Succinylcholin

Succinylcholine, also known as suxamethonium, is a depolarizing neuromuscular blocker used to produce rapid, short-lasting skeletal muscle paralysis to facilitate endotracheal intubation and brief surgical procedures. It has an ultra-rapid onset of 30 to 60 seconds and a duration of action typically 5 to 10 minutes in healthy adults.

Mechanism of action: It acts as an agonist at nicotinic acetylcholine receptors at the neuromuscular junction, causing an initial fasciculation followed by sustained depolarization that prevents further transmission of nerve impulses. This produces a phase I block; with large doses or prolonged exposure, a phase II block can occur, resembling nondepolarizing blockade.

Pharmacokinetics: Succinylcholine is hydrolyzed in the plasma by butyrylcholinesterase (pseudocholinesterase). Because breakdown depends on this enzyme, individuals with atypical or deficient pseudocholinesterase can experience markedly prolonged paralysis. Hepatic function has limited direct influence on its metabolism.

Clinical use and cautions: It is used to facilitate rapid sequence induction and quick tracheal intubation. It should be avoided or used with extreme caution in individuals at risk of hyperkalemia (eg, extensive burns, denervation injuries, major trauma, spinal cord injury, certain neuromuscular diseases) and in those with or at risk for malignant hyperthermia, a hereditary disorder triggered by anesthetic agents including succinylcholine. Other adverse effects include transient hyperkalemia, arrhythmias, increased intraocular/intracranial/intragastric pressure, myalgia, and bradycardia, particularly in children or with repeated dosing.

Due to safety concerns, many anesthesia protocols favor nondepolarizing relaxants or use succinylcholine only when its rapid onset and short duration offer clear advantages.