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Suxamethonium chloride parenteral

Updated 2 Feb 2023 | Depolarising muscle relaxants


Solution for injection containing suxamethonium chloride

Drugs List

  • ANECTINE 100mg/2ml injection
  • suxamethonium chloride 100mg/2ml injection
  • Therapeutic Indications


    Depolarising muscle relaxant

    Depolarising muscle relaxant with rapid onset and short duration for use in:
    i) endotracheal intubation
    ii) mechanical ventilation
    iii) other surgical and obstetric procedures

    Suxamethonium chloride may also be used to reduce the intensity of pharmacologically or electrically induced convulsions.


    Initial dosage is dependent on route of administration, degree of muscular relaxation required and body weight. Dosage should be adjusted in relation to the patient's individual response. Infants and young children are more resistant to suxamethonium chloride compared with adult.


    Intravenous injection Initial dose: 1mg/kg to 1.5mg/kg (doses above 1 mg/kg are outside the product license) may be given to aid endotracheal intubation. Effect can be seen in approximately 30 to 60 seconds with a duration of action of about 2 to 6 minutes.
    Supplementary doses of 50% to 100% of initial dose may then be given at intervals of 5 to 10 minutes to maintain muscle relaxation during short surgical procedures. Doubling the dose does not necessarily double the duration of action. Intravenous infusion Suxamethonium chloride injection diluted to 0.1% to 0.2% (in 5% glucose infusion or sterile isotonic saline solution) is used for longer surgical procedures at an initial infusion rate of 2.5mg/minute to 4mg/minute. Rate of infusion should be adjusted in relation to the individual response of the patient. The total maximum dose given via repeated intravenous injections or continuous infusion is 500mg per hour and must not be exceeded.


    Children aged 1 to 18 years
    Intravenous injection Initially 1mg/kg Intravenous infusion (See Dosage; Adult) but give at a reduced infusion rate proportionate to their lower body weight. Intramuscular injection Up to 4mg/kg can be administered to produce muscle relaxation after approximately 2 to 3 minutes. A maximum dose of 150mg should not be exceeded. Children aged 1 month to 1 year
    Intravenous injection Initially 2mg/kg Intramuscular injection Up to 4mg/kg to 5mg/kg can be administered to produce muscle relaxation after approximately 2 to 3 minutes. A maximum dose of 150mg should not be exceeded.


    Intravenous injection 2mg/kg Intramuscular injection Up to 4 mg/kg to 5mg/kg. A maximum dose of 150mg should not be exceeded.

    Patients with Renal Impairment

    A normal single dose of suxamethonium may be administered to patients with renal insufficiency in the absence of hyperkalaemia. Multiples or larger doses may cause clinically significant rises in serum potassium and should not be used.


    Suxamethonium may be given as an intravenous injection, intravenous infusion or intramuscular injection depending on the patient's age and condition.


    Familial history of malignant hyperthermia
    Inherited abnormal plasma cholinesterase activity
    Predisposition to malignant hyperthermia
    Severe trauma
    Cerebral palsy
    Duchenne muscular dystrophy
    Myotonia congenita
    Myotonic dystrophy
    Severe burn

    Precautions and Warnings

    Autoimmune disease
    Children under 18 years
    Chronic debilitating disease
    Plasma cholinesterase deficiency
    Prolonged immobilisation
    Severe generalised tetanus
    Severe sepsis
    Acute renal failure
    Cardiac impairment
    Chronic renal failure
    Collagen disorder
    Electrolyte imbalance
    Hepatic impairment
    Malignant neoplasm
    Myasthenia gravis
    Myasthenic Eaton-Lambert syndrome
    Neuromuscular disorder
    Penetrating ocular injury
    Respiratory impairment

    Patient must be fully anaesthetised before administration
    Treatment to be initiated and supervised by a specialist
    Do not mix with other injections or infusions prior to administration
    Monitor respiratory function
    Monitor using peripheral nerve stimulator during prolonged administration
    Use only when equipment adequate for cardiac/respiratory monitoring/support
    Repeated doses result in tachyphylaxis
    Driving or operating machinery not advisable following treatment

    Prolonged periods of suxamethonium administration may result in the change of the characteristic phase I (depolarising neuromuscular) block into a phase II (non-depolarising neuromuscular) block. A developing phase II block can not always be fully or permanently reversed by anticholinesterase agents. However, once fully established, the phase II block may be fully reversed with standard doses of neostigmine accompanied with an anticholinergic agent.

    Patients with reduced plasma cholinesterase activity may experience prolonged and intensified neuromuscular blockade following administration of suxamethonium. In these patients it may be advisable to administer reduced doses of suxamethonium injection.

    Pregnancy and Lactation


    The potential benefits to the mother should be weighed against any possible risk to the foetus before administering suxamethonium chloride.
    There have been no studies performed on the effect of suxamethonium on female fertility or pregnancy.

    There are no direct effects of suxamethonium on the uterus or other smooth muscle structures and it does not cross the placental barrier, at normal therapeutic levels, in sufficient amounts to affect the respiration of the foetus.

    Pregnant and puerperal patients may take longer to recover from the neuromuscular blockade following suxamethonium chloride injection. This is due to a fall in plasma cholinesterase levels during the first trimester of pregnancy ( to about 70 to 80% of pre-pregnancy levels); and a further fall within 2 to 4 days after delivery (to about 60 to 70% pre-pregnancy levels). These levels return to normal over the following 6 weeks.

    The use of all medication in pregnancy should be avoided whenever possible; particularly in the first trimester. Non-drug treatments should also be considered. When essential, a medication with the best safety record over time should be chosen, employing the lowest effective dose for the shortest possible time. Polypharmacy should be avoided. Teratogens taken in the pre-embryonic period, often quoted as lasting until 14-17 days post-conception, are believed to have an all-or-nothing effect. Where drugs have a short half-life, and when the date of conception is certain, this may allow women to be reassured where drug exposure has occurred within this time frame. Further advice may be available from the UK National Teratology Information Service (NTIS) and through ToxBase, available via password on the internet ( ) or if this is unavailable at the backup site ( ).


    The potential benefits to the mother should be weighed against any possible risk to the child before administering suxamethonium chloride.

    It is not certain whether suxamethonium chloride or its metabolites are secreted in human milk. It is ionised at physiological pH.

    Suxamethonium is rapidly eliminated and poorly absorbed orally. It is not likely to reach the bloodstream of the infant or cause any adverse effect in breastfed infants. Breastfeeding may be resumed once the mother has recovered from neuromuscular block.

    Neonates, infants born prematurely, those with low birth weight, those with an unstable gastrointestinal function or who have serious illnesses may require special consideration. For any infant, if a drug is prescribed to the nursing mother, it should be at the lowest practical dose and for the shortest time. When drug administration is unavoidable and breastfeeding is to continue, minimisation of exposure of the infant to the drug may sometimes be achieved by timing the maternal doses to just after a feeding episode. Infants exposed to drugs via breast milk should be monitored for unusual signs or symptoms. Interactions between the drug received by the infant from the mother's milk and medication prescribed for the infant should also be considered, for example, when the drug given to the infant may prevent metabolism of the drug received via breast milk.
    Specialist advice is available from the UK Drugs in Lactation Advisory Service at

    Effects on Ability to Drive and Operate Machinery

    Suxamethonium will always be used in combination with a general anaesthetic and therefore patients should be warned not to drive or operate machinery until all effects of anaesthesia and/or surgery have ceased.

    Side Effects

    Anaphylactic reaction
    Cardiac arrest
    Gastric secretions increased
    Increased bowel action
    Increased bronchial secretions
    Increased intra-gastric pressure
    Increased intra-ocular pressure
    Malignant hyperthermia
    Muscle pain
    Post-operative pain
    Respiratory depression


    It is strongly recommended that the UK National Poisons Information Service be consulted on cases of suspected or actual overdose where there is doubt over the degree of risk or about appropriate management.

    The following number will direct the caller to the relevant local centre (0844) 892 0111

    Information may be obtained if you have access to ToxBase the primary clinical toxicology database of the National Poisons Information Service. This is available via password on the internet ( ) or if this is unavailable at the backup site ( ).

    Further Information

    Last Full Review Date: March 2013

    Reference Sources

    Drugs During Pregnancy and Lactation: Treatment Options and Risk Assessment, 2nd edition (2007) ed. Schaefer, C., Peters, P. and Miller, R. Elsevier, London.

    Drugs in Pregnancy and Lactation: A Reference Guide to Fetal and Neonatal Risk, 9th edition (2011) ed. Briggs, G., Freeman, R. and Yaffe, S. Lippincott Williams & Wilkins, Philadelphia.

    Summary of Product Characteristics: Anectine Injection. GlaxoSmithKline UK. Revised January 2016.

    Summary of Product Characteristics: Suxamethonium Chloride Injection BP 50mg/2ml. Aurum Pharmaceuticals Ltd. Revised July 2007.

    Summary of Product Characteristics: Suxamethonium Chloride 50mg/ml Solution for Injection. Mercury Pharma group. Revised August 2012.

    NICE Evidence Services Available at: Last accessed: 01 September 2017

    US National Library of Medicine. Toxicology Data Network. Drugs and Lactation Database (LactMed).
    Available at:
    Succinylcholine Last revised: January 4, 2011
    Last accessed: March 14, 2013

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