Neuromuscular Blocker Pregnancy: C — safe in emergency RSI, crosses placenta minimally

Suxamethonium (Succinylcholine)

Brand names: Anectine, Scoline

Adult dose

Dose: RSI: 1.5mg/kg IV

Route: IV / IO

Frequency: Single dose

Max: 150mg

Laryngospasm: 0.1mg/kg IV (may need 1–2mg/kg for full relaxation). No IV access: 4mg/kg IM. Pre-treat with atropine in children <5 years.

Paediatric dose

Dose: 2 mg/kg

Route: IV

Frequency: Single RSI dose

Max: 150mg

Concentration: 50 mg/ml

Paediatric weight-based calculator

Patient weight (kg)

Clinical pearls

Fastest onset of any NMBA (~45–60 sec), shortest duration (~8–10 min). Ideal for RSI when cannot intubate is anticipated.
Children <5 years: always give atropine 20mcg/kg IV first — suxamethonium routinely causes bradycardia in young children.
Strictly contraindicated >48h after severe burns or crush injury — ACh receptor upregulation causes lethal hyperkalaemia.
If malignant hyperthermia suspected: give dantrolene 2.5mg/kg IV immediately, call for help, and cease all trigger agents.

Contraindications

Personal or family history of malignant hyperthermia (MH)
Hyperkalaemia or risk of hyperkalaemia — burns >48h, crush injury >48h, spinal cord injury >72h, prolonged denervation, myopathies
Personal or family history of pseudocholinesterase deficiency (prolonged apnoea risk)
Penetrating eye injury (raises intraocular pressure — relative)
Duchenne or Becker muscular dystrophy (life-threatening hyperkalaemia)

Side effects

Hyperkalaemia (0.5–1 mmol/L rise in normal patients — dangerous if pre-existing hyperkalaemia)
Bradycardia — especially with repeat doses or in children (give atropine first)
Fasciculations and post-operative myalgia
Raised intra-gastric, intraocular, and intracranial pressure
Malignant hyperthermia (rare — life-threatening)

Interactions

Organophosphates / anticholinesterases (neostigmine): prolonged block
Lithium: potentiates and prolongs block
Aminoglycosides: enhanced neuromuscular block
Volatile anaesthetics (halothane): MH trigger

Monitoring

Neuromuscular monitoring
ECG (hyperkalaemia)
temperature

Reference: BNFc; NICE BNF 84; Difficult Airway Society (DAS) 2015; UK MH Unit Guidelines. Verify against your local formulary and the latest BNF before prescribing.

Curated clinical cross-links plus same-class fallbacks.

Calculators

Drugs

Rocuronium · Neuromuscular Blocker

Pathways