conine

Coniine, also spelled conine in some texts, is a toxic piperidine alkaloid primarily found in poison hemlock (Conium maculatum) and related plants. It is the principal toxic constituent of hemlock and has historically been associated with poisoning of humans and livestock.

Chemically, coniine is a tertiary amine with a piperidine ring; natural product forms act as a nicotinic acetylcholine receptor agonist. It stimulates nicotinic receptors in the autonomic ganglia and at the neuromuscular junction, causing initial stimulation followed by blockade, leading to muscle weakness, paralysis, and respiratory failure.

It is rapidly absorbed after ingestion, with symptoms appearing within 30 minutes to a few hours depending on dose. Early signs include salivation, sweating, tremors, and nausea; progression can lead to skeletal muscle weakness, dyspnea, heart rate changes, blood pressure fluctuations, and, in severe cases, convulsions. Severe poisoning results in paralysis of respiratory muscles and death from respiratory failure. The prognosis depends on the dose and the timeliness of supportive care.

The name derives from the plant genus Conium. Coniine was identified in the 19th century as the active toxin in poison hemlock and has been studied as a model nicotinic receptor agonist.

There is no specific antidote for coniine poisoning. Management is supportive: secure the airway and breathing, provide circulatory support as needed, and employ decontamination if ingestion was recent (for example, activated charcoal). Recovery is possible with adequate supportive care, but high-dose exposure can be fatal.