Rocuronium

Why this drug is interesting

Rocuronium is a competitive antagonist at the nicotinic acetylcholine receptor of the neuromuscular junction. It has no effect on consciousness, no analgesic properties and no cardiovascular actions of consequence. It does exactly one thing, and the entire clinical discussion around it concerns timing.

For years the argument against using it for rapid sequence induction was duration: if the intubation failed and the patient could not be ventilated, you were committed to a prolonged period of paralysis with no way out. Suxamethonium, wearing off in minutes, appeared to offer an escape. Sugammadex changed that argument, and rocuronium has become the default paralytic in most UK emergency departments.

Dosing

Maintenance

• Bolus: 0.15 mg/kg — reduced to 0.075–0.1 mg/kg in long-term inhalational anaesthesia, in the elderly, and in hepatic, biliary or renal failure
• Infusion under intravenous anaesthesia: 0.3–0.6 mg/kg/h
• Infusion under inhalational anaesthesia: 0.3–0.4 mg/kg/h
• "Continuous monitoring of the neuromuscular block is essential" — requirements vary between patients and with anaesthetic technique¹

Rocuronium or suxamethonium?

The honest position is that rocuronium's advantages are the absence of contraindications and the absence of hyperkalaemia, not the availability of rescue. Sugammadex is worth having and worth knowing the dose of — but a plan that depends on it is a plan that depends on someone drawing up 16 mg/kg correctly under extreme pressure.

Reversal

Sugammadex is a modified γ-cyclodextrin that encapsulates aminosteroid relaxants in plasma, removing them from the neuromuscular junction. It reverses rocuronium at any depth of block, including immediately after an intubating dose, at 16 mg/kg.²

Sugammadex binds rocuronium and vecuronium. It does not bind benzylisoquinolinium relaxants such as atracurium or mivacurium, and there is no immediate-reversal data for vecuronium — the 16 mg/kg indication is for rocuronium only.

Practical use in the ED

1. Decide the induction agent dose with the same care as the relaxant. In shock, the induction agent dose comes down and the relaxant dose does not — rocuronium's onset is faster in a low cardiac output state only in the sense that everything circulates more slowly and less predictably. Under-dosing the sedative is how awareness happens.
2. Draw up and label both drugs before you start. Syringe swaps between relaxant and induction agent are a recognised never-event mechanism.
3. Time it. Sixty seconds is longer than it feels. Intubating at forty seconds after 1 mg/kg gives worse conditions than waiting.
4. Plan the sedation that follows. The commonest post-intubation error is a paralysed patient whose sedation infusion has not yet been started or has not yet reached them.
5. Know where the sugammadex is and what 16 mg/kg looks like in vials for your patient — before induction, not after.

Adverse effects and cautions

• Anaphylaxis — the label classes anaphylactic reaction as very rare (<1/10,000), but neuromuscular blocking agents are nonetheless a leading trigger of perioperative anaphylaxis, examined in detail in NAP6. Suspect it when hypotension and bronchospasm follow induction
• Pain on injection in the awake patient — relevant if given before the induction agent has taken effect, which is an argument for the order in which they are given
• Prolonged block in hepatic and renal impairment and in the elderly
• Interaction with magnesium, aminoglycosides and volatile anaesthetics, all of which potentiate the block
• Tachycardia at higher doses, from mild vagolytic activity — generally of no clinical consequence

There are no meaningful contraindications beyond hypersensitivity, which is the principal reason rocuronium has displaced suxamethonium as the default: the list of patients in whom it is unsafe is very short.

Critical appraisal

1. The rocuronium-versus-suxamethonium debate has been settled more by contraindications than by evidence. Meta-analyses have generally favoured suxamethonium marginally on intubating conditions at equivalent times. What changed practice was the recognition that suxamethonium's contraindications — hyperkalaemia, burns, prolonged immobility, neuromuscular disease — are common in emergency patients and frequently unknown at the moment of decision.
2. Sugammadex is often cited as making rocuronium safe, and that is an overstatement. It reverses the paralysis and nothing else. In a genuine can't-intubate-can't-oxygenate emergency, the correct response is a front-of-neck airway, not a dash for the sugammadex. (It is not a fridge item either — the label says store below 30°C.)
3. The 1 mg/kg versus 0.6 mg/kg choice is under-discussed. The higher dose buys thirty seconds and costs a substantially longer block. In a patient in whom the airway is expected to be straightforward and a rapid neurological reassessment matters, that trade is not automatic.
4. Dosing in obesity is genuinely unsettled. Rocuronium is conventionally dosed to actual body weight for RSI, which produces a very long block in the markedly obese patient; ideal or lean body weight gives a shorter block and potentially worse conditions. Follow local anaesthetic guidance rather than a monograph.

References

1. 1
   Rocuronium 10 mg/ml solution for injection/infusion — Summary of Product Characteristics, hameln pharma ltd. electronic Medicines Compendium. Sections 4.1, 4.2, 4.4, 4.8, 5.1. Verified 24 Aug 2026.
2. 2
   Bridion 100 mg/mL solution for injection (sugammadex) — Summary of Product Characteristics, MSD. electronic Medicines Compendium. Sections 4.2, 4.4, 6.4, 6.5. Verified 24 Aug 2026.
3. 3
   Royal College of Anaesthetists and Difficult Airway Society. NAP4: Major complications of airway management in the United Kingdom. nationalauditprojects.org.uk
4. 4
   Royal College of Anaesthetists. NAP6: Perioperative anaphylaxis. nationalauditprojects.org.uk — the UK audit of perioperative anaphylaxis, including neuromuscular blocking agents.
5. 5
   Difficult Airway Society. DAS guidelines for management of unanticipated difficult intubation in adults. das.uk.com
6. 6
   Rocuronium bromide — dosing and safety monograph. BNF, NICE. bnf.nice.org.uk