The risk of varenicline-induced seizure among those who have attempted to quit smoking using pharmacotherapy

OBJECTIVE

Varenicline is an effective smoking cessation agent; however, its use is limited because of black box warnings issued by regulatory agencies in the U.S. and Australia. The U.S. Food and Drug Administration updated the label for varenicline in 2015 to warn about the risk of varenicline-induced seizures. The objective of this study was to examine the risk of seizure associated with varenicline use.

METHODS

A nested case-control study was performed using IMS LifeLink PharMetrics Plus administrative claims data (2009-2015). The outcome was presumptive seizures. All smokers making an attempt to quit smoking and having no recent seizure events were included in the nest. Cases and controls were matched (1:4) on age (±5 years), sex, index date (±30 days), event date, and duration of enrollment. An exposure period of 90 days preceding the event date was used. Chi-square tests were used to compare the characteristics of cases and controls. Conditional logistic regression was conducted to determine if an association between presumptive seizures and varenicline use exists.

RESULTS

Our final sample was comprised of 1342 cases and 5368 controls. The adjusted analysis showed that odds of a seizure for patients with a varenicline prescription were 1.09 (confidence interval [CI] = 0.88-1.36) times those of patients with no varenicline exposure.

CONCLUSIONS

This study did not find a significant association between varenicline and increased risk of presumptive seizures. These findings raise questions regarding the necessity for a warning label for increased risk of seizures associated with varenicline.

Prevention of recurrent autonomic dysreflexia: a survey of current practice

OBJECTIVE

There is a dearth of literature on the treatment of chronic recurrent autonomic dysreflexia (AD), a well-known complication of spinal cord injury that can have life-threatening implications. This study sought to identify clinical practices regarding the treatment of AD, both acute and recurrent, in patients with spinal cord injury (SCI).

METHODS

Online survey regarding AD management in SCI composed of 11 questions designed to obtain information on respondent characteristics, AD treatment options, and causes of AD.

SETTING

Veterans Administration health care system.

PARTICIPANTS

Veterans Health Administration National SCI Staff Physicians were sent an electronic email to participate in the anonymous web-based survey.

INTERVENTION

None applicable.

RESULTS

The response rate was 52%. The most commonly prescribed medications for minor and severe acute manifestations of AD were nitrates. For recurrent AD, clonidine was the most commonly prescribed medication.

INTERPRETATION

Anti-hypertensive medications continue to be the mainstay in the management of both acute and chronic recurrent AD. Current literature is lacking in prospective randomized controlled trials investigating the relative efficacy of AD interventions. Evidence-based practice guidelines are necessary to improve clinical care.

The cannabinoid-1 receptor inverse agonist taranabant reduces abdominal pain and increases intestinal transit in mice

BACKGROUND

Constipation-predominant irritable bowel syndrome (IBS-C) is a common functional gastrointestinal (GI) disorder with abdominal pain and decreased motility. Current treatments of IBS-C are insufficient. The aim of this study was to evaluate the potential application of taranabant, a cannabinoid type 1 (CB1) inverse agonist using mouse models mimicking the symptoms of IBS-C.

METHODS

Changes in intestinal contractile activity were studied in vitro, using isolated mouse ileum and colon and intracellular recordings. In vivo, whole gastrointestinal transit (WGT) and fecal pellet output (FPO) were measured under standard conditions and with pharmacologically delayed GI transit. The antinociceptive effect was evaluated in mustard oil- and acetic acid-induced models of visceral pain. Forced swimming and tail suspension tests were performed and locomotor activity was measured to evaluate potential central side effects.

KEY RESULTS

In vitro, taranabant (10(-10) -10(-7) mol L(-1)) increased contractile responses in mouse ileum and blocked the effect of the CB agonist WIN 55,212-2. Taranabant had no effect on the amplitude of electrical field stimulation (EFS)-evoked junction potentials. In vivo, taranabant (0.1-3 mg kg(-1), i.p. and 3 mg kg(-1), p.o.) increased WGT and FPO in mice and reversed experimental constipation. The effect of taranabant was absent in CB1(-/-) mice. Taranabant significantly decreased the number of pain-related behaviors in animal models. At the doses tested, taranabant did not display mood-related adverse side effects typical for CB1 receptor inverse agonists.

CONCLUSIONS & INFERENCES

Taranabant improved symptoms related to slow GI motility and abdominal pain and may become an attractive template in the development of novel therapeutics targeting IBS-C.

Nicotine vaccines to treat tobacco dependence

Tobacco smoking is globally far more widespread than use of any other substance of abuse. Nicotine is an important tobacco constituent that is responsible for addictive properties of smoking. The currently available medications for the treatment of nicotine addiction have limited efficacy. A challenging novel therapeutic concept is vaccination against nicotine. An efficient vaccine would generate antibodies that sequester nicotine in the blood and prevent its access to the brain. The vaccine would have great potential for treating nicotine addiction and for relapse prevention. We reviewed the current status of vaccines against nicotine addiction that are undergoing clinical trials or are in preclinical development. We discuss problems associated with the development of nicotine vaccines, their efficacy in addiction treatment, challenges and ethical concerns. Existing evidence indicates that nicotine vaccination is well tolerated and capable of inducing an immune response but its effectiveness in increasing smoking abstinence has not been shown so far.

Varenicline attenuates cue-induced relapse to alcohol, but not nicotine seeking, while reducing inhibitory response control

RATIONALE

Treatment of the most widely abused drugs, nicotine and alcohol, is hampered by high rates of relapse. Varenicline tartrate, an α4β2 nicotinic receptor partial agonist, is currently prescribed as a smoking cessation aid. However, there is emerging evidence that it may also modulate alcohol seeking and cognitive functioning in rats.

OBJECTIVES

As preclinical data on alcohol taking and relapse are limited, we used a self-administration-reinstatement model to evaluate the effects of varenicline on operant responding for alcohol (12%, v/v), intravenous nicotine (40 μg/kg/inf.), sucrose (10%, w/v) and on cue-induced relapse to alcohol and nicotine seeking in rats. At the cognitive level, we assed varenicline's effects on 5-choice serial reaction time task (5-CSRTT) performance with a focus on correct responses (attention) and premature responding (impulsivity), modalities that have previously been associated with addictive behaviour.

RESULTS

Varenicline, at doses of 1.5 and 2.5 mg/kg, reduced alcohol and nicotine self-administration and enhanced operant responding for sucrose. At these doses, varenicline reduced cue-induced relapse to alcohol, but not nicotine seeking. In contrast, at 0.5 mg/kg, varenicline facilitated cue-induced nicotine seeking. Similar to nicotine, varenicline increased premature responding at low doses, but had no effect on any of the other behavioural parameters in the 5-CSRTT.

CONCLUSIONS

Our data indicate that varenicline specifically reduced responding for nicotine and alcohol, but not for natural reinforcers such as sucrose. Interestingly, varenicline strongly attenuated cue-induced relapse to alcohol seeking, but not nicotine seeking. Varenicline may therefore be a promising aid in the treatment of alcohol addiction.

Comparison of available treatments for tobacco addiction

Cigarette smoking is a major public health problem that causes more than 5 million deaths annually worldwide. Cigarette smoking is especially common among individuals with psychiatric comorbidity, including individuals with primary psychiatric disorders and other addictions. Effective behavioral and pharmacologic treatments for smoking cessation are available. Behavioral treatments including brief (< 3 min) counseling by physicians are effective. Seven first-line pharmacologic treatments are currently available: five nicotine replacement therapies, bupropion, and varenicline. In addition, clonidine and nortriptyline are second-line treatments for smoking cessation. These treatments increase the chances of quitting smoking by two- to threefold, supporting their use in smokers who are motivated to quit. However, effective treatments for many subpopulations, including smokers with psychiatric comorbidities as well as adolescent, pregnant, or postpartum smokers, remain to be developed and represent an important challenge.

Nicotine vaccines: will smokers take a shot at quitting?

INTRODUCTION

A vaccine against nicotine may soon be available to smokers who want to quit. The vaccine stimulates the production of antibodies that bind to nicotine, thereby impeding nicotine from crossing the blood-brain barrier and exerting psychoactive effects. The primary purpose of this study was to evaluate intentions to try a nicotine vaccine if one were to become available among a nationally representative sample of smokers. The secondary purpose was to assess whether information about genetic susceptibility to nicotine addiction had an effect on smokers' interest in receiving the vaccine.

METHODS

Four hundred and twenty-seven adults were randomized to read one of two versions of a short description about the vaccine. One version framed addiction as genetically influenced, while the other framed it as environmentally influenced. Smokers were then asked about their intentions to use a nicotine vaccine if one were to become available in the future.

RESULTS

Across both groups, 53% indicated that they would be likely or very likely to try the vaccine. Using multivariate linear regression, the strongest predictors of vaccination intention were having a favorable attitude toward a nicotine vaccine (beta = .41) and having a favorable attitude toward vaccination in general (beta = .22). There were no significant effects of the framing conditions on intention to receive the vaccine.

DISCUSSION

Intentions to try a nicotine vaccine as a cessation method are relatively high among smokers. If the vaccine becomes available, specific groups of smokers may be more interested than others; education and recruitment efforts could be targeted appropriately.