Nicotine Receptor Blockers

Medications that bind to nicotine receptors

Varenicline is a non-nicotine treatment that is used for smoking cessation.  It works by binding to the same receptors in the brain that nicotine binds to, which are the nicotinic acetylcholine receptors.  These are the receptors that when stimulated release dopamine in the reward circuits of the brain, producing the feelings of euphoria and relaxation associated with the smoking reward.  However, although it binds to the same receptors, varenicline does not stimulate the receptors as strongly as nicotine and less dopamine is released but the effect lasts longer than nicotine.  

Reduced need for nicotine

If nicotine is inhaled at the same time as using varenicline, the nicotine receptors in the brain are blocked by varenicline, reducing the usual feelings of satisfaction and reward from smoking, making smoking less pleasurable.  This helps relieve the craving for nicotine and as well as reducing the withdrawal symptoms experience when stopping smoking.

Varenicline is intended to be used initially before smoking ceases but eventually it should replace cigarettes as nicotine cravings and withdrawal symptoms become reduced.