Clinical question
How effective are nicotine receptor partial agonists (NRPAs) for smoking cessation?
Bottom line
Varenicline at standard dose (1mg twice a day) more than doubled the chances of quitting compared with placebo (NNT*11). Low-dose varenicline roughly doubled the chances of quitting, and reduced the number and severity of side effects. The most common side effect of varenicline was nausea. The number of people stopping smoking with varenicline was higher than with bupropion or with NRT (nicotine replacement therapy). Limited evidence suggested varenicline might have a role to play in relapse prevention. Cytisine was effective and affordable but absolute quit rates were modest. Dianicline was not effective and is no longer in development.
*NNT = number needed to treat to benefit 1 individual
Caveat
Early reports of possible links between varenicline and suicidal ideation and behaviour have not been confirmed but concerns have been raised that it may slightly increase cardiovascular events in people already at increased risk of those illnesses.
Context
NRPAs may help people to stop smoking by a combination of maintaining moderate levels of dopamine to counteract withdrawal symptoms and reducing smoking satisfaction. Varenicline is the most widely available treatment. Cytisine is a similar medication but is only available in central and eastern Europe and through internet sales.
Cochrane Systematic Review
Cahill K et al. Nicotine receptor partial agonists for smoking cessation. Cochrane Reviews, 2016, Issue 5. Art. No.: CD006103.DOI: 10.1002/14651858. CD006103.pub7. This review contains 44 studies involving 29,353 participants.
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