Low Nicotine Content Research Articles

Mouth-Level Nicotine Intake Estimates from Discarded Filter Butts to Examine Compensatory Smoking in Low Nicotine Cigarettes.

A mandated reduction in the nicotine content of cigarettes could reduce smoking rate and prevalence. However, one concern is that smokers may compensate by increasing the intensity with which they smoke each cigarette to obtain more nicotine. This study assessed whether smokers engage in compensatory smoking by estimating the mouth-level nicotine intake of low nicotine cigarettes smoked during a clinical trial. Smokers were randomly assigned to receive cigarettes with one of five nicotine contents for 6 weeks. An additional group received a cigarette with the lowest nicotine content, but an increased tar yield. The obtained mouth-level nicotine intake from discarded cigarette butts for a subset of participants (51-70/group) was estimated using solanesol as described previously. A compensation index was calculated for each group to estimate the proportion of nicotine per cigarette recovered through changes in smoking intensity. There was no significant increase in smoking intensity for any of the reduced nicotine cigarettes as measured by the compensation index (an estimated 0.4% of the nicotine lost was recovered in the lowest nicotine group; 95% confidence interval, -0.1 to 1.2). There was a significant decrease in smoking intensity for very low nicotine content cigarettes with increased tar yield. Reductions in nicotine content did not result in compensatory changes in how intensively participants smoked research cigarettes. Combined with data from clinical trials showing a reduction in cigarettes smoked per day, these data suggest that a reduction in nicotine content is unlikely to result in increased smoke exposure.

Dynamic borrowing in the presence of treatment effect heterogeneity.

A number of statistical approaches have been proposed for incorporating supplemental information in randomized clinical trials. Existing methods often compare the marginal treatment effects to evaluate the degree of consistency between sources. Dissimilar marginal treatment effects would either lead to increased bias or down-weighting of the supplemental data. This represents a limitation in the presence of treatment effect heterogeneity, in which case the marginal treatment effect may differ between the sources solely due to differences between the study populations. We introduce the concept of covariate-adjusted exchangeability, in which differences in the marginal treatment effect can be explained by differences in the distributions of the effect modifiers. The potential outcomes framework is used to conceptualize covariate-adjusted and marginal exchangeability. We utilize a linear model and the existing multisource exchangeability models framework to facilitate borrowing when marginal treatment effects are dissimilar but covariate-adjusted exchangeability holds. We investigate the operating characteristics of our method using simulations. We also illustrate our method using data from two clinical trials of very low nicotine content cigarettes. Our method has the ability to incorporate supplemental information in a wider variety of situations than when only marginal exchangeability is considered.

A fully Bayesian mixture model approach for identifying noncompliance in a regulatory tobacco clinical trial.

Identifying noncompliance in a randomized trial is challenging, but could be improved by leveraging biomarker data to identify participants that did not comply with their assigned treatment. For randomized trials of very low nicotine content (VLNC) cigarettes, the biomarker of total nicotine equivalents (TNE) could be used to identify noncompliance. Compliant participants should have lower levels of TNEs than participants that did not comply and smoked normal nicotine content cigarettes, resulting in a mixture of compliant and noncompliant participants at each dose level. Thresholds of TNE could then be identified from the compliant groups at each dose level and used to determine which study participants were compliant. Furthermore, proposed biological relationships of TNE with nicotine dose could be incorporated into improve the efficiency of estimation, but may introduce bias if misspecified. To account for multiple modeling assumptions across dose levels, we explore model averaging via reversible jump markov chain monte carlo (MCMC) within each dose level to take advantage of improvements in efficiency when the proposed relationship is true and to downweight the biological model when it is misspecified. In simulation studies, we demonstrate that model averaging in the presence of a correct biological relationship results in a decrease in the mean square error (MSE) of up to 85%, but downweights the model in dose levels where the relationship is not appropriate. We apply our approach to data from a randomized trial of VLNC cigarettes to estimate TNE thresholds and probability of compliance curves as a function of TNEs for each nicotine dose used in the trial.

Method for Estimating Non-study Cigarette Use among Switchers to Low Nicotine Content Cigarettes in Ambulatory Clinical Studies

Background: FDA is considering to establish a product standard to reduce nicotine in cigarettes to make them “minimally addictive or non addictive.” FDA has funded many clinical studies where smokers are switched to smoking low nicotine cigarettes to determine a nicotine ceiling that is appropriate for the protection of the public health. Unlike typical clinical trials involving pharmaceuticals or medical devices, ambulatory studies with low nicotine cigarettes face a unique challenge in that conventional nicotine nonstudy cigarettes are readily available to participants when protocols require them to exclusively use study cigarettes. As a consequence, protocol deviation in non-study product use is a major limitation common in such ambulatory studies, with up to 80 percent of participants using non-study cigarettes during the study. There is no published method for estimating the magnitude of such protocol deviation, i.e., the number of non-study cigarettes smoked by participants, in such studies. Methods: We present a method for estimating the magnitude of noncompliance based on the proposition that the level of biomarker of exposure to a smoke constituent is proportional to the amount of the constituent per cigarette and the number of cigarettes smoked by participants. The method estimates the number of non-study cigarettes smoked by participants based on the discrepancies between the yield of smoke constituents (e.g., nicotine) and the level of the corresponding biomarkers measured in a study. Results: Data from a confined study confirmed the validity of this method. Under-reporting on the magnitude of non-study cigarette use is widespread across studies using different low nicotine cigarettes. Participants in one of the largest published studies under-reported the number of non-study cigarette used by 79-90%. Conclusions: Controlling and accurately estimating non-study cigarette use is critical for ambulatory low nicotine cigarette switching studies to ensure the resulting data can be appropriately evaluated to support science-based regulatory decision-making. In planning future studies, researchers should consider incorporating specific biomarkers that would enable objective assessment of both the prevalence and the magnitude of non-study cigarette use.

Increasing Quit Attempts by Transitioning to Very Low Nicotine Content Cigarettes Versus Reducing Number of Cigarettes Per Day: A Secondary Analysis of an Exploratory Randomized Trial.

IntroductionThe Food and Drug Administration (FDA) has proposed reducing nicotine with very low nicotine content (VLNC) cigarettes. In contrast, reducing nicotine by reducing number of cigarettes per day (CPD) is common. Our prior findings demonstrate that VLNC cigarettes decreased dependence more and were more acceptable than reducing CPD. This secondary analysis explored which reduction strategy increased quit attempts (QA), self-efficacy, or intention to quit more.MethodsThis is a secondary analysis of 68 adult daily smokers not ready to quit randomized to smoke VLNC cigarettes versus reduce CPD over 5 weeks. All participants smoked study cigarettes with nicotine yield similar to most commercial cigarettes ad lib for 1 week (baseline). Participants were then randomized to gradually reduce to 70%, 35%, 15%, and 3% of baseline nicotine over 4 weeks by either (1) transitioning to lower nicotine VLNC cigarettes or (2) reducing the number of full nicotine CPD. All participants received nicotine patches to aid reduction. We assessed (1) QAs using nightly and weekly self-reports, (2) Velicer’s Self-Efficacy to Quit measure weekly, and (3) the Intention-to-Quit Ladder nightly.ResultsMore CPD (41%) than VLNC (17%) participants made any QA (odds ratio = 3.4, 95% confidence interval = 1.1, 10.5). There was no difference in QAs ≥24 h. Self-efficacy increased for VLNC but not CPD participants (interaction: F = 3.7, p < .01). The condition by time interaction for intention-to-quit was not significant.ConclusionsReducing number of CPD increased QAs more than reducing nicotine via switching to VLNC cigarettes. The lack of difference in longer QAs suggests replication tests are needed.ImplicationsReducing the frequency of smoking behavior (ie, CPD) could be a more effective strategy to increase QAs than reducing the magnitude of nicotine in each cigarette (ie, VLNC) per se.

The Impact of Gradual and Immediate Nicotine Reduction on Subjective Cigarette Ratings.

BackgroundA recent clinical trial showed that an immediate transition to very low nicotine content (VLNC) cigarettes, compared with a gradual transition, produced greater reductions in smoking behavior, smoke exposure, and dependence. However, there was less compliance with the instruction to smoke only VLNC cigarettes in the immediate versus gradual reduction condition. The goal of this study was to test whether nicotine reduction method alters subjective ratings of VLNC cigarettes, and whether subjective ratings mediate effects of nicotine reduction method on smoking behavior, smoke exposure, dependence, and compliance.MethodsThis is a secondary analysis of a randomized trial conducted across 10 sites in the United States. Smokers (n = 1250) were randomized to either a control condition, or to have the nicotine content of their cigarettes reduced immediately or gradually to 0.04 mg nicotine/g of tobacco during a 20-week study period. Participants completed the modified Cigarette Evaluation Questionnaire (mCEQ).ResultsAfter Week 20, the immediate reduction group scored significantly lower than the gradual reduction group on multiple subscales of the mCEQ (ps < .001). The Satisfaction subscale of the mCEQ mediated the impact of nicotine reduction method on smoke exposure, smoking behavior, dependence, compliance, and abstinence. Other subscales also mediated a subset of these outcomes.ConclusionsAn immediate reduction in nicotine content resulted in lower product satisfaction than a gradual reduction, suggesting that immediate reduction further reduces cigarette reward value. This study will provide the Food and Drug Administration with information about the impact of nicotine reduction method on cigarette reward value.ImplicationsThese data suggest that an immediate reduction in nicotine content will result in greater reductions in cigarette satisfaction than a gradual reduction, and this reduction in satisfaction is related to changes in smoking behavior and dependence.

Effects of 6-Week Use of Very Low Nicotine Content Cigarettes in Smokers With Serious Mental Illness.

IntroductionThe US Food and Drug Administration is considering implementing a reduced-nicotine standard for cigarettes. Given the high rate of smoking among people with serious mental illness (SMI), it is important to examine the responses of these smokers to very low nicotine content (VLNC) cigarettes.MethodsThis trial compared the effects of VLNC (0.4 mg nicotine/g tobacco) and normal nicotine content cigarettes (15.8 mg/g) over a 6-week period in non-treatment-seeking smokers with schizophrenia, schizoaffective disorder, or bipolar disorder (n = 58). Linear regression was used to examine the effects of cigarette condition on cigarettes per day, subjective responses, nicotine and tobacco toxicant exposure, craving, withdrawal symptoms, and psychiatric symptoms.ResultsAt week 6, participants in the VLNC condition smoked fewer cigarettes per day, had lower breath carbon monoxide levels, lower craving scores, and rated their study cigarettes lower in satisfaction, reward, enjoyment, and craving reduction than those in the normal nicotine content condition (ps < .05). Week 6 psychiatric and extrapyramidal symptoms did not differ by condition, except for scores on a measure of parkinsonism, which were lower in the VLNC condition (p < .05). There were no differences across conditions on total nicotine exposure, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol, withdrawal symptoms, or responses to abstinence.ConclusionsThese results suggest that a reduced-nicotine standard for cigarettes would reduce smoking among smokers with SMI. However, the lack of effect on total nicotine exposure indicates VLNC noncompliance, suggesting that smokers with SMI may respond to a reduced-nicotine standard by substituting alternative forms of nicotine.ImplicationsResults from this trial suggest that a reduced-nicotine standard for cigarettes would reduce smoking rates and smoke exposure in smokers with SMI, without increasing psychiatric symptoms. However, noncompliance with VLNC cigarettes was observed, suggesting that these smokers might respond to a reduced-nicotine standard by substituting alternative forms of nicotine.

Reducing Nicotine Without Misleading the Public: Descriptions of Cigarette Nicotine Level and Accuracy of Perceptions About Nicotine Content, Addictiveness, and Risk.

SignificanceThe public incorrectly believes very low nicotine content (VLNC) cigarettes are less carcinogenic than current cigarettes, a belief associated with lower motivation to quit under a VLNC standard. We examined how different descriptions of the nicotine level in VLNC cigarettes affect the accuracy of the public’s perceptions about nicotine content, addictiveness, and cancer risk.MethodsParticipants were a national convenience sample of 1353 US adults (22% smokers). In an online experiment, we randomized participants to a VLNC description using (1) concise language; (2) a percentage; (3) an interpretation; (4) a percentage and interpretation; (5) a percentage and a pictograph; or (6) a percentage, interpretation, and pictograph; or to a control description using (7) FDA's “minimally or nonaddictive” phrasing. We assessed accuracy of perceived nicotine content, addictiveness, and cancer risk compared to current cigarettes.ResultsCompared to control, the percentage description resulted in more accurate perceptions about nicotine content (76% vs. 49% accuracy) and addictiveness (44% vs. 34%), but less accurate perceptions about cancer risk (56% vs. 68%; all ps < .05). Adding interpretation or pictographs to the percentage description did not increase accuracy. The concise language description reduced accuracy of perceived nicotine content and addictiveness but increased accuracy of cancer risk (all ps < .05).ConclusionsStating that 95% of nicotine would be removed more accurately conveyed the nicotine content and addictiveness of VLNC cigarettes. However, descriptions that better conveyed nicotine content and addictiveness misled people about cancer risk.ImplicationsImplementation of a VLNC standard should include plans for a communication campaign that conveys that VLNC cigarettes will be less addictive but equally toxic to smoke. Stating the percent reduction in nicotine is likely to more clearly communicate reduced addictiveness but may also exacerbate risk misperceptions. VLNC communication requires further study to ensure the public accurately understands a VLNC standard.

Anticipated Effects of Nicotine Reduction on Youth Smoking Initiation and Maintenance.

This commentary summarizes emerging findings on the potential impact of a nicotine reduction policy on youth and young adults. We conclude that: (1) adolescent smokers and nonsmokers alike are likely to be less sensitive to reinforcement from very low nicotine content (VLNC) cigarettes compared with adults; (2) reducing nicotine in cigarettes to 0.4 mg/g would reduce the abuse potential of cigarettes in adolescents and young adults; (3) findings to date do not support concerns that nicotine reduction leads to compensatory smoking in young smokers; and (4) if the scope of a reduced nicotine product standard were applied to all combusted tobacco products, that would likely maximize public health benefit of this policy.

Interest in Illicit Purchase of Cigarettes Under a Very Low Nicotine Content Product Standard.

SignificanceThe US Food and Drug Administration (FDA) is considering a very low nicotine content (VLNC) product standard to substantially reduce nicotine in cigarettes. We examined whether learning about a potential VLNC standard increased smokers’ interest in illicit purchases of cigarettes with regular nicotine content if such a standard were adopted.MethodsParticipants were a national convenience sample of 1712 US adult smokers. In an online experiment, we randomly assigned smokers to view information about a new VLNC standard (experimental condition) or no information (control condition). The experimental condition explained that a VLNC standard would remove 95% of the nicotine in cigarettes and would require stores to only sell VLNC cigarettes. Then, the survey assessed smokers’ interest in purchasing regular cigarettes from three illicit sources.ResultsSmokers who learned about the VLNC standard were more likely to be very or extremely interested in purchasing regular cigarettes illicitly from a Web site compared to smokers in the control group (24% vs. 16%, p < .001). They were also more interested in illicitly buying cigarettes from a street vendor (19% vs. 13%, p < .001) and a store on an Indian reservation (28% vs. 22%, p < .05), compared to the control. The impact of learning about the VLNC standard on interest in illicit purchases did not differ by smoking frequency or current e-cigarette use.ConclusionsA VLNC standard could increase smokers’ interest in illicit purchases of regular nicotine cigarettes. To prevent VLNC-induced illicit trade from undermining public health, FDA should consider proven measures such as track and trace for these products.ImplicationsLittle is known about how a VLNC cigarette standard would affect consumer interest in regular content cigarettes purchased from illicit sources (eg, the Internet). We found that smokers informed about a potential VLNC product standard had greater interest in illicit cigarette purchases, compared to controls. This suggests the importance of proactive measures accompanying a VLNC standard, such as track-and-trace cigarette packaging regulations and communication campaigns, in order to maximize the standard’s public health impact.

The Importance of Estimating Causal Effects for Evaluating a Nicotine Standard for Cigarettes.

Recent evidence from randomized clinical trials (RCTs) of very low nicotine content (VLNC) cigarettes indicates that smokers randomized to VLNC cigarettes had significantly lower cigarette use, dependence, and biomarkers of exposure than smokers randomized to normal nicotine content control cigarettes. In these trials, a substantial number of participants did not adhere to their randomized treatment assignment, i.e., they used commercial cigarettes not provided by the trial in place of or in addition to the VLNC cigarettes provided by the trial. As with most RCTs, the analysis of these trials followed the intention-to-treat principle, where participants are analyzed according to their randomized treatment assignment regardless of adherence. Alternately, the analysis of an RCT could focus on the estimation and testing of the causal effect of the intervention, which is the treatment effect if all subjects were to adhere to their randomized treatment assignment. In this commentary, we compare these two approaches, highlighting the important role of causal estimation and inference for evaluating the regulatory effect of a nicotine standard for cigarettes. Additionally, we review the results of the secondary analyses of randomized trials of VLNC cigarettes using causal inference methodology to account for non-adherence to the assigned treatment and discuss the implications for a nicotine standard for cigarettes.

Potential Moderating Effects of Psychiatric Diagnosis and Symptom Severity on Subjective and Behavioral Responses to Reduced Nicotine Content Cigarettes.

IntroductionGiven FDA’s authority to implement a cigarette nicotine reduction policy, possible outcomes of this regulation must be examined, especially among those who may be most affected, such as those with comorbid psychiatric disorders.MethodsIn this secondary analysis of a multisite, randomized, clinical laboratory study, we used analyses of variance to examine the effects of nicotine dose (0.4, 2.4, 5.2, and 15.8 mg/g of tobacco), depressive and anxiety diagnoses (depression only, anxiety only, both, or neither), and depressive and anxiety symptom severity on cigarette choice, smoke exposure, craving, and withdrawal across three vulnerable populations: socioeconomically disadvantaged women of reproductive age, opioid-dependent individuals, and those with affective disorders (n = 169).ResultsDiagnosis and symptom severity largely had no effects on smoking choice, total puff volume, or CO boost. Significant main effects on craving and withdrawal were observed, with higher scores in those with both anxiety and depression diagnoses compared with depression alone or no diagnosis, and in those with more severe depressive symptoms (p’s < .001). These factors did not interact with nicotine dose. Cigarettes with <15.8 mg/g nicotine were less reinforcing, decreased total puff volume, and produced significant but lower magnitude and shorter duration reductions in craving and withdrawal than higher doses (p’s < .01).ConclusionsReducing nicotine dose reduced measures of cigarette addiction potential, with little evidence of moderation by either psychiatric diagnosis or symptom severity, providing evidence that those with comorbid psychiatric disorders would respond to a nicotine reduction policy similarly to other smokers.ImplicationsThus far, controlled studies in healthy populations of smokers have demonstrated that use of very low nicotine content cigarettes reduces cigarette use and dependence without resulting in compensatory smoking. These analyses extend those findings to a vulnerable population of interest, those with comorbid psychiatric disorders. Cigarettes with very low nicotine content were less reinforcing, decreased total puff volume, and produced significant but lower magnitude and shorter duration reductions in craving and withdrawal than higher doses. These nicotine dose effects did not interact with psychiatric diagnosis or mood symptom severity suggesting that smokers in this vulnerable population would respond to a nicotine reduction strategy similarly to other smokers.

Examining Age as a Potential Moderator of Response to Reduced Nicotine Content Cigarettes in Vulnerable Populations.

IntroductionYoung adults (aged 18–24 years) have a higher smoking prevalence than younger and older age groups and young adulthood is an important developmental period during which long-term behavior patterns like cigarette smoking are established. The aim of the current study was to examine how young adult smokers with additional vulnerabilities to smoking respond to reduced nicotine content cigarettes.MethodsThis is a secondary analysis of a double-blind, within-subject experiment conducted with 169 cigarette smokers recruited from populations with comorbid psychiatric conditions or socioeconomic disadvantage assessing acute effects of research cigarettes varying in nicotine content (0.4, 2.4, 5.2, 15.8 mg/g). Participants were dichotomized by chronological age (18–24 vs. ≥25 years). Across 14 laboratory sessions effects of nicotine content were examined on measures of relative reinforcing efficacy (Cigarette Purchase Task [CPT] and Concurrent Choice testing), subjective effects, craving/withdrawal, and smoking topography. Repeated measures analysis of variances were used to examine potential moderating effects of age.ResultsYoung adults exhibited lower demand for reduced nicotine content cigarettes than older adults across three of five CPT indices (ps < .05). No differences by age were observed on other measures of reinforcing efficacy, subjective effects, craving/withdrawal, or smoking topography where effects generally decreased as an orderly function of decreasing nicotine content (ps <.05).ConclusionOverall, these findings suggest that reducing the nicotine content of cigarettes would decrease the addiction potential of cigarette smoking in young adult smokers as much or perhaps more than older adult smokers from populations at increased vulnerability to smoking, addiction, and smoking-related health consequences.ImplicationsReducing the nicotine content in cigarettes to lower addiction potential of smoking has been proposed as a means to improve overall population health. It is imperative to examine how young adults may respond to a nicotine reduction policy. We saw minimal evidence that age moderates acute response and where there was evidence it was in the direction of reduced nicotine content cigarettes having less addictive potential among young versus older adults (eg, steeper decreases in demand for very low nicotine content cigarettes among young versus older adults). Overall, a nicotine reduction policy has the potential to reduce smoking across age groups.

Effects of Very Low Nicotine Content Cigarettes on Smoking Behavior and Biomarkers of Exposure in Menthol and Non-menthol Smokers.

IntroductionBecause 30% of cigarettes sold in the United States are characterized as menthol cigarettes, it is important to understand how menthol preference may affect the impact of a nicotine reduction policy.MethodsIn a recent trial, non-treatment-seeking smokers were randomly assigned to receive very low nicotine cigarettes (VLNC; 0.4 mg nicotine/g tobacco) or normal nicotine cigarettes (NNC; 15.5 mg/g) for 20 weeks. On the basis of preference, participants received menthol or non-menthol cigarettes. We conducted multivariable regression analyses to examine whether menthol preference moderated the effects of nicotine content on cigarettes per day (CPD), breath carbon monoxide (CO), urinary total nicotine equivalents (TNE), urinary 2-cyanoethylmercapturic acid (CEMA), and abstinence.ResultsAt baseline, menthol smokers (n = 346) reported smoking fewer CPD (14.9 vs. 19.2) and had lower TNE (52.8 vs. 71.6 nmol/mg) and CO (17.7 vs. 20.5 ppm) levels than non-menthol smokers (n = 406; ps < .05). At week 20, significant interactions indicated that menthol smokers had smaller treatment effects than non-menthol smokers for CPD (–6.4 vs. –9.3), TNE (ratio of geometric means, 0.22 vs. 0.10) and CEMA (ratio, 0.56 vs. 0.37; ps < .05), and trended toward a smaller treatment effect for CO (–4.5 vs. –7.3 ppm; p = .06). Odds ratios for abstinence at week 20 were 1.88 (95% confidence interval [CI] = 0.8 to 4.4) for menthol and 9.11 (95% CI = 3.3 to 25.2) for non-menthol VLNC smokers (p = .02) relative to the NNC condition.ConclusionsAlthough menthol smokers experienced reductions in smoking, toxicant exposure, and increases in quitting when using VLNC cigarettes, the magnitude of change was smaller than that observed for non-menthol smokers.ImplicationsResults of this analysis suggest that smokers of menthol cigarettes may respond to a nicotine reduction policy with smaller reductions in smoking rates and toxicant exposure than would smokers of non-menthol cigarettes.

The Role of Compensation in Nicotine Reduction

The available research on switching from normal nicotine to very low nicotine content cigarettes shows minimal evidence of compensatory smoking. Mathematical estimations suggest that substantial compensation after switching to very low nicotine cigarettes would be impossible. It is likely that smokers who are unable to tolerate the extent of proposed nicotine reduction would switch to other sources of nicotine, rather than try to compensate by smoking more very low nicotine content cigarettes more intensely.

Research on Behavioral Discrimination of Nicotine May Inform FDA Policy on Setting a Maximum Nicotine Content in Cigarettes.

IntroductionThe Food and Drug Administration may set a maximum nicotine content in cigarettes to minimize smoking’s addictiveness. Our recent research may indirectly support setting levels applicable to the population of dependent smokers below 1 mg/g (mg nicotine/g of tobacco filler).MethodsUsing a within-subjects design in laboratory-based studies totaling 61 nontreatment seeking adult dependent smokers, Spectrum research cigarettes with nicotine contents ranging from 1.3 to 17 mg/g (just one per session) were compared with the lowest content available, 0.4 mg/g. Identified for each participant was the smallest difference in nicotine content, or “threshold,” between cigarettes that still supported behavioral discrimination (ie, ability to objectively distinguish their difference). The next lower nicotine content cigarette, not discriminated (by definition), was labeled their “subthreshold.” Subjective perceptions and choice behavior were also assessed.ResultsThresholds varied widely among all 61 smokers but, importantly, fewer than 7% of smokers could discriminate the two lowest, 1.3 versus 0.4 mg/g nicotine, meaning more than 90% could not do so. Moreover, we found a consistent association between their nicotine discrimination threshold and their subjective perceptions and subsequent reinforcement behavior later in the session. Specifically, a participant’s discrimination threshold cigarette was also more highly rated and preferred (ie, self-administered), whereas their subthreshold cigarette was rated similarly to the 0.4 mg/g and not preferred.ConclusionsCigarette nicotine content below the threshold for perceiving nicotine’s effects (ie, its discriminability) in nearly all smokers from a no nicotine comparison is likely below 1.0 mg/g, or less than or equal to 10% of that in typical commercial cigarettes.ImplicationsCigarettes with nicotine contents able to be discriminated (threshold) are also reinforcing, and those unable to be discriminated are not reinforcing, as anticipated. Yet, research explicitly comparing cigarettes with contents below 1.0 mg/g versus no nicotine (ie, a “placebo”) is needed with larger samples. Results may confirm what nicotine content lower than 1.0 mg/g is below the threshold for discrimination (and self-administration) in the vast majority (>95%) of adult dependent smokers as well as teens beginning to smoke. Identifying that content would strongly support the Food and Drug Administration policy to establish a maximum nicotine content in cigarettes that will not maintain dependence.

Labelling accuracy in low nicotine e-cigarette liquids from a sampling of US manufacturers.

To assess labelling accuracy for low nicotine concentration e-cigarette liquids. Nicotine concentration in twelve e-liquids, available in 3 and 6mg/ml strengths, was assayed (5 replicates each) using liquid chromatography-tandem mass spectrometry. Average nominal concentrations of nicotine were lower than reported in 23/24 products tested, with 2/12 products labelled 3mg/ml, and 3/12 of the 6mg/ml products showing statistically significant differences from controls. Despite the emergence of a global regulatory environment for e-cigarettes, inaccuracies still exist in nicotine concentration labelling, which may affect user habits and reliability of products used in smoking cessation.

Very Low Nicotine Content Cigarettes Disrupt the Feedback Loop of Affective States and Smoking Behavior.

Smoking to reduce negative affect has been identified as a key motivational feature of tobacco use. Our recent work suggests that smoking very low nicotine content (VLNC) cigarettes reduces the relationship between negative affect and smoking behavior over a 6-week period. Here, we sought to extend our findings by evaluating whether a gradual or immediate approach to switching to VLNC cigarettes led to a differential reduction in the relationship between affect and smoking behavior over a longer (20-week) period. Participants (n = 1250) were adult smokers from 10 US sites randomized to one of three groups: gradual nicotine reduction (15.5, 11.7, 5.2, 2.4, and 0.4 mg of nicotine per gram of tobacco [mg/g]), immediate nicotine reduction (0.4 mg/g), or standard nicotine content cigarettes (15.5 mg/g; control), for 20 weeks. We examined whether the relationship between affect-both negative and positive-and cigarettes per day differed as a function of reduction group. We found that both negative and positive affect were associated with cigarette consumption in the control group, but not in the gradual or immediate reduction groups across the 20 weeks of exposure. Our results extend previous findings that switching to VLNC cigarettes disrupts the relationship between affect and cigarette consumption by showing that either gradually or immediately reducing cigarette nicotine content achieves this disruption. These findings provide further evidence that switching to VLNC cigarettes reduces nicotine-related reinforcement of cigarette smoking. These findings support the notion that switching to very low nicotine content cigarettes reduces the association between affect and smoking behavior, and that either a gradual or immediate nicotine reduction approach achieves this reduction. This provides further evidence that switching to very low nicotine content cigarettes weakens reinforcement mechanisms associated with nicotine dependence.

Smoking Topography Characteristics During a 6-Week Trial of Very Low Nicotine Content Cigarettes in Smokers With Serious Mental Illness.

A nicotine-reduction policy could have major benefits for smokers with serious mental illness (SMI). However, potential unintended consequences, such as compensatory smoking, should be considered to ensure that such a policy does not negatively affect this population. The purpose of this secondary analysis was to examine the impact of smoking very low nicotine content (VLNC) cigarettes for 6 weeks on smoking topography characteristics, indicators of compensatory smoking, among smokers with SMI. After a baseline usual brand smoking phase, smokers with SMI (N = 58) were randomly assigned under double-blind conditions to receive either VLNC (0.4 mg nicotine per g tobacco) or normal nicotine content (NNC; 15.8 mg nicotine per g tobacco) research cigarettes for 6 weeks. During two study visits scheduled 6 weeks apart, participants smoked either their usual brand (baseline) or assigned study cigarettes (postrandomization) through a handheld smoking topography device. Univariate analysis of variance compared smoking topography indices with cigarette condition (VLNC vs. NNC) as the between-subjects factor with corresponding baseline topography results included as covariates. At week 6, participants in the VLNC condition smoked fewer puffs per cigarette and had shorter interpuff intervals compared to participants in the NNC condition (ps < .05). There were no differences between research cigarette conditions at week 6 for cigarette volume, puff volume, puff duration, peak flow rate, or carbon monoxide boost. Findings are consistent with acute VLNC cigarette topography studies and indicate that a nicotine-reduction policy is unlikely to lead to compensation among smokers with SMI. Given the high smoking rates among people with SMI, understanding how a nicotine-reduction policy may affect this population is critically important. When considering the smoking topography results as a whole, smokers with SMI did not engage in compensatory smoking behavior when using VLNC cigarettes during a 6-week trial. Study findings suggest that compensatory smoking is not likely to occur among smokers with SMI if nicotine content is lowered to minimally addictive levels.

Randomized Trial of Low-Nicotine Cigarettes and Transdermal Nicotine

A mandated reduction in the nicotine content of cigarettes may decrease smoking, but also increase demand for other nicotine products. The present study tested the impact of smoking cigarettes with very low nicotine content and concurrent use of a transdermal nicotine patch. A balanced 2 × 2 factorial randomized clinical trial investigating the impact of cigarette nicotine content (double-blind, very low nicotine content versus normal nicotine content) and use of a transdermal nicotine patch (open label, patch versus no patch). Adult daily smokers (n=240) in the Pittsburgh, PA area. Participants were provided with research cigarettes and transdermal nicotine patches (if assigned to patch condition) for 7 weeks. Cigarettes were Spectrum brand (National Institute on Drug Abuse) and either 15.8 mg nicotine/g tobacco (normal nicotine content) or 0.4 mg nicotine/g tobacco (very low nicotine content). In the 7th week, participants were monetarily incentivized to abstain from smoking. Participants reported daily cigarette use throughout the trial and the primary outcome was average number of cigarettes smoked per day (study + nonstudy) during Week 6. Participants were recruited from 2015 to 2017 and data were analyzed between 2017 and 2018. Assignment to very low nicotine content cigarettes and assignment to wear a nicotine patch both reduced the number of cigarettes smoked per day during Week 6 (p=0.001 and 0.04, respectively). However, assignment to the patch along with very low nicotine content cigarettes did not significantly reduce cigarette smoking compared with assignment to very low nicotine content cigarettes alone. A mandated reduction in the nicotine content of cigarettes is likely to reduce the number of cigarettes smoked per day, but the added benefit of concurrent transdermal nicotine is unclear. Future studies should investigate whether alternative sources of noncombusted tobacco, such as e-cigarettes, enhance the effects of very low nicotine content cigarettes on smoking. This study is registered at www.clinicaltrials.gov NCT02301325.