Rocuronium

Clinical use &amp, dosing (adult)

Intubation (routine): 0.6 mg/kg IV
- Typical onset ~60–90 s, duration ~30–40 min (dose-dependent)
Rapid sequence induction (RSI): 1.0–1.2 mg/kg IV
- Onset often comparable to suxamethonium, duration longer (often 60–90 min)
Maintenance bolus: 0.1–0.2 mg/kg IV, or infusion ~5–12 micrograms/kg/min (titrate to monitoring)
- Aim for 1–2 twitches (TOF) intra-op, ensure full reversal/TOF ratio ≥0.9 before extubation
Paediatrics: similar mg/kg dosing, onset may be faster in infants/children, always titrate to monitoring

Reversal strategy (practical)

Neostigmine + glycopyrrolate: for shallow/moderate block with evidence of recovery (e.g., TOF count ≥2 and improving)
- Typical neostigmine 40–50 micrograms/kg with glycopyrrolate 10 micrograms/kg (local practice varies)
- Ceiling effect: ineffective for profound block, requires some spontaneous recovery
Sugammadex: specific binding reversal for aminosteroids (rocuronium &gt, vecuronium)
- 2 mg/kg for moderate block (TOF count 2), 4 mg/kg for deep block (PTC 1–2), 16 mg/kg for immediate rescue (e.g., cannot intubate/cannot ventilate soon after RSI dose)
- Recurarisation risk if under-dosed, always confirm recovery with quantitative monitoring

When to choose rocuronium

Alternative to suxamethonium for RSI when sux is contraindicated (e.g., hyperkalaemia risk, MH susceptibility, pseudocholinesterase deficiency, raised IOP/ICP considerations depending on context)
When predictable reversal with sugammadex is desirable (short cases, high aspiration risk, difficult airway planning)

Class, structure, presentation

Aminosteroid non-depolarising neuromuscular blocker, quaternary ammonium compound → poor oral absorption, does not cross BBB/placenta significantly
Usually supplied as aqueous solution (commonly 10 mg/mL), store per local guidance, check compatibility (avoid mixing with alkaline solutions in same line)

Mechanism of action (NMJ pharmacology)

Competitive antagonism at post-junctional nicotinic ACh receptors (Nm) → prevents depolarisation and muscle contraction
- Block is surmountable by increasing ACh (anticholinesterases) once some recovery has occurred
Produces fade on TOF/tetanus due to presynaptic effects reducing ACh mobilisation (feature of non-depolarising block)

Pharmacokinetics

Onset: relatively rapid for a non-depolariser (dose-dependent), faster with larger dose (RSI dosing)
Distribution: hydrophilic, Vd approximates extracellular fluid, high protein binding is not a dominant feature clinically
Elimination: predominantly hepatic uptake and biliary excretion, some renal excretion
- Prolonged duration in hepatic impairment and cholestasis, may be prolonged in renal failure (less than some agents but clinically relevant)
Metabolism: minimal, active metabolites are not a major clinical issue (contrast with vecuronium)

Pharmacodynamics &amp, clinical effects

Produces skeletal muscle paralysis including respiratory muscles, no analgesia, amnesia or sedation
Cardiovascular: generally stable, minimal histamine release, mild vagolytic effect may cause small ↑HR in some patients
Histamine release: low compared with atracurium/mivacurium, anaphylaxis remains possible

Factors altering effect (exam-friendly list)

Potentiation: volatile agents, aminoglycosides, magnesium, lithium, local anaesthetics (high dose), hypothermia, acidosis (variable), hypokalaemia, hypocalcaemia
Resistance/shorter duration: chronic anticonvulsants (enzyme induction), burns (after ~24–48 h), denervation/upper motor neuron lesions (upregulation of ACh receptors), hyperkalaemia (variable clinical relevance)
Organ dysfunction: hepatic dysfunction/cholestasis prolongs, renal failure may prolong, critical illness can cause unpredictable sensitivity/resistance

Monitoring

Use peripheral nerve stimulator, prefer quantitative monitoring (acceleromyography/EMG) to confirm TOF ratio ≥0.9
Deep block assessment: post-tetanic count (PTC) when TOF = 0

Adverse effects &amp, safety

Residual neuromuscular blockade → hypoventilation, airway obstruction, aspiration risk, common if no quantitative monitoring and/or inadequate reversal
Anaphylaxis: rocuronium is among the more commonly implicated NMBDs, cross-reactivity can occur due to quaternary ammonium epitopes
Injection site pain/withdrawal movement can occur (notably with rapid bolus in awake/semi-awake patients)

Comparisons (high-yield)

Vs suxamethonium: rocuronium has slower onset at standard dose but RSI dose approaches sux onset, duration much longer, can be rapidly reversed with sugammadex
Vs atracurium/cisatracurium: rocuronium relies on hepatic/biliary elimination (not Hofmann), less histamine, useful when avoidance of histamine desired but caution in hepatic dysfunction
Vs vecuronium: rocuronium faster onset, vecuronium has active metabolite (3-desacetyl) which can accumulate in renal failure, both reversed by sugammadex

Test yourself…

Describe rocuronium: class, mechanism, onset and duration.

Structure your answer: classification → NMJ mechanism → time course → key determinants (dose, co-administered agents, physiology).

Class: aminosteroid non-depolarising neuromuscular blocker
Mechanism: competitive antagonism at post-junctional nicotinic (Nm) receptors → prevents ACh-mediated depolarisation, causes fade on TOF/tetanus
Onset: relatively rapid, ~60–90 s after 0.6 mg/kg, faster with 1.0–1.2 mg/kg (RSI dosing)
Duration: dose-dependent, ~30–40 min after 0.6 mg/kg, often 60–90 min after RSI dose

How would you perform RSI with rocuronium and what are the implications for rescue reversal?

Examiners want: correct dose, expected onset, longer paralysis than sux, and a clear plan for failed intubation including sugammadex dosing and limitations.

Dose for RSI: 1.0–1.2 mg/kg IV (with appropriate induction agent and cricoid/RSI technique per local policy)
Implication: paralysis lasts much longer than sux → if airway difficulty occurs, cannot rely on spontaneous recovery within minutes
Rescue reversal: sugammadex 16 mg/kg for immediate reversal soon after large-dose rocuronium (e.g., cannot intubate/cannot ventilate scenario)
- Still must follow difficult airway algorithm, reversal is not a substitute for oxygenation/ventilation
Post-reversal: confirm recovery with quantitative monitoring, plan for re-paralysis if surgery must proceed (consider non-steroidal NMBD such as cisatracurium if sugammadex used, depending on timing and dose)

Outline the pharmacokinetics of rocuronium and how organ failure affects it.

Hit: distribution (hydrophilic), elimination (hepatic/biliary), and the clinical consequence (prolongation).

Hydrophilic quaternary ammonium compound → limited CNS/placental transfer, Vd approximates extracellular fluid
Elimination predominantly hepatic uptake and biliary excretion, some renal excretion
Hepatic impairment/cholestasis: prolonged duration and slower recovery, increased variability
Renal failure: may prolong effect (less reliance than some drugs but clinically relevant), use monitoring and consider alternative agents (e.g., cisatracurium) if prolonged paralysis undesirable

How do volatile anaesthetics and magnesium affect rocuronium block? Explain the mechanism and clinical implications.

This is a common FRCA physiology–pharmacology crossover: potentiation and monitoring/reversal implications.

Volatile agents potentiate non-depolarising block (greater depth and duration for a given dose), especially with longer exposure
Magnesium potentiates block by reducing presynaptic ACh release and decreasing postsynaptic excitability
Clinical implications: reduce maintenance dosing, use neuromuscular monitoring, anticipate delayed recovery and need for reversal

Discuss reversal of rocuronium with neostigmine versus sugammadex (indications, dosing, limitations).

Examiners look for: depth of block matters, neostigmine ceiling, sugammadex dose by TOF/PTC, monitoring and recurarisation risk.

Neostigmine: indirect reversal by increasing ACh, effective only when some spontaneous recovery present (e.g., TOF count ≥2), ceiling effect
Sugammadex: encapsulates free rocuronium in plasma → rapid reduction in free concentration → drug diffuses away from NMJ
Sugammadex dosing: 2 mg/kg (TOF count 2), 4 mg/kg (deep block PTC 1–2), 16 mg/kg (immediate rescue after RSI dose)
Limitations: under-dosing risks recurarisation, confirm TOF ratio ≥0.9, consider cost and availability, be aware of rare anaphylaxis to sugammadex

A patient has prolonged paralysis after rocuronium. Give a differential diagnosis and management plan.

A classic FRCA viva: think drug, patient, physiology, interactions, and monitoring error, then manage airway/ventilation and reverse appropriately.

Confirm: ensure adequate ventilation/sedation, check quantitative TOF, exclude equipment/monitoring error and wrong drug/dose
Drug factors: large dose/infusion, accumulation, potentiation by volatiles, magnesium, aminoglycosides, recent local anaesthetic toxicity/high dose
Patient factors: hypothermia, electrolyte disturbance (low K/Ca), acid–base disturbance, hepatic dysfunction/cholestasis, renal failure, critical illness/ICU weakness
Management: correct physiology (warm, correct electrolytes), stop potentiating drugs where possible, consider reversal (sugammadex if rocuronium and significant block, neostigmine only if partial recovery), continue ventilatory support until TOF ratio ≥0.9 and clinically strong

Discuss anaphylaxis to rocuronium: recognition, immediate management, and implications for future anaesthesia.

Common exam scenario: NMBDs are a leading cause of perioperative anaphylaxis, rocuronium is frequently implicated.

Recognition: sudden hypotension, bronchospasm, difficulty ventilating, rash/urticaria (may be absent), angioedema, consider differential (haemorrhage, high spinal, embolus)
Immediate management: call for help, stop suspected trigger, 100% O2, airway/ventilation, adrenaline titrated IV for severe reactions, large-volume IV fluids, adjuncts (antihistamine, steroid, bronchodilator) after adrenaline
Investigations: timed mast cell tryptase samples (per local protocol) and documentation of all drugs/exposures
Future: referral to specialist allergy clinic for testing, avoid culprit and consider cross-reactivity among NMBDs, provide patient information and anaesthetic alert

Compare rocuronium with atracurium/cisatracurium in a patient with severe liver disease.

This tests elimination pathways and choice of agent in organ failure.

Rocuronium: predominantly hepatic uptake/biliary excretion → prolonged and variable effect in liver disease/cholestasis
Atracurium/cisatracurium: organ-independent elimination (Hofmann ± ester hydrolysis) → more predictable in hepatic failure
Practical: if rocuronium used, reduce dose, avoid long infusions, monitor quantitatively, and plan reversal (sugammadex available) but still expect variability

Explain train-of-four fade with non-depolarising block and how you would use TOF/PTC to guide dosing and reversal for rocuronium.

A frequent FRCA viva theme: link physiology to clinical monitoring decisions.

Fade: non-depolarising agents reduce safety margin at NMJ and impair presynaptic ACh mobilisation → successive stimuli produce diminishing responses
Intra-op: titrate boluses/infusion to desired depth (often TOF 1–2), avoid unnecessary deep block unless specifically required
Deep block: if TOF=0, use PTC to estimate depth and guide sugammadex dosing (e.g., PTC 1–2 suggests deep block → 4 mg/kg)
Extubation: confirm TOF ratio ≥0.9 on quantitative monitor, clinical tests alone are insufficient