Menu Search Donate
Drug dosage identifier

Suxamethonium chloride

This document is only valid for the day on which it is accessed. Please read our disclaimer.

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

  1. Known hypersensitivity to suxamethonium chloride.
  2. Known or suspected deficiency of plasma pseudocholinesterase.
  3. Family history of malignant hyperthermia.
  4. Hyperkalaemia.
  5. Caution in preterm infants, especially extreme immaturity.
  6. Caution in neonates with renal impairment.
  7. Caution in neonates with cardiac arrhythmias.
  8. Caution in neonates with congenital myopathy.

Clinical pharmacology

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

  1. Bradycardia
  2. Hyperkalaemia
  3. Prolonged paralysis
  4. Phase II (dual) block
  5. Hypersensitivity reactions
  6. Malignant hyperthermia

Special considerations

  1. See Intubation Protocol.
  2. Should not be used without additional sedation.
  3. 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.
  4. Suxamethonium causes a transient rise in serum potassium. Usually not a problem unless serum potassium already very high, or potassium release is enhanced.
  5. Deficiency of pseudocholinesterase may be genetic or acquired. Incidence approximately 1:2000 in adult population.
  6. 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

  1. Administered only by medical staff/NS-ANP.
  2. Further dilution not required.
  3. Filter prior to administration through a 5 micron filter.
  4. Administered by slow IV injection.
  5. Compatible with NS, D5W.
  6. Do NOT mix with other drugs, IV solutions, blood or blood products.

Observation and documentation

  1. Monitor for signs of adverse reactions.
  2. Have supportive therapy: resuscitation equipment, oxygen and mechanical ventilation on hand.
  3. Continuous cardiorespiratory monitoring.
  4. Monitor oxygenation with blood gases, or pulse oximetry.
  5. Evaluate and document patient response to drug, recovery.
  6. Does NOT alter pain threshold.
  7. Monitor temperature closely.


  • Store in refrigerator 2°-8°C. Do NOT freeze.
  • Protect from light.

Selected references

  1. Cook DR, Wingard LB, Taylor FH. Pharmacokinetics of succinylcholine in infants, children, and adults. Clin Pharmacol Ther 1976; 20:493. 
  2. Nugent SK, Laravuso R, Rogers MC. Pharmacology and use of muscle relaxant in infants and children. J Pediatr 1979; 94:481-7. 
  3. Cook DR. Muscle relaxants in infants and children. Anaesth Analg 1981; 60:335-43. 
  4. Spear TM. Anaesthesia for premature and term infants: perioperative implications. J Pediatr 1992; 120:165-76.

Did you find this information helpful?

Document Control

  • Date last published: 31 January 2001
  • Document type: Drug Dosage Guideline
  • Services responsible: ADHB Pharmacy, Neonatology
  • Editor: Sarah Bellhouse
  • Review frequency: 2 years