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. The New York company plans to market the twice-daily tablet, intended for adults only.
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.
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.
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.