Nicotinoids

Agonists at nicotinic acetylcholine receptors — ligand-gated ion channels rather than monoamine transporters, so the stimulation has a different character and the dopamine release that drives the reinforcement is downstream of it. Nicotine is a full agonist; varenicline and cytisine are partial agonists used to reduce smoking, occupying the receptor while producing less at it; cotinine is nicotine's main metabolite and anabasine a minor tobacco alkaloid.

Route carries most of the difference in harm within this family. The bulk of smoking-related disease comes from combustion products rather than from nicotine, which is a statement about smoke and not a clean bill for the drug: concentrated liquid nicotine is acutely toxic swallowed or spilled on skin, nicotine constricts blood vessels and raises heart rate, and dependence forms faster with it than with almost anything else on this site.