Project description:INTRODUCTION:Pharmacogenomic studies have used genetic variants to identify smokers likely to respond to pharmacological treatments for smoking cessation. METHODS:We performed a systematic review and meta-analysis of primary and secondary analyses of trials of smoking cessation pharmacotherapies. Eligible were trials with data on a priori selected single nucleotide polymorphisms, replicated non-single nucleotide polymorphisms, and/or the nicotine metabolite ratio. We estimated the genotype × treatment interaction as the ratio of risk ratios (RRR) for treatment effects across genotype groups. RESULTS:We identified 18 trials (N = 9017 participants), including 40 active (bupropion, nicotine replacement therapy [NRT], varenicline, or combination therapies) versus placebo comparisons and 16 active versus active comparisons. There was statistical evidence of heterogeneity across rs16969968 genotypes in CHRNA5 with regard to both 6-month abstinence and end-of-treatment abstinence in non-Hispanic black smokers and end-of-treatment abstinence in non-Hispanic white smokers. There was also heterogeneity across rs1051730 genotypes in CHRNA3 with regard to end-of-treatment abstinence in non-Hispanic white smokers. There was no clear statistical evidence for other genotype-by-treatment combinations. Compared with placebo, NRT was more effective among non-Hispanic black smokers with rs16969968-GG with regard to both 6-month abstinence (RRR for GG vs. GA or AA, 3.51; 95% confidence interval [CI] = 1.19 to 10.30) and end-of-treatment abstinence (RRR for GG vs. GA or AA, 5.84; 95% CI = 1.89 to 18.10). Among non-Hispanic white smokers, NRT effectiveness relative to placebo was comparable across rs1051730 and rs169969960 genotypes. CONCLUSIONS:We did not identify widespread differential effects of smoking cessation pharmacotherapies based on genotype. The quality of the evidence is generally moderate. IMPLICATIONS:Although we identified some evidence of genotype × treatment interactions, the vast majority of analyses did not provide evidence of differential treatment response by genotype. Where we find some evidence, these results should be considered preliminary and interpreted with caution because of the small number of contributing trials per genotype comparison, the wide confidence intervals, and the moderate quality of evidence. Prospective trials and individual-patient data meta-analyses accounting for heterogeneity of treatment effects through modeling are needed to assess the clinical utility of genetically informed biomarkers to guide pharmacotherapy choice for smoking cessation.
Project description:BACKGROUND AND AIMS:Evidence suggests that both the nicotinic receptor ?5 subunit (CHRNA5) and Cytochrome P450 2A6 (CYP2A6) genotypes influence smoking cessation success and response to pharmacotherapy. We examine the effect of CYP2A6 genotype on smoking cessation success and response to cessation pharmacotherapy, and combine these effects with those of CHRNA5 genotypes. DESIGN:Placebo-controlled randomized smoking cessation trial. SETTING:Ambulatory care facility in Wisconsin, USA. PARTICIPANTS:Smokers (n?=?709) of European ancestry were randomized to placebo, bupropion, nicotine replacement therapy or combined bupropion and nicotine replacement therapy. MEASUREMENTS:Survival analysis was used to model time to relapse using nicotine metabolism derived from CYP2A6 genotype-based estimates. Slow metabolism is defined as the lowest quartile of estimated metabolic function. FINDINGS:CYP2A6-defined nicotine metabolic function moderated the effect of smoking cessation pharmacotherapy on smoking relapse over 90 days [hazard ratio (HR)?=?2.81, 95% confidence interval (CI)?=?1.32-5.99, P?=?0.0075], with pharmacotherapy significantly slowing relapse in fast (HR?=?0.39, 95% CI?=?0.28-0.55, P?=?1.97?×?10(-8)), but not slow metabolizers (HR?=?1.09, 95% CI?=?0.55-2.17, P?=?0.80). Further, only the effect of nicotine replacement, and not bupropion, varies with CYP2A6-defined metabolic function. The effect of nicotine replacement on continuous abstinence is moderated by the combined genetic risks from CYP2A6 and CHRNA5 (Wald?=?7.44, d.f.?=?1, P?=?0.0064). CONCLUSIONS:Nicotine replacement therapy is effective among individuals with fast, but not slow, CYP2A6-defined nicotine metabolism. The effect of bupropion on relapse likelihood is unlikely to be affected by nicotine metabolism as estimated from CYP2A6 genotype. The variation in treatment responses among smokers with genes may guide future personalized smoking cessation interventions.
Project description:One way to enhance therapeutic development is through the identification and development of evaluative tools such as biomarkers. This review focuses on putative diagnostic, pharmacodynamic, and predictive biomarkers for smoking cessation. These types of biomarkers may be used to more accurately diagnose a disease, personalize treatment, identify novel targets for drug discovery, and enhance the efficiency of drug development. Promising biomarkers are presented across a range of approaches including metabolism, genetics, and neuroimaging. A preclinical viewpoint is also offered, as are analytical considerations and a regulatory perspective summarizing a pathway toward biomarker qualification.
Project description:Strategies for assisting smoking cessation include behavioural counselling to enhance motivation and to support attempts to quit and pharmacological intervention to reduce nicotine reinforcement and withdrawal from nicotine. Three drugs are currently used as first line pharmacotherapy for smoking cessation, nicotine replacement therapy, bupropion and varenicline. Compared with placebo, the drug effect varies from 2.27 (95% CI 2.02, 2.55) for varenicline, 1.69 (95% CI 1.53, 1.85) for bupropion and 1.60 (95% CI 1.53, 1.68) for any form of nicotine replacement therapy. Despite some controversy regarding the safety of bupropion and varenicline, regulatory agencies consider these drugs as having a favourable benefit/risk profile. However, given the high rate of psychiatric comorbidity in dependent smokers, practitioners should closely monitor patients for neuropsychiatric symptoms. Second-line pharmacotherapies include nortriptyline and clonidine. This review also offers an overview of pipeline developments and issues related to smoking cessation in special populations such as persons with psychiatric comorbidity and pregnant and adolescent smokers.
Project description:Introduction: Rates of tobacco smoking are high in people with schizophrenia with greater difficulty of quitting smoking compared to the general population, which also relate to the increased cardiovascular and cancer risks in this co-occurring disorder. Therefore, effective smoking cessation pharmacotherapies addressing tobacco co-morbidity are imperative.Areas covered: In this review, the authors performed an extensive systematic electronic literature review examining the efficacy and safety of first-line pharmacotherapies for smoking cessation, including varenicline, sustained-release bupropion, and nicotine replacement therapies (NRT) using continuous abstinence rates over 10-12-week periods in smokers with schizophrenia. Twelve trials reporting smoking cessation outcomes using interventions in schizophrenia were included and risk ratio (RR) was used.Expert opinion: Our findings support the efficacy and safety of first-line pharmacotherapies for the treatment of tobacco use disorder in smokers with schizophrenia. Further research on the long-term effectiveness and safety of these agents in community samples is warranted. Smoking cessation pharmacotherapies may warrant the consideration of the emerging use of electronic nicotine delivery systems while neuromodulation techniques also offer promise.
Project description:Cigarette smoking has been associated with epigenetic alterations that may be reversible upon cessation. As the most-studied epigenetic modification, DNA methylation is strongly associated with smoking exposure, providing a potential mechanism that links smoking to adverse health outcomes. Here, we reviewed the reversibility of DNA methylation in accessible peripheral tissues, mainly blood, in relation to cigarette smoking cessation and the utility of DNA methylation as a biomarker signature to differentiate current, former, and never smokers and to quantify time since cessation. We summarized thousands of differentially methylated Cytosine-Guanine (CpG) dinucleotides and regions associated with smoking cessation from candidate gene and epigenome-wide association studies, as well as the prediction accuracy of the multi-CpG predictors for smoking status. Overall, there is robust evidence for DNA methylation signature of cigarette smoking cessation. However, there are still gaps to fill, including (1) cell-type heterogeneity in measuring blood DNA methylation; (2) underrepresentation of non-European ancestry populations; (3) limited longitudinal data to quantitatively measure DNA methylation after smoking cessation over time; and (4) limited data to study the impact of smoking cessation on other epigenetic features, noncoding RNAs, and histone modifications. Epigenetic machinery provides promising biomarkers that can improve success in smoking cessation in the clinical setting. To achieve this goal, larger and more-diverse samples with longitudinal measures of a broader spectrum of epigenetic marks will be essential to developing a robust DNA methylation biomarker assay, followed by meeting validation requirements for the assay before being implemented as a clinically useful tool.
Project description:Combination pharmacotherapy for smoking cessation has been shown to be more effective than monotherapy in meta-analyses. We address the question of whether combination pharmacotherapy should be used routinely with smokers or if some types of smokers show little or no benefit from combination pharmacotherapy versus monotherapy.Two smoking cessation trials were conducted using the same assessments and medications (bupropion, nicotine lozenge, nicotine patch, bupropion + lozenge, and patch + lozenge). Participants were smokers presenting either to primary care clinics in southeastern Wisconsin for medical treatment (Effectiveness trial, N = 1,346) or volunteering for smoking cessation treatment at smoking cessation clinics in Madison and Milwaukee, WI (Efficacy trial, N = 1,504). For each trial, decision tree analyses identified variables predicting outcome from combination pharmacotherapy versus monotherapy at the end of treatment (smoking 8 weeks after the target quit day).All smokers tended to benefit from combination pharmacotherapy except those low in nicotine dependence (longer latency to smoke in the morning as per item 1 of the Fagerström Test of Nicotine Dependence) who also lived with a spouse or partner who smoked.Combination pharmacotherapy was generally more effective than monotherapy among smokers, but one group of smokers, those who were low in nicotine dependence and who lived with a smoking spouse, did not show greater benefit from using combination pharmacotherapy. Use of monotherapy with these smokers might be justified considering the expense and side effects of combination pharmacotherapy.
Project description:Data regarding the efficacy and safety of smoking-cessation pharmacotherapy after stroke are lacking. We systematically reviewed data on this topic by searching Medline, Cochrane, and Clinicaltrials.gov to identify randomized clinical trials (RCT) and observational studies that assessed the efficacy and safety of nicotine replacement therapy (NRT), varenicline, and bupropion in patients with stroke and TIA. We included studies that reported rates of smoking cessation, worsening or recurrent cerebrovascular disease, seizures, or neuropsychiatric events. We identified 2 RCTs and 6 observational studies; 3 included ischemic stroke and TIA, 2 subarachnoid hemorrhage (SAH), and 3 did not specify. Four studies assessed efficacy; cessation rates ranged from 33% to 66% with pharmacological therapy combined with behavioral interventions versus 15% to 46% without, but no individual study demonstrated a statistically significant benefit. Safety data for varenicline and buopropion in ischemic stroke were scarce. Patients with SAH who received NRT had more seizures (9% vs 2%; P = 0.024) and delirium (19% vs 7%; P = 0.006) in one study, but less frequent vasospasm in 3 studies. In conclusion, combined with behavioral interventions, smoking-cessation therapies resulted in numerically higher cessation rates. Limited safety data may prompt caution regarding seizures and delirium in patients with subarachnoid hemorrhage.
Project description:IntroductionConverging clinical and biological evidence suggest sex is an important factor when selecting a pharmacological intervention for smoking cessation. The current investigation used network meta-analyses to estimate sex differences in the comparative efficacy of transdermal nicotine (TN), varenicline, and sustained release (SR) bupropion for smoking cessation.MethodsSystematically searched previously published reviews and databases (Medline, PsycINFO, Embase) of randomized, double-blind, placebo-controlled trials of bupropion-SR, TN, and varenicline for cigarette smoking cessation in primary care/general community samples were included.ResultsThirty-two studies met all criteria and 28 (88%) were included in the final analyses, representing 14 389 smokers (51% female). Results of the full sample (women and men combined) mirrored those from a Cochrane Tobacco Addiction Group network meta-analysis of smoking cessation pharmacotherapy, showing VAR>TN=BUP. All medications improved quit rates over placebo for both women and men. Relative to placebo, varenicline efficacy was similar for women and men. Significant sex differences were evident when comparing varenicline versus TN and varenicline versus bupropion. For women, varenicline was more efficacious than TN (RR = 1.41; 95% CI = 1.12,1.76) and bupropion (RR = 1.38; 95% CI = 1.08,1.77). For men, outcomes for those treated with TN and bupropion were similar to those treated with varenicline. There were no differences in efficacy when comparing bupropion versus TN.ConclusionsThe advantage of varenicline over bupropion SR and TN is greater for women than men. Clinicians should strongly consider varenicline as the first option treatment for women. Among men, the advantage of varenicline over TN or bupropion is less clear.ImplicationsThis study provides information for the sex-informed treatment of nicotine addiction among cigarette smokers. Relative to placebo, women and men achieved similar outcomes when treated with varenicline; however the advantages of varenicline over transdermal patch and bupropion were greater for women compared to men.