Tobacco dependence and withdrawal: science base, challenges and opportunities for pharmacotherapy

Inhibition of Nicotine Metabolism by Cannabidiol (CBD) and 7-Hydroxycannabidiol (7-OH-CBD)

Cannabis-based products have experienced notable increases in co-usage alongside tobacco products. Several cannabinoids exhibit inhibition of a number of cytochrome P450 (CYP) and UDP glucuronosyltransferase (UGT) enzymes, but few studies have examined their inhibition of enzymes involved in nicotine metabolism. The goal of the present study was to examine potential drug-drug interactions occurring in the nicotine metabolism pathway perpetrated by cannabidiol (CBD) and its active metabolite, 7-hydroxy-CBD (7-OH-CBD). The inhibitory effects of CBD and 7-OH-CBD were tested in microsomes from HEK293 cells overexpressing individual metabolizing enzymes and from human liver tissue. Assays with overexpressing microsomes demonstrated that CBD and 7-OH-CBD inhibited CYP-mediated nicotine metabolism. Binding-corrected IC50,u values for CBD inhibition of nicotine metabolism to cotinine and nornicotine, and cotinine metabolism to trans-3'-hydroxycotinine (3HC), were 0.27 ± 0.060, 0.23 ± 0.14, and 0.21 ± 0.14 μM, respectively, for CYP2A6; and 0.26 ± 0.17 and 0.029 ± 0.0050 μM for cotinine and nornicotine formation, respectively, for CYP2B6. 7-OH-CBD IC50,u values were 0.45 ± 0.18, 0.16 ± 0.08, and 0.78 ± 0.23 μM for cotinine, nornicotine, and 3HC formation, respectively, for CYP2A6, and 1.2 ± 0.44 and 0.11 ± 0.030 μM for cotinine and nornicotine formation, respectively, for CYP2B6. Similar IC50,u values were observed in HLM. Inhibition (IC50,u = 0.37 ± 0.06 μM) of 3HC to 3HC-glucuronide formation by UGT1A9 was demonstrated by CBD. Significant inhibition of nicotine metabolism pathways by CBD and 7-OH-CBD suggests that cannabinoids may inhibit nicotine metabolism, potentially impacting tobacco addiction and cessation.

Nicotine Replacement Therapy Does Not Reduce Headaches Following Subarachnoid Hemorrhage: A Propensity Score-Matched Study

BACKGROUND

A significant number of patients admitted for aneurysmal subarachnoid hemorrhage (aSAH) are active smokers and are at risk of developing nicotine withdrawal symptoms (e.g., cravings, irritability, insomnia, headaches, etc.). This study aimed to evaluate the use of nicotine replacement therapy (NRT) regarding headache severity and analgesics consumption.

METHODS

A retrospective study was conducted using prospectively collected data from 2014 to 2019 in the neurointensive care unit of the Hospices Civils in Lyon, France. We performed a propensity score matching analysis. The covariables used were age, sex, initial World Federation of Neurosurgical Societies score, Hijdra sum score, and factors associated with pain following aSAH (history of chronic pain, anxiety, or depression). Smokers received NRT through a transdermal device. The primary end point was headache control. Secondary end points were mean numerical pain rating scale score and analgesics consumption.

RESULTS

One hundred and fifty-five patients were included among 523 patients hospitalized for aSAH. Fifty-one patients underwent nicotine substitution and were matched to 51 unsubstituted patients. The headache control rate was not different between the two groups (43.1% vs. 31.4%, p = 0.736). The mean numeric pain rating scale score in the substituted group was 2.2 (1.1-3.5) and 2.4 (1.6-3.1) in the unsubstituted group (p = 0.533). The analgesics consumption (acetaminophen, tramadol, and morphine) was the same in the two groups.

CONCLUSIONS

The use of NRT in the acute phase of aSAH does not seem to have an impact on the intensity of headaches or analgesics consumption.

The effect of nicotine dependence on the risk of developing post-traumatic stress disorder: Results from the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC)

BACKGROUND

It is evident that an association between smoking and post-traumatic stress disorder (PTSD) exists, but research is lacking in establishing the directionality of the relationship.

METHODS

We used longitudinal data from wave I (2001-2002) and II (2004-2005) of the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC). Individuals with nicotine dependence (ND) were matched to individuals without ND using propensity score matching to estimate the risk of developing PTSD after trauma. We also matched smokers (with or without ND) to lifetime non-smokers to estimate their risk of developing PTSD after trauma. Lastly, we conducted a mediation analysis on the effect of ND severity on PTSD symptoms.

RESULTS

Individuals with ND (n = 1,514) were more likely to develop PTSD (OR: 1.59; 95%CI: 1.09-2.32; p = 0.017) compared to individuals without ND (n = 6,047). Smokers (regardless of ND status) (n = 2,335) compared to non-smokers (n = 5,226) had no significant effect on risk of PTSD (p = 0.26). Withdrawal was found to be a mediator of the effect of ND severity on PTSD symptoms.

CONCLUSION

ND, but not smoking status, increases a smoker's risk of developing PTSD. This provides information that could aid in preventive strategies for individuals with ND who are exposed to trauma.

IMPLICATIONS

This study provides evidence in a national representative sample of adults in the U.S. that nicotine dependence may increase one's risk of developing PTSD after exposure to trauma. It also shows the directionality of the association between smoking and PTSD. Lastly, it demonstrates that withdrawal may be the link to the association between nicotine dependence and PTSD. We hope that with these findings, preventative strategies are put in place for smokers who are dependent and are exposed to trauma, such that they do not develop PTSD.

Self-Reported Smoking Status 10-Months After a Single Session Intervention Including an Education Conference About Smoking Harms and Announcement of Spirometric Lung-Age

Background

Studies investigating the effects of announcing spirometric lung-age (SLA) on the smokers' self-reported smoking status reported conflicting results.

Main objective

To evaluate the effects of a single session intervention including an education conference about smoking harms and announcement of SLA on the participants' self-reported smoking status.

Methodology

An interventional study was conducted in a cable factory. The intervention included four steps: PowerPoint presentation about raising smoking hazards awareness; general questionnaire; measurement of the anthropometric and spirometric data, and announcement of SLA; and evaluation of the smokers' self-reported smoking status 10 months later (quitted smoking, decreased consumption; stable consumption, increased consumption).

Results

Thirty-six smokers completed the four steps. Ten months after the intervention, 11.1% of smokers quitted smoking, 52.7% decreased their consumption by 7  ±  4 cigarettes/day, 30.5% kept a stable consumption, and 5.5% increased their consumption by 9  ±  6 cigarettes/day.

Conclusion

Providing an education conference combined with announcing SLA motivated 64% of smokers to quit smoking or to reduce their cigarette consumption.

Effects of Smoking on Short-Term and Long-Term Mortality after Aneurysmal Subarachnoid Hemorrhage

OBJECTIVE

The relationship between smoking and clinical outcomes after aneurysmal subarachnoid hemorrhage (aSAH) is poorly clarified, and current pieces of evidence are inconsistent. The purpose of this multicenter cohort study is therefore to explore the relationship between smoking and mortality as well as several complications after aSAH.

METHODS

Databases of patient records were from 4 tertiary hospitals. We assessed the impact of tobacco use and tobacco dose (categorized based on smoking index [SI]) on several complication and overall outcome variables. The primary outcome was mortality within the longest follow-up. Logistic models were used to investigate univariate and multivariate relationships between predictors and outcomes. We also developed a propensity score matching for smoking status by using all known confounders.

RESULTS

A total of 6,578 patients with aSAH were analyzed. Current smoking and former smoking did not show association with mortality within the longest follow-up (odds ratio [OR], 0.95, 95% confidence interval [CI]: 0.69-1.30, p = 0.726; OR, 0.66, 95% CI: 0.38-1.15, p = 0.139, respectively). In addition, patients who were current smokers showed an independent association with the decreased occurrence of hydrocephalus (OR, 0.60; 95% CI: 0.41-0.88; p = 0.009) after matching all known confounders. We also found moderate smoking (SI between 384 and 625) was associated with reduced mortality in hospital.

CONCLUSIONS

Our results indicated that in patients with aSAH, current smoking or former smoking was not associated with all-cause mortality up to 7-year follow-up.

5-HT2A and 5-HT2C receptors as potential targets for the treatment of nicotine use and dependence

Nicotine use and dependence, typically achieved through cigarette smoking, but increasingly through vape products, is the leading cause of preventable death today. Despite a recognition that many current smokers would like to quit, the success rate at doing so is low and indicative of the persistent nature of nicotine dependence and the high urge to relapse. There are currently three main forms of pharmacotherapy approved as aids to treat nicotine dependence: a variety of nicotine replacement products (NRT's), the mixed NA/DA reuptake inhibitor bupropion (Zyban®), and the preferential nicotinic α4β2 receptor agonist drug, varenicline (Chantix®); the latter being generally recognized to be the most effective. However, each of these approaches afford only limited efficacy, and various other pharmacological approaches are being explored. This chapter focusses on approaches targeted to the serotonin (5-HT) system, namely, selective serotonin reuptake inhibitors (SSRI's) which served a pioneer role in the investigation of serotoninergic modulators in human smoking cessation trials; and secondly drugs selectively interacting with the 5-HT2A and 5-HT2C receptor systems. From an efficacy perspective, measured as smoking abstinence, the 5-HT2A agonist psychedelics, namely psilocybin, seem to show the most promise; although as the article highlights, these findings are both preliminary and there are significant challenges to the route to approval, and therapeutic use of this class should they reach approval status. Additional avenues include 5-HT2C receptor agonists, which until recently was pioneered by lorcaserin, and 5-HT2A receptor antagonists represented by pimavanserin. Each of these approaches has distinct profiles across preclinical tests of nicotine dependence, and may have therapeutic potential. It is anticipated as diagnostic and predictive biomarkers emerge, they may provide opportunities for subject stratification and opportunities for personalizing smoking cessation treatment. The clinical assessment of SSRI, 5-HT2A and/or 5-HT2C receptor-based treatments may be best served by this process.

Design, rationale, and baseline characteristics of a pilot randomized clinical trial of nicotine treatment for pulmonary sarcoidosis

Introduction

Sarcoidosis is a systemic granulomatous disease of unknown cause afflicting young to middle-aged adults. The majority of patients with active pulmonary sarcoidosis complain of overwhelming fatigue, which often persists despite administration of immune-modulating drugs typically used to treat sarcoidosis. Nicotine offers an alternative to conventional treatments, which are associated with a spectrum of serious untoward effects, including diabetes mellitus, osteoporosis, bone marrow suppression, severe infections, cirrhosis. The described pilot randomized trial aims to provide preliminary data required to design subsequent Phase II/III trials to formally evaluate nicotine as a novel low-cost and highly-effective, safe treatment option for patients with active pulmonary sarcoidosis.

Methods

and Design: This is a randomized double-blind controlled trial of adults with confirmed pulmonary sarcoidosis, allocated in equal proportion to sustained release transdermal nicotine or placebo patch. The primary objective outcome is the improvement in forced vital capacity at study week 26 from baseline measurement. Secondary measures include lung texture score, and self-reported outcomes including the Fatigue Assessment Scale, the St George's Respiratory Questionnaire, and the Sarcoidosis Assessment Tool.

Discussion

Current therapies for active pulmonary sarcoidosis, remain either expensive and often with numerous side-effects, as with novel industry developed therapies, or with reduced quality of life, as with corticosteroids. Nicotine therapy provides promise as a safe, available, and cost-effective intervention strategy, which we expect to be acceptable to patients.

ClinicalTrials.gov

NCT02265874.

Short-term nicotine deprivation alters dorsal anterior cingulate glutamate concentration and concomitant cingulate-cortical functional connectivity

Most cigarette smokers who wish to quit too often relapse within the first few days of abstinence, primarily due to the aversive aspects of the nicotine withdrawal syndrome (NWS), which remains poorly understood. Considerable research has suggested that the dorsal anterior cingulate cortex (dACC) plays a key role in nicotine dependence, with its functional connections between other brain regions altered as a function of trait addiction and state withdrawal. The flow of information between dACC and fronto-striatal regions is secured through different pathways, the vast majority of which are glutamatergic. As such, we investigated dACC activity using resting state functional connectivity (rsFC) with functional magnetic resonance imaging (fMRI) and glutamate (Glu) concentration with magnetic resonance spectroscopy (MRS). We also investigated the changes in adenosine levels in plasma during withdrawal as a surrogate for brain adenosine, which plays a role in fine-tuning synaptic glutamate transmission. Using a double-blind, placebo-controlled, randomized crossover design, nontreatment seeking smoking participants (N = 30) completed two imaging sessions, one while nicotine sated and another after 36 h nicotine abstinence. We observed reduced dACC Glu (P = 0.029) along with a significant reduction in plasma adenosine (P = 0.03) and adenosine monophosphate (AMP; P < 0.0001) concentrations during nicotine withdrawal in comparison with nicotine sated state. This withdrawal state manipulation also led to an increase in rsFC strength (P < 0.05) between dACC and several frontal cortical regions, including left superior frontal gyrus (LSFG), and right middle frontal gyrus (RMFG). Moreover, the state-trait changes in dACC Glu and rsFC strength between the dACC and both SFG and MFG were positively correlated (P = 0.012, and P = 0.007, respectively). Finally, the change in circuit strength between dACC and LSFG was negatively correlated with the change in withdrawal symptom manifestations as measured by the Wisconsin Smoking Withdrawal Scale (P = 0.04) and Tobacco Craving Questionnaire (P = 0.014). These multimodal imaging-behavioral findings reveal the complex cascade of changes induced by acute nicotine deprivation and call for further investigation into the potential utility of adenosine- and glutamate-signaling as novel therapeutic targets to treat the NWS.

Preclinical evidence for combining the 5-HT2C receptor agonist lorcaserin and varenicline as a treatment for nicotine dependence

Varenicline, a nicotinic acetylcholine receptor partial agonist, is used to treat nicotine dependence. Lorcaserin, a 5-HT_2C receptor agonist has been approved in some countries to treat obesity. Based on preclinical and preliminary clinical evidence, lorcaserin may have potential to treat nicotine dependence. These experiments examined in rats the effects of combining varenicline (0.5 or 1 mg/kg) and lorcaserin (0.3, 0.6 and 1 mg/kg) on nicotine self-administration, reinstatement of nicotine seeking, responding for food and impulsive action. Both drugs alone reduced nicotine self-administration. Combining varenicline and 0.6 mg/kg lorcaserin reduced responding to a greater extent than either drug alone. In a relapse model, extinguished nicotine seeking was reinstated by a priming injection of nicotine and nicotine-associated cues. Reinstatement was reduced by varenicline (1 mg/kg) and by lorcaserin (0.3 mg/kg). Combining lorcaserin (0.3 mg/kg) with varenicline (0.5 or 1 mg/kg) reduced reinstatement to a greater degree than either drug alone. Both drugs had minimal effects on responding for food, alone or in combination. In the five-choice serial reaction time test, varenicline (0.5 or 1 mg/kg) increased impulsivity, measured as increased premature responding. This effect was reduced by lorcaserin (0.3 mg/kg). Plasma levels of varenicline or lorcaserin were not altered by co-administration of the other drug. Varenicline and lorcaserin have additive effects on nicotine self-administration, and on nicotine seeking. Lorcaserin prevents impulsivity induced by varenicline. This pattern of effects suggests that co-administration of varenicline and lorcaserin has potential as a treatment for nicotine dependence that may exceed the value of either drug alone.

Progesterone for smoking relapse prevention following delivery: A pilot, randomized, double-blind study

INTRODUCTION

Close to half of women who were smokers prior to conception quit smoking in pregnancy, when endogenous progesterone levels are high. However, at least half resume pre-pregnancy smoking levels within weeks after delivery and when progesterone levels drop. The current pilot study tested the feasibility and preliminary efficacy of postpartum progesterone replacement in preventing relapse to smoking in postpartum women with a history of pre-pregnancy smoking.

METHODS

This was an 8-week, double-blind, parallel, randomized, placebo-controlled pilot trial of 41 women with a history of pre-pregnancy smoking who achieved abstinence by 32 weeks of gestation. Immediately following delivery women were randomized to oral micronized progesterone (200mg twice daily) or placebo via computerized urn randomization program. The main outcome measures were descriptions of study feasibility: recruitment and retention. Secondary outcomes were 7-day point prevalence of abstinence at week 8, time to relapse and smoking cravings.

RESULTS

The trial was feasible with adequate randomization, 64% (41/64) of eligible women, and trial retention, 78% (32/41) completed the trial. Women taking progesterone were 1.8 times more likely to be abstinent during week 8 and took longer to relapse (10 vs. 4 weeks) compared to the placebo group, although these differences did not reach statistical significance. After adjusting for age and pre-quit smoking level, the number needed to treat was 7. There was a 10% greater decline per week in craving ratings in the progesterone group compared to placebo (β=-0.10, 95% CI: -0.15, -0.04, p<0.01). No serious adverse events occurred during the trial.

CONCLUSIONS

These preliminary findings support the promise of progesterone treatment in postpartum smokers and could constitute a therapeutic breakthrough.If these preliminary findings can be evaluated and replicated in a larger study with sufficient power, this may constitute an acceptable and safe smoking relapse prevention strategy for use during lactation.

Nicotine self-administration research: the legacy of Steven R. Goldberg and implications for regulation, health policy, and research

BACKGROUND AND RATIONALE

Steven R. Goldberg was a pioneering behavioral pharmacologist whose intravenous drug self-administration studies advanced the understanding of conditioned stimuli and schedules of reinforcement as determinants of pattern and persistence of drug-seeking behavior, and in particular, the importance of nicotine in tobacco use. His passing in 2014 led to invitations to contribute articles to psychopharmacology dedicated to his work.

OBJECTIVES

The objectives of this review are to summarize and put into historical perspective Goldberg's contributions to elucidate the reinforcing effects of nicotine and to summarize the implications of his research for medication development, tobacco regulation, and potential tobacco control policy options. This includes a review of intravenous nicotine self-administration research from the 1960s to 2016.

RESULTS

Goldberg's application of behavioral pharmacology methods to investigate nicotine reinforcement and the influence of schedule of reinforcement and conditioned stimuli on nicotine administration contributed to the conclusions of the US National Institute on Drug Abuse, and the Surgeon General, that nicotine met the criteria as a dependence-producing drug and cigarette smoking as a prototypic drug dependency or "addiction." Equally important, this work has been systematically extended to other species and applied to address a range of factors relevant to tobacco use, medication development, regulation, and public health policy.

CONCLUSIONS

Steven R. Goldberg was a pioneering scientist whose systematic application of the science of behavioral pharmacology advanced the understanding of tobacco and nicotine use and contributed to the scientific foundation for tobacco product regulation and potential public health tobacco control policy development.

Longitudinal changes in smoking abstinence symptoms and alternative reinforcers predict long-term smoking cessation outcomes

BACKGROUND

Transdermal nicotine, with behavioral counseling, is among the most popular approaches used to quit smoking. Yet, 6-month cessation rates rarely exceed 20-25%. Identifying factors associated with cessation success may help researchers and clinicians develop enhanced interventions that can improve quit rates. This study examined longitudinal changes in withdrawal, craving, depression and anxiety symptoms, and alternative reinforcers, from a baseline assessment to a 6-month outcome, as predictors of 6-month smoking cessation outcomes following 8 weeks of nicotine patch treatment and counseling.

METHODS

A sample of 180 smokers, who completed an effectiveness trial that provided counseling and 8 weeks of 21mg nicotine patches, was analyzed. Generalized estimating equations evaluated changes in withdrawal and craving, depression and anxiety symptoms, and alternative reinforcers over time, between participants who were smoking at 6-months and participants who were abstinent (confirmed with carbon monoxide) at 6-months. Multiple logistic regression assessed changes in these variables as predictors of relapse.

RESULTS

Controlling for covariates associated with cessation (i.e., nicotine dependence, patch adherence, and rate of nicotine metabolism), participants who were abstinent at 6 months showed significantly lower craving and withdrawal and significantly higher substitute reinforcers from baseline to 6 months, vs. those who were smoking at 6 months (p<0.001). An increase in craving predicted relapse to smoking (p<0.05).

CONCLUSIONS

These results support continued efforts to strengthen interventions that reduce withdrawal and craving and the development of interventions to address alternative reinforcers in order to promote long-term smoking abstinence following nicotine patch treatment.

Stress-related increases in risk taking and attentional failures predict earlier relapse to smoking in young adults: A pilot investigation

Substantial evidence links greater impulsivity and stress exposure to poorer smoking cessation outcomes. Results from adolescents also indicate that stress-related change in risk taking can impede cessation attempts. We investigated the effects of stress-related change in impulsivity, risk taking, attention and nicotine withdrawal, and craving in young adult smokers on time to smoking relapse in a relapse analogue paradigm. Twenty-six young adult smokers (50% women; mean age: 20.9 ± 1.8) were exposed to a stress imagery session followed by a contingency management-based relapse analogue paradigm. Participants smoked at least 5 cigarettes daily, with a mean baseline carbon monoxide (CO) level of 13.7 (± 5.1) ppm. Repeated measures analysis of variance (ANOVA) and paired t tests examined stress induction validity and Cox regressions of proportional hazards examined the effects of stress-related changes in nicotine withdrawal, nicotine craving, attention, impulsivity, and risk taking on time to relapse. While stress-related change in impulsivity, nicotine craving and withdrawal did not predict time to relapse (all ps > .10), greater stress-related increases in reaction time (RT) variability (p = .02) were predictive of shorter time to relapse, with trend-level findings for inattention and risk taking. Furthermore, changes in stress-related risk taking affected outcome in women more than in men, with a significant relationship between stress-related change in risk taking only in women (p = .026). Smoking cessation attempts in young adults may be adversely impacted by stress-related increases in risk taking and attentional disruption. Clinicians working with young adults attempting cessation may need to target these stress-related impairments by fostering more adaptive coping and resilience.

Higher stimulus control is associated with less cigarette intake in daily smokers

It is well established that environmental stimuli influence smoking in light, and to a lesser degree, heavy smokers. A 2-factor model of dependence suggests that the influence of stimulus control is masked among heavier smokers who primarily smoke for nicotine maintenance. The current study aimed to assess the influence of stimulus control across a range of moderate to heavy daily smokers. Furthermore, as local tobacco control policies may change the role of stimulus control, the study aimed to replicate previous U.S. findings on stimulus control in an Australian setting marked by strong tobacco control policies. In 2 Ecological Momentary Assessment studies, 420 participants monitored antecedents of smoking and nonsmoking situations. In a set of idiographic logistic regression analyses, situational antecedents were used to predict smoking occasions within each individual's data. Linear regression analysis was used to test for the association between stimulus control and smoking rate, and to test for differences between the 2 samples. Daily smokers' smoking was under considerable stimulus control, which was weaker at higher smoking rates. Overall, there was greater stimulus control in the Australian sample. Daily smokers also experience a degree of stimulus control, which is less influential in heavier smokers.

A critical assessment of the scientific basis, and implementation, of regulations for the safety assessment and marketing of innovative tobacco-related products

Our scientific, logistical, ethical and animal welfare-related concerns about the latest US Food and Drug Administration (FDA) regulations for existing and so-called 'new' tobacco products, aimed at reducing harmful exposures, are explained. Such claims for sales in the USA now have to be based on a wide range of information, a key part of which will increasingly be data on safety and risk. One of the pathways to achieve marketing authorisation is to demonstrate substantial equivalence (SE) with benchmark products, called predicates. However, the regulations are insufficiently transparent with regard to: a) a rationale for the cut-off date for 'old' and 'new' products, and for exempting the former from regulation; b) the scientific validity and operation of SE; c) options for product labelling to circumvent SE; d) the experimental data required to support, and criteria to judge, a claim; and e) a strategy for risk assessment/management. Scientific problems related to the traditional animal methods used in respiratory disease and inhalation toxicology, and the use of quantitative comparators of toxicity, such as the No Observed Adverse Effect Level, are discussed. We review the advantages of relevant in vitro, mechanism-based, target tissue-oriented technologies, which an advisory report of the Institute of Medicine of the US National Academy of Sciences largely overlooked. These benefits include: a) the availability, for every major site in the respiratory tract, of organotypic human cell-based tissue culture systems, many of which are already being used by the industry; b) the accurate determination of concentrations of test materials received by target cells; c) methods for exposure to particulate and vapour phases of smoke, separately or combined; d) the ability to study tissue-specific biotransformation; and e) the use of modern, human-focused methodologies, unaffected by species differences. How data extrapolation, for risk assessment, from tissue culture to the whole animal, could be addressed, is also discussed. A cost (to animal welfare)-benefit (to society, including industry and consumers) analysis was conducted, taking into account the above information; the potential for animal suffering; the extensive data already available; the existence of other, less hazardous forms of nicotine delivery; the fact that much data will be generated solely for benchmarking; and that many smokers (especially nicotine-dependents) ignore health warnings. It is concluded that, in common with policies of several tobacco companies and countries, the use of laboratory animals for tobacco testing is very difficult, if not impossible, to justify. Instead, we propose and argue for an integrated testing scheme, starting with extensive chemical analysis of the ingredients and by-products associated with the use of tobacco products and their toxicity, followed by use of in vitro systems and early clinical studies (involving specific biomarkers) with weight-of-evidence assessments at each stage. Appropriate adjustment factors could be developed to enable concentration-response data obtained in vitro, with the other information generated by the strategy, to enable the FDA to meet its objectives. It is hoped that our intentionally provocative ideas will stimulate further debate on this contentious area of regulatory testing and public safety.

Therapeutic Potential of 5-HT2C Receptor Agonists for Addictive Disorders

The neurotransmitter 5-hydroxytryptamine (5-HT; serotonin) has long been associated with the control of a variety of motivated behaviors, including feeding. Much of the evidence linking 5-HT and feeding behavior was obtained from studies of the effects of the 5-HT releaser (dex)fenfluramine in laboratory animals and humans. Recently, the selective 5-HT2C receptor agonist lorcaserin received FDA approval for the treatment of obesity. This review examines evidence to support the use of selective 5-HT2C receptor agonists as treatments for conditions beyond obesity, including substance abuse (particularly nicotine, psychostimulant, and alcohol dependence), obsessive compulsive, and excessive gambling disorder. Following a brief survey of the early literature supporting a role for 5-HT in modulating food and drug reinforcement, we propose that intrinsic differences between SSRI and serotonin releasers may have underestimated the value of serotonin-based pharmacotherapeutics to treat clinical forms of addictive behavior beyond obesity. We then highlight the critical involvement of the 5-HT2C receptor in mediating the effect of (dex)fenfluramine on feeding and body weight gain and the evidence that 5-HT2C receptor agonists reduce measures of drug reward and impulsivity. A recent report of lorcaserin efficacy in a smoking cessation trial further strengthens the idea that 5-HT2C receptor agonists may have potential as a treatment for addiction. This review was prepared as a contribution to the proceedings of the 11th International Society for Serotonin Research Meeting held in Hermanus, South Africa, July 9-12, 2014.

Reinforcer devaluation as a consequence of acute nicotine exposure and withdrawal

RATIONALE

Nicotine discontinuation produces behaviors in rats that are congruent with anhedonia, and these symptoms may be related to the devaluation of non-nicotine reinforcers.

OBJECTIVE

Four separate experiments were performed to explore the parameters surrounding nicotine-induced reinforcer devaluation.

METHODS

In Experiments 1 and 2, nicotine (0.1 or 0.3 mg/kg) or 0.3 mg/kg nicotine plus 1.0 mg/kg mecamylamine was delivered to rats prior to progressive ratio (PR) schedule sessions in which sucrose was used as a reinforcer. In order to evaluate (a) reinforcer enhancement by nicotine and (b) reinforcer devaluation in the absence of nicotine, all rats experienced two PR schedule sessions per day for 10 days. Experiment 3 involved nicotine (0.3 mg/kg) and a visual stimulus in place of sucrose reinforcement. In Experiment 4, rats received nicotine (0.3 mg/kg) either before or after a single PR schedule session for 10 days.

RESULTS

Experiments 1 and 2 demonstrate that reinforcer devaluation is related to the occupation of nicotinic-acetylcholine receptors. Results from Experiment 3 provide some evidence that devaluation occurs with either sucrose or visual-stimulus reinforcement. Experiment 4 demonstrates that a necessary condition for reinforcer devaluation to occur is the concurrent exposure to the reinforcer and nicotine.

CONCLUSIONS

Reinforcer devaluation in rats emerges rapidly in a progressive, orderly fashion that coincides with accumulated exposure to nicotine. These results suggest that reinforcer devaluation may be a feature of nicotine that contributes to the abuse liability of tobacco products.

Drug-dependent behaviors and nicotinic acetylcholine receptor expressions in Caenorhabditis elegans following chronic nicotine exposure

Nicotine, the major psychoactive compound in tobacco, targets nicotinic acetylcholine receptors (nAChRs) and results in drug dependence. The nematode Caenorhabditis elegans' (C. elegans) genome encodes conserved and extensive nicotinic receptor subunits, representing a useful system to investigate nicotine-induced nAChR expressions in the context of drug dependence. However, the in vivo expression pattern of nAChR genes under chronic nicotine exposure has not been fully investigated. To define the role of nAChR genes involved in nicotine-induced locomotion changes and the development of tolerance to these effects, we characterized the locomotion behavior combining the use of two systems: the Worm Tracker hardware and the WormLab software. Our results indicate that the combined system is an advantageous alternative to define drug-dependent locomotion behavior in C. elegans. Chronic (24-h dosing) nicotine exposure at 6.17 and 61.7μM induced nicotine-dependent behaviors, including drug stimulation, tolerance/adaption, and withdrawal responses. Specifically, the movement speed of naïve worms on nicotine-containing environments was significantly higher than on nicotine-free environments, suggesting locomotion stimulation by nicotine. In contrast, the 24-h 6.17μM nicotine-treated worms exhibited significantly higher speeds on nicotine-free plates than on nicotine-containing plates. Furthermore significantly increased locomotion behavior during nicotine cessation was observed in worms treated with a higher nicotine concentration of 61.7μM. The relatively low locomotion speed of nicotine-treated worms on nicotine-containing environments also indicates adaption/tolerance of worms to nicotine following chronic nicotine exposure. In addition, this study provides useful information regarding the comprehensive in vivo expression profile of the 28 "core" nAChRs following different dosages of chronic nicotine treatments. Eleven genes (lev-1, acr-6, acr-7, acr-11, lev-8, acr-14, acr-16, acr-20, acr-21, ric-3, and unc-29) were significantly up-regulated following 61.7μM nicotine treatment, in which worms showed significantly increased locomotion behavior. This study provides insights into the linkage between nicotine-induced locomotion behavior and the regulation of nicotinic acetylcholine receptors.

The tobacco endgame: it's all about behavior

One of the ten great public health achievements in the 20th century was turning the tide on one of the greatest public health disasters of that century: the tobacco use and related disease epidemic. The premature death and disease caused by tobacco can be considered largely as a side-effect of tobacco use behavior and the disease of addiction. The spread of that disease was fostered by an industry that researched the behavioral and biological basis of tobacco use and addiction and applied its findings and knowledge to develop products and marketing approaches to increase the likelihood that people, especially young people, would try tobacco products and develop persistent use and addiction. Researchers outside of the tobacco industry also investigated the behavioral biology of tobacco use and their research has been critical in turning the tide of the tobacco and disease epidemic. The behavioral factors are considered vital to understand and address by United States Food and Drug Administration and Surgeon General, as well as the World Health Organization in their tobacco control efforts. This commentary discusses key behavioral factors in the rise and fall of the epidemic, as well as some of those increasingly discussed as potential contributors to the endgame.

Association between cigarette smoking and the vaginal microbiota: a pilot study

Background

Smoking has been identified in observational studies as a risk factor for bacterial vaginosis (BV), a condition defined in part by decimation of Lactobacillus spp. The anti-estrogenic effect of smoking and trace amounts of benzo[a]pyrene diol epoxide (BPDE) may predispose women to BV. BPDE increases bacteriophage induction in Lactobacillus spp. and is found in the vaginal secretions of smokers. We compared the vaginal microbiota between smokers and non-smokers and followed microbiota changes in a smoking cessation pilot study.

Methods

In 2010–2011, 20 smokers and 20 non-smokers were recruited to a cross-sectional study (Phase A) and 9 smokers were enrolled and followed for a 12-week smoking cessation program (Phase B). Phase B included weekly behavioral counseling and nicotine patches to encourage smoking cessation. In both phases, participants self-collected mid-vaginal swabs (daily, Phase B) and completed behavioral surveys. Vaginal bacterial composition was characterized by pyrosequencing of barcoded 16S rRNA genes (V1-V3 regions). Vaginal smears were assigned Nugent Gram stain scores. Smoking status was evaluated (weekly, Phase B) using the semi-quantitative NicAlert® saliva cotinine test and carbon monoxide (CO) exhalation.

Results

In phase A, there was a significant trend for increasing saliva cotinine and CO exhalation with elevated Nugent scores (P value <0.005). Vaginal microbiota clustered into three community state types (CSTs); two dominated by Lactobacillus (L. iners, L. crispatus), and one lacking significant numbers of Lactobacillus spp. and characterized by anaerobes (termed CST-IV). Women who were observed in the low-Lactobacillus CST-IV state were 25-fold more likely to be smokers than those dominated by L. crispatus (aOR: 25.61, 95 % CI: 1.03-636.61). Four women completed Phase B. One of three who entered smoking cessation with high Nugent scores demonstrated a switch from CST-IV to a L.iners-dominated profile with a concomitant drop in Nugent scores which coincided with completion of nicotine patches. The other two women fluctuated between CST-IV and L. iners-dominated CSTs. The fourth woman had low Nugent scores with L. crispatus-dominated CSTs throughout.

Conclusion

Smokers had a lower proportion of vaginal Lactobacillus spp. compared to non-smokers. Smoking cessation should be investigated as an adjunct to reducing recurrent BV. Larger studies are needed to confirm these findings.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2334-14-471) contains supplementary material, which is available to authorized users.

Vaccination against smoking: an annotated agenda for debate. A review of scientific journals, 2001-13

BACKGROUND AND AIMS

The ongoing development of novel nicotine vaccines makes it urgent to identify the normative questions around this innovative health technology against smoking.

METHODS

A qualitative thematic analysis of peer-reviewed papers on nicotine vaccination published between 2001 and 2013.

RESULTS

In the scientific discourse, nicotine vaccination is presented in a neurobiological frame as a potent concept for (long-term) smoking cessation. Nicotine vaccination is also considered a hypothetical strategy to prevent nicotine addiction in minors. Ethical assessments are conducted for the use of nicotine vaccination in public health and clinical medicine. Whereas vaccination for primary prevention is usually associated with public health, the hypothetical case of nicotine prevention in minors is also assessed for individualized protection. Therapeutic and preventive applications are given uneven attention: the classic goal of vaccination (primary prevention in minors) receives methodical consideration and invokes lively debate. The unprecedented use of vaccination, namely smoking cessation, is left largely unattended in the ethical analyses.

CONCLUSIONS

While health innovations such as nicotine vaccination need broad reflection to guide decisions on their further development and possible future implementations, only a small part of the ethical and social issues of this innovative technology has been discussed. For a debate to come into existence, a 'neurobio-psycho-socio-cultural' frame of smoking and quitting appears fruitful. Important topics for reflection are the human activities and social processes in a vaccine-supported quit attempt, next to respect for individuals, possible harms and questions of (global) justice and research ethics.

Nicotine dependence and smoking habits in patients with head and neck cancer

OBJECTIVE

To assess smoking habits and nicotine dependence (ND) in patients with head and neck cancer Methods: This study involved 71 smokers or former smokers with squamous cell carcinoma in the oral cavity, pharynx, or larynx who were treated at a university hospital in the city of São Paulo between January and May of 2010. We used the Fagerström Test for Nicotine Dependence to evaluate smoking habits and ND in the sample. Data regarding cancer treatment were collected from medical records. Depending on the variables studied, we used the chi-square test, Fisher's exact test, Student's t-test, or Spearman's correlation test.

RESULTS

Of the 71 patients, 47 (66.2%) presented with high or very high ND, 40 (56.3%) smoked more than 20 cigarettes/day, and 32 (45.1%) smoked their first cigarette within 5 min of awakening. Advanced disease stage correlated significantly with the number of cigarettes smoked per day (p = 0.011) and with smoking history (p = 0.047). We found that ND did not correlate significantly with gender, disease stage, smoking cessation, or number of smoking cessation attempts, nor did the number of cigarettes smoked per day correlate with smoking cessation or gender. Treatment for smoking cessation was not routinely offered.

CONCLUSIONS

In most of the patients studied, the level of ND was high or very high. The prevalence of heavy smoking for long periods was high in our sample. A diagnosis of cancer is a motivating factor for smoking cessation. However, intensive smoking cessation treatment is not routinely offered to smoking patients diagnosed with cancer.

Effects of chronic varenicline treatment on nicotine, cocaine, and concurrent nicotine+cocaine self-administration

Nicotine dependence and cocaine abuse are major public health problems, and most cocaine abusers also smoke cigarettes. An ideal treatment medication would reduce both cigarette smoking and cocaine abuse. Varenicline is a clinically available, partial agonist at α4β2* and α6β2* nicotinic acetylcholine receptors (nAChRs) and a full agonist at α7 nAChRs. Varenicline facilitates smoking cessation in clinical studies and reduced nicotine self-administration, and substituted for the nicotine-discriminative stimulus in preclinical studies. The present study examined the effects of chronic varenicline treatment on self-administration of IV nicotine, IV cocaine, IV nicotine+cocaine combinations, and concurrent food-maintained responding by five cocaine- and nicotine-experienced adult rhesus monkeys (Macaca mulatta). Varenicline (0.004-0.04 mg/kg/h) was administered intravenously every 20 min for 23 h each day for 7-10 consecutive days. Each varenicline treatment was followed by saline-control treatment until food- and drug-maintained responding returned to baseline. During control treatment, nicotine+cocaine combinations maintained significantly higher levels of drug self-administration than nicotine or cocaine alone (P<0.05-0.001). Varenicline dose-dependently reduced responding maintained by nicotine alone (0.0032 mg/kg/inj) (P<0.05), and in combination with cocaine (0.0032 mg/kg/inj) (P<0.05) with no significant effects on food-maintained responding. However, varenicline did not significantly decrease self-administration of a low dose of nicotine (0.001 mg/kg), cocaine alone (0.0032 and 0.01 mg/kg/inj), or 0.01 mg/kg cocaine combined with the same doses of nicotine. We conclude that varenicline selectively attenuates the reinforcing effects of nicotine alone but not cocaine alone, and its effects on nicotine+cocaine combinations are dependent on the dose of cocaine.

Alcohol, nicotine, and iatrogenic withdrawals in the ICU

OBJECTIVES

The neurophysiology, risk factors, and screening tools associated with alcohol withdrawal syndrome in the ICU are reviewed. Alcohol withdrawal syndrome assessment and its treatment options are discussed. Description of nicotine withdrawal and related publications specific to the critically ill are also reviewed. A brief comment as to sedative and opiate withdrawal follows.

DATA AND SUMMARY

The role of currently published alcohol withdrawal syndrome pharmacologic strategies (benzodiazepines, ethanol, clomethiazole, antipsychotics, barbiturates, propofol, and dexmedetomidine) is detailed. Studies on nicotine withdrawal management in the ICU focus mainly on the safety (mortality) of nicotine replacement therapy. Study characteristics and methodological limitations are presented.

CONCLUSION

We recommend a pharmacologic regimen titrated to withdrawal symptoms in ICU patients with alcohol withdrawal syndrome. Benzodiazepines are a reasonable option; phenobarbital appears to confer some advantages in combination with benzodiazepines. Propofol and dexmedetomidine have not been rigorously tested in comparative studies of drug withdrawal treatment; their use as additional or alternative strategies for managing withdrawal syndromes in ICU patients should therefore be individualized to each patient. Insufficient data preclude recommendations as to nicotine replacement therapy and management of iatrogenic drug withdrawal in ICU patients.

Neural bases of pharmacological treatment of nicotine dependence - insights from functional brain imaging: a systematic review

BACKGROUND

Nicotine dependence is difficult to treat, and the biological mechanisms that are involved are not entirely clear. There is an urgent need to develop better drugs and more effective treatments for clinical practice. A critical step towards accelerating progress in medication development is to understand the neurobehavioral effects of pharmacotherapies on clinical characteristics associated with nicotine dependence.

OBJECTIVES

This review sought to summarize the functional magnetic resonance imaging (fMRI) literature on smoking cessation with the aim to better understand the neural processes underlying the effects of nicotinic and non-nicotinic pharmacological smoking cessation treatments on specific symptoms of nicotine dependence and withdrawal.

DATA SOURCES

We conducted a search in Pubmed, Web of Science and PsycINFO databases with the keywords 'fMRI' or 'functional magnetic resonance imaging' and 'tobacco' or 'nicotine' or 'smok*'. The date of the most recent search was May 2012.

STUDY ELIGIBILITY CRITERIA, PARTICIPANTS AND INTERVENTIONS

The original studies that were included were those of smokers or nicotine-dependent individuals, published in the English language, with pharmacological treatment for nicotine dependence and use of fMRI with blood oxygen level-dependent (BOLD) imaging or continuous arterial spin labelling (CASL). No date limit was applied.

STUDY APPRAISAL AND SYNTHESIS METHODS

Two of the authors read the abstracts of all studies found in the search (n = 1,260). The inclusion and exclusion criteria were applied, and 1,224 articles were excluded. In a second step, the same authors read the remaining 36 studies. Nineteen of the 36 articles were excluded. The results were tabulated by the number of individuals and their mean age, the main sample characteristics, smoking status, study type and methodology, and the main fMRI findings.

RESULTS

Seventeen original fMRI studies involving pharmacological treatment of smokers were selected. The anterior and posterior cingulate cortex, medial and lateral orbitofrontal cortex, ventral striatum, amygdala, thalamus and insula are heavily involved in the maintenance of smoking and nicotine withdrawal. The effects of varenicline and bupropion in alleviating withdrawal symptoms and decreasing smoking correlated with modulation of the activities of these areas. Nicotine replacement therapy seems to improve cognitive symptoms related to withdrawal especially by modulating activities of the default-network regions; however, nicotine replacement does not necessarily alter the activities of neural circuits, such as the cingulate cortices, that are associated with nicotine addiction.

LIMITATIONS

The risk of bias in individual studies, and across studies, was not assessed, and no method of handling data and combining results of studies was carried out. Most importantly, positron emission tomography (PET) studies were not included in this review.

CONCLUSIONS AND IMPLICATION OF KEY FINDINGS

fMRI studies delineate brain systems that contribute to cognitive deficits and reactivity to stimuli that generate the desire to smoke. Nicotinic and non-nicotinic pharmacotherapy may reduce smoking via distinct neural mechanisms of action. These findings should contribute to the development of new medications and discovery of early markers of the therapeutic response of cigarette smokers.

Ear acupressure for smoking cessation: a randomised controlled trial

This study investigated the efficacy and safety of ear acupressure (EAP) as a stand-alone intervention for smoking cessation and the feasibility of this study design. Adult smokers were randomised to receive EAP specific for smoking cessation (SSEAP) or a nonspecific EAP (NSEAP) intervention which is not typically used for smoking cessation. Participants received 8 weekly treatments and were requested to press the five pellets taped to one ear at least three times daily. Participants were followed up for three months. Primary outcome measures were a 7-day point-prevalence cessation rate confirmed by exhaled carbon monoxide and relief of nicotine withdrawal symptoms (NWS). Intention-to-treat analysis was applied. Forty-three adult smokers were randomly assigned to SSEAP (n = 20) or NSEAP (n = 23) groups. The dropout rate was high with 19 participants completing the treatments and 12 remaining at followup. One participant from the SSEAP group had confirmed cessation at week 8 and end of followup (5%), but there was no difference between groups for confirmed cessation or NWS. Adverse events were few and minor.

From obesity to substance abuse: therapeutic opportunities for 5-HT2C receptor agonists

The recent US Food and Drug Administration (FDA) approval of the serotonin (5-hydroxytryptamine, 5-HT) 5-HT2C receptor agonist lorcaserin for the treatment of obesity represents a new therapeutic drug class available to the clinic. Preclinical evidence supports the potential for this drug class to treat other related conditions such as substance abuse. In the present article we review this evidence and further suggest that overlapping neurobiological systems may contribute to an anti-addictive and anti-obesity profile. The availability of selective 5-HT2C agonists provides an opportunity to evaluate their potential as treatments for nicotine dependence or psychostimulant abuse, conditions for which there is significant medical need but only limited available treatment options.

Ear acupressure for smoking cessation: study protocol for a randomised controlled trial

BACKGROUND

Smoking is the largest preventable cause of death and disease worldwide but smokers often fail to quit due to nicotine withdrawal symptoms. Current available pharmaceutical therapies may assist with smoking cessation but may have side effects. Ear acupressure (EAP) and ear acupuncture have been used for smoking cessation, and some positive results have been reported. The aim of the study is to assess the efficacy and safety of EAP in assisting individuals to quit smoking and/or support them in the management of nicotine withdrawal symptoms.

METHODS

This study will be a randomised, single-blind, sham-controlled study conducted at RMIT University in Melbourne, Australia. Adult smokers will be randomly assigned to receive EAP specifically for smoking cessation or nonspecific EAP treatments. After a 2-week run-in, participants will be treated once a week for 8 weeks and followed up for 12 weeks. The primary outcome measures will be 7 day point-prevalence cessation rate by self-report validated by expired carbon monoxide and nicotine withdrawal symptoms measured by the Mood and Physical Symptoms Score questionnaire. Secondary outcomes will be self-reported usage of nicotine replacement therapies, cigarette consumption, body weight change and quality of life. The safety end point will be self-reported adverse events associated with EAP. Intention-to-treat analysis will be applied.

DISCUSSION

Findings from this study will determine if this EAP intervention alone can be an effective and safe therapy to assist with smoking cessation and the management of nicotine withdrawal symptoms.

Evaluation of chemically diverse 5-HT₂c receptor agonists on behaviours motivated by food and nicotine and on side effect profiles

RATIONALE

Selective 5-HT2C receptor agonists, such as lorcaserin, are being developed for the treatment of obesity. Studies suggest that they may also have therapeutic potential for addictive behaviours including nicotine dependence, although few drugs of this class have been evaluated.

OBJECTIVES

The primary aim was to evaluate the highly selective 5-HT2C agonist, CP-809101, against food-motivated (operant FR5 and progressive ratio schedules, palatability-induced feeding) and nicotine-motivated (intravenous self-administration, drug discrimination) behaviours in rats and to compare with equivalent findings for the structurally distinct 5-HT2C receptor agonists lorcaserin and Ro 60-0175. The secondary aims were to evaluate the side effect profiles of lorcaserin and CP-809101 and to determine the plasma levels of lorcaserin at a dose (1 mg/kg) that reduces both food and nicotine reinforcement for comparison to plasma concentrations reported in human trials.

RESULTS

CP-809101 (0.3-3 mg/kg SC) reduced responding for both nicotine and food and blocked the discriminative stimulus properties of nicotine in a similar manner to lorcaserin and Ro 60-0175. Behaviours such as hypolocomotion, chewing and ptosis became evident following both CP-809101 and lorcaserin administration at higher doses. Plasma levels of lorcaserin were of similar range to those reported in obesity trials.

CONCLUSIONS

These studies support the utility of 5-HT2C agonists as a therapeutic approach to treat nicotine dependence. Plasma exposure levels after acute lorcaserin treatment suggest that equivalent dosages could be used to evaluate these drugs in obesity and smoking cessation trials. Finally, there may be differences in the side effect profiles between lorcaserin and CP-809101, raising the possibility for tolerability differences amongst 5-HT2C agonists.

[Tobacco use and illicit substance use disorders: what should we have to do?]

Tobacco use is a commonplace phenomenon in our society. Its use is responsible for more death and disease than any other noninfectious cause. More deaths are caused each year by tobacco use than by all deaths from HIV, illegal drug use, alcohol use, motor vehicle injuries, suicides, and murders combined. Tobacco remains responsible for greater morbidity than alcohol and all other drugs combined. Tobacco dependence is highly prevalent among drug-dependent patients. Substance abuse patients smoke more and are more vulnerable to the effects of smoking than general populations. Traditional substance abuse therapeutic programs too frequently focus only on treatment of alcohol or other drugs rather than including treatment for tobacco dependence. Currently, there are no official medical recommendations for the treatment of tobacco addiction in illicit polysubstance users.

METHODS

A comprehensive literature search from a range of electronic databases (PubMed, Embase, PsycInfo, Google Scholar) was conducted for the period from 1988 to September 2012, using the following keywords alone or in combination: tobacco, nicotine, cocaine, cannabis, amphetamines, opiates, substance abuse, substance dependence, addiction, treatment. There were no restrictions on the identification or inclusion of studies in terms of publication status, language and design type.

RESULTS

Our literature review will focus on epidemiological, neurobiological, clinical interactions between tobacco, alcohol and other illicit drugs. It will also focus on therapeutic programs in this dual addictive disorder. The aim of this literature review is to make proposals for the treatment of tobacco addiction in polysubstance users entering in specific therapeutic programs.

Urge to smoke over 52 weeks of abstinence

RATIONALE

Cigarette cravings are well documented during the first weeks of smoking abstinence. Treatments focus on helping smokers reduce these acute cravings. Cravings experienced later on are less well understood and may be important when considering treatment duration.

OBJECTIVE

We conducted a longitudinal study of cravings over 52 weeks of smoking abstinence.

METHODS

Cravings were operationalised as strength of, and time spent with, urges to smoke. These were assessed among 452 smokers quitting with behavioural support but without pharmacotherapies. Individuals maintaining abstinence were assessed at 1, 2, 3, 4, 26 and 52 weeks after quitting (n = 197, 156, 139, 131, 66 and 38, respectively). Abstinence was validated at each assessment by expired carbon monoxide. Time courses were plotted for those abstinent for 52 weeks and for those abstinent up to earlier time points. Correlations were examined between ratings of urges at consecutive time points.

RESULTS

Ratings of strength of urges to smoke followed an exponential decline over 52 weeks of abstinence, but 6 months after quitting 13 % of ex-smokers still reported strong urges. At 12 months, no ex-smokers reported strong urges, although 34 % reported some urges. Strength of urges to smoke after 1, 2, 3 and 4 weeks of abstinence predicted strength of urges at 6 months.

CONCLUSIONS

Strength of urges to smoke decline exponentially over time following smoking cessation, though some smokers report strong urges after 6 months of abstinence, and urges are still reported by a third of smokers after 12 months. Relapse prevention treatments may need to target prolonged craving.

Transcranial direct current stimulation reduces negative affect but not cigarette craving in overnight abstinent smokers

Transcranial direct current stimulation (tDCS) can enhance cognitive control functions including attention and top-down regulation over negative affect and substance craving in both healthy and clinical populations, including early abstinent (∼1.5 h) smokers. The aim of this study was to assess whether tDCS modulates negative affect, cigarette craving, and attention of overnight abstinent tobacco dependent smokers. In this study, 24 smokers received a real and a sham session of tDCS after overnight abstinence from smoking on two different days. We applied anode to the left dorsolateral prefrontal cortex and cathode to the right supra-orbital area for 20 min with a current of 2.0 mA. We used self-report questionnaires Profile of Mood States (POMS) to assess negative affect and Urge to Smoke (UTS) Scale to assess craving for cigarette smoking, and a computerized visual target identification task to assess attention immediately before and after each tDCS. Smokers reported significantly greater reductions in POMS scores of total mood disturbance and scores of tension-anxiety, depression-dejection, and confusion-bewilderment subscales after real relative to sham tDCS. Furthermore, this reduction in negative affect positively correlated with the level of nicotine dependence as assessed by Fagerström scale. However, reductions in cigarette craving after real vs. sham tDCS did not differ, nor were there differences in reaction time or hit rate change on the visual task. Smokers did not report significant side effects of tDCS. This study demonstrates the safety of tDCS and its promising effect in ameliorating negative affect in overnight abstinent smokers. Its efficacy in treating tobacco dependence deserves further investigation.

The 5-HT2C receptor agonist lorcaserin reduces nicotine self-administration, discrimination, and reinstatement: relationship to feeding behavior and impulse control

Lorcaserin ((1R)-8-chloro-1-methyl-2,3,4,5-tetrahydro-1H-3-benzazepine HCl) is a selective 5-HT(2C) receptor agonist with clinical efficacy in phase-III obesity trials. Based on evidence that this drug class also affects behaviors motivated by drug reinforcement, we compared the effect of lorcaserin on behavior maintained by food and nicotine reinforcement, as well as the stimulant and discriminative stimulus properties of nicotine in the rat. Acutely administered lorcaserin (0.3-3 mg/kg, subcutaneous (SC)) dose dependently reduced feeding induced by 22-h food deprivation or palatability. Effects up to 1 mg/kg were consistent with a specific effect on feeding motivation. Lorcaserin (0.6-1 mg/kg, SC) reduced operant responding for food on progressive and fixed ratio schedules of reinforcement. In this dose range lorcaserin also reversed the motor stimulant effect of nicotine, reduced intravenous self-administration of nicotine, and attenuated the nicotine cue in rats trained to discriminate nicotine from saline. Lorcaserin also reduced the reinstatement of nicotine-seeking behavior elicited by a compound cue comprising a nicotine prime and conditioned stimulus previously paired with nicotine reinforcement. Lorcaserin did not reinstate nicotine-seeking behavior or substitute for a nicotine cue. Finally, lorcaserin (0.3-1 mg/kg) reduced nicotine-induced increases in anticipatory responding, a measure of impulsive action, in rats performing the five-choice serial reaction time task. Importantly, these results indicate that lorcaserin, and likely other selective 5-HT(2C) receptor agonists, similarly affect both food- and nicotine-motivated behaviors, and nicotine-induced impulsivity. Collectively, these findings highlight a therapeutic potential for 5-HT(2C) agonists such as lorcaserin beyond obesity into addictive behaviors, such as nicotine dependence.

The dynamics of the urge-to-smoke following smoking cessation via pharmacotherapy

AIMS

To examine person-specific urge-to-smoke trajectories during the first 7 days of abstinence and the relationship of trajectory parameters to continuous abstinence, demographics, medication and smoking history.

DESIGN

Hierarchical linear modeling was used to model person-specific trajectories for urge-to-smoke.

SETTING

Two university-based smoking cessation trials.

PARTICIPANTS

Treatment-seeking smokers in a clinical trial of transdermal nicotine (n = 275) versus nicotine spray (n = 239) and of bupropion (n = 223) versus placebo (n = 198).

MEASUREMENTS

Self-reported urge-to-smoke for 7 days after the planned quit date, and 7-day point prevalence and continuous abstinence at end of treatment (EOT) and 6 months.

FINDINGS

Urge-to-smoke trajectory parameters (average level, slope, curvature and volatility) varied substantially among individuals, had modest intercorrelations and predicted continuous and point prevalence abstinence at EOT and at 6 months. Higher trajectory level, slope and volatility were all significantly (P ≤ 0.001) associated with a reduced likelihood of abstinence at EOT (odds ratios 0.44-0.75) and at 6-month follow-up (odds ratios from 0.63 to 0.78), controlling for demographic, medication and smoking use variables.

CONCLUSION

Higher urge-to-smoke trajectory parameters of level, slope and volatility (measured over 7 days) predict continuous and 7-day point prevalence at EOT and 6 months. Although there were some associations of trajectory parameters with demographics and smoking history, the associations of trajectory parameters with relapse were relatively uninfluenced by demographics and smoking history.

Nicotine replacement therapy after subarachnoid hemorrhage is not associated with increased vasospasm

BACKGROUND AND PURPOSE

A significant number of patients with aneurysmal subarachnoid hemorrhage are active smokers and at risk for acute nicotine withdrawal. There is conflicting literature regarding the vascular effects of nicotine and theoretical concern that it may worsen vasospasm. The literature on the safety of nicotine replacement therapy and its effects on vasospasm is limited.

METHODS

A retrospective analysis was conducted of a prospectively collected database of aneurysmal subarachnoid hemorrhage patients admitted to the neurointensive care unit from 1994 to 2008. Paired control subjects matched for age, sex, Fisher score, aneurysm size and number, hypertension, and current medication were analyzed. The primary outcome was clinical and angiographic vasospasm and the secondary outcome was Glasgow Outcome Score on discharge. Conditional logistic models were used to investigate univariate and multivariate relationships between predictors and outcome.

RESULTS

Two hundred fifty-eight active smoking patients were included of which 87 were treated with transdermal nicotine replacement therapy. Patients were well matched for age, sex, gender, Fisher score, aneurysm size and number, hypertension, and current medications, but patients who received nicotine replacement therapy had less severe Hunt-Hess scores and Glasgow coma scores. There was no difference in angiographic vasospasm, but patients who received nicotine replacement therapy were less likely to have clinical vasospasm (19.5 versus 32.8%; P=0.026) and a Glasgow Outcome Score <4 on discharge (62.6% versus 81.6%; P=0.005) on multivariate analysis.

CONCLUSIONS

Nicotine replacement therapy was not associated with increased angiographic vasospasm and was associated with less clinical vasospasm and better Glasgow Outcome Score scores on discharge.

Varenicline for tobacco dependence: panacea or plight?

INTRODUCTION

This review examines the postmarketing experience with varenicline, including case reports, newer clinical trials and secondary analyses of large clinical datasets.

AREAS COVERED

Varenicline has been shown to be an effective treatment in a broad range of tobacco users with medical, behavioral and diverse demographic characteristics. Recent studies finding excellent safety and efficacy in groups of smokers with diseases including chronic obstructive pulmonary disease are particularly encouraging and call for increased use of this medication for smoking cessation. Despite case reports of serious neuropsychiatric symptoms in patients taking varenicline, including changes in behavior and mood, causality has not been established. Recent analyses of large datasets from clinical trials have not demonstrated that varenicline is associated with more depression or suicidality than other treatments for smoking cessation.

EXPERT OPINION

Now that additional clinical trials in specific populations and observational studies on treatment-seeking smokers outside of clinical trials have been published, we can be confident that varenicline remains the most efficacious monotherapy for smoking cessation and that its side-effect profile remains good. The risk-to-benefit ratio of receiving varenicline to quit smoking must include the increased chances of quitting smoking and avoiding the sizeable risks of smoked-caused disease and death that remain if tobacco addiction is not properly treated.

Pharmacotherapy for smoking cessation: current advances and research topics

Promoting smoking cessation is among the key medical interventions aimed at reducing worldwide morbidity and mortality in this century. Both behavioural counselling and pharmacotherapy have been shown to significantly increase long-term abstinence rates, and combining the two treatment modalities is recommended. This article provides an update on pharmacotherapy for smoking cessation in the general population. Current first-line agents used to support quit attempts are nicotine replacement therapy (NRT), bupropion and varenicline. Research suggests that abstinence rates can be increased by combining different forms of NRT or simultaneously administering NRT and non-nicotine medications. New treatments targeting the nicotinic acetylcholine receptor as well as other pathophysiological pathways involved in nicotine addiction are being developed, with nicotine vaccines now being tested in phase III clinical trials. Among the numerous research topics currently addressed, pharmacogenetics and tailoring therapy to specific groups of smokers look most promising. However, substantial progress is unlikely to be made unless social gradients impeding effective treatment of all smokers are overcome. In addition, public smoking bans and reimbursement of medication costs are crucial in reducing the future burden of disease caused by smoking on a global level.

Brain nicotinic receptors as emerging targets for drug addiction: neurobiology to translational research

Drug addiction, a chronic relapsing disorder, is a serious public health problem around the world. A growing body of preclinical and clinical evidence suggests that mammalian brain nicotinic acetylcholine receptors (nAChRs), the heterogeneous family of ion channels, play a pivotal role in drug addiction, including nicotine and alcohol dependence. As a result, there is an increasing interest in developing nAChR-based therapies for the treatment of addictive disorders. The current review summarizes the important preclinical and clinical data, demonstrating the ability of nAChR ligands to modulate nicotine and alcohol-induced biobehavioral and neurochemical changes in laboratory animals and humans. Recent studies suggest that partial agonists and antagonists at nAChRs have therapeutic potential for the management of nicotine and alcohol dependence. The complexity of nAChRs and their regulation for the development of nAChR-based drug candidates as novel pharmacotherapy for other addictive disorders will also be discussed. Taken together, this review will provide new insights into nAChR-based compounds and offer innovative translational strategies for combating drug addictive disorders.

The noradrenergic action in antidepressant treatments: pharmacological and clinical aspects

Even though noradrenaline has been recognized as one of the key neurotransmitters in the pathophysiology of major depression (MD), noradrenergic compounds have been less extensively utilized in clinical practice, compared to selective serotonin reuptake inhibitors (SSRIs). The development of the first selective noradrenergic reuptake inhibitor (NRI), Reboxetine, has not substantially changed the state of the art. In addition, Atomoxetine, a relatively pure NRI used for the treatment of ADHD, has shown mixed results when administered in augmentation to depressed subjects. Through a Medline search from 2000 to 2010, the present article provides an updated overview of the main pharmacological and clinical aspects of antidepressant classes that, partially or selectively, act on the noradrenergic systems. The noradrenergic action plays an important clinical effect in different antidepressant classes, as confirmed by the efficacy of dual action antidepressants such as the serotonin noradrenaline reuptake inhibitors (SNRIs), the noradrenergic and dopaminergic reuptake inhibitor (NDRI) Bupropion, and other compounds (e.g., Mianserin, Mirtazapine), which enhance the noradrenergic transmission. In addition, many tricyclics, such as Desipramine and Nortriptyline, have prevalent noradrenergic effect. Monoamine oxidase inhibitors (MAOIs), moreover, block the breakdown of serotonin, noradrenaline, dopamine and increase the availability of these monoamines. A novel class of antidepressants--the triple reuptake inhibitors--is under development to selectively act on serotonin, noradrenaline, and dopamine. Finally, the antidepressant effect of the atypical antipsychotic Quetiapine, indicated for the treatment of bipolar depression, is likely to be related to the noradrenergic action of its metabolite Norquetiapine. Even though a pure noradrenergic action might not be sufficient to obtain a full antidepressant effect, a pronoradrenergic action represents an important element for increasing the efficacy of mixed action antidepressants. In particular, the noradrenergic action seemed to be related to the motor activity, attention, and arousal.

Role of progesterone in nicotine addiction: evidence from initiation to relapse

Nicotine addiction continues to be the main cause of preventable death in developed countries. Women and teen girls appear to be more vulnerable on certain aspects of nicotine addiction compared with men and boys. While the mechanism of gender differences in nicotine addiction is not yet clear, evidence suggests that while estrogen may underlie enhanced vulnerability in females, progesterone may protect females. Thus, progesterone may have therapeutic use for tobacco addiction, especially in female smokers. A greater understanding of the role of progesterone in nicotine addiction is important not only from a treatment standpoint, but also from a prevention standpoint: hormone transition phases, such as those that occur at adolescence, and during pregnancy and following birth, as well as following hormonal manipulation (e.g., using methods of hormonal birth control), may all contribute to changes in vulnerability to nicotine addiction. In this review, we summarize recent evidence from clinical and preclinical studies examining the role of progesterone in nicotine addiction focusing on its role during initiation of use and during later phases of the addiction process as a potential relapse prevention treatment. We conclude with future directions including further examination of progesterone as a potential intervention and treatment of nicotine addiction.

Nicotine reduction revisited: science and future directions

Regulation of nicotine levels in cigarettes and other tobacco products is now possible with the passage of the Family Smoking Prevention and Tobacco Control Act (FSPTCA) in 2009, giving the US Food and Drug Administration (FDA) authority to regulate tobacco products, and with Articles 9-11 of the WHO Framework Convention on Tobacco Control. Both regulatory approaches allow establishing product standards for tobacco constituents, including nicotine. The FSPTCA does not allow nicotine levels to be decreased to zero, although the FDA has the authority to reduce nicotine yields to very low, presumably non-addicting levels. The proposal to reduce levels of nicotine to a level that is non-addicting was originally suggested in 1994. Reduction of nicotine in tobacco products could potentially have a profound impact on reducing tobacco-related morbidity and mortality. To examine this issue, two meetings were convened in the US with non-tobacco-industry scientists of varied disciplines, tobacco control policymakers and representatives of government agencies. This article provides an overview of the current science in the area of reduced nicotine content cigarettes and key conclusions and recommendations for research and policy that emerged from the deliberations of the meeting members.

Meta-analysis of the acute effects of nicotine and smoking on human performance

RATIONALE AND OBJECTIVE

Empirical studies indicate that nicotine enhances some aspects of attention and cognition, suggesting a role in the maintenance of tobacco dependence. The purpose of this review was to update the literature since our previous review (Heishman et al. Exp Clin Psychopharmacol 2:345-395, 1994) and to determine which aspects of human performance were most sensitive to the effects of nicotine and smoking.

METHODS

We conducted a meta-analysis on the outcome measures of 41 double-blind, placebo-controlled laboratory studies published from 1994 to 2008. In all studies, nicotine was administered, and performance was assessed in healthy adult nonsmokers or smokers who were not tobacco-deprived or minimally deprived (

RESULTS

There were sufficient effect size data to conduct meta-analyses on nine performance domains, including motor abilities, alerting and orienting attention, and episodic and working memory. We found significant positive effects of nicotine or smoking on six domains: fine motor, alerting attention-accuracy and response time (RT), orienting attention-RT, short-term episodic memory-accuracy, and working memory-RT (effect size range = 0.16 to 0.44).

CONCLUSIONS

The significant effects of nicotine on motor abilities, attention, and memory likely represent true performance enhancement because they are not confounded by withdrawal relief. The beneficial cognitive effects of nicotine have implications for initiation of smoking and maintenance of tobacco dependence.

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Key Words

• nicotine
• tobacco
• smoking
• performance
• motor
• attention
• memory
• cognition
• smokers
• nonsmokers

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MESH Headings

• Attention/drug effects
• Dose-Response Relationship, Drug
• Humans
• Memory/drug effects
• Motor Skills/drug effects
• Nicotine/administration & dosage
• Nicotine/pharmacology
• Psychomotor Performance/drug effects
• Smoking/psychology

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Grants

• T32 DA007209 NIDA NIH HHS
• ZIA DA000483-06 Intramural NIH HHS
• ZIA DA000484-06 Intramural NIH HHS
• T32DA007209-29 NIDA NIH HHS

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Affiliation(s)

Stephen J Heishman Nicotine Psychopharmacology Section, National Institute on Drug Abuse, NIH Intramural Research Program, 251 Bayview Blvd., Baltimore, MD 21224, USA.
Bethea A Kleykamp
Edward G Singleton

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Noradrenergic alpha1 receptors as a novel target for the treatment of nicotine addiction

Nicotine is the main psychoactive ingredient in tobacco and its rewarding effects are considered primarily responsible for persistent tobacco smoking and relapse. Although dopamine has been extensively implicated in the rewarding effects of nicotine, noradrenergic systems may have a larger role than previously suspected. This study evaluated the role of noradrenergic alpha(1) receptors in nicotine and food self-administration and relapse, nicotine discrimination, and nicotine-induced dopamine release in the nucleus accumbens in rats. We found that the noradrenergic alpha(1) receptor antagonist prazosin (0.25-1 mg/kg) dose dependently reduced the self-administration of nicotine (0.03 mg/kg), an effect that was maintained over consecutive daily sessions; but did not reduce food self-administration. Prazosin also decreased reinstatement of extinguished nicotine seeking induced by either a nicotine prime (0.15 mg/kg) or nicotine-associated cues, but not food-induced reinstatement of food-seeking, and decreased nicotine-induced (0.15 mg/kg) dopamine release in the nucleus accumbens shell. However, prazosin did not have nicotine-like discriminative effects and did not alter the dose-response curve for nicotine discrimination. These findings suggest that stimulation of noradrenergic alpha(1) receptors is involved in nicotine self-administration and relapse, possibly via facilitation of nicotine-induced activation of the mesolimbic dopaminergic system. The findings point to alpha(1) adrenoceptor blockade as a potential new approach to the treatment of tobacco dependence in humans.

The effects of the mGluR5 receptor antagonist 6-methyl-2-(phenylethynyl)-pyridine (MPEP) on behavioural responses to nicotine

RATIONALE

Previous studies have shown that blockade of metabotropic glutamate 5 receptors (mGluR5) results in inhibition of nicotine self-administration in experimental animals. However, these studies have not established the behavioural mechanisms which mediate these effects or the extent to which the effects of mGluR5 antagonism on nicotine self-administration reflect a selective attenuation of nicotine reinforcement.

OBJECTIVES

To investigate the effects of antagonising mGluR5 receptors on psychopharmacological responses to nicotine measured using conditioned and unconditioned behaviours.

RESULTS

2-Methyl-6-(phenylethynyl)-pyridine (MPEP) significantly (P < 0.01) reduced nicotine self-administration and attenuated (P < 0.01) the ability of non-contingent nicotine to enhance the reinforcing properties of a weak reinforcer (extinguishing the house light in an operant chamber). It also attenuated (P < 0.05) the much lower levels of responding for this reinforcer measured in control animals treated with saline. MPEP did not attenuate the increase in locomotor activity induced by acute and repeated nicotine in animals habituated on the test day to the test environment. Furthermore, it had no significant effects on responding for a palatable food reward. By contrast, MPEP significantly reduced (P < 0.001) conditioned locomotor stimulation evoked by pairing nicotine with a specific environment.

CONCLUSION

The results are consistent with the hypothesis that mGluR5 receptors play an important role in mediating the effects of contextual cues in conditioned behavioural responses to nicotine.

Modeling withdrawal syndrome in zebrafish

The zebrafish (Danio rerio) is rapidly becoming a popular model species in behavioral neuroscience research. Zebrafish behavior is robustly affected by environmental and pharmacological manipulations, and can be examined using exploration-based paradigms, paralleled by analysis of endocrine (cortisol) stress responses. Discontinuation of various psychotropic drugs evokes withdrawal in both humans and rodents, characterized by increased anxiety. Sensitivity of zebrafish to drugs of abuse has been recently reported in the literature. Here we examine the effects of ethanol, diazepam, morphine and caffeine withdrawal on zebrafish behavior. Overall, discontinuation of ethanol, diazepam and morphine produced anxiogenic-like behavioral or endocrine responses, demonstrating the utility of zebrafish in translational research of withdrawal syndrome.