The addictive properties of nicotine are thought to be a result of nicotine triggering the acute release of dopamine, a pleasurable event that a person seeks to repeat. Varenicline is a partial agonist of the nicotine receptors, therefore also triggering the release of dopamine but in a more sustained and moderate manner, which could counter the low dopamine levels arising from a lack of nicotine and therefore aid craving. Also, by binding to these nicotine receptors in advance of smoking, it could stop nicotine from binding and creating pleasurable effects.