Pharm 101: Rocuronium

Class

Paralytic agent


Pharmacodynamics
  • Non-depolarising steroid neuromuscular blocking agent used as a paralytic in rapid sequence induction
  • At low doses, acts predominately as a competitive inhibitor of Acetylcholine at nicotinic receptors
  • At higher doses, can enter the pore of the ion channel causing greater neuromuscular blockade

Pharmacokinetics
  • Undergoes rapid distribution
  • Highly ionised therefore small volume of distribution 0.1L/kg
  • Onset of action: 45-60 seconds
  • Intermediate acting: duration of action 20-35 minutes
  • Metabolism: liver
  • Elimination: liver (75-90%) and kidney

Clinical uses
  • Rapid Sequence Induction (RSI)
    • Dose 1.2mg/kg (accepted range 0.9-1.2mg/kg)
  • Clinical effects:
    • Initially motor weakness followed by skeletal muscles becoming flaccid and unexcitable to electrical stimulation
    • Larger muscles (e.g. abdominal, trunk, diaphragm) are more resistant to neuromuscular blockade and recover more rapidly than smaller muscles (e.g. facial, foot, hand)
    • Diaphragm is the last muscle to be paralysed

Sugammadex
  • Sugammadex is a modified cyclodextrin antidote used for rapid reversal of rocuronium and vecuronium
  • Binds tightly to rocuronium in a 1:1 ratio, and this complex is excreted unchanged in the urine
  • This decreases free plasma concentration and establishes a concentration gradient for rocuronium to diffuse away from the neuromuscular junction back into circulation for further binding to free sugammadex
  • Dosing varies for desired reversal effects:
    • 2mg/kg: reversal of shallow neuromuscular blockade
    • 4mg/kg: reversal of deeper blockade
    • 16mg/kg: immediate reversal following administration of single dose 1.2mg/kg rocuronium
  • Adverse effects:
    • Anaphylaxis in 0.3% of patients receiving 16mg/kg dosage
    • Hypersensitivity reactions are common
    • Bradycardia (may progress rapidly to cardiac arrest)
    • Coagulopathy: 25% elevation of APTT and PT/INR values lasting up to one hour

Further Reading

Pharm 101 700

Pharmacology 101

Top 200 drugs

MBBS (UWA) CCPU Emergency Medicine Advanced Trainee based in Melbourne, Australia. Co-author of the LITFL ECG Library. Likes Ultrasound, Echo, ECGs, and anything and everything with caffeine. Part of the 2021 ANZCEN Clinician Educator Incubator Programme | @rob_buttner | ECG Library |

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.