Varenicline — Drug Monograph

Brand names: Chantix, Champix

Drug class: Other

Mechanism of Action

A selective partial agonist at the α4β2 nicotinic acetylcholine receptor. By partially stimulating the receptor it triggers a mild, sustained dopamine release that eases withdrawal and cravings, while binding tightly enough to block inhaled nicotine from attaching to the same receptor — so if a patient slips and smokes, the usual rewarding sensation of the cigarette is largely neutralized.

FDA Indications

• Smoking cessation in adults (as an aid to smoking-cessation treatment)

Common Side Effects

• Nausea (dose-related; the most common effect)
• Vivid or abnormal dreams
• Insomnia
• Headache
• Constipation, flatulence

Clinical Pearl

Varenicline is the single most effective monotherapy for smoking cessation and can be combined with nicotine patch for added benefit in heavy smokers. The EAGLES trial reassured on neuropsychiatric safety, leading the FDA to remove the boxed warning — but clinicians should still ask about mood at follow-up.

Related Therapies & Mechanisms

• Bupropion (Zyban) — Other · Tobacco Cessation
• Adagrasib (Krazati) — Other
• Arsenic Trioxide (Trisenox) — Other
• Asparaginase (L-asparaginase, E. coli) (Elspar) — Other