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Varenicline (Chantix®, Pfizer, usually as varenicline tartrate) is a prescription medication used to treat smoking addiction. By acting similarly to nicotine on the brain it reduces cravings for cigarettes and may assist some patients in smoking cessation. In May, 2006, it was approved for sale in the United States; it is expected to go on sale in July, 2006. It has not yet been approved for sale in any other country.
Use and dosing
Varenicline is indicated for smoking cessation. It is an alternative to bupropion (Zyban) and nicotine replacement therapy (NRT), such as nicotine patches.
Varenicline will be available as 0.5 mg and 1 mg tablets. Standard dosing will be 1 mg twice daily. The FDA has approved it use in for twelve weeks; if smoking cessation has been achieved it may be continued for another twelve weeks.U.S. Food and Drug Administration. FDA Approves Novel Medication for Smoking Cessation. Press release, 11 May 2006.
Mechanism of action
Varenicline is a partial agonist of the α4β2 subtype of the nicotinic acetylcholine receptor. In addition it acts on α3β4 and weakly on α3β2 and α6-containing receptors. A full agonism was displayed on α7-receptors.Mihalak KB, Carroll FI, Luetje CW. Varenicline is a partial agonist at α4β2 and a full agonist at α7 neuronal nicotinic receptors. Mol Pharmacol 2006 in press. PMID 16766716.
Pharmacokinetics
Most of the active compound is excreted renally (81%). A small proportion is glucuronidated, oxidated, N-formylated or conjugated to a hexose.Obach RS, Reed-Hagen AE, Krueger SS, Obach BJ, O'Connell TN, Zandi KS, Miller S, Coe JW. Metabolism and disposition of varenicline, a selective alpha4beta2 acetylcholine receptor partial agonist, in vivo and in vitro. Drug Metab Dispos 2006;34:121-30. PMID 16221753.
Side-effects
Side-effects include:
History
Varenicline was selected from a large number of compounds that showed affinity to the α4β2 nicotinic receptorCoe JW, Brooks PR, Vetelino MG, Wirtz MC, Arnold EP, Huang J, Sands SB, Davis TI, Lebel LA, Fox CB, Shrikhande A, Heym JH, Schaeffer E, Rollema H, Lu Y, Mansbach RS, Chambers LK, Rovetti CC, Schulz DW, Tingley FD 3rd, O'Neill BT. Varenicline: an alpha4beta2 nicotinic receptor partial agonist for smoking cessation. J Med Chem 2005;48:3474-7. PMID 15887955. It derives chemically from cytisine
Varenicline received a "priority review" by the U.S. Food and Drug Administration in February 2006, shortening the usual 10-month review period to 6 months because of its demonstrated effectiveness in clinical trials.Kuehn BM. FDA speeds smoking cessation drug review. JAMA 2006;295:614. PMID 16467225. The agency's approval of the drug came on 11 May, 2006.
References
External links
"Varenicline"