A tablet shown to help more than one in five smokers quit joined the limited number of effective stop-smoking drugs on Thursday, approved by federal regulators.
When varenicline goes on sale later this year, it will become the first new prescription drug for smoking cessation approved by the Food and Drug Administration in nearly a decade and only the second stop-smoking drug that is nicotine-free, according to Pfizer Inc.
The New York company plans to market the twice-daily tablet, intended for adults only, as Chantix.
“It’s a welcome new addition. It’s like with cancer or heart disease or high blood pressure or diabetes: The more effective treatments you have, the better off patients are,” said Dr. Steven Schroeder, a professor of medicine at the University of California, San Francisco, who is active in smoking cessation efforts.
Varenicline works in two ways, by cutting the pleasure of smoking and reducing the withdrawal symptoms that lead smokers to light up over and over again.
Most other stop-smoking drugs are various nicotine-replacement therapies, sold by prescription and over the counter in gum, patch, lozenge, nasal spray or inhaler form. In 1997, the FDA approved bupropion, an antidepressant already sold as Wellbutrin but then rebranded 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, versus 16 percent among those given Zyban. Just 8 percent of those given dummy medicines had stopped after a year.
The approved course of Chantix treatment is 12 weeks, a period that can be doubled in patients who successfully quit to increase the likelihood they will remain smoke-free, the FDA said.
Other clinical trials have shown that the drug’s effect is more pronounced in the short-term: 44 percent of longtime, pack-a-day smokers quit following a 12-week course of treatment with Chantix, compared with the 30 percent of Zyban patients who quit, according to Pfizer. However, smoking cessation experts said the longer-term data are more applicable, given the difficulty of quitting the habit for good. Even Pfizer acknowledged it can take smokers 10 attempts.
“It’s not going to be a revolution, it’s going to be a substantial step forward,” Thomas Glynn, director of cancer science and trends at the American Cancer Society, said of varenicline. Glynn added that the greatest value will be for smokers who have tried Zyban or nicotine-replacement therapy but failed to quit.
“My bet is that it will work as well as they do and, from the look of things, a little bit better,” he said. The FDA does not recommend that Chantix be used with any other stop-smoking drug.
Varenicline latches on to the same receptors in the brain that nicotine binds to when inhaled in cigarette smoke, an action that leads to the release of dopamine in the pleasure centers of the brain. Taking the drug blocks any inhaled nicotine from reinforcing that effect. Its most common side effect is nausea.
The drug also slows the release of dopamine, thereby cutting the craving to smoke that occurs when nicotine’s effect wears off, said Pfizer research chemist Jothan Coe, who invented the drug.
“It’s a shield and at the same time, it stabilizes you and prevents you from having the lows, which lead to craving and withdrawal, but at the same time, it shields you from the highs,” said Coe, a former 2 1/2 pack-a-day smoker who quit smoking the first time cold turkey and then a second time with the help of nicotine gum.
One in five American adults, or nearly 45 million people, smoke. An estimated 32 million of those smokers would like to quit, according to the Centers for Disease Control and Prevention. Smoking kills nearly 440,000 Americans a year.
“Tobacco use, particularly cigarette smoking, is the single most preventable cause of death in the United States and is responsible for a growing list of cancers, as well as chronic diseases including those of the lung and heart,” said Dr. Scott Gottlieb, the FDA’s Deputy Commissioner for Medical and Scientific Affairs.
Fewer than one in 20 smokers can quit without help, said Schroeder of UC San Francisco. Even with help, whether it’s a drug, counseling or both, the success rate rises at most to roughly one in five, he added.
Both the FDA and European regulators recently rejected applications by Sanofi-Aventis to gain approval for rimonabant, or Accomplia, as a stop-smoking aid. Both have recommended that the drug, which blocks the same pleasure centers in the body activated when pot smokers get the munchies, be approved for weight loss.
And at least two vaccines are being developed that could block nicotine from ever reaching the brain.
Pfizer wouldn’t say what Chantix will cost. The company had predicted annual sales of $1 billion, but analyst Barbara Ryan at Deutsche Bank is predicting $500 million in annual sales by 2009.
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