What is Chantix?

Varenicline, known by its trade name Chantix, is the most recent medication that is FDA approved to treat smoking addiction. It is available by prescription only. Currently there is no generic form. Varenicline is a partial agonist[1] to a subtype of the nicotinic acetylcholine receptor. A partial agonist is a compound that both stimulates and inhibits the receptor to a mild degree, thereby eliminating any withdrawal effects associated with smoking cessation, but also eliminating the possibility of deriving any additional pleasure from smoking. It therefore acts like a thermostat, stimulating the receptor when nicotine levels are low and blocking the receptor when nicotine levels are high.

Varenicline was developed by Pfizer through modifying the structure of cytisine, a chemical found in a variety of plants that is known to be a nicotine receptor agonist and has been used as a smoking cessation aid in its own right in Eastern Europe for at least 40 years. Varenicline was fast tracked by the U.S. Food and Drug Administration in February 2006, shortening its approval from 10 to 6 months because of its demonstrated effectiveness in clinical trials and perceived lack of safety issues. The FDA approved varenicline on May 11, 2006, which became available in the U.S. public August 1, 2006, and in the European Union September 29, 2006.

Varenicline comes as a tablet to be taken by mouth. It is usually taken once or twice daily with a full glass of water after eating. Group support programs or individual counseling are strongly recommended as an adjunct to the medication regime.


Your doctor will probably start you on a low dose of varenicline and gradually increase the dose over the first week of treatment.

Set a quit date to stop smoking, and start taking varenicline one week before that date. You may continue to smoke during this first week, but stop smoking on the quit date. It may take several weeks for you to feel the full benefit of varenicline.

You may slip and smoke during your treatment. If this happens, you will still be able to stop smoking.

Continue to take varenicline for 12 weeks.

If you have completely stopped smoking at the end of the 12 weeks, your doctor may tell you to take varenicline for another 12 weeks. Continuing to take varenicline may ensure that you will not start to smoke again.

Once you have stopped smoking, your doctor may need to change the doses of some of your other medications.

If you have not stopped smoking at the end of 12 weeks, tell your doctor so he or she can help you to understand why you were not able to stop smoking and make plans for you to try to quit again.

Do not use varenicline with other smoking cessation products.

Varenicline may make you drowsy. Do not drive a car or operate machinery.

If you forget a dose: Take the missed dose as soon as you remember it. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for the missed one.

Do NOT drink alcohol while taking this medication. (However, instructions on the package may not specify if you can drink any alcohol while taking this prescription.)

Call your doctor if you experience any of the following side effects: thinking about harming or killing yourself, planning or trying to do so, or thinking about harming someone else; changes in your usual thoughts, mood, or behavior.

Call your doctor immediately and report it to: The Food and Drug Administration's (FDA) Medwatch Adverse Event Reporting program online (at fda.gov/MedWatch/report .htm) or by phone (1-800-332-1088).

  • [1] A chemical (such as a drug)that can both block and stimulate a receptor depending upon the relative amount of neurotransmitter present in the synaptic cleft. If the amount of neurotransmitter is large, the chemical acts as an antagonist and if the amount of neurotransmitter is low, the chemical acts as an agonist.
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