SMOKERS GET HOOKED by more than nicotine. If they light up 20 times a day, they're in the habit of taking 200 or more puffs daily, often timed to pleasurable things like coffee, alcohol, food or sex. So the chances of smokers quitting on their own are estimated at as low as 1% to 7%.
Thus, there has been considerable buzz among smoking-cessation doctors about a new Pfizer Inc. drug called varenicline, which the company plans to market this month under the brand name Chantix. Research published this week shows the drug appears to increase significantly the numbers of people who are able to give up smoking -- even compared with patients using current drug therapy to help.
Despite the positive findings, there were several limitations to the research. One is the fact that people with pre-existing conditions such as depression, alcohol or drug abuse, and diabetes requiring insulin were excluded from some of the studies. Another stems from the fact that the majority of authors of the three studies, which were published in the Journal of the American Medical Association, either have done consulting work or received honoraria or research grants from Pfizer and other drug companies, or are Pfizer employees or shareholders.
Such apparent conflicts of interest won't normally change the major findings of research. But they can affect nuances and shadings of the way they're presented. "All of these papers were rigorously peer-reviewed," says the University of Wisconsin's Douglas E. Jorenby, who headed one of the studies. (He has received research funding from Pfizer but not consulting fees or honoraria.) A Pfizer spokeswoman says, "Regarding consultation fees, Pfizer follows standard protocols for consulting agreements and provides adequate disclosure."
One study at the University of Wisconsin and elsewhere shows that during the last four weeks of a 12-week treatment session, 43.9% of patients abstained from smoking on Chantix. By comparison, 17.6% of people on placebo pills kicked their habit. Chantix patients had more success than those on a current drug, bupropion (the brand names of bupropion are Zyban and Wellbutrin, from GlaxoSmithKline PLC), on which 29.8% were able to quit. Another study at Oregon Health & Science University in Portland produced almost identical results to the Wisconsin study.
Other research at the University of Oslo in Norway and elsewhere examined the question of what happened to former smokers after a year. Smokers who had quit during the first 12 weeks of research tended to stay off cigarettes in greater proportions if they were treated with the Pfizer drug than if they were on placebo pills. This effect was more modest -- 43.6% as opposed to 36.9% -- but significant.
"The research was very robust," says Andrea King, an associate professor of psychiatry at the University of Chicago who wasn't involved in the studies.
By far the main side effect with Chantix was nausea, although Norwegian researchers described it as "mostly mild and tolerable." Norwegian researchers said 32% of participants experienced nausea but that "only 3% discontinued the medication because of it." In the Wisconsin study, 29.4% of patients got nauseated, versus 7.4% on Wellbutrin and 9.7% on a placebo.
Nicotine patches and bupropion do help to increase the rate of quitting, but still, most who try to stop smoking aren't successful. "People will tell you that quitting smoking is more difficult than quitting any other addictive behavior," says Robert C. Klesges, a professor of preventive medicine at the University of Tennessee Health Science Center in Memphis.
Nicotine from a patch attaches to nicotine receptors in the brain but doesn't block attachment of more nicotine, so that if someone starts smoking again, he or she will still feel a "reward" from that cigarette. But the patch nicotine is supposed to lessen the urge. Chantix, which the Food and Drug Administration approved in May, attaches to nicotine receptors and blocks nicotine's ability to attach; thus someone isn't supposed to get that physiological "reward" from smoking again. Bupropion is a "dopamine reuptake inhibitor." That means it works through a different mechanism -- prolonging the presence in the brain of chemicals including dopamine, which is believed to play a role in decreasing cravings.
To stop smoking, people are supposed to take Chantix for 12 weeks. Then patients who successfully quit are supposed to take the drug (which comes in pill form) for 12 more weeks to lessen the chance that they will start smoking again. (Since the drug hasn't come to market yet, there isn't a price tag on it.)
Smoking leads to an estimated 420,000 deaths annually in the U.S. alone, from various diseases including cancers, cardiovascular disease and emphysema. Fear of those illnesses causes roughly one-third of smokers to at least try quitting during a typical year. Dr. Jorenby says that "attempt" rate has been fairly constant of late, but that there now are greater percentages of smokers who smoke heavily, or who have depression or anxiety. This confounds the problem, Dr. Jorenby says, because "people with depression have a tough time quitting."
Dr. Jorenby says the effects of Chantix appear to be to increase the quit rate by 1.5 to 2 times, compared with existing drugs. But people in smoking research tend to be highly motivated. And because they live near big teaching hospitals, they tend to be more medically aware and -- apart from smoking -- healthier than the general population. So there are doubts the findings will apply fully to most people.
"Most of these academic centers attract highly motivated, nonrepresentative smokers," says Tennessee's Dr. Klesges, who co-wrote an editorial in JAMA about the new research. "In the real world, the effectiveness diminishes." Moreover, he notes that the fact that some studies excluded people with depression or a history of alcohol or drug use increases the likelihood within the studies of people being able to kick the smoking habit. "Some of these exclusions will increase your numbers" in research reports, he says. So quit rates in the real world may not end up being as impressive.
Dr. Klesges also is skeptical of the findings of the study from Norway that evaluated whether successful cigarette quitters stayed off them for a year or suffered a relapse. In particular, he didn't find it surprising that a relatively greater percentage of people taking Chantix avoided relapses after a year than did those on placebo. After all, these were all patients who had quit smoking by 24 weeks through using Chantix.
"Chances are that if the drug worked for you before, it'll work for you again," he says. "So I think the results are more optimistic than what would really happen."
--- Kicking the Habit Here are some methods to help smokers quit. -- Nicotine patches can reduce the urge to smoke. -- The drug bupropion can reduce cravings by prolonging the presence in the brain of chemicals, including dopamine. -- Chantix is meant to block smoking's psychological 'reward.'
more drug pipeline at: http://www.chartsbank.com/PipelineList.aspx
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