Suxamethonium chloride, also known as suxamethonium or succinylcholine, or simply sux by medical abbreviation, is a medication used to cause short-term paralysis as part of general anesthesia. This is done to help with tracheal intubation or electroconvulsive therapy. It is administered by injection, either into a vein or into a muscle. When used in a vein, onset of action is generally within one minute and effects last for up to 10 minutes.Common side effects include low blood pressure, increased saliva production, muscle pain, and rash. Serious side effects include malignant hyperthermia and allergic reactions. It is not recommended in people who are at risk of high blood potassium or a history of myopathy. Use during pregnancy appears to be safe for the baby. Suxamethonium is in the neuromuscular blocker family of medications and is of the depolarizing type. It works by blocking the action of acetylcholine on skeletal muscles. Side effects of succinylcholine chloride injection include anaphylaxis, hyperkalemia, and malignant hyperthermia.Suxamethonium was described as early as 1906 and came into medical use in 1951. It is on the World Health Organizations List of Essential Medicines. Suxamethonium is available as a generic medication. It may colloquially be referred to as "sux". Medical uses
Succinylcholine chloride injection is indicated, in addition to general anesthesia, to facilitate tracheal intubation and to provide skeletal muscle relaxation during surgery or mechanical ventilation.Its medical uses are limited to short-term muscle relaxation in anesthesia and intensive care, usually for facilitation of endotracheal intubation.
Acquired factors that affect plasma cholinesterase activity include pregnancy, liver disease, kidney failure, heart failure, thyrotoxicosis, and cancer, as well as a number of other drugs.If unrecognized by a clinician it could lead to awareness if anesthesia is discontinued whilst still paralyzed or hypoxemia (and potentially fatal consequences) if artificial ventilation is not maintained. Normal treatment is to maintain sedation and ventilate the patient on an intensive care unit until muscle function has returned. Blood testing for cholinesterase function can be performed.Mivacurium, a non-depolarizing neuromuscular blocking drug, is also metabolized via the same route with a similar clinical effect in patients deficient in plasma cholinesterase activity.Deliberate induction of conscious apnea using this drug led to its use as a form of aversion therapy in the 1960s and 1970s in some prison and institutional settings. This use was discontinued after negative publicity concerning the terrifying effects on subjects of this treatment and ethical questions about the punitive use of painful aversion. Mechanism of action
There are two phases to the blocking effect of suxamethonium. Phase 1 block
Phase 1 blocking has the principal paralytic effect. Binding of suxamethonium to the nicotinic acetylcholine receptor results in opening of the receptors monovalent cation channel; a disorganized depolarization of the motor end-plate occurs and calcium is released from the sarcoplasmic reticulum. In normal skeletal muscle, acetylcholine dissociates from the receptor following depolarization and is rapidly hydrolyzed by acetylcholinesterase. The muscle cell is then ready for the next signal.