Varenicline (trade name Chantix and Champix) is a medication used for smoking cessation. Varenicline is also used for the treatment of dry eye disease.The most common side-effects include nausea (feeling sick), insomnia (difficulty sleeping), abnormal dreams, headache and nasopharyngitis (inflammation of the nose and throat).It is a high-affinity partial agonist for the α4β2 nicotinic acetylcholine receptor subtype (nACh) that leads to the release of the neurotransmitter dopamine in the nucleus accumbens reward center of the brain when activated, and therefore, has the capacity to reduce the feelings of craving and withdrawal caused by smoking cessation. In this respect it is similar to cytisine and different from the nicotinic antagonist bupropion and nicotine replacement therapies (NRTs) like nicotine patches and nicotine gum. It is estimated that varenicline successfully helps one of every eleven people who smoke remain abstinent from tobacco at six months. It is on the World Health Organizations List of Essential Medicines. It is available as a generic medication. Medical uses
Varenicline is used to help people stop smoking tobacco (smoking cessation). A meta-analysis found that less than 20% of people treated with varenicline remain abstinent from smoking at one year. In a 2009 meta-analysis varenicline was found to be more effective than bupropion (odds ratio 1.40) and nicotine replacement therapies (NRT) (odds ratio 1.56).A 2013 Cochrane overview and network meta-analysis concluded that varenicline is the most effective medication for tobacco cessation and that smokers were nearly three times more likely to quit tobacco use while on varenicline than with placebo treatment.
Incidence of nausea is dose-dependent: incidence of nausea was higher in people taking a larger dose (30%) versus placebo (10%) as compared to people taking a smaller dose (16%) versus placebo (11%). Depression and suicide
In 2007, the US FDA had announced it had received post-marketing reports of thoughts of suicide and occasional suicidal behavior, erratic behavior, and drowsiness among people using varenicline for smoking cessation. In 2009, the US FDA required varenicline to carry a boxed warning that the drug should be stopped if any of these symptoms are experienced.A 2014 systematic review did not find evidence of an increased suicide risk. Other analyses have reached the same conclusion and found no increased risk of neuropsychiatric side effects with varenicline. No evidence for increased risks of cardiovascular events, depression, or self-harm with varenicline versus nicotine replacement therapy was found in one post-marketing surveillance study.In 2016 the FDA removed the black box warning. People are still advised to stop the medication if they "notice any side effects on mood, behavior, or thinking." Cardiovascular disease
In June 2011, the US FDA issued a safety announcement that varenicline may be associated with "a small, increased risk of certain cardiovascular adverse events in people who have cardiovascular disease. "A prior 2011 review had found increased risk of cardiovascular events compared with placebo. Expert commentary in the same journal raised doubts about the methodology of the review, concerns which were echoed by the European Medicines Agency and subsequent reviews.