|Dr Carl Kuschel
and Brenda Hughes
Dose and Administration
- 1-2 mg/kg/dose slow IV injection or 2 mg/kg/dose IM.
- Short duration muscle relaxation to facilitate
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).