How is physostigmine as anti acetylcholinesterase?

Nitrogenous carbamic acid ester in plants (Calabar) tertiary amine. Substrate for acetylcholinesterase forms stable enzyme substrate intermediate reversibly inhibiting the enzyme, results in potentiation of cholinergic activity throughout the body. Actions (intermediate acting, stimulates cholinergic sites at CNS) Therapeutic uses: increases GI and bladder motility, produces miosis and spasm of accomodation lowering intraocular pressure, treats overdoses such as atropine, phenothiazines (antipsychotic), and tricyclic antidepressants. Adverse reactions: CNS convulsions in high doses, bradycardia and fall of CO, paralysis of skeletal muscle by increasing Ach at nicotinic receptors in neuromuscular synapse causing flaccid paralysis