Profile of the Nicotinic Cholinergic Receptor Alpha 7 Subunit Gene Expression is Associated with Response to Varenicline Treatment.

INTRODUCTION: Smoking is considered the leading cause of preventable morbidity and mortality worldwide. Studies have sought to identify predictors of response to smoking cessation treatments. The aim of this study was to analyze a possible association of target gene expression for smoking cessation with varenicline. METHODS: We included 74 smokers starting treatment with varenicline. Gene expression analysis was performed through the custom RT² Profiler qPCR array assay, including 17 genes. Times for sample collection were before the start of therapy (T0) and two weeks (T2) and four weeks (T4) after the start of treatment. RESULTS: For gene expression analysis, we selected 14 patients who had success and 13 patients resistant to varenicline treatment. Success was considered to be when a patient achieved tobacco abstinence until the fourth week of treatment and resistant was when a patient had not stopped smoking as of the fourth week of treatment. We observed a significant difference for CHRNA7 gene expression: in the resistant group, samples from T2 and T4 had lower expression compared with T0 (fold change: 0.38, P = 0.007; fold change: 0.67, P = 0.004; respectively). CONCLUSION: This exploratory clinical study, searching for a possible predictor of effectiveness for varenicline, reaffirmed the association of the α7 nAChR subunit for nicotine dependence and smoking therapy effectiveness with varenicline.

The Novel CYP2A6 Inhibitor, DLCI-1, Decreases Nicotine Self-Administration in Mice.

During tobacco and e-cigarette use, nicotine is mainly metabolized in the human liver by cytochrome P450 2A6 (CYP2A6). Given that a slower CYP2A6 metabolism has been associated with less vulnerability to develop nicotine dependence, the current studies sought to validate a novel CYP2A6 inhibitor, (5-(4-ethylpyridin-3-yl)thiophen-2-yl)methanamine (DLCI-1), for its effects on intravenous nicotine self-administration. Male and female mice were trained to self-administer nicotine across daily sessions. Once stable responding was achieved, DLCI-1 or vehicle control was administered prior to nicotine sessions. We found that the lower 25 mg/kg and moderate 50 mg/kg doses of DLCI-1 induced a significant decrease in nicotine intake for both males and females. DLCI-1 was further shown to be more effective than a moderate 1 mg/kg dose of bupropion on reducing nicotine intake and did not exert the adverse behavioral effects found with a high 75 mg/kg dose of bupropion. Although mice treated with DLCI-1 self-administered significantly less nicotine, similar nicotine-mediated behavioral effects on locomotion were observed. Together, along with the analysis of nicotine metabolites during self-administration, these findings support the contention that blocking hepatic nicotine metabolism would allow for similar activation of nicotinic acetylcholine receptors at lower nicotine doses. Moreover, these effects of DLCI-1 were specific to nicotine self-administration, as DLCI-1 did not result in any behavioral changes during food self-administration. Taken together, these studies validate DLCI-1 as a novel compound to decrease nicotine consumption, which may thereby promote tobacco and nicotine product cessation. SIGNIFICANCE STATEMENT: Current pharmacological approaches for nicotine and tobacco cessation have only been able to achieve limited efficaciousness in promoting long-term abstinence. In this work, we characterize the effects of a novel compound, (5-(4-ethylpyridin-3-yl)thiophen-2-yl)methanamine (DLCI-1), which inhibits the main enzyme that metabolizes nicotine, and we report a significant decrease in intravenous nicotine self-administration in male and female mice, supporting the potential of DLCI-1 as a novel tobacco cessation pharmacotherapeutic.

Cytochrome P450 2A6 and 2B6 polymorphisms and smoking cessation success in patients treated with varenicline.

BACKGROUND: The identification of variants in genes involved in nicotine metabolism may have implications for the pharmacological therapy of smoking. In the scenario of precision medicine, the aim of this study was to evaluate a possible association of cytochrome P450 2A6 and 2B6 polymorphisms with varenicline pharmacotherapy. METHODS: The present study included 167 patients treated with varenicline in monotherapy who were from a cohort study of 1049 patients (treated with smoking cessation drugs: nicotine replacement therapy, bupropion, varenicline, or combinations of same). Smoking cessation success was considered for patients who completed 6 months of continuous abstinence. The CYP2A6 rs1801272 and rs28399433 and CYP2B6 rs8109525 polymorphisms were genotyped by real-time PCR using the TaqMan® platform. RESULTS: Patients with AG or GG genotypes for CYP2B6 rs8109525 had a higher success rate of smoking cessation with varenicline (51.2%) compared with carriers of the AA genotypes (33.3%, P = 0.03, n = 167). The AG or GG genotypes were also associated with a higher odds ratio of success, even in a multivariate analysis adjusting for potential confounders (OR = 2.01; 95%CI = 1.01 to 4.00; P = 0.047). CONCLUSION: CYP2B6 rs8109525 was associated with a higher success rate of smoking cessation with varenicline treatment. This finding may be useful in pharmacogenomic strategies for smoking cessation therapy.

"Vive Sin Tabaco ¡Decídete!" Feasibility and Acceptability of an e-Health Smoking Cessation Informed Decision-Making Tool Integrated in Primary Healthcare in Mexico.

Introduction:While smoking remains one of the leading causes of death in Mexico, uptake of evidence-based cessation therapy remains low. Widespread use of mobile devices and internet in Mexico has created new avenues for providing access to cessation treatment.Methods:We assessed the feasibility and acceptability of "Vive Sin Tabaco… ¡Decídete!" (English: Live without Tobacco…. Decide!), a web-based, informed decision-making tool designed to help Mexican smokers develop a quit plan and take advantage of cessation resources. We invited 164 smokers in two primary care clinics. Measures included physical, situational, and psychological nicotine dependence, interest in using pharmacotherapy and counseling, smoking status at 3 months, and satisfaction with the program.Results:Most participants were light smokers and reported low-to-moderate nicotine dependence. Immediately after using ¡Vive Sin Tabaco… ¡Decídete!, the majority were interested in quitting, set a quit date, and reported interest in using pharmacotherapy and cessation counseling. Follow-up rate at 3 months was 81.5%; seven-day point prevalence abstinence was 19.1% using intention-to-treat analysis.Conclusion:Integration of e-Health tools in primary healthcare settings has the potential to improve knowledge about cessation treatments among smokers and integrate smoking cessation into routine of care.

Predictors of Varenicline Adherence Among Cancer Patients Treated for Tobacco Dependence and its Association With Smoking Cessation.

INTRODUCTION: The degree to which smokers adhere to pharmacotherapy predicts treatment success. The development of interventions to increase adherence requires identification of predictors of treatment adherence, particularly among specific clinical populations. METHODS: Using data from a 12-week open-label phase of a clinical trial of varenicline for tobacco dependence among cancer patients (N = 207), we examined: (1) the relationship between self-reported varenicline adherence and verified smoking cessation and (2) demographic and disease-related variables, and early changes in cognition, affect, withdrawal, the reinforcing effects of smoking, and medication side effects, as correlates of varenicline adherence. RESULTS: At the end of 12 weeks, 35% of the sample had quit smoking and 52% reported taking ≥80% of varenicline. Varenicline adherence was associated with cessation (p < .001): 58% of participants who were adherent had quit smoking versus 11% of those who were not. Participants who experienced early reductions in depressed mood and satisfaction from smoking and experienced an increase in the toxic effects of smoking, showed greater varenicline adherence (p < .05); the relationship between greater adherence and improved cognition, reduced craving, and reduced sleep problems and vomiting approached significance (p < .10). CONCLUSIONS: Among cancer patients treated for tobacco dependence with varenicline, adherence is associated with smoking cessation. Initial changes in depressed mood and the reinforcing effects of smoking are predictive of adherence. IMPLICATIONS: The benefits of varenicline for treating tobacco dependence among cancer patients may depend upon boosting adherence by addressing early signs of depression and reducing the reinforcing dimensions of cigarettes.