Nicotine is a potent parasympathomimetic alkaloid found in the nightshade family of plants (Solanaceae) and is a stimulant drug. Nicotine is a nicotinic acetylcholine receptor (nAChR) agonist, except at nAChRa9 and nAChRa10 where it acts as an antagonist. It is made in the roots of and accumulates in the leaves of the nightshade family of plants. Nicotine is found in the leaves of Nicotiana rustica in amounts of 2–14%, the tobacco plant Nicotiana tabacum, Duboisia hopwoodii and Asclepias syriaca.