to identify safe and efficacious smoking cessation medications for pregnant women who continue to smoke.

Project description:Background and aimsDespite the availability of several efficacious smoking cessation treatments, fewer than 25% of smokers who quit remain abstinent 1 year post-treatment. This study aimed to determine if varenicline and bupropion combination treatment would result in higher abstinence rates than varenicline alone.DesignA double-blind, randomized, parallel-group smoking cessation clinical trial in which participants were exposed to 12 weeks of treatment and followed for 12 months.SettingHospital-based out-patient clinic in Texas, USA specializing in cancer prevention.ParticipantsA total of 385 community smokers (58.44% male) who smoked 1 pack of cigarettes/day [mean = 19.66 cigarettes/day, standard deviation (SD) = 9.45]; had average carbon monoxide (CO) of 26.43 parts per million (SD = 13.74); and were moderately dependent (Fagerström Test for Cigarette Dependence = 4.79; SD = 2.07).Interventions and comparatorSmokers were randomized in a 3 : 1 (active: Placebo) ratio to 12 weeks of treatment as follows: placebo (n = 56), varenicline (Var; n = 166), and varenicline + bupropion (Combo; n = 163).MeasurementsA priori primary outcome: prolonged abstinence at 12 months.Secondary outcomes7-day point prevalence abstinence and continuous abstinence; all abstinence measures at end of treatment and 6-month follow-ups.FindingsIntention-to-treat analysis: the Combo group (n = 163) failed to demonstrate superiority to the Var group (n = 166) for prolonged abstinence at 12 months [odds ratio (OR) = 0.91, 95% confidence interval (CI) = 0.50-1.64], supported by Bayes factor = 0.06. Both the Var (OR = 6.66, 95% CI = 1.61-59.27) and Combo groups (OR = 6.06, 95% CI = 1.45-54.09) demonstrated superiority to the Placebo group (n = 56; score = 8.38, P < 0.016).ConclusionsThe addition of bupropion to varenicline treatment does not appear to increase smoking abstinence rates above that of varenicline alone. The findings support previous research showing a consistently favorable effect of both varenicline and the combination of varenicline and bupropion on smoking cessation compared with placebo.

Project description:This study replicated and extended results of a previous trial, which found that combination varenicline/bupropion treatment increased smoking abstinence in smokers who were male, highly dependent, and who did not respond to prequit nicotine patch treatment with a >50% reduction in expired-air carbon monoxide in the first week.One hundred and twenty-two male nicotine patch nonresponders and 52 responders were identified. Smokers in each group were randomized to receive 12 weeks of varenicline plus bupropion treatment versus varenicline plus placebo. The primary outcome was continuous smoking abstinence at weeks 8-11 after the target quit date.For smokers with a high level of dependence, judged by having a baseline Fagerstrom Test for Nicotine Dependence (FTND) score ? 6 and cigarette consumption ? 20/d, combination varenicline/bupropion treatment increased the abstinence rate relative to varenicline alone: 71.0% versus 43.8% (odds ratio = 3.14; 95% confidence interval = 1.11-8.92, p [one tailed] = .016). In contrast, less dependent smokers did not show a benefit of combination treatment relative to varenicline (abstinence rates of 32.1% vs. 45.6%, respectively); there was a significant interaction of treatment and dependence level. Patch nonresponders tended to benefit the most from combination treatment, which was well tolerated overall.Combination varenicline/bupropion treatment proved significantly more efficacious than varenicline alone among highly dependent male smokers. These results, together with prior studies, support an adaptive treatment paradigm that assigns smoking cessation treatment according to baseline smoker characteristics and initial response to nicotine patch treatment.This study replicated, in a prospective manner, an important and surprising retrospective finding from a previous clinical trial, which showed that a specific subpopulation of smokers benefited substantially from receiving a combination treatment of varenicline plus bupropion, relative to varenicline plus placebo. Specifically, male smokers having high baseline nicotine dependence (FTND score ? 6 and cigarette consumption ? 20/d), showed a marked increase in smoking abstinence rate on combination pharmacotherapy. The present study likewise found an enhancement in end-of-treatment abstinence rate in this subgroup, from 43.8% to 71.0%. The adaptive treatment paradigm, which classifies smokers based on initial dependence level and response to prequit nicotine patch treatment, may be used to identify target populations of smokers whose success can be enhanced by intervening with combination pharmacotherapy before the quit-smoking date.ClinicalTrials.gov identifier: NCT01806779.

Project description:BACKGROUND:Varenicline and bupropion are efficacious, prescription-only pharmacotherapies for smoking cessation; however, their real-world impact is limited by prescriber knowledge, affordability, and accessibility. OBJECTIVE:The primary objective of the MATCH (Medication Aids for Tobacco Cessation Health) study was to evaluate the real-world, long-term effectiveness of mailed bupropion and varenicline in a sample of interested smokers with the utilization of Web-based recruitment and follow-up. In addition, the study aims to investigate the genotypic and phenotypic predictors of cessation. METHODS:This is a two-group, parallel block, randomized (1:1) open-label clinical trial. This study will be conducted online with the baseline enrollment through the study's website and follow-up by emails. In addition, medication prescriptions will be filled by the study contract pharmacy and couriered to participants. Individuals who smoke ?10 cigarettes per day and intend to quit within the next 30 days will be recruited through Public Health Units and Tobacco Control Area Networks throughout Ontario by word-of-mouth and the internet. Eligible participants will receive an email with a prescription for 12-week assigned medication and a letter to take to their physician. The recruitment and randomization will continue until 500 participants per arm have received medication. All participants will receive weekly motivational emails during the treatment phase. The primary outcome measure is the smoking status after 6 months, biochemically confirmed by mailed-in salivary cotinine. Follow-ups will be conducted through emails after 4, 8, 12, 26, and 52 weeks of starting the treatment to assess the smoking prevalence and continuous smoking abstinence. In addition, mailed-in saliva samples will be used for genetic and nicotine metabolism analyses. Furthermore, personality characteristics will be assessed using the Big Five Aspect Scales. RESULTS:The project was funded in 2014 and enrollment was completed in January 2017. Data analysis is currently underway. CONCLUSIONS:To the best of our knowledge, this is the first randomized controlled trial to mass distribute prescription medications for smoking cessation. We expect this method to be logistically feasible and cost effective with quit outcomes that are comparable to published clinical trials. TRIAL REGISTRATION:ClinicalTrials.gov NCT02146911; https://clinicaltrials.gov/ct2/show/NCT02146911 (Archived by WebCite at http://www.webcitation.org/72CZ6AvXZ). REGISTERED REPORT IDENTIFIER:RR1-10.2196/10826.

Dataset Information

Smoking cessation pharmacogenetics: analysis of varenicline and bupropion in placebo-controlled clinical trials.

Publications

Smoking cessation pharmacogenetics: analysis of varenicline and bupropion in placebo-controlled clinical trials.

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