varenicline

noun

va·​ren·​i·​cline və-ˈre-nə-klən 

: a drug taken orally in the form of its tartrate C₁₃H₁₃N₃·C₄H₆O₆ as an aid to stop smoking

Note: Varenicline binds to nicotinic cell receptors to block the activity of nicotine while also acting as an agonist to reduce nicotine cravings and withdrawal symptoms. Varenicline is marketed under the trademark Chantix.