Bethanechol

Bethanechol is a direct-acting cholinergic agonist and a derivative of acetylcholine. It selectively binds to muscarinic acetylcholine receptors, mainly the M2 and M3 receptor subtypes. When it binds to M3 receptors on the detrusor muscle of the bladder, it activates the IP3/Ca²⁺ pathway, promoting contraction of bladder smooth muscle while relaxing the bladder sphincter, thereby enhancing urination-related reflexes and bladder emptying. When it binds to M3 receptors on intestinal smooth muscle, it increases intestinal motility and tone, thereby enhancing gastrointestinal peristaltic activity. Bethanechol can also bind to M2 receptors in the heart, leading to a reduction in heart rate.