Recent advances in the treatment of tobacco dependence

Sex- and age-dependent differences in nicotine susceptibility evoked by developmental exposure to tobacco smoke and/or ethanol in mice

Either tobacco smoking or alcohol consumption during pregnancy sex-selectively increases susceptibility to drugs of abuse later in life. Considering that pregnant smoking women are frequently intermittent consumers of alcoholic beverages, here, we investigated whether a short-term ethanol exposure restricted to the brain growth spurt period when combined with chronic developmental exposure to tobacco smoke aggravates susceptibility to nicotine in adolescent and adult mice. Swiss male and female mice were exposed to tobacco smoke (SMK; research cigarettes 3R4F, whole-body exposure, 8 h/daily) or ambient air during the gestational period and until the tenth postnatal day (PN). Ethanol (ETOH, 2 g/Kg, 25%, i.p.) or saline was injected in the pups every other day from PN2 to PN10. There were no significant differences in cotinine (nicotine metabolite) and ethanol serum levels among SMK, ETOH and SMK + ETOH groups. During adolescence (PN30) and adulthood (PN90), nicotine (NIC, 0.5 mg/Kg) susceptibility was evaluated in the conditioned place preference and open field tests. NIC impact was more evident in females: SMK, ETOH and SMK + ETOH adolescent females were equally more susceptible to nicotine-induced place preference than control animals. At adulthood, SMK and SMK + ETOH adult females exhibited a nicotine-evoked hyperlocomotor profile in the open field, with a stronger effect in the SMK + ETOH group. Our results indicate that ethanol exposure during the brain growth spurt, when combined to developmental exposure to tobacco smoke, increases nicotine susceptibility with stronger effects in adult females. This result represents a worsened outcome from the early developmental dual exposure and may predispose nicotine use/abuse later in life.

Complementing the Standard Multicomponent Treatment for Smokers With Denicotinized Cigarettes: A Randomized Trial

INTRODUCTION

Standard treatments (STs) for smoking cessation typically combine pharmacotherapy and behavioral support but do not address the sensory and behavioral aspects of smoking which may play a role in maintaining smoking behavior. Replacing such sensations temporarily after cessation may enhance treatment efficacy. We hypothesized that denicotinized cigarettes (DNCs), which have a very low nicotine content but provide these sensory and behavioral stimuli, could help alleviate urges to smoke and tobacco withdrawal symptoms and in turn enhance the efficacy of ST.

METHODS

Two hundred smokers seeking treatment received nine weekly behavioral support sessions and pharmacotherapy (100 used varenicline, 100 used nicotine replacement therapy). They were randomized on the target quit day to receive 280 DNCs (used ad libitum over 2 weeks in addition to ST) or ST alone.

RESULTS

Urge-to-smoke frequency (2.61 vs. 2.96, P = .03) but not strength (2.85 vs. 3.10, P = .20) in the first week of abstinence was significantly lower in DNC users versus ST alone. There were no differences in composite withdrawal scores between groups. Abstinence was significantly higher among DNC users versus ST alone at 1 (OR = 2.07; 95% CI: 1.63% to 3.70%) and 4 weeks (OR = 1.83; 95% CI: 1.05% to 3.21%), but not at 12 weeks (OR = 1.42; 95% CI: 0.79% to 2.55%). DNC use was a significant predictor of abstinence at 1 and 4 weeks (OR = 2.63; 95% CI: 1.40% to 4.93% and OR = 2.38; 95% CI: 1.26% to 4.46%), but not at 12 weeks.

CONCLUSIONS

Adding DNCs to ST has the potential to assist smokers early in their quit attempt, but research is needed to determine how best to utilize DNCs in treatment.

Tobacco smoke containing high or low levels of nicotine during adolescence: effects on novelty-seeking and anxiety-like behaviors in mice

RATIONALE

Thousands of adolescents start smoking daily but information on the effects of tobacco exposure on this age group is scarce. Moreover, the available animal models rely on the effects of nicotine, neglecting other neuroactive components of tobacco.

OBJECTIVES

We investigated the effects of exposure of adolescent mice to tobacco smoke generated from cigarettes containing either high or low levels of nicotine on novelty seeking and anxiety-like behaviors.

METHODS

From postnatal day (PN) 30 to 45, male and female Swiss mice were exposed to tobacco smoke (whole body exposure, 8 h/day, 7 days/week) generated from 2R1F (HighNic group: 1.74 mg nicotine/cigarette) or 4A1 (LowNic group: 0.14 mg nicotine/cigarette) research cigarettes, whereas control mice were exposed to ambient air. By the end (PN44-45), shortly (PN49-50), or long after (PN74-75) exposure, mice were tested on the elevated plus maze and on the hole board.

RESULTS

While HighNic mice presented an increased number of head-dips (increased novelty-seeking) and decreased grooming (increased anxiety-like behavior) by the end of adolescent exposure, only the latter effect persisted shortly after its end. Distinctively, LowNic mice presented reduced head-dips both by the end and shortly after exposure as well as decreased grooming shortly and long after the end of exposure. Interestingly, only HighNic mice presented detectable cotinine (nicotine metabolite) serum levels (109.1 ± 24.0 ng/ml).

CONCLUSION

Our results demonstrate that even adolescent exposure to tobacco smoke with very low nicotine content can have significant short- and long-term behavioral effects, supporting the hypothesis that adolescents can be particularly vulnerable to the effects of cigarette consumption.

Reduced-nicotine content cigarettes: Is there potential to aid smoking cessation?

INTRODUCTION

Current smoking cessation treatments largely address pharmacological dependence on nicotine. New approaches are needed that address both nicotine dependence and psychological dependence on cigarettes as the source of nicotine. One such approach is the use of cigarettes with reduced nicotine content.

METHODS

We reviewed the available literature on the use of reduced-nicotine content cigarettes as a cessation aid.

RESULTS

One case series study and trial data indicate that reduction in the level of nicotine in cigarette tobacco can reduce the level of nicotine dependence in smokers and do so without adverse effects on cardiovascular biomarkers or significant compensatory smoking. We identified three clinical trials (total n = 489) that suggest that smokers can dissociate nicotine delivery from the act of smoking if they use reduced-nicotine content cigarettes in combination with nicotine replacement therapy.

DISCUSSION

The identified studies point to a benefit but involved only a small number of participants and provide only limited data on long-term abstinence. More definitive evidence from larger trials with longer follow-up is needed to clarify the role of reduced nicotine cigarettes as an aid to smoking cessation.

Varenicline: a first-line treatment option for smoking cessation

BACKGROUND

Varenicline acts as a partial agonist/antagonist with affinity and selectivity for alpha(4) beta(2) nicotinic acetylcholine receptors. This activity at the nicotine-receptor level may help patients achieve smoking cessation by reducing cravings/withdrawal symptoms and smoking satisfaction.

OBJECTIVE

This article reviews the literature on the pharmacologic properties, therapeutic efficacy, and tolerability of varenicline for smoking cessation.

METHODS

Pertinent controlled clinical trials, meta-analyses, meeting abstracts, case reports, and review articles published in English between 1966 and May 2008 were identified through searches of MEDLINE and OVID using the terms varenicline, smoking, tobacco cessation, and CP 526555.

RESULTS

Eight clinical trials were identified that compared <or=12 weeks of varenicline treatment with placebo and/or bupropion sustained release (SR); one of the trials reported follow-up data to 24 weeks, and the remainder reported data to 52 weeks. During treatment with oral varenicline titrated to 1 mg BID, CO-confirmed 4-week continuous quit rates/continuous abstinence rates (CQRs/CARs) in weeks 9 through 12 ranged from 43.9% (odds ratio [OR] = 3.85 [95% CI, 2.69-5.50; P < 0.001 vs placebo]; OR = 1.90 [95% CI, 1.38-2.62; P < 0.001 vs bupropion SR]) to 65.4% (OR = 2.98 [95% CI, 1.78-4.99; P < 0.001 vs placebo]). In 4 of these trials, varenicline 1 mg BID was associated with significantly higher CQRs/CARs compared with placebo at week-52 follow-up, ranging from 21.9% (P < 0.001) to 34.6% (P = 0.036). One trial reported a significantly higher CAR at 52 weeks with varenicline compared with bupropion SR (23.0% vs 14.6%, respectively; P = 0.004), and another reported a significantly higher CAR at 52 weeks with varenicline compared with nicotine replacement therapy (25.9% vs 19.8%, respectively; P = 0.040). In a relapse-prevention study that included a 12-week extension period for participants who were abstinent after the initial 12 weeks of treatment, CARs were significantly improved at 24 weeks with varenicline relative to placebo (70.5% vs 49.6%, respectively; OR = 2.48; 95% CI, 1.95-3.16; P < 0.001). Treatment with varenicline was generally well tolerated in study populations with no major comorbidities. In a pooled analysis of 2 Phase III trials, the most commonly reported adverse events (AEs) with varenicline, bupropion SR, and placebo were nausea (28.8%, 9.9%, and 9.1%, respectively), insomnia (14.2%, 21.5%, and 12.6%), and headache (14.2%, 11.1%, and 12.4%). In a pooled analysis of 2 identically designed Phase III trials, bupropion SR was associated with the highest overall rates of discontinuation due to all-cause AEs compared with varenicline and placebo (13.9%, 9.5%, and 8.2%, respectively) and due to AEs considered related to study drug (12.1%, 7.9%, and 6.4%). In double-blind clinical trials of varenicline, nausea was the most frequently reported AE (16.3%-41.9%). Varenicline treatment should begin 7 days before the proposed smoking quit date; dose titration is recommended to minimize dose-related nausea. Based on postmarketing reports of serious AEs in vareniclinetreated patients, caution is recommended when operating vehicles or heavy machinery. Patient education and monitoring for potential AEs are also recommended, particularly in patients with a history of psychiatric illness.

CONCLUSIONS

Varenicline has a unique mechanism of action compared with other first-line options for smoking cessation. Available clinical-trial data support its use as an effective and generally well-tolerated therapy for smoking cessation in healthy adult smokers, although there is a need for further efficacy and safety evaluation in the general population, particularly those with comorbid conditions.

Practical total syntheses of epiquinamide enantiomers

Short and practical syntheses of epiquinamide and its enantiomer were accomplished with high overall yields and high stereoselectivity from readily available starting materials.

Expanding treatment of tobacco dependence

Nicotine dependence is the leading preventable cause of adult morbidity and mortality in the world. New research on the treatment of this disorder ranges from studies evaluating access to treatment to studies elucidating the molecular mechanisms of nicotine addiction. As our understanding of the neurobiology of tobacco addiction grows, the number of potential therapeutic targets by which we can intervene in this pernicious disorder also increases. This paper presents an overview of recent research trends in the treatment of tobacco dependence. We review several novel mechanisms of action that may serve as therapeutic targets for the pharmacologic treatment of tobacco dependence, including drugs that affect monamine oxidase, selective nicotinic receptors, glutamate and gamma-aminobutyric acid receptors, and the endocannabinoid system. For each of these therapeutic targets, we discuss medications in development that affect these pathophysiologic mechanisms.