Cytisine is an organic heterotricyclic compound that is the toxic principle in Laburnum seeds and is found in many members of the Fabaceae (legume, pea or bean) family. An acetylcholine agonist, it is widely used throughout Eastern Europe as an aid to giving up smoking. It has a role as a nicotinic acetylcholine receptor agonist, a phytotoxin and a plant metabolite. It is an alkaloid, an organic heterotricyclic compound, a secondary amino compound, a lactam and a bridged compound.