NIDA-supported researchers from Yale University Transdisciplinary Tobacco Use Research Center (TTURC) have found more evidence that monoamine oxidase-B (MAO-B) inhibitors may be an effective treatment for nicotine addiction. MAO-B is an enzyme that breaks down dopamine. The symptoms of nicotine withdrawal have been associated with a decrease in the concentration of dopamine, so increasing dopamine levels with MAO-B inhibitors may be helpful for the treatment of nicotine addiction.
Prior to the start of the study, researchers administered a battery of tests to volunteers to assess their dependence on nicotine and the intensity of their nicotine cravings. Those with current symptoms of major depression or alcohol or drug dependence were excluded from the study. Volunteers currently prescribed antidepressant or opioid medications were also excluded.
Forty cigarette smokers were then assigned to receive the MAO-B inhibitor, selegiline hydrochloride (SEL), or a placebo for 8 weeks. During the first 7 days, the medication was administered once per day and on day eight, it was increased to twice daily for the remainder of the study. Day 15 was designated as the smoking “quit date.” Smoking cessation counseling, which included motivational enhancement therapy and relapse prevention strategies, was provided. Each month, volunteers answered a series of standardized questionnaires to assess symptoms of depression and the intensity of their nicotine cravings. Their breath and plasma were also analyzed to verify abstinence from using tobacco. After completion of the study, medication was tapered for one week and then discontinued. Six months later, smoking abstinence rates were also determined.
After 8 weeks of treatment, 45 percent of participants receiving SEL had quit smoking tobacco compared to 15 percent of those receiving placebo. During the last 4 weeks of the study, 30 percent of participants receiving SEL reported that they had completely abstained from smoking compared to 5 percent of those receiving placebo. At the 6-month follow-up, smoking cessation rates were 20 percent for those that received SEL and 5 percent for placebo. Cravings for nicotine were not affected by SEL.
WHAT IT MEANS: These findings suggest that the MAO-B inhibitor, selegiline hydrocholoride (SEL), may be an effective treatment for nicotine addiction. Further studies of this medication for smoking cessation are needed.
This study was published by lead investigator Dr. Tony George in the January 15, 2003 issue of Biological Psychiatry.
The above story is based on materials provided by NIH/National Institute On Drug Abuse. Note: Materials may be edited for content and length.
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