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Genetic Variant Is Linked to a Greater Effectiveness of Zyban

September 10, 2007

- National Institute of Health –

Researchers identified specific genetic variant, the presence of which in people was linked to higher effectiveness of smoking cessation medication Zyban. Certain variant form of the CYP2B6 gene was detected in nearly half of Americans of European ancestry, and all those people were more successful in quitting smoking with Zyban. Besides, people with that generic variant were also less likely to resume smoking after the therapy. The research was supported by the National Institute on Drug Abuse (NIDA) and the National Cancer Institute (NCI), part of the National Institutes of Health (NIH).

More than 300 smokers participated in the study. All the participants were tested for the presence of a variant form of the CYP2B6 gene. Then the patients were treated with either bupropion (Zyban) or placebo (sugar pills) for 10 weeks. The scientists continued to examine periodically all the participants for 6 months after the treatment period to see whether smoking will be resumed or not.

The results of the study showed that people with the genetic variant had significantly higher rates of quitting with the help of Zyban than those who took placebo pills. On the other hand, people without that specific gene had practically similar results of quitting irrespective to what pill they took (Zyban or sugar pill). Besides, one of the researchers said that among all the participants who took bupropion, those with this variant were less likely than those without it to have resumed smoking at the six month follow-up.

"This kind of genetic research is helping us to better understand why some people respond to certain smoking cessation treatments, and others don't." NIH Director Dr. Elias A. Zerhouni said.

It is interesting to note that the variant form of the CYP2B6 gene has certain connection with the ancestry. Thus, previous researches found out that this very gene is present in about 45 % of Americans, whose ancestors were from Europe. The same genetic variant was found in about 50% of African Americans and only in 25 % of Asian Americans.

Consequently, genetic testing for the presence of this particular gene variant may help doctors foresee whether the patient will benefit form the treatment with Zyban or some other options of smoking secession should be considered.

Zyban belongs to the class of antidepressants. This medication was approved by the FDA for the treatment of smoking in 1997. Unlike nicotine-replacements, such as gums, patches or inhalers, Zyban does not supply any nicotine into human organism. It helps people quit smoking by reducing the severity of withdrawal symptoms, such as irritability, frustration, anger, anxiety, difficulty concentrating, restlessness, etc. Besides, Zyban can reduce the craving for cigarettes.

For a long time Zyban has been the only oral pill against smoking. But recently, a new drug, Chantix, was designed by Pfizer to treat smoking in people. Unlike Zyban, which is actually an antidepressant, Chantix was originally developed to target nicotine receptors in brains and thus help people quit smoking.

Nick

External resources
http://www.accessdata.fda.gov/scripts/cder/drugsatfda/index.cfm?fuseaction=Se...
http://www.nih.gov/news/pr/sep2007/nida-10.htm
http://www.drugabuse.gov/newsroom/07/NR9-10.html
http://www.sciencedaily.com/releases/2007/09/070917112216.htm
http://www.quitsmoking.com/zyban/index.htm