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Dose and administration
1-2 mg/kg/dose slow IV injection or 2 mg/kg/dose IM.
Short duration muscle relaxation to facilitate intubation.
Contraindications and precautions
- Known hypersensitivity to suxamethonium chloride.
- Known or suspected deficiency of plasma pseudocholinesterase.
- Family history of malignant hyperthermia.
- Caution in preterm infants, especially extreme immaturity.
- Caution in neonates with renal impairment.
- Caution in neonates with cardiac arrhythmias.
- Caution in neonates with congenital myopathy.
Suxamethonium chloride (also known as succinylcholine) is a depolarising muscle relaxant. Action due to initial stimulation then prolonged depolarisation of receptors for acetylcholine at the neuromuscular junction. Suxamethonium may have a number of effects apart from skeletal muscle relaxation (hyperkalaemic response, cardiac arrhythmias).
Poorly absorbed from gastrointestinal tract - must be given IM or IV. Rapidly and completely hydrolysed by hepatic and plasma pseudocholinesterase. Very rapid onset of action (1-2 minutes). Continuous administration over a prolonged period of time may result in irreversible blockage (phase II block). Short duration of action: 3-5 minutes (with IM administration may be prolonged 10-15 minutes).
Possible adverse effects
- Prolonged paralysis
- Phase II (dual) block
- Hypersensitivity reactions
- Malignant hyperthermia
- See Intubation Protocol.
- Should not be used without additional sedation.
- Bradycardia common in neonates and children, especially after a second dose of suxamethonium. May be prevented by administration of atropine 20 mcg/kg prior to administration of suxamethonium.
- Suxamethonium causes a transient rise in serum potassium. Usually not a problem unless serum potassium already very high, or potassium release is enhanced.
- Deficiency of pseudocholinesterase may be genetic or acquired. Incidence approximately 1:2000 in adult population.
- Management of suxamethonium overdose and/or toxicity is supportive (ventilation, insulin glucose infusion for hyperkalaemia, antiarrhythmic agents).
Management of Suxamethonium administration
- Clear, colourless solution 50 mg/ml in 2 ml plastic ampoules.
- For IV use only. Contains no bacteriostat.
- Charted on the stat page of the prescription chart in mg/dose.
- Note: If the quick reference chart for intubation drugs has been used, it is acceptable to chart the drug dose in ml.
Slow IV Injection
- Administered only by medical staff/NS-ANP.
- Further dilution not required.
- Filter prior to administration through a 5 micron filter.
- Administered by slow IV injection.
- Compatible with NS, D5W.
- Do NOT mix with other drugs, IV solutions, blood or blood products.
Observation and documentation
- Monitor for signs of adverse reactions.
- Have supportive therapy: resuscitation equipment, oxygen and mechanical ventilation on hand.
- Continuous cardiorespiratory monitoring.
- Monitor oxygenation with blood gases, or pulse oximetry.
- Evaluate and document patient response to drug, recovery.
- Does NOT alter pain threshold.
- Monitor temperature closely.
- Store in refrigerator 2°-8°C. Do NOT freeze.
- Protect from light.
- Cook DR, Wingard LB, Taylor FH. Pharmacokinetics of succinylcholine in infants, children, and adults. Clin Pharmacol Ther 1976; 20:493.
- Nugent SK, Laravuso R, Rogers MC. Pharmacology and use of muscle relaxant in infants and children. J Pediatr 1979; 94:481-7.
- Cook DR. Muscle relaxants in infants and children. Anaesth Analg 1981; 60:335-43.
- Spear TM. Anaesthesia for premature and term infants: perioperative implications. J Pediatr 1992; 120:165-76.
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- Date last published: 31 January 2001
- Document type: Drug Dosage Guideline
- Services responsible: ADHB Pharmacy, Neonatology
- Editor: Sarah Bellhouse
- Review frequency: 2 years