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ROCURONIUM

CLASS

Non-depolarising neuromuscular blocker

PRESENTATION

Clear, colourless solution.

Formulations

  • 5ml vial; 50mg, 10mg/ml

INDICATIONS & DOSING

Paralysis; endotracheal intubation, surgical immobility, ventilator synchrony/chest-wall compliance, facilitate pneumoperitoneum/reduce intra-abdominal pressure, prevention of shivering/coughing

  • Adult; 40-70mg IV (routine), 70-100mg IV (modified rapid sequence induction)
  • Paediatric; 0.6mg/kg IV, 1mg/kg IV (modified rapid sequence induction)

PRACTICALITIES

Administration

  • Administered as neat solution
  • Care to prevent accidental storage of neuromuscular blocker within the IV set following administration; may result in subsequent undesired paralysis and respiratory arrest

Incompatibilities

  • Alkaline solutions; thiopentone 
  • Antibiotics; cephazolin, amoxicillin, vancomycin, others
  • Others; dexamethasone, insulin, intralipid, frusemide

Practice tips

  • Titrate to desired depth of paralysis via neuromuscular monitoring 
  • Dose according to ideal body weight cf. total body weight
  • Subsequent maintenance dosing is dependent on required depth/duration; ~20% of the establishment dose is required to maintain paralysis due to partial receptor occupation
  • Unopened vials are stable for 12 weeks if stored at room temperature
  • Faster onset/offset in paediatric population and high cardiac output states
  • Slower offset with hypothermia, acidaemia, hypokalaemia, hypocalcaemia, hypermagnesaemia

PHARMACOKINETICS

Onset

  • 0.6mg/kg IV; 2-3 minutes
  • 1mg/kg IV; 60-90 seconds

Duration of action

  • 0.6mg/kg IV; 30-40 minutes
  • 1mg/kg IV; 60 minutes

Metabolism

  • Minimal hepatic metabolism to inactive compounds

Elimination

  • Majority biliary excretion in unchanged form
  • 1/3 renal excretion

MECHANISM

Non-depolarising competitive inhibition of acetylcholine receptors at the neuromuscular junction prevents neuromuscular transmission and muscle depolarisation.

DESIRED CLINICAL EFFECTS

Airway

  • Facilitation of endotracheal intubation; relaxation of vocal cords, ablation of airway reflexes 

Respiratory

  • Improved chest-wall compliance
  • Improved ventilator synchrony
  • Prevention of coughing (and associated rises in ICP) 

Musculoskeletal

  • Flaccid paralysis; surgical immobility, prevention of ECT-related injury, prevention of shivering (oxygen consumption) 

Gastrointestinal

  • Relaxation of abdominal wall musculature; reduction in intra-abdominal pressure (facilitation of pneumoperitoneum, intra-abdominal compartment syndrome)

OTHER CLINICAL EFFECTS, ADVERSE EFFECTS & TOXICITIES

Respiratory

  • Respiratory arrest
  • Residual paralysis; micro-aspiration, pneumonia, respiratory failure 

Neurological

  • Awareness under anaesthesia 

Immune

  • Anaphylaxis 

Musculoskeletal

  • ICU-Acquired Weakness (ICUAW); association only 

Antidote

  • Sugammadex
  • Neostigmine (competitive)

CONSIDERATIONS

Precautions

  • Renal/hepatic impairment; prolongation of neuromuscular blockade (more clinically relevant with subsequent dosing)
  • Disuse atrophy including cachexia, debilitation; profound paralysis
  • Neuromuscular disease – myasthenia gravis, Lambert-Eaton syndrome; profound paralysis 
  • Burns, denervation; resistance to neuromuscular blockade

Obstetric 

ADEC category B2

Drug interactions

  • Volatile anaesthesia, magnesium, aminoglycosides (gentamicin), lithium; augmentation of neuromuscular blockade
  • Phenytoin, carbamazepine, chronic corticosteroids; inhibition of neuromuscular blockade

REFERENCES

Drug information has been compiled from multiple sources including

  • Drugs in Anaesthesia and Intensive Care (Scarth & Smith)
  • Micromedex (IBM)
  • BJA Education (Oxford Academic)
  • Pharmacology for Anaesthesia and Intensive Care (Cambridge)
  • Australian Prescriber (NPS MedicineWise)

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