WEDNESDAY, Nov. 16, 2005 (HealthDay News) -- An experimental drug might make it a lot easier to stop smoking, new research suggests.
The drug, varenicline, quadrupled the chances that smokers could ditch their cigarettes when compared to a placebo; the chances were doubled when compared to Zyban, a drug already on the market to help smokers quit.
If approved, varenicline could become another weapon in the war against smoking.
"It becomes another option to help people quit," said Dr. Raymond Gibbons, president-elect of the American Heart Association. "It might capture more of the population."
But Gibbons warned that the drug "is not a magic bullet."
"There was only a 1-in-5 success rate at a year," he said. "It shows the importance of public education programs so people don't start in the first place."
Gibbons was not involved in the research, which was presented Tuesday at the American Heart Association's annual meeting in Dallas.
Varenicline is one of a new class of drugs and works by binding to the same receptors as nicotine in the brain.
"Varenicline is a non-nicotine drug, but by attaching and occupying the receptor, it prevents nicotine from getting there, so all the downstream effects of nicotine such as reward, reinforcement and a large increase of dopamine in the reward centers of the brain are stopped," explained study author Dr. Serena Tonstad, an attending physician in the department of preventive cardiology at Ulleval University Hospital in Oslo, Norway.
The findings came from three studies funded by Pfizer, which makes the drug.
Two were identical, double-blinded trials involving about 2,000 smokers who were randomized to take one of three pills: varenicline, Zyban (or bupropion, also marketed as Wellbutrin for depression), and a placebo.
The participants, all of whom wanted to quit smoking, were given the pills for 12 weeks, then were followed for an additional 40 weeks. All study participants also received motivational support, Tonstad said.
After 12 weeks in both studies, about 44 percent of the people taking varenicline quit smoking, vs. 30 percent in the Zyban group and 17.7 percent in the placebo group.
A single puff of a cigarette, measured by carbon monoxide in expired breath, counted as a return to smoking.
At the end of a year, 22.1 percent of the people in the varenicline group were still smoke-free, vs. 16.4 percent in the Zyban group and 8.4 percent in the placebo group. The numbers were comparable in the second study (23 percent, 15 percent and 10 percent, respectively).
Participants who succeeded in quitting in the initial two studies were then further randomized for the third study. Half received varenicline and half a placebo for an additional 12 weeks.
Continuous abstinence for another 12 weeks for those in the varenicline group was 70.6 percent, vs. 49.8 percent for those receiving a placebo.
After one year, 44 percent of those who had taken varenicline were still smoke-free, vs. 37 percent for the placebo group.
"An additional 12 weeks of treatment was more beneficial than placebo both to the end of treatment and to one year," Tonstad said. "In all three studies, varenicline was safe and well-tolerated."
Some participants taking varenicline reported nausea, but most of these people said the problem was mild. Less than 3 percent left the trial because of this side effect.
There were no signs of withdrawal from varenicline, even though the drug was stopped abruptly.
Although there were definite benefits in people taking varenicline, "the absolute numbers were perhaps a little disappointing," said Dr. Timothy Gardner, medical director of the Center for Heart and Vascular Health at Christiana Care Health Services in Wilmington, Del.
And that just highlights the importance of prevention. "We need to keep people from starting, and this is why," Gibbons emphasized. "In the best of hands, the success rate is not high."
Smoking is implicated in a variety of serious health problems, including lung cancer and heart disease.
Men who smoke die an average of 13.2 years earlier than nonsmoking men, while women who smoke die an average of 14.5 years earlier than nonsmoking women, according to the U.S. Surgeon General.
"It's incredibly important to stop smoking," Gibbons added, "Within a year of quitting, cardiovascular risk goes down 50 percent."
With about 50 million people in the United States still smoking, there has been a rush to come up with quitting aids.
At least two other vaccines and one other drug are currently in development.
More information
The U.S. Centers for Disease Control and Prevention has resources on quitting smoking.
