Smokers receiving a 12-week course of Chantix therapy -- 1 mg twice daily -- nearly quadrupled the likelihood of quitting compared to those taking placebo.

Pfizer officials said the drug is the first new prescription medication approved for smoking cessation in nearly a decade.

Addiction to nicotine is a habit that is very difficult for many smokers to quit because when smokers inhale smoke from a cigarette, nicotine reaches the brain within seconds and binds to nicotinic receptors, according to Pfizer. This activates the reward pathway in brain circuitry and stimulates the pleasure center in the brain.

Reduces Severity of Craving

Chantix is specifically designed to partially activate the nicotinic receptor and reduce the severity of the smoker's craving and the withdrawal symptoms from nicotine, according to Pfizer.

In two identically designed studies, smokers receiving a 12-week course of Chantix therapy -- 1 mg twice daily -- nearly quadrupled the likelihood of quitting than those taking placebo and had nearly twice the likelihood of quitting than those patients taking buproprion -- 150 mg twice daily -- after the 12-week course of therapy.

Chantix was generally well tolerated, with overall discontinuation rates similar to placebo and most common side effects being nausea, changes in dreaming, constipation, gas and vomiting.