Bulbocapnine hydrochloride is the water-soluble form of the bulbocapnine alkaloid group, substances which act as acetylcholinesterase and tyrosine hydroxylase inhibitors. Activity from these chemicals causes dopamine biosynthesis to stall. Bulbocapnine hydrochloride is therefore a dopamine receptor antagonist but has also been used as a tyrosine 3-monooxygenase inhibitor (EC 1.14.16.2) and diamine oxidase inhibitor (EC 1.4.3.22). Because bulbocapnine is a plant metabolite, the substance has been responsible for lethal poisoning in livestock.