Suxamethonium chloride is a nicotinic acetylcholine receptor agonist, used to induce muscle relaxation and short-term paralysis, usually to facilitate tracheal intubation. It is used as a paralytic agent for euthanasia/immobilization of horses. It is colloquially referred to as "sux" in hospital settings. Suxamethonium acts as a depolarizing neuromuscular blocker. It acts on nicotinic receptors resulting in persistent depolarization of the motor end plate. It is degraded by butyrylcholinesterase, a plasma cholinesterase. This hydrolysis by butyrylcholinesterase is much slower than that of acetylcholine by acetylcholinesterase. Suxamethonium is an odourless, white crystalline substance. Aqueous solutions have a pH of about 4. The dihydrate melts at 160 °C, whereas the anhydrous melts at 190 °C. Suxamethonium is a hygroscopic compound. The compound consists of two acetylcholine molecules that are linked by their acetyl groups.
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