The drug varenicline shows effectiveness in helping smokers quit and abstain from smoking when compared to placebo and the smoking cessation medication bupropion, according to three studies in the July 5 issue of JAMA.

Varenicline is a non-nicotine drug that is thought to be beneficial for smoking cessation by stimulating the release of the chemical dopamine in the brain to reduce craving and withdrawal while simultaneously blocking the reinforcing effects of smoked nicotine. Most other smoking cessation pharmacotherapies are nicotine replacement products.

One study found that the drug reduced craving and withdrawal and, for those who smoked while receiving study drug, also reduced smoking satisfaction. No sex differences in efficacy for varenicline were observed. Varenicline was safe and generally well tolerated, with study drug discontinuation rates similar to those for placebo. The most common adverse events for participants receiving active-drug treatment were nausea for varenicline and insomnia for bupropion SR.

“Varenicline is an efficacious therapy for smoking cessation. In this trial, varenicline was more efficacious than placebo at all time points and more efficacious than bupropion SR at the end of 12 weeks of treatment and at 24 weeks,” the authors write.

A second, similar study of the drug was also performed. The authors arrived at the following conclusion: “Advances can be made by improving the use of existing smoking cessation treatments and by developing better treatments. Varenicline … has demonstrated a robust ability to increase cessation rates (short-term and long-term) compared with both placebo and a first-line smoking cessation medication (bupropion SR), and may represent an advance in the treatment of tobacco dependence.”

A third study evaluated the efficacy of an additional 12 weeks of varenicline used for relapse prevention in smokers who successfully achieved abstinence following an initial 12-week varenicline treatment. In their concluding comments, the researchers of this study wrote, “Extended use of varenicline helps recent ex-smokers to maintain their abstinence and prevent relapse. Varenicline is the first smoking cessation treatment to demonstrate a significant long-term relapse prevention effect.”

The above-mentioned studies were supported by Pfizer Inc.