A Pfizer drug shown to help more than one in five smokers quit after a year's use received U.S. federal approval on Thursday, adding another option to the limited number of effective anti-smoking prescription medicines. Pfizer's Varenicline is only the second nicotine-free anti-smoking drug to win Food and Drug Administration (FDA) approval. Pfizer plans to market the twice-daily pill as Chantix. Varenicline works in two ways, by limiting the pleasure of smoking and reducing the withdrawal symptoms that lead smokers to continue to smoke. Most other anti-smoking drugs are various nicotine-replacement therapies. In 1997, the FDA approved bupropion, an anti-depressant already sold was Wellbutrin but re-branded it as Zyban, an anti-smoking drug. Several studies conducted in Europe on about 2,000 smokers and presented in November at an American Heart Association conference showed that a year after initial treatment with Varenicline, abstinence rates were 22 percent, compared to 16 percent among those given Zyban. The approved course of Chantix treatment is 12 weeks, a period that can be doubled in patients who successfully quit to increase the likelihood that they will continue to be non-smokers, the FDA said.
