Action and Spectrum

Actions and spectrum: 

suxamethonium, also known as succinylcholine, is a depolarizing neuromuscular blocking agent. It acts as an agonist at the nicotinic acetylcholine receptor (nAChR) at the neuromuscular junction, causing rapid and short-lived depolarization of the muscle fiber. This results in muscle relaxation, making it useful for facilitating endotracheal intubation and providing short-term muscle relaxation during surgery. 

suxamethonium is effective in blocking skeletal muscle, including the diaphragm, but has no effect on consciousness or pain perception. Its onset of action is rapid, typically within 30 to 60 seconds, and its duration of action is short, typically lasting 5 to 10 minutes.

Its effect can be reversed by the administration of cholinesterase inhibitors such as neostigmine. suxamethonium is mainly used in anesthesia, especially in emergency situations, and is not commonly used outside of a clinical setting. 

Drug Interaction

Adverse Reaction

Frequency not defined 

Muscle fasciculation 

Apnea 

Bradycardia 

Cardiac arrhythmias  

Increased IOP 

Excessive salivation 

Hypersensitivity reactions 

Myoglobinemia/myoglobinuria(rare) 

Jaw rigidity 

Respiratory depression 

Hypotension 

Sinus tachycardia 

Salivary gland enlargement 

Rash 

Malignant hyperthermia 

Black Box Warning

Black Box Warning:  

suxamethonium can cause malignant hyperthermia, a rare but potentially fatal condition in which the body temperature rapidly increases and muscles break down, releasing harmful substances into the blood.

suxamethonium is generally used only in emergency situations, such as during intubation or electroconvulsive therapy (ECT) or in certain surgical procedures. 

Contraindication / Caution

Contraindication/Caution: 

Contraindication: 

• Hypersensitivity: The drug should not be administered to individuals with a known hypersensitivity to the drug or its components. 
• Personal or family history of malignant hyperthermia (MH): suxamethonium can trigger MH in susceptible individuals. 
• Hyperkalemia: The drug should not be used in patients with hyperkalemia or conditions that increase serum potassium levels (e.g., extensive muscle trauma, spinal cord injuries, severe burns). 
• Muscle disorders: suxamethonium should not be used in patients with certain muscle disorders, such as myotonia congenita, muscular dystrophy, and myopathies, as it can cause prolonged paralysis. 
• Renal failure: suxamethonium is contraindicated in patients with advanced renal failure, as they are at an increased risk of developing hyperkalemia.

Caution: 

• Personal or family history of malignant hyperthermia (MH) 
• History of hyperkalemia or electrolyte imbalances 
• Neuromuscular disorders such as Eaton-Lambert syndrome, myasthenia gravis, or muscular dystrophy 
• Severe burns or crush injuries 
• Acute narrow-angle glaucoma 
• Prolonged immobilization or bed rest 
• Liver disease 
• Kidney disease 
• Chronic obstructive pulmonary disease (COPD) or other respiratory conditions 
• Dehydration or volume depletion

Comorbidities: 

• Muscle disorders: suxamethonium can lead to hyperkalemia, an excessive amount of potassium in the blood, which can be dangerous for patients with certain muscle disorders, such as muscular dystrophy. 
• Kidney disease: Patients with kidney disease may be at an increased risk of developing hyperkalemia as a result of suxamethonium administration. 
• Liver disease: suxamethonium is metabolized in the liver, and patients with liver disease may be at an increased risk of experiencing adverse effects as a result. 
• Electrolyte imbalances: Patients with electrolyte imbalances, such as low levels of calcium or magnesium, may have an increased risk of developing muscle spasms or other adverse effects following suxamethonium administration. 
• Obesity: Obese patients may require larger doses of suxamethonium to achieve adequate muscle relaxation, which can increase the risk of adverse effects. 

Pregnancy / Lactation

Pregnancy warnings:     

US FDA pregnancy category: unassigned  

Breastfeeding warnings:  

The release of the drug into the human breastmilk is unknown 

Pregnancy Categories:      

Category A: Satisfactory and well-controlled studies show no risk to the fetus in the first or later trimester.      

Category B: No evidence shown of risk to the fetus found in animal reproduction studies, and there are not enough studies on pregnant women      

Category C: Adverse effects on the fetus found with evidence in animal reproduction studies and no adequate evidence for a result in humans must take care of potential risks in pregnant women      

Category D: There is adequate data available with sufficient evidence of human fetal risk from various platforms, but despite the potential risk, and used only in emergency cases for potential benefits      

Category X: Drugs listed in this category outweigh risks over benefits. Hence these categories of drugs need to be avoided by pregnant women.      

Category N: There is no data available for the drug under this category

Pharmacology

Pharmacology: 

suxamethonium, also known as succinylcholine, is a depolarizing neuromuscular blocking agent that acts as an agonist at the nicotinic acetylcholine receptors at the neuromuscular junction. 

suxamethonium has a rapid onset of action, typically taking effect within seconds after administration, and a short duration of action, with effects wearing off within a few minutes. It is metabolized by the enzyme pseudocholinesterase in the plasma and liver, with a half-life of approximately 3-5 minutes. 

suxamethonium has two phases of action. In the first phase, it initially stimulates the nicotinic acetylcholine receptors, causing depolarization of the muscle cell membrane and muscle contraction. In the second phase, the drug continues to occupy the receptors but does not cause further depolarization, leading to muscle paralysis.  

Pharmacodynamics: 

suxamethonium, also known as succinylcholine, is a depolarizing neuromuscular blocking agent that acts on the nicotinic acetylcholine receptors in the neuromuscular junction. It mimics the action of acetylcholine and produces a brief depolarizing muscle relaxation by opening the ion channels and allowing the influx of sodium ions, leading to muscle contraction. However, unlike acetylcholine, suxamethonium is resistant to degradation by acetylcholinesterase, leading to persistent muscle depolarization. 

The pharmacodynamic effects of suxamethonium are rapid onset and short duration of action. It produces muscle relaxation within 1 minute of intravenous injection, and the effects last for about 5-10 minutes. It is used for short-term muscle relaxation during surgical procedures, mechanical ventilation, and endotracheal intubation. 

suxamethonium can also cause a phase II block, characterized by resistance to depolarization, which can result in muscle weakness or paralysis. This is due to the desensitization of the nicotinic receptors and is more likely to occur with prolonged exposure to suxamethonium or in patients with certain medical conditions.  

Pharmacokinetics: 

Absorption 

suxamethonium is administered intravenously and is rapidly absorbed into the bloodstream. 

Distribution 

suxamethonium is distributed rapidly throughout the body, with a large volume of distribution. It does not cross the blood-brain barrier or the placenta. 

Metabolism 

suxamethonium is rapidly metabolized by plasma cholinesterase into inactive metabolites, succinylmonocholine, and succinic acid. Genetic variations in plasma cholinesterase activity can result in prolonged effects of suxamethonium. 

Elimination and excretion 

The metabolites of suxamethonium are excreted in the urine. 

Adminstartion

Administration: 

suxamethonium (succinylcholine) is administered intravenously. The dose and rate of administration depend on the indication for use and the patient’s age, weight, and overall health status. suxamethonium should only be administered by qualified healthcare professionals who are trained in its use and in the management of potential adverse effects. 

The onset of action of suxamethonium is rapid, typically occurring within 30 seconds to one minute after administration. Its duration of action is short, typically lasting for 5 to 10 minutes, after which the drug is rapidly metabolized by plasma cholinesterase enzymes. 

Patient Information Leaflet

Patient information leaflet 

Generic Name: succinylcholine 

Pronounced: [ suks-in-il-KOE-leen ]  

Why do we use succinylcholine? 

suxamethonium (succinylcholine) is a neuromuscular blocking agent used for short-term muscle relaxation during surgical procedures or mechanical ventilation. It is used to facilitate intubation and improve surgical conditions during general anesthesia.

It is also used to induce paralysis in emergency situations, such as to facilitate tracheal intubation in critically ill patients or for rapid sequence intubation in the emergency department. Additionally, suxamethonium may be used for electroconvulsive therapy (ECT) to prevent muscle contractions during the procedure.