Decamethonium bromide (Syncurine) is a neuromuscular blocker and nicotinic AChR partial agonist.

At the motor neuromuscular endplate, Decamethonium induces a depolarization that prevents the normal release of acetylcholine from presynaptic terminals from acting further, thereby preventing the nerve stimulus from affecting the muscle. During binding, Decamethonium actually activates (depolarizes) the motor endplate, but does not degrade itself, so the cell membrane remains depolarized and unresponsive to normal acetylcholine release. As a depolarizing muscle relaxant or neuromuscular blocker, Decamethonium is used in anesthesia to induce paralysis. It has a short duration of action similar to that of acetylcholine and acts as a partial agonist at nicotinic acetylcholine-like receptors.