REVIEW Demecarium is an indirect-acting parasympathomimetic agent, also known as a cholinesterase inhibitor and anticholinesterase. Cholinesterase inhibitors prolong the effect of acetylcholine, which is released at the neuroeffector junction of parasympathetic postganglion nerves, by inactivating the cholinesterases that break it down. Demecarium inactivates both pseudocholinesterase and acetylcholinesterase. In the eye, this causes constriction of the iris sphincter muscle (causing miosis) and the ciliary muscle (affecting the accommodation reflex and causing a spasm of the focus to near vision). The outflow of the aqueous humor is facilitated, which leads to a reduction in intraocular pressure. Of the two actions, the effect on the accommodation reflex is the more transient and generally disappears before termination of the miosis.
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