Suxamethonium chloride (also known as succinylcholine or informally as sux) is a medication widely used in emergency medicine and anesthesia to induce muscle relaxation, usually to make endotracheal intubation possible. Suxamethonium is sold the trade names Anectine and Scoline.
Suxamethonium acts as a depolarizing neuromuscular blocker. It imitates the action of acetylcholine at the neuromuscular junction, acting on muscle type nicotinic receptors, but it is degraded not by acetylcholinesterase but by butyrylcholinesterase, a plasma cholinesterase. This hydrolysis by butyrylcholinesterase is much slower than that of acetylcholine by acetylcholinesterase.
Suxamethonium is a white crystalline substance, it is odourless; solutions have a pH of about 4, the dihydrate melts about 160 °C, the anhydrous melts at about 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 has been in use since the pharmacological properties of succinylcholine were discovered around 1950 by K.H. Ginzel, H Klupp, and Gerhard Werner in Vienna, Austria.
There are two phases to the blocking effect of suxamethonium; Phase 1 block is the principal paralytic effect.
Binding of suxamethonium to the nicotinic acetylcholine receptor results in opening of the receptor's nicotinic sodium channel; sodium moves into the cell, a disorganised depolarisation of the motor end plate occurs and calcium is released from the sarcoplasmic reticulum. This results in fasciculation.
In the normal muscle, following depolarisation, acetylcholine is rapidly hydrolysed by acetylcholinesterase and the muscle cell is able to 'reset' ready for the next signal.
Suxamethonium has a longer duration of effect than acetylcholine and is...