Tag: Physostigmine

Pharmacologically, physostigmine is a reversible cholinesterase inhibitor, a critical distinction from the highly toxic irreversible organophosphates used in nerve agents and pesticides. Derived from the Calabar bean, this compound temporarily blocks the enzyme that breaks down acetylcholine, impacting both the central and peripheral nervous systems. This reversible action defines its therapeutic application, primarily as an antidote in toxicology.

Physostigmine is a tertiary amine carbamate and a reversible inhibitor of acetylcholinesterase, the enzyme responsible for breaking down acetylcholine. This mechanism of action confirms that physostigmine is cholinergic, acting indirectly to increase the concentration of acetylcholine and enhance cholinergic transmission throughout the nervous system.

Datura, also known as jimsonweed or devil's trumpet, is a plant containing potent and highly toxic anticholinergic alkaloids like atropine and scopolamine. Overdose can lead to a range of severe symptoms requiring immediate medical attention, with the specific antidote for severe anticholinergic effects being physostigmine. However, the approach to managing Datura poisoning is comprehensive and depends heavily on the severity of the patient's condition.

Originally isolated from the Calabar bean, physostigmine was first used therapeutically in 1877 to control high ocular pressure in glaucoma patients. However, its modern primary use is in toxicology, where the drug physostigmine is a critical antidote for reversing the severe central and peripheral effects of anticholinergic poisoning.