Varenicline is a prescription medication used to treat smoking addiction. Varenicline stimulates nicotine receptors more weakly than nicotine does, that is, it is a nicotinic receptor partial agonist

Partial agonist

Partial agonists bind and activate a given receptor, but have only partial efficacy at the receptor relative to a full agonist...

. In this respect it is similar to cytisine

Cytisine

Cytisine, also known as baphitoxine and sophorine, is a pyridine-like alkaloid. In medical use, it improves the rate of smoking cessation. It is less effective but much cheaper than similar products. Its structure is similar to nicotine and has similar pharmacological effects...

 and different from the nicotinic antagonist

Receptor antagonist

A receptor antagonist is a type of receptor ligand or drug that does not provoke a biological response itself upon binding to a receptor, but blocks or dampens agonist-mediated responses...

, bupropion

Bupropion

Bupropion is an atypical antidepressant and smoking cessation aid. The drug is a non-tricyclic antidepressant and differs from most commonly prescribed antidepressants such as SSRIs, as its primary pharmacological action is thought to be norepinephrine-dopamine reuptake inhibition...

, and nicotine replacement therapies

Nicotine replacement therapy

Nicotine replacement therapy is the remedial administration of nicotine to the body by means other than tobacco, usually as part of smoking cessation. Common forms of nicotine replacement therapy are nicotine patches and nicotine gum...

 (NRTs) like nicotine patch

Nicotine patch

A nicotine patch is a transdermal patch that releases nicotine into the body through the skin. It is used as an aid in nicotine replacement therapy , a process for smoking cessation. The first published study of the pharmacokinetics of a transdermal nicotine patch in humans was authored by Jed E....

es and nicotine gum

Nicotine gum

Nicotine gum is a type of chewing gum that delivers nicotine to the body. It is used as an aid in nicotine replacement therapy , a process for smoking cessation and quitting smokeless tobacco. The nicotine is delivered to the bloodstream via absorption by the tissues of the mouth.It is currently...

. As a partial agonist it both reduces cravings for and decreases the pleasurable effects of cigarettes and other tobacco products.