Cannabinoid type 1 receptor antagonists (rimonabant) for smoking cessation

The endocannabinoidome in neuropsychiatry: Opportunities and potential risks

The endocannabinoid system (ECS) comprises two cognate endocannabinoid receptors referred to as CB1R and CB2R_. ECS dysregulation is apparent in neurodegenerative/neuro-psychiatric disorders including but not limited to schizophrenia, major depressive disorder and potentially bipolar disorder. The aim of this paper is to review mechanisms whereby both receptors may interact with neuro-immune and neuro-oxidative pathways, which play a pathophysiological role in these disorders. CB1R is located in the presynaptic terminals of GABAergic, glutamatergic, cholinergic, noradrenergic and serotonergic neurons where it regulates the retrograde suppression of neurotransmission. CB1R plays a key role in long-term depression, and, to a lesser extent, long-term potentiation, thereby modulating synaptic transmission and mediating learning and memory. Optimal CB1R activity plays an essential neuroprotective role by providing a defense against the development of glutamate-mediated excitotoxicity, which is achieved, at least in part, by impeding AMPA-mediated increase in intracellular calcium overload and oxidative stress. Moreover, CB1R activity enables optimal neuron-glial communication and the function of the neurovascular unit. CB2R receptors are detected in peripheral immune cells and also in central nervous system regions including the striatum, basal ganglia, frontal cortex, hippocampus, amygdala as well as the ventral tegmental area. CB2R upregulation inhibits the presynaptic release of glutamate in several brain regions. CB2R activation also decreases neuroinflammation partly by mediating the transition from a predominantly neurotoxic "M1" microglial phenotype to a more neuroprotective "M2" phenotype. CB1R and CB2R are thus novel drug targets for the treatment of neuro-immune and neuro-oxidative disorders including schizophrenia and affective disorders.

Cannabinoids and Epilepsy

Cannabis has been used for centuries to treat seizures. Recent anecdotal reports, accumulating animal model data, and mechanistic insights have raised interest in cannabis-based antiepileptic therapies. In this study, we review current understanding of the endocannabinoid system, characterize the pro- and anticonvulsive effects of cannabinoids [e.g., Δ9-tetrahydrocannabinol and cannabidiol (CBD)], and highlight scientific evidence from pre-clinical and clinical trials of cannabinoids in epilepsy. These studies suggest that CBD avoids the psychoactive effects of the endocannabinoid system to provide a well-tolerated, promising therapeutic for the treatment of seizures, while whole-plant cannabis can both contribute to and reduce seizures. Finally, we discuss results from a new multicenter, open-label study using CBD in a population with treatment-resistant epilepsy. In all, we seek to evaluate our current understanding of cannabinoids in epilepsy and guide future basic science and clinical studies.

Translational strategies for therapeutic development in nicotine addiction: rethinking the conventional bench to bedside approach

Tobacco produces an impressive burden of disease resulting in premature death in half of users. Despite effective smoking cessation medications (nicotine replacement therapies, bupropion and varenicline), there is a very high rate of relapse following quit attempts. The use of efficient strategies for the development of novel treatments is a necessity. A 'bench to bedside strategy' was initially used to develop cannabinoid CB1 receptor antagonists for the treatment of nicotine addiction. Unfortunately, after being tested on experimental animals, what seemed to be an interesting approach for the treatment of nicotine addiction resulted in serious unwanted side effects when tested in humans. Current research is focusing again on pre-clinical models in an effort to eliminate unwanted side effects while preserving the initially observed efficacy. A 'bed side to bench strategy' was used to study the role of the insula (part of the frontal cortex) in nicotine addiction. This line of research started based on clinical observations that patients suffering stroke-induced lesions to the insula showed a greater likelihood to report immediate smoking cessation without craving or relapse. Subsequently, animal models of addiction are used to explore the role of insula in addiction. Due to the inherent limitations existing in clinical versus preclinical studies, the possibility of close interaction between both models seems to be critical for the successful development of novel therapeutic strategies for nicotine dependence.

Pharmacologic treatment of alcoholism

Progress in understanding the neuroscience of addiction has significantly advanced the development of more efficacious medications for the treatment of alcohol use disorders (AUD). While several medications have been approved by regulatory bodies around the world for the treatment of AUD, they are not universally efficacious. Recent research has yielded improved understanding of the genetics and brain circuits that underlie alcohol reward and its habitual use. This research has contributed to pharmacogenetic studies of medication response, and will ultimately lead to a more "personalized medicine" approach to AUD pharmacotherapy. This chapter summarizes work on clinically available medications (both approved by regulatory bodies and investigational) for the treatment of alcohol dependence, as well as the psychiatric disorders that are commonly comorbid with AUD. Studies that have evaluated genetic influences on medication response and those that have employed neuroimaging to probe mechanisms of medication action or response are highlighted. Finally, new targets discovered in animal models for possible pharmacologic intervention in humans are overviewed and future directions in medications development provided.

THC reduces the anticipatory nucleus accumbens response to reward in subjects with a nicotine addiction

Recent evidence has implicated the endocannabinoid (eCB) system in nicotine addiction. The eCB system also has an important role in reward mechanisms, and nicotine addiction has been associated with aberrant reward processing. Motivated by this evidence, we tested the hypothesis that eCB modulation of reward processing is altered in subjects with a nicotine addiction (NAD). For this purpose, we compared reward-related activity in NAD with healthy controls (HC) in a pharmacological magnetic resonance imaging (MRI) study using Δ(9)-tetrahydrocannabinol (THC) administration to challenge the eCB system. Eleven HC and 10 NAD participated in a 3-T functional MRI (fMRI) study with a double-blind, cross-over, placebo-controlled design, using a Monetary Incentive Delay (MID) paradigm with three reward levels. Reward activity in the nucleus accumbens (NAcc) and caudate putamen during anticipation and feedback of reward was compared after THC and placebo. fMRI results indicated a significant reduction of reward anticipation activity in the NAcc in NAD after THC administration, which was not present in HC. This is indicated by a significant group by drug by reward interaction. Our data show that THC significantly reduces the NAcc response to monetary reward anticipation in NAD. These results suggest that nicotine addiction is associated with altered eCB modulation of reward processing in the NAcc. This study adds important human data to existing evidence implicating the eCB system in nicotine addiction.

Development of novel pharmacotherapeutics for tobacco dependence: progress and future directions

INTRODUCTION

The vast majority of tobacco smokers seeking to quit will relapse within the first month of abstinence. Currently available smoking cessation agents have limited utility in increasing rates of smoking cessation and in some cases there are notable safety concerns related to their use. Hence, there is a pressing need to develop safer and more efficacious smoking cessation medications.

METHODS

Here, we provide an overview of current efforts to develop new pharmacotherapeutic agents to facilitate smoking cessation, identified from ongoing clinical trials and published reports.

RESULTS

Nicotine is considered the major addictive agent in tobacco smoke, and the vast majority of currently available smoking cessation agents act by modulating nicotinic acetylcholine receptor (nAChR) signaling. Accordingly, there is much effort directed toward developing novel small molecule therapeutics and biological agents such as nicotine vaccines for smoking cessation that act by modulating nAChR activity. Our increasing knowledge of the neurobiology of nicotine addiction has revealed new targets for novel smoking cessation therapeutics. Indeed, we highlight many examples of novel small molecule drug development around non-nAChR targets. Finally, there is a growing appreciation that medications already approved for other disease indications could show promise as smoking cessation agents, and we consider examples of such repurposing efforts.

CONCLUSION

Ongoing clinical assessment of potential smoking cessation agents offers the promise of new effective medications. Nevertheless, much of our current knowledge of molecular mechanisms of nicotine addiction derived from preclinical studies has not yet been leveraged for medications development.

Interventions for preventing weight gain after smoking cessation

BACKGROUND

Most people who stop smoking gain weight. There are some interventions that have been designed to reduce weight gain when stopping smoking. Some smoking cessation interventions may also limit weight gain although their effect on weight has not been reviewed.

OBJECTIVES

To systematically review the effect of: (1) Interventions targeting post-cessation weight gain on weight change and smoking cessation.(2) Interventions designed to aid smoking cessation that may also plausibly affect weight on post-cessation weight change.

SEARCH METHODS

Part 1 - We searched the Cochrane Tobacco Addiction Group's Specialized Register and CENTRAL in September 2011.Part 2 - In addition we searched the included studies in the following "parent" Cochrane reviews: nicotine replacement therapy (NRT), antidepressants, nicotine receptor partial agonists, cannabinoid type 1 receptor antagonists and exercise interventions for smoking cessation published in Issue 9, 2011 of the Cochrane Library.

SELECTION CRITERIA

Part 1 - We included trials of interventions that were targeted at post-cessation weight gain and had measured weight at any follow up point and/or smoking cessation six or more months after quit day.Part 2 - We included trials that had been included in the selected parent Cochrane reviews if they had reported weight gain at any time point.

DATA COLLECTION AND ANALYSIS

We extracted data on baseline characteristics of the study population, intervention, outcome and study quality. Change in weight was expressed as difference in weight change from baseline to follow up between trial arms and was reported in abstinent smokers only. Abstinence from smoking was expressed as a risk ratio (RR). We used the most rigorous definition of abstinence available in each trial. Where appropriate, we performed meta-analysis using the inverse variance method for weight and Mantel-Haenszel method for smoking using a fixed-effect model.

MAIN RESULTS

Part 1: Some pharmacological interventions tested for limiting post cessation weight gain (PCWG) resulted in a significant reduction in WG at the end of treatment (dexfenfluramine (Mean difference (MD) -2.50 kg, 95% confidence interval (CI) -2.98 to -2.02, 1 study), phenylpropanolamine (MD -0.50 kg, 95% CI -0.80 to -0.20, N=3), naltrexone (MD -0.78 kg, 95% CI -1.52 to -0.05, N=2). There was no evidence that treatment reduced weight at 6 or 12 months (m). No pharmacological intervention significantly affected smoking cessation rates.Weight management education only was associated with no reduction in PCWG at end of treatment (6 or 12m). However these interventions significantly reduced abstinence at 12m (Risk ratio (RR) 0.66, 95% CI 0.48 to 0.90, N=2). Personalised weight management support reduced PCWG at 12m (MD -2.58 kg, 95% CI -5.11 to -0.05, N=2) and was not associated with a significant reduction of abstinence at 12m (RR 0.74, 95% CI 0.39 to 1.43, N=2). A very low calorie diet (VLCD) significantly reduced PCWG at end of treatment (MD -3.70 kg, 95% CI -4.82 to -2.58, N=1), but not significantly so at 12m (MD -1.30 kg, 95% CI -3.49 to 0.89, N=1). The VLCD increased chances of abstinence at 12m (RR 1.73, 95% CI 1.10 to 2.73, N=1). There was no evidence that cognitive behavioural therapy to allay concern about weight gain (CBT) reduced PCWG, but there was some evidence of increased PCWG at 6m (MD 0.74, 95% CI 0.24 to 1.24). It was associated with improved abstinence at 6m (RR 1.83, 95% CI 1.07 to 3.13, N=2) but not at 12m (RR 1.25, 95% CI 0.83 to 1.86, N=2). However, there was significant statistical heterogeneity.Part 2: We found no evidence that exercise interventions significantly reduced PCWG at end of treatment (MD -0.25 kg, 95% CI -0.78 to 0.29, N=4) however a significant reduction was found at 12m (MD -2.07 kg, 95% CI -3.78 to -0.36, N=3).Both bupropion and fluoxetine limited PCWG at the end of treatment (bupropion MD -1.12 kg, 95% CI -1.47 to -0.77, N=7) (fluoxetine MD -0.99 kg, 95% CI -1.36 to -0.61, N=2). There was no evidence that the effect persisted at 6m (bupropion MD -0.58 kg, 95% CI -2.16 to 1.00, N=4), (fluoxetine MD -0.01 kg, 95% CI -1.11 to 1.10, N=2) or 12m (bupropion MD -0.38 kg, 95% CI -2.00 to 1.24, N=4). There were no data on WG at 12m for fluoxetine.Overall, treatment with NRT attenuated PCWG at the end of treatment (MD -0.69 kg, 95% CI -0.88 to -0.51, N=19), with no strong evidence that the effect differed for the different forms of NRT. There was evidence of significant statistical heterogeneity caused by one study which reported a 4.3 kg reduction in PCWG due to NRT. With this study removed, the difference in weight change at end of treatment was -0.45 kg (95% CI -0.66 to -0.27, N=18). There was no evidence of an effect on PCWG at 12m (MD -0.42 kg, 95% CI -0.92 to 0.08, N=15).We found evidence that varenicline significantly reduced PCWG at end of treatment (MD -0.41 kg, 95% CI -0.63 to -0.19, N=11), but this effect was not maintained at 6 or 12m. Three studies compared the effect of bupropion to varenicline. Participants taking bupropion gained significantly less weight at the end of treatment (-0.51 kg (95% CI -0.93 to -0.09 kg), N=3). Direct comparison showed no significant difference in PCWG between varenicline and NRT.

AUTHORS' CONCLUSIONS

Although some pharmacotherapies tested to limit PCWG show evidence of short-term success, other problems with them and the lack of data on long-term efficacy limits their use. Weight management education only, is not effective and may reduce abstinence. Personalised weight management support may be effective and not reduce abstinence, but there are too few data to be sure. One study showed a VLCD increased abstinence but did not prevent WG in the longer term. CBT to accept WG did not limit PCWG and may not promote abstinence in the long term. Exercise interventions significantly reduced weight in the long term, but not the short term. More studies are needed to clarify whether this is an effect of treatment or a chance finding. Bupropion, fluoxetine, NRT and varenicline reduce PCWG while using the medication. Although this effect was not maintained one year after stopping smoking, the evidence is insufficient to exclude a modest long-term effect. The data are not sufficient to make strong clinical recommendations for effective programmes to prevent weight gain after cessation.

Involvement of the endocannabinoid system in reward processing in the human brain

RATIONALE

Disturbed reward processing in humans has been associated with a number of disorders, such as depression, addiction, and attention-deficit hyperactivity disorder. The endocannabinoid (eCB) system has been implicated in reward processing in animals, but in humans, the relation between eCB functioning and reward is less clear.

OBJECTIVES

The current study uses functional magnetic resonance imaging (fMRI) to investigate the role of the eCB system in reward processing in humans by examining the effect of the eCB agonist Δ(9)-tetrahydrocannabinol (THC) on reward-related brain activity.

METHODS

Eleven healthy males participated in a randomized placebo-controlled pharmacological fMRI study with administration of THC to challenge the eCB system. We compared anticipatory and feedback-related brain activity after placebo and THC, using a monetary incentive delay task. In this task, subjects are notified before each trial whether a correct response is rewarded ("reward trial") or not ("neutral trial").

RESULTS

Subjects showed faster reaction times during reward trials compared to neutral trials, and this effect was not altered by THC. THC induced a widespread attenuation of the brain response to feedback in reward trials but not in neutral trials. Anticipatory brain activity was not affected.

CONCLUSIONS

These results suggest a role for the eCB system in the appreciation of rewards. The involvement of the eCB system in feedback processing may be relevant for disorders in which appreciation of natural rewards may be affected such as addiction.

Nicotine dependence: health consequences, smoking cessation therapies, and pharmacotherapy

Nicotine dependence is a significant addiction with many health consequences. Consistent attempts and efforts at addressing this condition, guiding and advising afflicted patients using motivational techniques and the 5-A stepwise strategies, and instituting appropriate therapies will result in better health outcomes and less incidence of diseases. In pharmacotherapy, Nicotine replacement therapy and oral medications can be used alone or in combination with varying degrees of success.

Cannabinoid type 1 receptor antagonists for smoking cessation

BACKGROUND

Selective type 1 cannabinoid (CB1) receptor antagonists may assist with smoking cessation by restoring the balance of the endocannabinoid system, which can be disrupted by prolonged use of nicotine. They also seeks to address many smokers' reluctance to persist with a quit attempt because of concerns about weight gain.

OBJECTIVES

To determine whether selective CB1 receptor antagonists (currently rimonabant and taranabant) increase the numbers of people stopping smoking To assess their effects on weight change in successful quitters and in those who try to quit but fail.

SEARCH STRATEGY

We searched the Cochrane Tobacco Addiction Review Group specialized register for trials, using the terms ('rimonabant' or 'taranabant') and 'smoking' in the title or abstract, or as keywords. We also searched MEDLINE, EMBASE, CINAHL and PsycINFO, using major MESH terms. We acquired electronic or paper copies of posters of preliminary trial results presented at the American Thoracic Society Meeting in 2005, and at the Society for Research on Nicotine and Tobacco European Meeting 2006. We also attempted to contact the authors of ongoing studies of rimonabant, and Sanofi Aventis (manufacturers of rimonabant). The most recent search was in January 2011.

SELECTION CRITERIA

Types of studies Randomized controlled trialsTypes of participants Adult smokersTypes of interventions Selective CB1 receptor antagonists, such as rimonabant and taranabant. Types of outcome measures The primary outcome is smoking status at a minimum of six months after the start of treatment. We preferred sustained cessation rates to point prevalence, and biochemically verified cessation to self-reported quitting. We regarded smokers who drop out or are lost to follow up as continuing smokers. We have noted any adverse effects of treatment.A secondary outcome is weight change associated with the cessation attempt.

DATA COLLECTION AND ANALYSIS

Two authors checked the abstracts for relevance, and attempted to acquire full trial reports. One author extracted the data, and a second author checked them.

MAIN RESULTS

We found three trials which met our inclusion criteria, covering 1567 smokers (cessation: STRATUS-EU and STRATUS-US), and 1661 quitters (relapse prevention: STRATUS-WW). At one year, the pooled risk ratio (RR) for quitting with rimonabant 20 mg was 1.50 (95% confidence interval (CI) 1.10 to 2.05). No significant benefit was demonstrated for rimonabant at 5 mg dosage. Adverse events included nausea and upper respiratory tract infections. In the relapse prevention trial, smokers who had quit on the 20 mg regimen were more likely to remain abstinent on either active regimen than on placebo; the RR for the 20 mg maintenance group was 1.29 (95% CI 1.06 to 1.57), and for the 5 mg maintenance group 1.30 (95% CI 1.06 to 1.59). There appeared to be no significant benefit of maintenance treatment for the 5 mg quitters. One trial of taranabant was not included in our meta-analyses, as it followed participants only until end of treatment; at eight weeks it found no benefit for treatment over placebo, with an OR of 1.2 (90% CI 0.6 to 2.5). For rimonabant, weight gain was reported to be significantly lower among the 20 mg quitters than in the 5 mg or placebo quitters. During treatment, overweight or obese smokers tended to lose weight, while normal weight smokers did not. For taranabant, weight gain was significantly lower for 2-8 mg versus placebo at the end of eight weeks of treatment. In 2008, post-marketing surveillance led the European Medicines Agency (EMEA) to require Sanofi Aventis to withdraw rimonabant, because of links to mental disorders. The development of taranabant was also suspended by Merck & Co because of unacceptable adverse events.

AUTHORS' CONCLUSIONS

From the trial reports available, rimonabant 20 mg may increase the chances of quitting approximately 1½-fold. The evidence for rimonabant in maintaining abstinence is inconclusive. Rimonabant 20 mg may moderate weight gain in the long term. Taranabant 2-8 mg may moderate weight gain, at least in the short term. In 2008, development of both rimonabant and taranabant was discontinued by the manufacturers.

Methods of the pharmacological imaging of the cannabinoid system (PhICS) study: towards understanding the role of the brain endocannabinoid system in human cognition

Various lines of (pre)clinical research indicate that cannabinoid agents carry the potential for therapeutic application to reduce symptoms in several psychiatric disorders. However, direct testing of the involvement of cannabinoid brain systems in psychiatric syndromes is essential for further development. In the Pharmacological Imaging of the Cannabinoid System (PhICS) study, the involvement of the endocannabinoid system in cognitive brain function is assessed by comparing acute effects of the cannabinoid agonist Δ9-tetrahydrocannabinol (THC) on brain function between healthy controls and groups of psychiatric patients showing cognitive dysfunction. This article describes the objectives and methods of the PhICS study and presents preliminary results of the administration procedure on subjective and neurophysiological parameters. Core elements in the methodology of PhICS are the administration method (THC is administered by inhalation using a vaporizing device) and a comprehensive use of pharmacological magnetic resonance imaging (phMRI) combining several types of MRI scans including functional MRI (fMRI), Arterial Spin Labeling (ASL) to measure brain perfusion, and resting-state fMRI. Additional methods like neuropsychological testing further specify the exact role of the endocannabinoid system in regulating cognition. Preliminary results presented in this paper indicate robust behavioral and subjective effects of THC. In addition, fMRI paradigms demonstrate activation of expected networks of brain regions in the cognitive domains of interest. The presented administration and assessment protocol provides a basis for further research on the involvement of the endocannabionoid systems in behavior and in psychopathology, which in turn may lead to development of therapeutic opportunities of cannabinoid ligands.

Pharmacotherapies for obesity: past, current, and future therapies

Past therapies for the treatment of obesity have typically involved pharmacological agents usually in combination with a calorie-controlled diet. This paper reviews the efficacy and safety of pharmacotherapies for obesity focusing on drugs approved for long-term therapy (orlistat), drugs approved for short-term use (amfepramone [diethylpropion], phentermine), recently withdrawn therapies (rimonabant, sibutamine) and drugs evaluated in Phase III studies (taranabant, pramlintide, lorcaserin and tesofensine and combination therapies of topiramate plus phentermine, bupropion plus naltrexone, and bupropion plus zonisamide). No current pharmacotherapy possesses the efficacy needed to produce substantial weight loss in morbidly obese patients. Meta-analyses support a significant though modest loss in bodyweight with a mean weight difference of 4.7 kg (95% CI 4.1 to 5.3 kg) for rimonabant, 4.2 kg (95% CI 3.6 to 4.8 kg) for sibutramine and 2.9 kg (95% CI 2.5 to 3.2 kg) for orlistat compared to placebo at ≥12 months. Of the Phase III pharmacotherapies, lorcaserin, taranabant, topiramate and bupropion with naltrexone have demonstrated significant weight loss compared to placebo at ≥12 months. Some pharmacotherapies have also demonstrated clinical benefits. Further studies are required in some populations such as younger and older people whilst the long term safety continues to be a major consideration and has led to the withdrawal of several drugs.

Neurobiological mechanisms involved in nicotine dependence and reward: participation of the endogenous opioid system

Nicotine is the primary component of tobacco that maintains the smoking habit and develops addiction. The adaptive changes of nicotinic acetylcholine receptors produced by repeated exposure to nicotine play a crucial role in the establishment of dependence. However, other neurochemical systems also participate in the addictive effects of nicotine including glutamate, cannabinoids, GABA and opioids. This review will cover the involvement of these neurotransmitters in nicotine addictive properties, with a special emphasis on the endogenous opioid system. Thus, endogenous enkephalins and beta-endorphins acting on mu-opioid receptors are involved in nicotine-rewarding effects, whereas opioid peptides derived from prodynorphin participate in nicotine aversive responses. An up-regulation of mu-opioid receptors has been reported after chronic nicotine treatment that could counteract the development of nicotine tolerance, whereas the down-regulation induced on kappa-opioid receptors seems to facilitate nicotine tolerance. Endogenous enkephalins acting on mu-opioid receptors also play a role in the development of physical dependence to nicotine. In agreement with these actions of the endogenous opioid system, the opioid antagonist naltrexone has shown to be effective for smoking cessation in certain sub-populations of smokers.

Second-order schedules of nicotine reinforcement in rats: effect of AM251

The endocannabinoid system has been implicated in the motivational effects of nicotine and nicotine-associated stimuli but the neural circuitry underlying tobacco addiction is not fully characterised. The present study aimed to establish a second-order schedule of nicotine reinforcement to compare the role of the endocannabinoid system in nicotine- and cue-maintained responding. The male rats were successfully trained to respond on a second-order schedule [FR5 (FR5: S) or FI 10' (FR3: S)] under which presentation of the CS (brief light oscillation) was intermittently reinforced by nicotine (0.03 mg/kg/infusion). The relative contribution of nicotine and the CS towards responding was then compared. Nicotine and the CS were only able to independently maintain responding to similar level under the [FI 10' (FR3: S)] schedule, which was subsequently employed to examine the effects of the selective CB1 receptor antagonist AM251. AM251 (0.1, 0.3 and 1 mg/kg, intraperitoneal [i.p.]) was used to examine the role of endocannabinoids in responding under the second-order schedule and responding maintained by independent presentation of nicotine and the CS. Responding under the second-order schedule was dose-dependently attenuated by AM251, whereas responding for independent presentation of nicotine and the CS was not affected. The establishment of second-order schedules of nicotine reinforcement in rodents highlighted the utility of such schedules for investigation of the neurobiology that underlies nicotine- and cue-maintained behaviour. Additionally, the role of CB1 receptors in nicotine-motivated behaviours was extended to those controlled under a second-order schedule.

A second-order schedule of food reinforcement in rats to examine the role of CB1 receptors in the reinforcement-enhancing effects of nicotine

Nicotine is believed to enhance the motivational value of reinforcers. Although endogenous cannabinoids acting on CB1 receptors have been implicated in the motivational effects of nicotine, their role in the 'reinforcement-enhancing' properties of nicotine is unknown. This study compared the effect of acute and chronic non-contingent nicotine administration on responding for an unconditioned reinforcing stimulus (UCS) and a visual conditioned stimulus (CS) and the role of CB1 receptors was examined. Male hooded Lister rats were trained on a second-order schedule [FI 15' (FR5: S)] under which presentation of the CS (5s/5Hz light oscillation) was intermittently reinforced by the UCS (food). The rats were treated with daily saline or nicotine (0.4 mg/kg, subcutaneous [s.c.]) throughout the study. The effect of the acute nicotine challenge (0.05, 0.1 and 0.2 mg/kg, s.c.) and the CB1 receptor antagonist AM251 (0.1, 0.3 and 1 mg/kg, intraperitoneal [i.p.]) on responding for the CS and/or UCS was examined. The acute nicotine challenge increased responding for both the UCS and CS in the rats chronically treated with nicotine, an effect which was less robust in the nicotine-naive rats. AM251 significantly reduced responding for the UCS and CS, and an interaction with the nicotine challenge was found. These data support and extend the hypothesis that nicotine can enhance the motivational value of reinforcing stimuli and suggest the increases in responding produced by nicotine involve CB1 receptors. Furthermore, this study highlights the utility of second-order schedules of reinforcement for investigation of the neural circuits underlying the reinforcement-enhancing effects of nicotine.

Management of the metabolic syndrome in cardiovascular disease

The main components of the metabolic syndrome (MS) are abdominal obesity, atherogenic dyslipidemia, raised blood pressure, insulin resistance with or without glucose intolerance, and proinflammatory and prothrombotic states. The clustering of these metabolic risk factors significantly increases the risk of type 2 diabetes and promotes vascular endothelial dysfunction, inflammation, and increased oxidative stress. The net result is an increase in the risk of atherosclerotic cardiovascular disease. Therefore, management of MS is of utmost importance, especially considering its rapidly increasing prevalence in a population with rising obesity rates and its significant cardiovascular implications. The primary management of this syndrome involves the correction of the underlying risk factors--obesity, physical inactivity, and an atherogenic diet--with lifestyle modifications including increased physical activity and dietary modification. Smoking cessation also should be encouraged. However, pharmacologic therapies are often required to address cardiovascular risk factors. These agents can be categorized broadly into 1) anorectic agents, 2) insulin-sensitizing agents, 3) statins, and 4) renin-angiotensin system antagonists. Emerging therapies include adipokines, endocannabinoid inhibitors, and metabolic modulators, such as perhexiline and trimetazidine. To date, these therapies have not been shown to normalize the metabolic and cardiovascular burden of MS, and there still is no single therapeutic agent for its management.

Randomized, controlled, double-blind trial of taranabant for smoking cessation

RATIONALE

It has been proposed that cannabinoid-1 receptor inverse agonists might be effective for smoking cessation. We evaluated this hypothesis with the cannabinoid-1 receptor inverse agonist taranabant.

METHODS

Adults who smoked > or =10 cigarettes a day for >1 year and had an expired CO level of > or =10 ppm participated in a randomized, double-blind, 8-week, study of taranabant (N = 159) or placebo (N = 158). Taranabant was titrated from 2 mg once daily to 8 mg once daily. Patients received smoking cessation counseling. The primary efficacy endpoint was continuous abstinence, defined as no cigarettes assessed by daily patient self-report and verified by breath CO level (<10 ppm) and plasma cotinine test (<10 ng/ml), during the last 4 weeks of the 8-week treatment period.

RESULTS

The percentage of patients achieving continuous abstinence was 7.5% for taranabant 2-8 mg and 6.3% for placebo (odds ratio = 1.2 [90% confidence interval (CI), 0.6, 2.5], P = 0.678). Change from baseline in body weight in the taranabant 2-8-mg group was -1.5 (90% CI, -1.8, -1.3) versus 0.6 kg (90% CI, 0.4, 0.9) in the placebo group. Compared to placebo, taranabant 2-8 mg was associated with an increased incidence of psychiatric-related adverse events (e.g., depression, 8.2% versus 2.5%, P = 0.048), gastrointestinal-related adverse events (e.g., nausea, 49.7% versus 19.0%, P < 0.001), and flushing/hot flash adverse events (10.7% versus 1.9%, P = 0.002).

CONCLUSIONS

Taranabant 2-8 mg did not improve smoking cessation and was associated with increased incidences of psychiatric-related, gastrointestinal-related, and flushing adverse events (ClinicalTrials.gov NCT00109135).

Addressing tobacco use disorder in smokers in early remission from alcohol dependence: the case for integrating smoking cessation services in substance use disorder treatment programs

Despite the declining overall rate of cigarette smoking in the general population in the United States, the prevalence of smoking is estimated to be as high as 80% among treatment-seeking alcoholics. The serious adverse health effects of tobacco and heavy alcohol use are synergistic and recent evidence suggests that smoking slows the process of cognitive recovery following alcohol abstinence. In addition, substantial evidence shows that treatment for tobacco dependence does not jeopardize alcohol abstinence. In this paper, we focus on the impact and treatment implications of tobacco dependence among treatment-seeking alcoholics through a review of five areas of research. We begin with brief reviews of two areas of research: studies investigating the genetic and neurobiological vulnerability of comorbid tobacco and alcohol dependence and studies investigating the consequences of comorbid dependence on neurobiological and cognitive functioning. We then review literature on the effects of smoking cessation on drinking urges and alcohol use and the effectiveness of smoking cessation interventions with alcoholic smokers. Finally, we offer recommendations for research with an emphasis on clinical research for enhancing smoking cessation outcomes in this population.

The alpha4beta2 nicotinic acetylcholine-receptor partial agonist varenicline inhibits both nicotine self-administration following repeated dosing and reinstatement of nicotine seeking in rats

INTRODUCTION

The alpha4beta2 nicotinic acetylcholine receptor partial agonist varenicline has greater efficacy than other pharmacotherapeutic aids for smoking cessation. This presents an opportunity to evaluate the predictive validity of rat models of nicotine taking and relapse. The aim of this study was to evaluate the ability of varenicline to attenuate nicotine self-administration and relapse, as modelled by the reinstatement model of nicotine relapse in rats.

MATERIALS AND METHODS

Rats were trained to respond for intravenous nicotine under a fixed ratio schedule of reinforcement. The effects of varenicline (0.3-3.0 mg/kg s.c.) on both nicotine and food self-administration and reinstatement of nicotine seeking were evaluated.

RESULTS AND DISCUSSION

Varenicline dose-dependently reduced nicotine self-administration and attenuated both nicotine prime and combined nicotine prime plus nicotine-paired cue-induced reinstatement. Varenicline had no effect on cue-induced reinstatement in the absence of a nicotine prime nor did it induce reinstatement when given alone.

CONCLUSION

The effects of varenicline on nicotine-induced reinstatement of drug-seeking are consistent with the demonstrated clinical efficacy of varenicline for smoking cessation.

Systematic reviews on tobacco control from Cochrane and the Community Guide: different methods, similar findings

OBJECTIVES

To compare the methods and findings of systematic reviews (SRs) on common tobacco control interventions from two organizations: the Cochrane Collaboration ("Cochrane") and the US Task Force for Community Preventive Services ("the Guide").

STUDY DESIGN AND SETTING

Literature review. We retrieved all reviews pertaining to tobacco control produced by the Cochrane and the Guide. We identified seven common topics and compared methods and findings of the retrieved reviews.

RESULTS

There was considerable variability in the designs of included studies and methods of data synthesis. On average, Cochrane identified more studies than did the Guide (Mean 43.7 vs. 19.0), with only limited overlap between sets of included studies. Most Cochrane reviews (71.4%) were synthesized narratively, whereas most Guide reviews (85.7%) were synthesized using a median of effect size. Despite these differences, findings of the reviews yielded substantial agreement.

CONCLUSION

Cochrane and the Guide conduct SRs on similar tobacco control-related topics differently. The SRs of the two organizations include overlapping, but nonidentical sets, of studies. Still, they usually reach similar conclusions. Identification of all pertinent original studies seems to be a weak point in the SR process. Policy makers should use reviews from both organizations in formulating tobacco control policy.

Novel pharmacological approaches to drug abuse treatment

The field of pharmacologic addiction treatment is expanding rapidly. While there are currently several FDA-approved medications for nicotine, alcohol, and opiate dependence, research into novel pharmacological approaches for these and additional substances is legion. Each drug of abuse, while sharing a common final neural pathway of increasing dopaminergic tone, has unique and individual characteristics that are important in developing improved and varied treatments. In this chapter, we discuss such research and present the neurobiological underpinnings of these explorations. In general, addiction treatment is focused on four areas: (1) reducing withdrawal discomfort, (2) diminishing cravings, (3) blocking rewarding effects of the drug, and (4) treating comorbidities, such as depression or ADHD. We present current ideas in pharmacologic research for nicotine, alcohol, cannabis, stimulants, and opiates.

Interventions for promoting smoking cessation during pregnancy

BACKGROUND

Tobacco smoking in pregnancy remains one of the few preventable factors associated with complications in pregnancy, low birthweight, preterm birth and has serious long-term health implications for women and babies. Smoking in pregnancy is decreasing in high-income countries and increasing in low- to middle-income countries and is strongly associated with poverty, low educational attainment, poor social support and psychological illness.

OBJECTIVES

To assess the effects of smoking cessation interventions during pregnancy on smoking behaviour and perinatal health outcomes.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (June 2008), the Cochrane Tobacco Addiction Group's Trials Register (June 2008), EMBASE, PsycLIT, and CINAHL (all from January 2003 to June 2008). We contacted trial authors to locate additional unpublished data.

SELECTION CRITERIA

Randomised controlled trials where smoking cessation during pregnancy was a primary aim of the intervention.

DATA COLLECTION AND ANALYSIS

Trials were identified and data extracted by one person and checked by a second. Subgroup analysis was conducted to assess the effect of risk of trial bias, intensity of the intervention and main intervention strategy used.

MAIN RESULTS

Seventy-two trials are included. Fifty-six randomised controlled trials (over 20,000 pregnant women) and nine cluster-randomised trials (over 5000 pregnant women) provided data on smoking cessation outcomes.There was a significant reduction in smoking in late pregnancy following interventions (risk ratio (RR) 0.94, 95% confidence interval (CI) 0.93 to 0.96), an absolute difference of six in 100 women who stopped smoking during pregnancy. However, there is significant heterogeneity in the combined data (I(2) > 60%). In the trials with the lowest risk of bias, the interventions had less effect (RR 0.97, 95% CI 0.94 to 0.99), and lower heterogeneity (I(2) = 36%). Eight trials of smoking relapse prevention (over 1000 women) showed no statistically significant reduction in relapse.Smoking cessation interventions reduced low birthweight (RR 0.83, 95% CI 0.73 to 0.95) and preterm birth (RR 0.86, 95% CI 0.74 to 0.98), and there was a 53.91g (95% CI 10.44 g to 95.38 g) increase in mean birthweight. There were no statistically significant differences in neonatal intensive care unit admissions, very low birthweight, stillbirths, perinatal or neonatal mortality but these analyses had very limited power.

AUTHORS' CONCLUSIONS

Smoking cessation interventions in pregnancy reduce the proportion of women who continue to smoke in late pregnancy, and reduce low birthweight and preterm birth. Smoking cessation interventions in pregnancy need to be implemented in all maternity care settings. Given the difficulty many pregnant women addicted to tobacco have quitting during pregnancy, population-based measures to reduce smoking and social inequalities should be supported.

The future of endocannabinoid-oriented clinical research after CB1 antagonists

INTRODUCTION

Great interest has been shown by the medical community and the public in the cannabinoid CB(1) receptor antagonists, such as rimonabant, for treatment of obesity, metabolic syndrome, and possibly drug addiction.

DISCUSSION

This novel class of drug has therapeutic potential for other disorders, as the endocannabinoid system is involved in various health conditions. However, rimonabant, the first clinically available member of this class of drugs, has been linked to increased risk of anxiety, depression, and suicidality. Due to those risks, the European Medicines Agency called for its withdrawal from the market in October, 2008. Shortly after this decision, several pharmaceutical companies (Sanofi-aventis, Merck, Pfizer, Solvay) announced that they would stop further clinical research on this class of drug. Here, we provide an overview of those events and make several suggestions for continuing such clinical research, while safeguarding the safety of patients and clinical trial subjects.

Update on smoking cessation therapies

As a reflection of an exponential increase in smoking rates throughout the world during the last century, the economic and human burden of mortality and morbidity related to smoking is now clearly defined. Smoking cessation is associated with health benefits for people of all ages. In this paper we provide a comprehensive review of current licensed pharmacological smoking cessation agents including efficacy and safety profiles, with comparisons of individual therapies available. Furthermore, we offer a prospective on the need for further testing of other agents including novel avenues of therapy.

A randomized controlled trial of adding the nicotine patch to rimonabant for smoking cessation: efficacy, safety and weight gain

AIMS

Because smoking cessation rates might be improved by combining drugs and by reducing post-cessation weight gain, we tested the smoking cessation efficacy, safety and effect on body weight of adding the nicotine patch to rimonabant, a cannabanoid type-1 receptor antagonist that reduces body weight.

DESIGN

Randomized double-blind placebo-controlled trial.

SETTING

Fifteen US research centers.

PARTICIPANTS

A total of 755 smokers (> OR = 15 cigarettes/day). Intervention Rimonabant (20 mg daily) was given open-label for 9 weeks. The 735 participants completing week 1 were randomized at day 8 (target quit day) to add a nicotine patch (n = 369) or placebo patch (n = 366) for 10 weeks (21 mg daily for 8 weeks plus a 2-week taper). Participants received weekly smoking counseling and were followed for 24 weeks.

MEASUREMENTS

Biochemically validated 4-week continuous abstinence at end-of-treatment (weeks 6-9; primary end-point); 7-day point prevalence abstinence at weeks 9 and 24; sustained abstinence (weeks 6-24); change in body weight; and adverse events.

FINDINGS

Rimonabant plus nicotine patch was superior to rimonabant plus placebo in validated continuous abstinence at weeks 6-9 (39.0% versus 21.3%; odds ratio 2.36, 95% confidence interval: 1.71-2.37; P < 0.01) and in all other efficacy measures. Mean end-of-treatment weight gain among quitters did not differ between groups (0.04 kg for combination versus 0.49 kg for rimonabant only, P = 0.15) and was similar in weight-concerned smokers. Serious adverse event rates did not differ between groups. Depression- and anxiety-related adverse events occurred in 32 (4.2%) and 44 (5.8%) subjects, respectively; eight (1.1%) and nine (1.2%) subjects stopped the drug due to depression and anxiety, respectively.

CONCLUSIONS

Adding a nicotine patch to rimonabant was well tolerated and increased smoking cessation rates over rimonabant alone. There was little post-cessation weight gain in either group, even among weight-concerned smokers, during drug treatment.

Pharmacotherapy for smoking cessation

Tobacco dependence is a chronic relapsing disease that needs continuous treatment. In combination with behavioural support, pharmacotherapy is a proven key component for supporting smoking cessation. Effective drugs are available and recommended: nicotine replacement therapy (NRT), bupropion and varenicline. Much research into new pharmacological approaches is ongoing, combining 'old' and 'new' drugs and personalizing a pharmacological treatment for a single smoker/patient; other new medications and vaccines are in development. Overall, pharmacotherapy seems to have efficacy and cost-effectiveness in real life, thus physicians should become familiar with these medicines. Further efforts should be aimed at optimizing treatment management and increasing smoking cessation rates in the general population.

Interventions for preventing weight gain after smoking cessation

BACKGROUND

Most people who stop smoking gain weight, on average about 7 kg in the long term. There are some interventions that have been specifically designed to tackle smoking cessation whilst also limiting weight gain. Many smoking cessation pharmacotherapies and other interventions may also limit weight gain.

OBJECTIVES

This review is divided into two parts. (1) Interventions designed specifically to aid smoking cessation and limit post-cessation weight gain (2) Interventions designed to aid smoking cessation that may also plausibly have an effect on weight

SEARCH STRATEGY

Part 1: We searched the Cochrane Tobacco Addiction Group's Specialized Register which includes trials indexed in MEDLINE, EMBASE, SciSearch and PsycINFO, and other reviews and conference abstracts. Part 2: We searched the included studies of Cochrane smoking cessation reviews of nicotine replacement therapy, antidepressants, nicotine receptor partial agonists, cannabinoid type 1 receptor antagonists (rimonabant), and exercise interventions, published in Issue 4, 2008 of The Cochrane Library.

SELECTION CRITERIA

Part 1: We included trials of interventions designed specifically to address both smoking cessation and post-cessation weight gain that had measured weight at any follow-up point and/or smoking six months or more after quitting.Part 2: We included trials from the selected Cochrane reviews that could plausibly modify post-cessation weight gain if they had reported weight gain by trial arm at end of treatment or later.

DATA COLLECTION AND ANALYSIS

We extracted data in duplicate on smoking and weight for part 1 trials, and on weight only for part 2. Abstinence from smoking is expressed as a risk ratio (RR), using the most rigorous definition of abstinence available in each trial, and biochemically validated rates if available. The outcome is expressed as the difference in weight change between trial arms from baseline. Where appropriate, we performed meta-analysis using the Mantel-Haenszel method for smoking and inverse variance for weight using a fixed-effect model.

MAIN RESULTS

We found evidence that pharmacological interventions aimed at reducing post-cessation weight gain resulted in a significant reduction in weight gain at the end of treatment (dexfenfluramine (-2.50kg [-2.98kg to -2.02kg], fluoxetine (-0.80kg [-1.27kg to -0.33kg], phenylpropanolamine (PPA) (-0.50kg [-0.80kg to -0.20kg], naltrexone (-0.76kg [-1.51kg to -0.01kg])). No evidence of maintenance of the treatment effect was found at six or 12 months.Among the behavioural interventions, only weight control advice was associated with no reduction in weight gain and with a possible reduction in abstinence. Individualized programmes were associated with reduced weight gain at end of treatment and at 12 months (-2.58kg [-5.11kg to -0.05kg]), and with no effect on abstinence (RR 0.74 [0.39 to 1.43]). Very low calorie diets (-1.30kg (-3.49kg to 0.89kg] at 12 months) and cognitive behavioural therapy (CBT) (-5.20kg (-9.28kg to -1.12kg] at 12 months) were both associated with improved abstinence and reduced weight gain at end of treatment and at long-term follow up.Both bupropion (300mg/day) and fluoxetine (30mg and 60mg/day combined) were found to limit post-cessation weight gain at the end of treatment (-0.76kg [-1.17kg to -0.35kg] I(2)=48%) and -1.30kg [-1.91kg to -0.69kg]) respectively. There was no evidence that the weight reducing effect of bupropion was dose-dependent. The effect of bupropion at one year was smaller and confidence intervals included no effect (-0.38kg [-2.001kg to 1.24kg]).We found no evidence that exercise interventions significantly reduced post-cessation weight gain at end of treatment but evidence for an effect at 12 months (-2.07kg [-3.78kg, -0.36kg]).Treatment with NRT resulted in attenuation of post-cessation weight gain (-0.45kg [-0.70kg, -0.20kg]) at the end of treatment, with no evidence that the effect differed for different forms of NRT. The estimated weight gain reduction was similar at 12 months (-0.42kg [-0.92kg, 0.08kg]) but the confidence intervals included no effect.There were no relevant data on the effect of rimonabant on weight gain.We found no evidence that varenicline significantly reduced post-cessation weight gain at end of treatment and no follow-up data are currently available. One study randomizing successful quitters to 12 more weeks of active treatment showed weight to be reduced by 0.71kg (-1.04kg to -0.38kg). In three studies, participants taking bupropion gained significantly less weight at the end of treatment than those on varenicline (-0.51kg [-0.93kg to -0.09kg]).

AUTHORS' CONCLUSIONS

Behavioural interventions of general advice only are not effective and may reduce abstinence. Individualized interventions, very low calorie diets, and CBT may be effective and not reduce abstinence. Exercise interventions are not associated with reduced weight gain at end of treatment, but may be associated with worthwhile reductions in weight gain in the long term, Bupropion, fluoxetine, nicotine replacement therapy, and probably varenicline all reduced weight gain while being used. Although this effect was not maintained one year after quitting for bupropion, fluoxetine, and nicotine replacement, the evidence is insufficient to exclude a modest long-term effect. The data are not sufficient to make strong clinical recommendations for effective programmes.

Tobacco and cannabis co-occurrence: does route of administration matter?

BACKGROUND

Qualitative research suggests that a shared route of administration (i.e. via inhalation) for the common forms of both tobacco (i.e. cigarettes) and cannabis (i.e. joints) may contribute to their co-occurring use.

METHODS

We used data on 43,093 U.S. adults who participated in the 2001-2002 National Epidemiologic Survey on Alcohol and Related Conditions (NESARC) to examine whether cannabis use and abuse/dependence were associated with smoked (cigarettes, cigars, pipes) versus smokeless (snuff, chewed tobacco) forms of tobacco use, even after controlling for socio-demographic, psychiatric and substance-related covariates.

RESULTS

Tobacco smoking was associated with a 3.3-4.5 times increased risk for cannabis use and abuse/dependence respectively. After covariate adjustment, importantly for nicotine dependence, smoking tobacco (but not smokeless tobacco) was still significantly associated with both cannabis use (multinomial odds-ratio (MOR) 1.99) and cannabis dependence (MOR 1.55). In contrast, use of smokeless tobacco was not significantly correlated with elevated rates of cannabis use (MOR 0.96) or abuse/dependence (MOR 1.04).

CONCLUSIONS

Route of administration may play an important role in the observed association between tobacco and cannabis use. This may represent a physiological adaptation of the aero-respiratory system and/or index social and cultural influences surrounding the use of smoked versus smokeless forms of tobacco.

Early cannabis use and DSM-IV nicotine dependence: a twin study

BACKGROUND

Evidence suggests that cannabis users are at increased risk for cigarette smoking--if so, this may potentially be the single most alarming public health challenge posed by cannabis use. We examine whether cannabis use prior to age 17 years is associated with an increased likelihood of DSM-IV nicotine dependence and the extent to which genetic and environmental factors contribute to this association.

METHODS

A population-based cohort of 24-36-year-old Australian male and female twins (n=6257, 286 and 229 discordant pairs) was used. The co-twin-control method, with twin pairs discordant for early cannabis use, was used to examine whether, after controlling for genetic and familial environmental background, there was evidence for an additional influence of early cannabis use on DSM-IV nicotine dependence. Bivariate genetic models were fitted to the full data set to quantify the genetic correlation between early cannabis use and nicotine dependence.

RESULTS

The early cannabis-using twin was about twice as likely to report nicotine dependence, when compared to their co-twin who had experimented with cigarettes but had never used cannabis. Even when analyses were restricted to cannabis users, earlier age cannabis use onset conferred greater risk (1.7) for nicotine dependence than did later onset. This association was governed largely by common genetic liability to early cannabis use and nicotine dependence, as demonstrated by genetic correlations of 0.41-0.52.

CONCLUSIONS

Early-onset cannabis users are at increased risk for nicotine dependence, but this risk is attributable largely to common genetic vulnerability. There is no evidence for a causal relationship between cannabis use and nicotine dependence.

Meta-analysis of repeated measures study designs

RATIONALE, AIMS AND OBJECTIVES

Repeated measures studies are found in many areas of research, particularly in areas of healthcare. There is currently little information available to inform the method of meta-analysis of repeated measures studies so that the structural dependence of the data is appropriately accommodated and the findings are meaningful.

METHOD

Using a published meta-analysis on the impact of diet advice on weight reduction of obese or overweight individuals, we demonstrate possible approaches for repeated measures meta-analysis. These approaches differ in terms of the type of result obtained (e.g. effect at a particular time-point, trend over time, change between time-points) and the data needed for the analysis (e.g. means, regression slope estimates). Some approaches involve violating assumptions of independence in the data structure and so to investigate the impact of this violation a simulation study is carried out.

RESULTS

The different approaches described for the meta-analyses of repeated measures studies can all provide useful effect estimates depending on the question to be addressed by the meta-analysis. However, violation of the independence assumption in some approaches can lead to biased estimates.

CONCLUSIONS

In practice, the methods available to carry out meta-analyses of repeated measures studies will not only depend upon the question of interest, but also on the data available from the primary studies.

Pharmacotherapies for smoking cessation: a meta-analysis of randomized controlled trials

BACKGROUND

Many placebo-controlled trials have demonstrated the efficacy of individual pharmacotherapies approved for smoking cessation. However, few direct or indirect comparisons of such interventions have been conducted. We performed a meta-analysis to compare the treatment effects of 7 approved pharmacologic interventions for smoking cessation.

METHODS

We searched the US Centers for Disease Control and Prevention's Tobacco Information and Prevention database as well as MEDLINE, EMBASE and the Cochrane Library for published reports of placebo-controlled, double-blind randomized controlled trials of pharmacotherapies for smoking cessation. We included studies that reported biochemically validated measures of abstinence at 6 and 12 months. We used a hierarchical Bayesian random-effects model to summarize the results for each intervention.

RESULTS

We identified 70 published reports of 69 trials involving a total of 32 908 patients. Six of the 7 pharmacotherapies studied were found to be more efficacious than placebo: varenicline (odds ratio [OR] 2.41, 95% credible interval [CrI] 1.91-3.12), nicotine nasal spray (OR 2.37, 95% CrI 1.12-5.13), bupropion (OR 2.07, 95% CrI 1.73-2.55), transdermal nicotine (OR 2.07, 95% CrI 1.69-2.62), nicotine tablet (OR 2.06, 95% CrI 1.12-5.13) and nicotine gum (OR 1.71, 95% CrI 1.35-2.21). Similar results were obtained regardless of which measure of abstinence was used. Although the point estimate favoured nicotine inhaler over placebo (OR 2.17), these results were not conclusive because the credible interval included unity (95% CrI 0.95-5.43). When all 7 interventions were included in the same model, all were more efficacious than placebo. In our analysis of data from the varenicline trials that included bupropion control arms, we found that varenicline was superior to bupropion (OR 2.18, 95% CrI 1.09-4.08).

INTERPRETATION

Varenicline, bupropion and the 5 nicotine replacement therapies were all more efficacious than placebo at promoting smoking abstinence at 6 and 12 months.

Psychosis following anti-obesity treatment with rimonabant

BACKGROUND

In this report, we present the case of a patient with a relapse of schizophrenia following an episode of depression and increased anxiety after antiobesity treatment with rimonabant, a cannabinoid type 1 receptor antagonist.

CASE REPORT

After 4 weeks of treatment the patient developed psychiatric symptoms, i.e. depressed mood and elevated anxiety. Four months after the discontinuation of rimonabant, the patient presented with psychotic symptoms fulfilling ICD-10 criteria of paranoid schizophrenia. Antipsychotic treatment with quetiapine was initialized. A stable recovery took further 4 weeks in which combined treatment with quetiapine and ziprasidone was given.

CONCLUSION

The course of the illness suggests that the continuous affective symptoms, which were most likely a side effect of rimonabant, may have triggered the psychosis analogous to the stress-diathesis model of schizophrenia. As a consequence, rimonabant may not be the first choice in obese patients with a history of schizophrenia due to a potentially increased risk of a relapse via an indirect mechanism.

Cannabinoid-1 receptor antagonists in type-2 diabetes

Type-2 diabetes is closely related to abdominal obesity and is generally associated with other cardiometabolic risk factors, resulting in a risk of major cardiovascular disease. Several animal and human observations suggest that the endocannabinoid system is over-active in the presence of abdominal obesity and/or diabetes. Both central and peripheral endocannabinoid actions, via the activation of CB1 receptors, promote weight gain and associated metabolic changes. Rimonabant, the first selective CB(1) receptor blocker in clinical use, has been shown to reduce body weight, waist circumference, triglycerides, blood pressure, insulin resistance index and C-reactive protein levels, and to increase high-density lipoprotein (HDL) cholesterol and adiponectin concentrations in both non-diabetic and diabetic overweight/obese patients. In addition, a 0.5-0.7% reduction in HbA1c levels was observed in metformin- or sulphonylurea-treated patients with type-2 diabetes and in drug-naïve diabetic patients. Almost half of the metabolic changes, including HbA1c reduction, could not be explained by weight loss, suggesting that there are direct peripheral effects. Rimonabant was generally well-tolerated, and the safety profile was similar in diabetic and non-diabetic patients, with a higher incidence of depressed mood disorders, nausea and dizziness. In conclusion, the potential role of rimonabant in overweight/obese patients with type-2 diabetes and at high risk of cardiovascular disease deserves much consideration.