Measures and predictors of varenicline adherence in the treatment of nicotine dependence

Genetic Prediction of Smoking Cessation Medication Side Effects: A Genome-Wide Investigation of Abnormal Dreams on Varenicline

Varenicline, the most efficacious smoking cessation monotherapy, produces abnormal dreams. Although genetic contributions to varenicline-associated nausea and cessation have been identified, the role of genetics in abnormal dreams is unknown. We conducted a genomewide association study (GWAS) of abnormal dreams in 188 European ancestry smokers treated with varenicline (NCT01314001). Additive genetic models examined the likelihood of experiencing abnormal dreams 2 weeks following varenicline initiation. For the top locus, we tested for selectivity to varenicline, effects on cessation, replication, and generalizability to African ancestry (AA) individuals. The top GWAS variant associated with abnormal dreams was rs901886, mapping to intron 2 of ICAM5 on chromosome 19. The prevalence of abnormal dreams in those with rs901886 CC, CT, and TT genotypes was 15%, 36%, and 62%, respectively (odds ratio = 2.94 for T vs. C, 95% confidence interval = 1.92-4.55, P = 2.03e-7; T allele frequency = 52%). This rs901886 association was selective to varenicline (P values > 0.05 on nicotine patch and placebo). There were also positive associations for rs901886 T (vs. C allele, P = 0.03) and for abnormal dreams (P = 0.06) with varenicline-aided cessation. Neither rs901886 (P = 0.40) nor abnormal dreams (P = 0.24) were associated with adherence. A similar direction of effect of rs901886 on abnormal dreams was observed in a second varenicline trial (NCT01836276). In AA individuals (n = 137), rs901886 was not associated with abnormal dreams (P = 0.41), but there was an association for a variant located ~ 74.4 kb 5' of ICAM5 (P = 2.56e-3). Variation in ICAM5 may influence abnormal dreams and cessation on varenicline. These findings provide additional support for genetically optimized smoking cessation approaches.

Relationships Between the Nicotine Metabolite Ratio and Laboratory Assessments of Smoking Reinforcement and Craving Among Adults in a Smoking Cessation Trial

INTRODUCTION

People who metabolize nicotine more quickly are generally less successful at quitting smoking. However, the mechanisms that link individual differences in the nicotine metabolite ratio (NMR), a phenotypic biomarker of the rate of nicotine clearance, to smoking outcomes are unclear. We tested the hypotheses that higher NMR is associated with greater smoking reinforcement, general craving, and cue-induced cigarette craving in a treatment-seeking sample.

METHODS

Participants were 252 adults who smoke cigarettes enrolled in a randomized controlled smoking cessation trial (NCT03262662) conducted in Buffalo, New York, USA. Participants completed the Choice Behavior Under Cued Conditions (CBUCC) paradigm, a laboratory choice procedure, ~1 week before the first cessation treatment visit, at which time a saliva sample was collected for NMR assessment. On each CBUCC trial, participants reported cigarette craving during cue presentation (cigarette, water) and spent $0.01-$0.25 for a chance (5%-95%) to sample the cue (one puff, sip), providing measures of smoking reinforcement (spending for cigarettes vs. water), general cigarette craving (averaged across cigarette and water cues), and cue-specific craving (cigarette craving during cigarette vs. water cues).

RESULTS

As observed in prior work, the NMR was significantly higher among White and female participants. As expected, both spending and cigarette craving were significantly greater on cigarette compared to water trials. However, contrary to our hypotheses, higher NMR was not associated with greater smoking reinforcement, general craving, or cue-specific craving.

CONCLUSIONS

The present data do not support that smoking reinforcement or craving is related to nicotine metabolism among individuals seeking to quit smoking.

IMPLICATIONS

Though greater smoking reinforcement, general craving, and cue-specific craving are hypothesized to be linked to faster nicotine metabolism, there was no evidence of such relationships in the present sample of adults seeking to quit smoking. Further research, including replication and consideration of alternate hypotheses, is warranted to elucidate the mechanisms by which the NMR is related to smoking cessation.

Identifying determinants of varenicline adherence using the Theoretical Domains framework: a rapid review

BACKGROUND

Adhering to varenicline has been shown to significantly improve the chances of successfully quitting smoking, with studies indicating a twofold increase in 6-month quit rates. However, despite its potential benefits, many individuals struggle with maintaining good adherence to varenicline; thus there is a need to develop scalable strategies to help people adhere. As a first step to inform the development of an intervention to improve adherence to varenicline, we conducted a rapid literature review to identify: 1) modifiable barriers and facilitators to varenicline adherence, and 2) behaviour change techniques associated with increased adherence to varenicline.

METHODS

We searched MEDLINE, Embase, APA PsycINFO, CINAHL, and the Cochrane Central Register of Controlled Trials for relevant studies published between 2006 and 2022. Search terms included "varenicline," "smoking cessation," and "adherence," and their respective subject headings and synonyms. We screened and included studies reporting modifiable determinants of adherence to varenicline and then assessed quality, extracted modifiable determinants and mapped them to the Theoretical Domains Framework version 2 and the Behaviour Change Technique Taxonomy version 1.

RESULTS

A total of 1,221 titles were identified through the database searches; 61 met the eligibility criteria. Most of the studies were randomized controlled trials and predominantly focused on barriers to varenicline. Only nine studies explicitly mentioned behaviour change techniques used to help varenicline adherence. Eight domains were identified as barriers to varenicline adherence (behavioural regulation, memory, goals, intentions, beliefs about capabilities, beliefs about consequences, optimism/pessimism, and environmental context) and five as facilitators (knowledge, behavioural regulation, beliefs about capabilities, social influences, and environmental context).

CONCLUSIONS

This study identifies barriers and facilitators that should be addressed when developing a complex adherence intervention tailored to patients' needs based on modifiable determinants of medication adherence, some of which are under- used by existing adherence interventions. The findings from this review will inform the design of a theory-based healthbot planned to improve varenicline adherence in people undergoing smoking cessation treatment.

SYSTEMATIC REVIEW REGISTRATION

This study was registered with PROSPERO (# CRD42022321838).

AI Conversational Agent to Improve Varenicline Adherence: Protocol for a Mixed Methods Feasibility Study

BACKGROUND

Varenicline is a pharmacological intervention for tobacco dependence that is safe and effective in facilitating smoking cessation. Enhanced adherence to varenicline augments the probability of prolonged smoking abstinence. However, research has shown that one-third of people who use varenicline are nonadherent by the second week. There is evidence showing that behavioral support helps with medication adherence. We have designed an artificial intelligence (AI) conversational agent or health bot, called "ChatV," based on evidence of what works as well as what varenicline is, that can provide these supports. ChatV is an evidence-based, patient- and health care provider-informed health bot to improve adherence to varenicline. ChatV has been programmed to provide medication reminders, answer questions about varenicline and smoking cessation, and track medication intake and the number of cigarettes.

OBJECTIVE

This study aims to explore the feasibility of the ChatV health bot, to examine if it is used as intended, and to determine the appropriateness of proceeding with a randomized controlled trial.

METHODS

We will conduct a mixed methods feasibility study where we will pilot-test ChatV with 40 participants. Participants will be provided with a standard 12-week varenicline regimen and access to ChatV. Passive data collection will include adoption measures (how often participants use the chatbot, what features they used, when did they use it, etc). In addition, participants will complete questionnaires (at 1, 4, 8, and 12 weeks) assessing self-reported smoking status and varenicline adherence, as well as questions regarding the acceptability, appropriateness, and usability of the chatbot, and participate in an interview assessing acceptability, appropriateness, fidelity, and adoption. We will use "stop, amend, and go" progression criteria for pilot studies to decide if a randomized controlled trial is a reasonable next step and what modifications are required. A health equity lens will be adopted during participant recruitment and data analysis to understand and address the differences in uptake and use of this digital health solution among diverse sociodemographic groups. The taxonomy of implementation outcomes will be used to assess feasibility, that is, acceptability, appropriateness, fidelity, adoption, and usability. In addition, medication adherence and smoking cessation will be measured to assess the preliminary treatment effect. Interview data will be analyzed using the framework analysis method.

RESULTS

Participant enrollment for the study will begin in January 2024.

CONCLUSIONS

By using predetermined progression criteria, the results of this preliminary study will inform the determination of whether to advance toward a larger randomized controlled trial to test the effectiveness of the health bot. Additionally, this study will explore the acceptability, appropriateness, fidelity, adoption, and usability of the health bot. These insights will be instrumental in refining the intervention and the health bot.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05997901; https://classic.clinicaltrials.gov/ct2/show/NCT05997901.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

PRR1-10.2196/53556.

Pairwise comparisons of three medication adherence outcomes in adolescents who use alcohol

BACKGROUND

Accurate assessment of medication adherence is important for understanding pharmacotherapy outcomes across all phases of adolescent substance use disorder (SUD) clinical trials. The objective of this study was to describe and assess the pairwise concordance between three commonly used non-biological medication adherence assessment methods in adolescents who use alcohol to inform the selection of medication adherence measures for use in future youth SUD trials.

METHODS

Participants (N = 32, 17-19-years-old) took N-acetylcysteine and placebo, in a randomized cross-over design, for 10 days each. Medication adherence was assessed (20 days total) via pill count, medication videos submitted twice daily, and the Medication Event Monitoring System (MEMS®). Lin's Concordance Correlation Coefficient (CCC) assessed concordance and Bland-Altman plots are reported. Linear mixed-effects models with main effects of medication, treatment block (first medication, second medication), and sequence were also run.

RESULTS

Medication videos yielded the lowest (64%) and pill count yielded the highest (89%) adherence estimates. CCC values indicated poor correspondence, except between pill count and MEMS. The Bland-Altman plots showed good pairwise agreement between all methods. Linear mixed-effects models indicated a difference between the first and second cross-over medication, with adherence estimates being lower for the second medication, regardless of whether it was N-acetylcysteine or placebo.

CONCLUSIONS

The study yielded important and practical information. First, incorporating more than one method of adherence assessment may capture estimated floor and ceiling adherence in the absence of a biological marker. This is particularly relevant for remote or hybrid studies where bio-marker collection is challenging. Selection of the assessment methods will depend on study goals. Second, the continuation of medication adherence research can benefit each phase of clinical trials and inform rigorous pharmacotherapy evaluation.

Efficacy of insula deep repetitive transcranial magnetic stimulation combined with varenicline for smoking cessation: A randomized, double-blind, sham controlled trial

BACKGROUND

Current smoking cessation treatments are limited in terms of efficacy, particularly with regards to long term abstinence. There is a large amount of evidence implicating the insula in nicotine addiction.

OBJECTIVE

To examine the efficacy of bilateral repetitive transcranial magnetic stimulation (rTMS) directed to the insular cortex with the H11 coil, relative to sham stimulation, on smoking abstinence and smoking outcomes in smokers who are receiving standard varenicline treatment.

METHODS

This randomized, double-blind, sham controlled trial recruited 42 participants who were randomized to receive either active (n = 24) or sham (n = 18) high frequency rTMS directed to the insula (4 weeks), while receiving varenicline treatment (12 weeks). The primary outcome was 7-day point prevalence abstinence at the end of 12 weeks.

RESULTS

Smokers in the active group had significantly higher abstinence rates than those in the sham group (82.4% vs. 30.7%, p = 0.013) at the end of treatment (Week 12). Secondary outcome measures of abstinence rate at the end of rTMS treatment (Week 4), abstinence rate at 6 months, and smoking outcomes (e.g., craving, withdrawal) showed no significant differences between groups. No differences were found in adverse events reported between the groups.

CONCLUSION

This study provides evidence of the potential benefit of having a combined treatment for smoking cessation using insula rTMS with the H11 coil and varenicline. Maintenance rTMS sessions and continuation of varenicline for those in abstinence may induce longer-term effects and should be considered in future studies.

Can Treatment Support Mitigate Nicotine Metabolism-Based Disparities in Smoking Abstinence? Secondary Analysis of the Helping HAND 4 Trial

INTRODUCTION

The nicotine metabolite ratio (NMR), a biomarker of CYP2A6-mediated nicotine metabolism, predicts the efficacy of nicotine replacement therapy (NRT), with fast metabolizers benefiting less than slow metabolizers. Whether treatment support to optimize NRT use (henceforth "treatment support") modifies this pharmacogenetic relationship is unknown.

METHODS

Hospitalized adult daily smokers were assigned to one of two post-discharge smoking cessation interventions offering NRT and counseling: (1) Transitional Tobacco Care Management, which delivered enhanced treatment support via free combination NRT at discharge and automated counseling, and (2) a quitline-based approach representing usual care (UC). The primary outcome was biochemically verified 7-day point prevalence abstinence 6 months after discharge. Secondary outcomes were the use of NRT and counseling during the 3-month intervention period. Logistic regression models tested for interactions between NMR and intervention, controlling for sex, race, alcohol use, and BMI.

RESULTS

Participants (N = 321) were classified as slow (n = 80) or fast (n = 241) metabolizers relative to the first quartile of NMR (0.012-0.219 vs. 0.221-3.455, respectively). Under UC, fast (vs. slow) metabolizers had lower odds of abstinence at 6 months (aOR 0.35, 95% CI 0.13-0.95) and similar odds of NRT and counseling use. Compared to UC, enhanced treatment support increased abstinence (aOR 2.13, 95% CI 0.98-4.64) and use of combination NRT (aOR 4.62, 95% CI 2.57-8.31) in fast metabolizers, while reducing abstinence in slow metabolizers (aOR 0.21, 95% CI 0.05-0.87; NMR-by-intervention interaction p = .004).

CONCLUSIONS

Treatment support increased abstinence and optimal use of NRT among fast nicotine metabolizers, thereby mitigating the gap in abstinence between fast and slow metabolizers.

IMPLICATIONS

In this secondary analysis of two smoking cessation interventions for recently hospitalized smokers, fast nicotine metabolizers quit at lower rates than slow metabolizers, but providing fast metabolizers with enhanced treatment support doubled the odds of quitting in this group and mitigated the disparity in abstinence between fast and slow metabolizers. If validated, these findings could lead to personalized approaches to smoking cessation treatment that improve outcomes by targeting treatment support to those who need it most.

Treatment adherence in a smoking cessation clinical trial for individuals with current or past major depressive disorder: Predictors and association with cessation

INTRODUCTION

Individuals with major depressive disorder (MDD) exhibit high rates of tobacco use and lower responsiveness to tobacco cessation treatments. Treatment adherence is a strong predictor of treatment outcomes in the general population but has not been evaluated in this under-served community of smokers with MDD.

METHODS

We used data from a randomized clinical trial on smoking cessation treatment among 300 smokers with MDD to examine the rate of adherence (medication and counseling), the association of adherence with cessation outcomes, and factors associated with adherence, including demographic and smoking characteristics, psychiatric characteristics, smoking cessation processes (e.g., withdrawal, reinforcers), and treatment-related side effects (e.g., nausea).

RESULTS

Overall, 43.7% of participants were adherent with medication and 63.0% were adherent with counseling. Medication adherence was significantly associated with cessation, with 32.1% of adherent vs. 13.0% of non-adherent participants quitting smoking at EOT. Counseling adherence was also significantly associated with cessation, with 32.3% of adherent vs. 2.7% of non-adherent participants quitting smoking. Multivariate regression models showed that medication adherence was associated with higher engagement in complementary reinforcers and higher baseline smoking reward, while counseling adherence was associated with identifying as female, lower alcohol use and nicotine dependence, higher baseline smoking reward, and higher engagement in substitute and complementary reinforcers within the first weeks of medication use.

CONCLUSIONS

As with the general population of smokers, non-adherence to treatment in smokers experiencing depression is widespread and a significant barrier to cessation. Interventions that target reinforcers may improve rates of treatment adherence.

Medication Adherence in Tobacco Cessation Clinical Trials

Adherence is a critical mediator of treatment outcome across health conditions and low rates of adherence undermine success in smoking cessation treatment. This narrative review provides an overview of different techniques that can be used to measure adherence to smoking cessation treatments and outlines strategies to address treatment adherence. Techniques to measure adherence include conducting pill counts, collecting self-reports of adherence, directly observed therapy, biochemical verification methods, and electronic data collection via medication events monitoring systems. Techniques examined for increasing tobacco cessation treatment adherence include counseling, automated adherence calls, feedback from electronic monitors, contingency management and directly observed therapy. Adherence monitoring and optimization should be a standard component of smoking cessation treatment research.

Cocreation of a conversational agent to help patients adhere to their varenicline treatment: A study protocol

Objective

Varenicline is the most efficacious approved smoking cessation medication, making it one of the most cost-effective clinical interventions for reducing tobacco-related morbidity and mortality. Adhering to varenicline is strongly associated with smoking cessation. Healthbots have the potential to help people adhere to their medications by scaling up evidence-based behavioral interventions. In this protocol, we outline how we will follow the UK's Medical Research Council's guidance to codesign a theory-informed, evidence-based, and patient-centered healthbot to help people adhere to varenicline.

Methods

The study will utilize the Discover, Design and Build, and Test framework and will include three phases: (a) a rapid review and interviews with 20 patients and 20 healthcare providers to understand barriers and facilitators to varenicline adherence (Discover phase); (b) Wizard of Oz test to design the healthbot and get a sense of the questions that chatbot has to be able to answer (Design phase); and (c) building, training, and beta-testing the healthbot (Building and Testing phases) where the Nonadoption, Abandonment, Scale-up, Spread, and Sustainability framework will be used to develop the healthbot using the simplest sensible solution, and 20 participants will beta test the healthbot. We will use the Capability, Opportunity, Motivation-Behavior (COM-B) model of behavior change and its associated framework, the Theoretical Domains Framework, to organize the findings.

Conclusions

The present approach will enable us to systematically identify the most appropriate features for the healthbot based on a well-established behavioral theory, the latest scientific evidence, and end users' and healthcare providers' knowledge.

Effect of Extending the Duration of Prequit Treatment With Varenicline on Smoking Abstinence: A Randomized Clinical Trial

IMPORTANCE

Even with varenicline, the leading monotherapy for tobacco dependence, smoking abstinence rates remain low. Preliminary evidence suggests that extending the duration of varenicline treatment before quitting may increase abstinence.

OBJECTIVE

To test the hypotheses that, compared with standard run-in varenicline treatment (1 week before quitting), extended run-in varenicline treatment (4 weeks before quitting) reduces smoking exposure before the target quit date (TQD) and enhances abstinence, particularly among women.

DESIGN, SETTING, AND PARTICIPANTS

This double-blind, randomized, placebo-controlled clinical trial enrolled participants from October 2, 2017, to December 9, 2020, at a single-site research clinic in Buffalo, New York. Of 1385 people screened, 320 adults reporting smoking 5 or more cigarettes per day (CPD) were randomized and followed up for 28 weeks. Data were analyzed from August 2021 to June 2022.

INTERVENTIONS

In the pre-TQD period (weeks 1-4), the extended run-in group received 4 weeks of varenicline; the standard run-in group received 3 weeks of placebo followed by 1 week of varenicline. Both groups received open-label varenicline during weeks 5 to 15 and brief quit counseling at 6 clinic visits.

MAIN OUTCOMES AND MEASURES

The primary outcome consisted of cotinine-verified (at end of treatment [EOT]) self-reported continuous abstinence from smoking (in CPD) during the last 4 weeks of treatment. Secondary outcomes included bioverified self-report of continuous abstinence at the 6-month follow-up and percentage of reduction in self-reported smoking rate during the prequit period (week 1 vs week 4).

RESULTS

A total of 320 participants were randomized, including 179 women (55.9%) and 141 men (44.1%), with a mean (SD) age of 53.7 (10.1) years. Continuous abstinence during the final 4 weeks of treatment (weeks 12-15; EOT) was not greater in the extended run-in group (64 of 163 [39.3%]) compared with the standard run-in group (57 of 157 [36.3%]; odds ratio [OR], 1.13 [95% CI, 0.72-1.78]), nor was the hypothesized group × sex interaction significant (OR, 0.52 [95% CI, 0.21-1.28]). Similar nonsignificant results were obtained for continuous abstinence at the 6-month follow-up. The mean (SE) decrease in self-reported smoking rate during the prequit period was greater in the extended run-in group (-38.8% [2.8%]) compared with the standard run-in group (-17.5% [2.7%]).

CONCLUSIONS AND RELEVANCE

Among adult daily smokers, extending the duration of prequit varenicline treatment beyond the standard 1-week run-in period reduced prequit smoking exposure but, more importantly, did not significantly improve continuous abstinence rates.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03262662.

Does sex alter the relationship between CYP2B6 variation, hydroxybupropion concentration and bupropion-aided smoking cessation in African Americans? A moderated mediation analysis

BACKGROUND AND AIMS

CYP2B6, a genetically variable enzyme, converts bupropion to its active metabolite hydroxybupropion. CYP2B6 activity and bupropion-aided cessation differ between women and men. The aim of this study was to determine whether genetically normal (versus reduced) CYP2B6 activity increases bupropion-aided cessation in African American smokers via higher hydroxybupropion concentration, and whether this differs by sex.

DESIGN AND SETTING

Secondary analysis of a smoking cessation clinical trial (NCT00666978).

PARTICIPANTS/CASES

African American light smokers (≤ 10 cigarettes/day).

INTERVENTIONS

Participants were treated with bupropion for 7 weeks.

MEASUREMENTS

Participants with detectable bupropion and/or hydroxybupropion concentrations were divided into normal (n = 64) and reduced (n = 109) CYP2B6 activity groups based on the presence of decreased-function CYP2B6*6 and CYP2B6*18 alleles. Biochemically verified smoking cessation was assessed at week 3, end of treatment (7 weeks) and follow-up (26 weeks).

FINDINGS

Normal (versus reduced) CYP2B6 activity was associated with increased cessation at week 7, which was mediated by higher hydroxybupropion concentration [odds ratio (OR) = 1.25, 95% confidence interval (CI) = 1.03, 1.78]; this mediation effect persisted at week 26 (OR = 1.23, 95% CI = 1.02, 1.70). The mediation effect was similar in women (n = 116; OR = 1.33, 95% CI = 1.01, 2.30) and men (n = 57; OR = 1.33, 95% CI = 0.92, 3.87). Moreover, sex did not appear to moderate the mediation effect, although this should be tested in a larger sample.

CONCLUSIONS

In African American light smokers with verified early bupropion use, genetically normal CYP2B6 activity appears to be indirectly associated with greater smoking cessation success in a relationship mediated by higher hydroxybupropion concentration. The mediating effect of higher hydroxybupropion concentration on smoking cessation persists beyond the active treatment phase and does not appear to differ by sex.

Stability of Varenicline Concentration in Saliva Over 21 Days at Three Storage Temperatures

INTRODUCTION

Varenicline is the most efficacious drug for smoking cessation; saliva varenicline concentrations can be useful for the evaluation of adherence in smoking cessation trials. Saliva is a useful noninvasive matrix for mail-in specimen collection, if stable. We investigated the stability of varenicline in saliva at different storage temperatures simulating the time it takes to mail in a sample.

METHODS

We evaluated the concentrations of varenicline, nicotine, cotinine, 3'-hydroxycotinine, and 3'-hydroxycotinine/cotinine (3HC/COT) ratio in quality control saliva samples (and after repeated freezing and thawing), and in smokers' saliva samples, stored for up to 21 days at room temperature (~25°C), 4°C, and -80°C.

RESULTS

In saliva quality control samples, concentrations of varenicline, nicotine, cotinine, 3'-hydroxycotinine, and 3HC/COT remained unchanged and showed little within-sample variation (CV ≤ 5.5%) for up to 21 days at the three storage temperatures; they were also not altered after three thaw-freeze cycles. In smokers' saliva, a significant main effect of storage duration, but not temperature, was observed for varenicline, cotinine, and 3'-hydroxycotinine, but not for nicotine or the 3HC/COT ratio. However, these changes were within analytical (i.e., equipment) variation resulting in little within-sample variation (CV ≤ 5.8%) for all analytes in smokers' saliva.

CONCLUSIONS

Varenicline, the other analytes, and the 3HC/COT ratio remained stable in saliva during storage for 21 days at all temperatures tested and after repeated freezing and thawing with only minor changes in concentration over time. These findings support the potential use of mail-in approach for saliva samples in varenicline smoking cessation clinical trials.

IMPLICATIONS

Assessing saliva varenicline concentrations can be useful for the evaluation of adherence in smoking cessation trials. Saliva is a noninvasive matrix suitable for mail-in specimen collection. This is the first investigation of stability of varenicline in saliva. Varenicline, nicotine, cotinine, 3'-hydroxycotinine, and 3HC/COT were stable in saliva for up to 21 days at room temperature (~25°C), 4°C, and -80°C, supporting the use of a mail-in approach for saliva specimen in smoking cessation trials.

A Genome-Wide Association Study of Nausea Incidence in Varenicline-Treated Cigarette Smokers

INTRODUCTION

Varenicline is the most efficacious smoking cessation treatment; however, long-term cessation rates tend to be <25%. Nausea, the most common side effect of varenicline, observed in ~28% of individuals treated, peaks early following treatment initiation and reduces cessation success. Genetic variation influences treatment response, however genetic contributors to individual differences in side effects are less understood.

METHODS

We conducted a genome-wide association study of nausea incidence at 1 week following the initiation of varenicline treatment (corresponding to the target quit date) in 189 cigarette smokers of European ancestry (NCT01314001). Additive genetic models examining the likelihood of experiencing any versus no nausea controlled for population substructure, age, and sex. Variants with minor allele frequencies (MAF)≥10% were considered.

RESULTS

Fifty-seven (30.2%) out of 189 participants reported nausea. The top variant associated with nausea was rs1568209 (odds ratio [OR] = 2.61 for A vs. G allele; 95% confidence interval [CI] = 1.65,4.15; p = 2.1e-7; MAF = 48.7%), mapping to the SLCO3A1 drug transporter gene on chromosome 15. In the same trial, rs1568209 was not associated with nausea in either the nicotine patch (p = .56; n = 181) or placebo (p = .59; n = 174) arms. In varenicline-treated smokers, the incidence of nausea was higher in females (44.6%; n = 74) versus males (20.9%; n = 115) (p = .001), however there was no evidence of a difference in the influence of rs1568209 on nausea between the sexes (p for sex*genotype interaction = .36). Future studies in larger samples are required to test the robustness of this finding.

CONCLUSIONS

Variation in SLCO3A1 may influence the risk for developing nausea in varenicline-treated smokers, which may alter adherence and cessation.

IMPLICATIONS

Varenicline-associated nausea reduces adherence and limits cessation success. Previous candidate gene association studies showed genetic factors influence nausea on varenicline. This pilot genome-wide investigation of nausea, the most common side effect associated with varenicline treatment and an important cause of treatment discontinuation, suggests the potential involvement of common variation in the SLCO3A1 drug transporter gene.

Medication adherence and rate of nicotine metabolism are associated with response to treatment with varenicline among smokers with HIV

INTRODUCTION

PLWHA who smoke have shown lower cessation rates within placebo-controlled randomized trials of varenicline. Adherence and rate of nicotine metabolism may be associated with quit rates in such clinical trials.

METHODS

This secondary analysis of a randomized placebo-controlled trial of varenicline for smoking among PLWHA (N = 179) examined the relationship between varenicline adherence (pill count, ≥80% of pills), nicotine metabolism (based on the nicotine metabolite ratio; NMR) and end-of-treatment smoking cessation (self-reported 7-day point prevalence abstinence, confirmed with carbon monoxide of ≤ 8 ppm, at the end of treatment; EOT).

RESULTS

Combining varenicline and placebo arms, greater adherence (OR = 1.011, 95% CI:1.00-1.02, p = 0.051) and faster nicotine metabolism (OR = 3.08, 95% CI:1.01-9.37, p = 0.047) were related to higher quit rates. In separate models, adherence (OR = 1.009, 95% CI:1.004-1.01, p < 0.001) and nicotine metabolism rate (OR = 2.04, 95% CI:1.19-3.49, p = 0.009) interacted with treatment arm to effect quit rates. The quit rate for varenicline vs. placebo was higher for both non-adherent (19% vs. 5%; χ²[1] = 2.80, p = 0.09) and adherent (35% vs. 15%; χ²[1] = 6.51, p = 0.01) participants, but the difference between treatment arms was statistically significant only for adherent participants. Likewise, among slow metabolizers (NMR < 0.31), the varenicline quit rate was not significantly higher vs. placebo (14% vs. 5%; χ²[1] = 1.17, p = 0.28) but, among fast metabolizers (NMR ≥ 0.31), the quit rate for varenicline was significantly higher vs. placebo (33% vs. 14%; χ²[1] = 4.43, p = 0.04).

CONCLUSIONS

Increasing varenicline adherence and ensuring that fast nicotine metabolizers receive varenicline may increase quit rates for PLWHA.

Remote Methods for Conducting Tobacco-Focused Clinical Trials

Most tobacco-focused clinical trials are based on locally conducted studies that face significant challenges to implementation and successful execution. These challenges include the need for large, diverse, yet still representative study samples. This often means a protracted, costly, and inefficient recruitment process. Multisite clinical trials can overcome some of these hurdles but incur their own unique challenges. With recent advances in mobile health and digital technologies, there is now a promising alternative: Remote Trials. These trials are led and coordinated by a local investigative team, but are based remotely, within a given community, state, or even nation. The remote approach affords many of the benefits of multisite trials (more efficient recruitment of larger study samples) without the same barriers (cost, multisite management, and regulatory hurdles). The Coronavirus Disease 2019 (COVID-19) global health pandemic has resulted in rapid requirements to shift ongoing clinical trials to remote delivery and assessment platforms, making methods for the conduct of remote trials even more timely. The purpose of the present review is to provide an overview of available methods for the conduct of remote tobacco-focused clinical trials as well as illustrative examples of how these methods have been implemented across recently completed and ongoing tobacco studies. We focus on key aspects of the clinical trial pipeline including remote: (1) study recruitment and screening, (2) informed consent, (3) assessment, (4) biomarker collection, and (5) medication adherence monitoring. Implications With recent advances in mobile health and digital technologies, remote trials now offer a promising alternative to traditional in-person clinical trials. Remote trials afford expedient recruitment of large, demographically representative study samples, without undo burden to a research team. The present review provides an overview of available methods for the conduct of remote tobacco-focused clinical trials across key aspects of the clinical trial pipeline.

Counseling alone or in combination with nicotine replacement therapy for treatment of black non-daily smokers: a randomized trial

BACKGROUND AND AIMS

One-third of US tobacco users are non-daily smokers (NDS). Black NDS have strikingly high levels of nicotine and carcinogen exposure. No smoking cessation studies have been conducted with this high-risk group. This study compared the effectiveness in black NDS of smoking cessation counseling alone or in combination with the participant's choice of nicotine replacement therapy.

DESIGN

Two-arm parallel-group individually randomized clinical trial (allocation ratio of 2 : 1 intervention to control) SETTING: Academic medical and federally qualified health centers in three US cities.

PARTICIPANTS

Non-Hispanic black adult NDS receiving counseling with nicotine replacement therapy (C + NRT, n = 185) or counseling alone (C, n = 93).

INTERVENTIONS

Twelve weeks of in-person and telephone smoking cessation counseling in combination with nicotine replacement therapy (NRT; C + NRT) or counseling alone (C). All participants received five sessions of counseling; those randomized to C + NRT received their choice of nicotine gum, patch and/or lozenge after a 9-day product trial period. The target quit day was set at 2 weeks post-baseline for both groups.

MEASUREMENTS

Primary outcome was biochemically verified 30-day abstinence at week 12. Secondary outcomes were change in nicotine and carcinogen exposure [4-(methynitrosamino)-1-(3) pyridyle-1-butanol; NNAL] and tobacco consumption patterns.

FINDINGS

Abstinence was 11.4% in C + NRT and 8.6% in C [odds ratio (OR) = 1.4, 95% confidence interval (CI) = 0.6, 3.2, P = 0.48]. Both groups experienced significant reduction in NNAL (C + NRT: 53% reduction, C: 50% reduction, within-group P < 0.0001) but non-significant changes in cotinine (P = 0.69). C + NRT reported more days abstinent (P < 0.001) and fewer total cigarettes (P = 0.002) compared with C. There was no evidence of compensation with other tobacco products.

CONCLUSIONS

Among black non-daily smokers in the United States, there was no difference in abstinence between nicotine replacement therapy (NRT) and counseling alone. NRT led to greater increase in days abstinent and reduction in cigarettes, with no evidence of compensation from other sources of nicotine.

Evaluation of nicotine patch adherence measurement using self-report and saliva cotinine among abstainers in a smoking cessation trial

BACKGROUND

Adherence to nicotine patches relates to cessation. This is the first study to examine the validity of self-reported nicotine patch adherence relative to saliva cotinine.

METHODS

We used data from 198 clinical trial participants who received 11 weeks of nicotine patches, self-reported patch use, had saliva cotinine 1-week after the start of treatment assessed, and were not smoking when saliva was collected (CO < 6). Self-reported patch adherence was defined as: 3-day (before saliva collection), 7-day (before saliva collection), 3-week use (7 days before, and 14 days after, saliva collection), and 11-week use (7 days before, and 10 weeks after, saliva collection). Analyses, including receiver operating characteristic curves, considered differences in nicotine metabolism. Sensitivity, specificity and positive (PPV) and negative predictive value (NPV) assessed optimal cotinine cut-point for adherence.

RESULTS

Self-reported 7-day (r = 0.13) and 3-week (r = 0.13) patch use marginally correlated with week 1 cotinine (p's = 0.08) but not 3-day or 11-week. Significant area under the curve (AUC) values of 0.67 (95 %CI: 0.55-0.79) and 0.72 (95 %CI: 0.57-0.88) were found using 7-day self-report for the overall sample and for slow metabolizers (p's<0.01), but not for normal metabolizers. Optimal 1-week cotinine cut-points using 7-day self-report were 170 ng/mL (overall) and 184 ng/mL (slow), with sensitivity = 0.56-0.62, specificity = 0.69-0.78, PPV = 0.96-0.97, and NPV = 0.13-0.14.

CONCLUSIONS

Among CO-confirmed abstainers, self-reported patch use and saliva cotinine assessed 1-week into treatment, were modestly correlated and optimal cotinine cut-point differed by rate of nicotine metabolism. Seven-day patch use may be a more valid self-report measure of patch adherence based on cotinine than 3-day, 3-week, or 11-week. Rate of nicotine metabolism may affect this relationship.

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.

Correlates of varenicline adherence among smokers with HIV and its association with smoking cessation

INTRODUCTION

With medical advances, the life expectancy of people living with HIV/AIDS (PLWHA) has improved; however, tobacco use remains a prominent risk for mortality. Although studies have examined the efficacy of varenicline for treating smoking among PLWHA, the relationship between varenicline adherence and cessation and correlates of varenicline adherence remain under-studied.

METHODS

We conducted secondary analyses from a randomized placebo-controlled trial of varenicline for smoking among PLWHA, using data from participants who received varenicline (N = 89). The relationship between varenicline adherence (based on pill count) and end-of-treatment smoking cessation was assessed, as were correlates of varenicline adherence.

RESULTS

Those who were abstinent took an average of 137.1 pills (SD = 39.3), or 83% of pills prescribed, vs. 105.3 pills (SD = 64.1), or 64%, for those who were smoking (OR = 1.01, 95% CI: 1.001-1.021, p = 0.03); 52/89 (58%) participants were adherent based on taking ≥80% of pills. The quit rate for adherent participants was 35% (18/52) vs. 19% (7/37) for non-adherent participants. Adherent participants were older, smoked fewer cigarettes each day, started smoking at an older age, and had lower baseline creatinine vs. non-adherent participants (p < 0.05). There was a significant time-by-group interaction effect for anxiety (F[1,72] = 6.24, p = 0.02), depression (F[1,72] = 4.2, p = 0.04), and insomnia (F[1,72] = 7.73, p = 0.007), indicating that adherent participants had less depression, anxiety, and insomnia during the initial weeks of treatment, vs. non-adherent participants.

CONCLUSIONS

Our findings underscore the importance of varenicline adherence for determining cessation and highlight the role of early changes in anxiety, depression, and insomnia determining varenicline adherence.

The Use of the Nicotine Metabolite Ratio as a Biomarker to Personalize Smoking Cessation Treatment: Current Evidence and Future Directions

The nicotine metabolite ratio (NMR), a genetically informed biomarker of rate of nicotine metabolism, has been validated as a tool to select the optimal treatment for individual smokers, thereby improving treatment outcomes. This review summarizes the evidence supporting the development of the NMR as a biomarker of individual differences in nicotine metabolism, the relationship between the NMR and smoking behavior, the clinical utility of using the NMR to personalize treatments for smoking cessation, and the potential mechanisms that underlie the relationship between NMR and smoking cessation. We conclude with a call for additional research necessary to determine the ultimate benefits of using the NMR to personalize treatments for smoking cessation. These future directions include measurement and other methodologic considerations, disseminating this approach to at-risk subpopulations, expanding the NMR to evaluate its efficacy in predicting treatment responses to e-cigarettes and other noncigarette forms of nicotine, and implementation science including cost-effectiveness analyses.See all articles in this Special Collection Honoring Paul F. Engstrom, MD, Champion of Cancer Prevention.

Impact of early nausea on varenicline adherence and smoking cessation

BACKGROUND AND AIMS

Varenicline effectiveness may be related to the level of adherence, which might be reduced by adverse effects such as nausea. The aim of the study was to test a possible effect of nausea on smoking cessation outcomes mediated by adherence.

DESIGN

Mediation path analysis.

SETTING

Multiple sites within Canada and the United States.

PARTICIPANTS

Treatment-seeking smokers receiving varenicline from two smoking cessation clinical trials: Quit2Live (NCT01836276; n = 449) and Pharmacogenetics of Nicotine Addiction Treatment (PNAT) (NCT01314001; n = 421).

MEASUREMENTS

Nausea severity was collected through self-report and adherence was biologically assessed using varenicline concentrations (Quit2Live, plasma sample at week 4; PNAT, saliva sample at week 2). In Quit2Live, the end-points were cotinine-verified abstinence at weeks 4, 12 and 26. In PNAT, the end-points were carbon monoxide-verified abstinence at weeks 2, 12 and 26.

FINDINGS

Early nausea was not directly associated with abstinence [odds ratio (OR) ranging from 0.73-1.28; P ≥ 0.26]. However early nausea was indirectly associated with lower cessation rates at multiple timepoints (ORs ranging from 0.92-0.94; 95% CI between 0.83-0.99) in a relationship mediated by reduced varenicline adherence (assessed by plasma varenicline concentrations) in the primary trial (Quit2Live). This relationship between nausea, adherence and cessation was similar in direction but weaker in effect size (ORs ranging from 0.98-0.99; 95% CI between 0.90-1.03) in a secondary trial (PNAT), where adherence was assessed using salivary varenicline concentrations.

CONCLUSIONS

These data suggest that early nausea during varenicline treatment may be indirectly associated with lower likelihood of smoking cessation through reducing varenicline adherence. Differences in robustness between the trials may be due to the different biological matrices (plasma vs. saliva) and/or timing used to assess varenicline adherence. The results of the first study suggest that improved management of early nausea during varenicline treatment may positively impact smoking cessation success through increasing varenicline adherence.

Placebo-controlled randomized clinical trial testing the efficacy and safety of varenicline for smokers with HIV

BACKGROUND

People living with HIV/AIDS (PLWH) smoke tobacco at higher rates and have more difficulty quitting than the general population, which contributes to significant life-years lost. The effectiveness of varenicline, one of the most effective tobacco dependence treatments, is understudied in HIV. We evaluated the safety and efficacy of varenicline for smoking cessation among PLWH.

METHODS

This was a single-site randomized, double-blind, placebo-controlled, phase 3 clinical trial (NCT01710137). PLWH on antiretroviral therapy (ART) who were treatment-seeking daily smokers were randomized (1:1) to 12 weeks of varenicline (n = 89) or placebo (n = 90). All participants were offered six smoking cessation behavioral counseling sessions. The primary outcome was 7-day point prevalence abstinence, confirmed with breath carbon monoxide, at Weeks 12 and 24. Continuous abstinence and time to relapse were secondary outcomes. Safety measures were treatment-related side effects, adverse events, blood pressure, viral load, and ART adherence.

RESULTS

Of the 179 smokers, 81% were African American, and 68% were male. Varenicline increased cessation at Week 12 (28.1% vs. 12.1%; OR = 4.54, 95% CI:1.83-11.25, P = .001). Continuous abstinence from Week 9 to 12 was higher for varenicline vs. placebo (23.6% vs. 10%; OR = 4.65, 95% CI:1.71-12.67, P = .003); at Week 24, there was no effect of varenicline for point prevalence (14.6% vs. 10%), continuous abstinence (10.1% vs. 6.7%), or time to relapse (Ps > .05). There were no differences between varenicline and placebo on safety measures (Ps > .05).

CONCLUSIONS

Varenicline is safe and efficacious for short-term smoking cessation among PLWH and should be used to reduce tobacco-related life-years lost in this population.

Methods to reduce the incidence of false negative trial results in substance use treatment research

Treatment development and evaluation for substance use disorders are hindered when randomized controlled trials fail to show a treatment effect when one exists. This manuscript provides an overview of addressable methodological factors that may contribute to incorrect trial results. The collection of remote, naturalistic, real-time adherence and substance use data through ambulatory assessment methods in everyday life is presented as a partial solution. Other recommendations related to participant recruitment and selection, ensuring adequate consistency/fidelity and dose of treatment, and rigorously assessing clinical outcomes are discussed. With implementation of eligibility criteria verification, treatment adherence monitoring, and remote assessment of substance use and biomarkers, ambulatory assessment may help improve clinical trial success rates by improving precision, increasing reproducibility, and reducing the impact of methodological issues that may lead to inaccurate trial results.

A randomized controlled trial of 24 weeks of varenicline for tobacco use among cancer patients: Efficacy, safety, and adherence

OBJECTIVE

Continuing to smoke after a cancer diagnosis undermines prognosis. Yet few trials have tested Food and Drug Administration (FDA)-approved tobacco use medications in this population. Extended use varenicline may represent an effective treatment for cancer patients who smoke given barriers to cessation including a prolonged time line for relapse.

METHODS

A placebo-controlled randomized trial tested 12 weeks of varenicline plus 12 weeks of placebo (standard [ST]) vs 24 weeks of varenicline (extended [ET]) with seven counseling sessions for treatment-seeking cancer patients who smoke (N = 207). Primary outcomes were 7-day biochemically confirmed abstinence at weeks 24 and 52. Treatment adherence and side effects, adverse and serious adverse events, and blood pressure were assessed.

RESULTS

Point prevalence and continuous abstinence quit rates at weeks 24 and 52 were not significantly different across treatment arms (P's > 0.05). Adherence (43% of sample) significantly interacted with treatment arm for week 24 point prevalence (odds ratio [OR] = 2.31; 95% confidence interval [CI], 1.15-4.63; P = 0.02) and continuous (OR = 5.82; 95% CI, 2.66-12.71; P < 0.001) abstinence. For both outcomes, adherent participants who received ET reported higher abstinence (60.5% and 44.2%) vs ST (44.7% and 27.7%), but differences in quit rates between arms were not significant for nonadherent participants (ET: 9.7% and 4.8%; ST: 12.7% and 10.9%). There were no significant differences between treatment arms on side effects, adverse and serious adverse events, and rates of high blood pressure (P's > 0.05).

CONCLUSIONS

Compared with ST, ET varenicline does not increase patient risk and increases smoking cessation rates among patients who adhere to treatment. Studies are needed to identify effective methods to increase medication adherence to treat patient tobacco use effectively.

Predicting smoking abstinence with biological and self-report measures of adherence to varenicline: Impact on pharmacogenetic trial outcomes

INTRODUCTION

Adherence to pharmacotherapies for tobacco dependence, such as varenicline, is necessary for effective treatment. The relationship between varenicline adherence, determined by commonly used indirect (i.e., self-reported pill counts) and infrequently used direct (i.e., varenicline levels) methods, and abstinence outcomes have not been previously examined, nor has their impact on the outcomes of a genetically randomized clinical trial been assessed.

METHODS

At Week 1 following target quit date, self-reported pill count and salivary varenicline levels were obtained from participants (N = 376) in a smoking cessation clinical trial (NCT01314001). Point-prevalence abstinence was biochemically-verified by salivary cotinine at Week 1 and by exhaled carbon monoxide at Week 1, end-of-treatment, 6 and 12 months following treatment. Blood nicotine metabolite ratio (NMR) was obtained at baseline.

RESULTS

Adherent individuals based on varenicline levels were significantly more likely to be abstinent than non-adherent individuals at Week 1 (odds ratios [ORs] 1.92-3.16, p's≤0.006), end-of-treatment (OR = 2.53, p = .004), and six months following treatment (OR = 2.30, p = .03). In contrast, pill counts did not consistently predict abstinence. Including direct measures of adherence enhanced the association between rate of nicotine metabolism (NMR) and end-of-treatment abstinence; normal metabolizers (NMR ≥ 0.31) were significantly more likely than slow metabolizers (NMR < 0.31) to be abstinent at end-of-treatment (OR = 2.00, p = .005).

CONCLUSION

Adherence based on salivary varenicline, rather than on pill counts, is predictive of Week 1 abstinence, irrespective of the biomarker of abstinence assessed, and of long-term abstinence. Direct measures of adherence enhance the ability to assess the impact of a biomarker or genetic marker on abstinence outcomes.

The association between self-reported varenicline adherence and varenicline blood levels in a sample of cancer patients receiving treatment for tobacco dependence

Introduction

The degree to which smokers quit successfully with varenicline is strongly associated with their adherence to the medication regimen. Thus, measuring varenicline adherence to identify smokers needing additional intervention is a priority. Few studies, however, have examined the validity of self-reported varenicline adherence, using a biological assessment of adherence as a reference. No study has examined this issue among cancer patients trying to quit smoking, who may show unique patterns of adherence given their medical comorbidity.

Methods

This study used data from 76 cancer patients who received varenicline and provided self-reported varenicline adherence data (pill count) and a blood sample to determine varenicline metabolites 4 weeks after initiating varenicline.

Results

Receiver operating characteristic (ROC) curve analyses of plasma varenicline levels showed that 4 ng/ml was the optimal cut-point for differentiating adherence with significant (p's < 0.04) area under the curve values, ranging from 0.73–0.80 for 3-day, 7-day, and 4-week self-reported pill count; specificity values ranged from 0.63–0.78 and sensitivity values ranged from 0.82–0.94. Using this cut-point, adherence was high (88%). However, plasma varenicline levels were weakly correlated with 3-day and 4-week pill count and total pill count (12 weeks) was not correlated with plasma varenicline levels. Patients with head and neck cancer, gastrointestinal cancer, and more advanced disease showed lower varenicline adherence and lower plasma varenicline.

Conclusions

Using the 4 ng/ml cut-point, this study suggests validity of short-term self-reported varenicline adherence among cancer patients undergoing tobacco dependence treatment in contrast to studies in the general population, which supported 12-week pill count.

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First study of the validity of self-reported varenicline use among cancer patients

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Identified cut-point for varenicline plasma adherence

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Supports the validity of short-term self-reported varenicline adherence

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Cancer-related variables influence varenicline adherence

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Varenicline adherence may be higher among cancer patients

Improvement of the association between self-reported pill count and varenicline levels following exclusion of participants with misreported pill count: A commentary on Peng et al. (2017)

INTRODUCTION

We previously reported poor associations between salivary varenicline and pill counts, and a substantial overestimation of adherence by pill counts in "Measures and predictors of varenicline adherence in the treatment of nicotine dependence" (Peng et al., 2017). We have since conducted supplementary analyses characterizing, and then excluding, individuals with established inaccurate pill count recall.

METHODS

Based on published varenicline pharmacokinetics (including drug levels, and the long half-life) and our detection limits, conservatively we should be able to detect varenicline in anyone who took at least one pill during the 48h prior to saliva collection; thus, those reporting 1 or more pills in this time frame but who had undetectable salivary varenicline were deemed to have inaccurate pill count recall. Correlations between pill counts and salivary varenicline, and Receiver Operating Characteristics curve analyses were conducted following exclusion of participants with inaccurate pill count recall.

RESULTS

Nearly 20% of our participants (N=67/376) had inaccurate self-reported pill counts. These participants were younger, non-white, lower income, and unmarried (evaluated using chi-square or Mann-Whitney U test). Following exclusion of these individuals, the correlations between salivary varenicline and pill count improved and the area under the curve (AUC) of pill counts for discriminating adherence improved modestly.

CONCLUSION

When the 20% of individuals with inaccurate pill count recall were excluded, an improved association between self-reported pill count and salivary varenicline was observed, albeit still weak. A substantial overestimation of adherence by pill counts relative to salivary varenicline is still observed even after exclusion of almost 20% of the group having established inaccurate reporting suggesting that these individuals, with identifiable inaccuracies, were only part of the overestimation of adherence.

Evaluation of Prolonged Exposure to Varenicline in Adult Rats: Haematological, Biochemical and Anatomopathological Studies

Varenicline is a synthetic chemical substance produced from the alkaloid cytisine, used for smoking treatment, which acts as a partial agonist for α4β2 and α3β4 nicotinic cholinergic receptors and as a total agonist for α7 receptor. While there are studies regarding varenicline's non-smoking-related effects, as in treatment for drug dependence, there are no studies in the literature evaluating the long-term toxicity of varenicline through a physiological approach. Thus, the aim of this study was to evaluate possible toxicity through haematological, biochemical and anatomopathological parameters of prolonged exposure (30 days) to varenicline in rats. Three doses of varenicline were used: 0.03 (therapeutic dose for human beings), 0.1 and 0.3 mg/kg orally (gavage). Body-weight, water and food intake were measured weekly during treatment. On the 30th treatment day, blood and various organs were collected for haematological, biochemical and anatomopathological evaluations. The results show a decrease in some biochemical parameters in animals from the 0.1 and 0.3 mg/kg group, although the values are within the normal range of the species. There were no changes in the other evaluations performed. Together, these data indicate that prolonged exposure of rats to different doses of varenicline was not able to alter haematological, biochemical and anatomopathological parameters.