indication

For the treatment of glaucoma, and in the treatment of severe anticholinergic toxicity.

pharmacology

Physostigmine is a parasympathomimetic, specifically, a reversible cholinesterase inhibitor which effectively increases the concentration of acetylcholine at the sites of cholinergic transmission. Physostigmine is used to treat glaucoma. Because it crosses the blood-brain barrier, it is also used to treat the central nervous system effects of atropine overdose and other anticholinergic drug overdoses. Physostigmine can reverse both central and peripheral anticholinergia.

mechanism of action

Physostigmine inhibits acetylcholinesterase, the enzyme responsible for the breakdown of used acetylcholine. By interfering with the metabolism of acetylcholine, physostigmine indirectly stimulates both nicotinic and muscarinic receptors due to the consequential increase in available acetylcholine at the synapse.

toxicity

Side effects include increased sweating, loss of bladder control, muscle weakness, nausea, vomiting, diarrhea, or stomach cramps or pain, shortness of breath, tightness in chest, or wheezing, slow or irregular heartbeat, unusual tiredness or weakness, watering of mouth, blurred vision or change in near or distant vision, and eye pain.

biotransformation

Quickly hydrolyzed by cholinesterases