Suxamethonium chloride

Suxamethonium chloride (INN), also known as suxamethonium or succinylcholine, is a nicotinic acetylcholine receptor agonist, used to induce muscle relaxation and short-term paralysis, usually to facilitate tracheal intubation. Suxamethonium is sold under the trade names Anectine and Quelicin. It is sometimes used in combination with analgesics and sedatives for euthanasia and 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 into succinic acid and choline. This hydrolysis by butyrylcholinesterase is much slower than that of acetylcholine by acetylcholinesterase. It is on the World Health Organization's List of Essential Medicines, a list of the most important medication needed in a basic health system. Medical uses- A vial of suxamethonium chloride: Its medical uses are limited to short-term muscle relaxation in anesthesia and intensive care, usually for facilitation of endotracheal intubation. Despite its adverse effects, including life-threatening malignant hyperthermia, hyperkalaemia, and anaphylaxis, it is perennially popular in emergency medicine because it has the fastest onset and shortest duration of action of all muscle relaxants. The former is a major point of consideration in the context of trauma care, where endotracheal intubation may need to be completed very quickly. The latter means that, should attempts at endotracheal intubation fail and the patient cannot be ventilated, there is a prospect for neuromuscular recovery and the onset of spontaneous breathing before hypoxemia occurs. Suxamethonium is also commonly used as the sole muscle relaxant during electroconvulsive therapy, favoured for its short duration of action. Suxamethonium is quickly degraded by plasma butyrylcholinesterase and the duration of effect is usually in the range of a few minutes. When plasma levels of butyrylcholinesterase are greatly diminished or an atypical form is present (an otherwise harmless inherited disorder), paralysis may last much longer, as is this the case in liver failure or in neonates. Chemistry: Suxamethonium is an odorless, white crystalline substance. Aqueous solutions have a pH of about 4. The dihydrate melts at 160 °C, whereas the anhydrous melts at 190 °C. It is highly soluble in water (1 gram in about 1 mL), soluble in alcohol (1 gram in about 350 mL), slightly soluble in chloroform, and practically insoluble in ether. Suxamethonium is a hygroscopic compound. The compound consists of two acetylcholine molecules that are linked by their acetyl groups. It can also be viewed as a central moiety of succinic acid with two choline moieties, one on each end. History: Suxamethonium was first discovered in 1906 by Reid Hunt and René de M. Taveau. When studying the drug, animals were given curare and thus they missed the neuromuscular blocking properties of suxamethonium. Instead in 1949 an Italian group led by Daniel Bovet was first to describe succinylcholine induced paralysis. The clinical introduction of suxamethonium was described in 1951 by several groups. Papers published by Stephen Thesleff and Otto von Dardel in Sweden are important but also to be mentioned is work by Bruck, Mayrhofer and Hassfurther in Austria, Scurr and Bourne in UK, and Foldes in America.