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Thomas S. May, M.A.Medical Writer |
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Are You Itching to Quit Smoking?
Thomas S. May, Medical Writer Introduction We know that wearing a nicotine patch on your skin can help you quit smoking. But scientists have discovered that being treated for psoriasis, a disorder marked by red, flaky patches on the skin, may also help smokers kick the habit. Researchers at the University of Toronto, Ontario, Canada have discovered that the drug methoxsalen (8-MOP, Oxsoralen), used to treat psoriasis, has an interesting side effect: It slows down the metabolism of nicotine in the body.
Heavy smokers are addicted to nicotine, and they usually try to maintain
their blood nicotine levels by smoking cigarettes (or some other tobacco
products) pretty regularly. When the concentration of nicotine in their
blood drops, smokers light up again to increase the concentration and
reduce the craving.
Methoxsalen can lower the craving by making nicotine stay in the blood longer, the researchers say. As a result, smokers taking the drug should find it easier to cut down on the number of cigarettes smoked. The hope is that this will make it much easier for them to quit eventually.
"It's easier to jump off a curb than it is out of a first floor window," says Edward Sellers, MD, PhD, a professor of pharmacology and lead author of the study. "People can stop more easily if their patterns of smoking are much lower." In one of the experiments conducted by Dr. Sellers and his colleagues, smokers were given either methoxsalen or placebo (fake pills) in combination with nicotine or placebo. After 60 minutes of abstinence, the subjects were allowed to smoke at will for 90 minutes. Smokers who received methoxsalen plus nicotine smoked fewer cigarettes, had longer intervals between cigarettes, and took fewer puffs on each cigarette than those who were assigned to the other groups. "It was a very, very large effect," says Dr. Sellers, referring to the results.
The investigators also measured the amount of carbon monoxide in the
breath of all study participants at the end of the free-smoking period.
They found that methoxsalen plus nicotine given orally decreased breath
carbon monoxide concentration by an average of 47%. More Nicotine, Less Poison? Giving smokers a combination of methoxsalen and nicotine temporarily increases the amount of nicotine in their blood, the researchers admit. But aside from the fact that it is highly addictive, nicotine is not a very dangerous substance, they say. "Toxic effects of nicotine aren't really observed in smokers," according to Rachel Tyndale, PhD, one of the co-authors of the study. "Nicotine has very low toxicity in smokers or ex-smokers, as they have a high tolerance for the effects of this drug," Dr. Tyndale explains. Also, because they cut down on the amount of smoke inhaled, smokers are exposed to much less of the hundreds of poisonous chemicals contained in cigarette smoke, the investigators argue.
"Nicotine is really quite safe compared to all the nasty stuff in tobacco
smoke," says Dr. Sellers. "So reducing your smoking or stopping, even if
you still have some nicotine in your system, is a huge, huge advantage
over smoking," he adds. Pop Pill, Chuck Butt Of
course, the ultimate goal of most smokers is to be able to give up the
habit completely. In the United States, for example, about 70% of smokers
say they want to quit, but only 2.5% succeed per year, according to the
most recent statistics from the Centers for Disease Control and Prevention
(CDC).
These low success rates could be increased significantly if smokers had access to a pill that would reduce their cravings for nicotine, Dr. Sellers says. The main reason for this is that "most people prefer to take their medication in the form of a pill," he says.
Nicotine replacement therapy (NRT) is a method of smoking cessation that aims to reduce smokers' cravings for nicotine. NRT is available as a gum, nasal spray, inhaler, or skin patch. NRT does not come in a pill because nicotine, if taken by mouth, is quickly metabolized in the liver and not enough of it gets into the bloodstream to reduce the craving. But if nicotine could be combined with a drug like methoxsalen, which inhibits its metabolism, oral replacements would be viable, according to Dr. Sellers. A
combined nicotine-methoxsalen pill would have other benefits too, besides
being more convenient than other, currently available forms of NRT, the
researchers point out. For example, "it would allow accurate predictions
of the blood levels of nicotine achieved, and, therefore, accurate
dosing," says Dr. Tyndale. How Far Away? Although the initial research results look promising, a "stop-smoking pill" is likely to be at least a couple of years away, according to Dr. Sellers. "We need to do longer-term studies to establish the efficacy and safety [of a combination nicotine-methoxsalen pill]," he says. Jack Henningfield, PhD, a renowned expert on nicotine addiction, agrees: "At this point, the science base tells little more than that methoxsalen merits further consideration and study for smoking cessation," he explains.
Giving smokers extra nicotine, along with a drug that slows its
metabolism, may involve some risks, Dr. Henningfield cautions. "We must
bear in mind, however, that tobacco dependence is an extremely severe
disorder with a premature mortality rate of 50% and enormous health gains
for those who quit. So, if methoxsalen offers an effective and acceptable
treatment for persons who find other treatments unacceptable or
ineffective, the potential benefits may easily outweigh such risks," he
says.
Thomas S. May is a medical
journalist based in Toronto, Ontario, Canada. He has a master's degree in
psychology from Simon Fraser University in Burnaby, British Columbia. Source: Medscape Health
Reprinted from Medscape Health for Consumers.
Thomas S. May is a medical
journalist based in Toronto, Ontario, Canada. He has a master's degree in
psychology from Simon Fraser University in Burnaby, British Columbia. Source: Medscape Health
Reprinted from Medscape Health for Consumers.
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