Nicotine patches and other licensed drugs are effective in helping people kick the habit of smoking, a new study shows, with one of the most commonly used medications improving smoking cessation by 80 percent.

In the study published in The Cochrane Library, researchers found that successful drugs helped individuals stop smoking for six months or more.

"This review provides strong evidence that the three main treatments, nicotine replacement therapy, bupropion and varenicline, can all help people to stop smoking," said Kate Cahill, study author and senior researcher of the Department of Primary Care Health Sciences at the University of Oxford.

Researchers collected findings from 267 studies, which involved more than 100,000 people that used licensed and unlicensed smoking cessation medications and placebo trials, to find that three widely-used licensed drugs and cytisine are capable of improving a smoker's chances of quitting.

"Although cytisine is not currently licensed for smoking cessation in most of the world, these data suggest it has potential as an effective and affordable therapy," Cahill said.

Specifically, single nicotine replacement therapies (NRT), or bupropion, marketed as Zyban, helped people quit 80 percent more than placebo drugs did, while varenicline, or Chantix, helped quit between two to three times more than placebo and was 50 percent more effective than NRT patches, gum, sprays, lozenges, and inhalers.

Cytisine, the unlicensed drug, improved smoking cessation almost four-fold when compared to the control study.

Additionally, nortriptyline, the antidepressant drug called Pamelor, was found effective but didn't provide added benefits when it was combined with NRT.

When the researchers tested the safety of the medications, NRT, bupropion, and varenicline were found to be low risk, though findings on varenicline were still relatively unclear. Bupriopion has been thought to cause occasional seizures in vulnerable users. These new findings, however, show that the slow-release version did not increase seizures in those trying to quit.

"Further research may be warranted into the safety of varenicline," said Cahill. "However, in the trials we looked at we did not detect evidence of any increase in neuropsychiatric, heart or circulatory problems."

Source: Cahill K, Stevens S, Perera R, et al. Pharmacological interventions for smoking cessation: an overview and network meta-analysis. The Cochrane Library. 2013.