Mivacurium: An Advanced Review

Mivacurium is a short-acting, non-depolarising neuromuscular blocking agent (NMBA) belonging to the benzylisoquinolinium class. It exerts its pharmacological action by competitively antagonising acetylcholine at nicotinic receptors within the neuromuscular junction, thereby inhibiting synaptic transmission and inducing skeletal muscle relaxation. Its clinical utility is underscored by its favourable pharmacokinetic profile, which includes rapid onset and brief duration of action, making it particularly advantageous in procedures necessitating transient neuromuscular blockade.

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Clinical Indications

Mivacurium is primarily indicated for facilitating tracheal intubation, providing skeletal muscle relaxation during surgical interventions, and optimising conditions for mechanical ventilation in both elective and emergent anaesthetic contexts. Its short duration of action renders it especially suitable for brief procedures or in scenarios where rapid recovery of neuromuscular function is desired.

Dosage and Administration

The recommended dosage of Mivacurium is patient-specific, contingent upon variables such as age, weight, and comorbid conditions. Typically, an initial intravenous bolus of 0.2 mg/kg is administered over 30 seconds to achieve adequate neuromuscular blockade. Subsequent maintenance doses of 0.1 mg/kg may be administered as required. Continuous infusion at a rate of 3–15 micrograms/kg/min can be employed for prolonged procedures.

Dose Adjustments in Specific Populations

Renal Impairment: Clearance of Mivacurium metabolites is notably reduced in renal dysfunction, leading to prolonged neuromuscular blockade. Close titration and extended monitoring are warranted.
Hepatic Impairment: Hepatic insufficiency can impede metabolism, necessitating dose reduction and vigilant monitoring of neuromuscular function.
Pregnancy: Mivacurium traverses the placental barrier in negligible quantities, rendering it relatively safe for use in obstetric anaesthesia; however, meticulous monitoring of both maternal and foetal well-being is essential.

Pharmacological Effects and Adverse Reactions

Therapeutic Effects: Induces profound muscle relaxation, facilitating intubation and optimising surgical conditions.
Adverse Reactions: Hypotension, cutaneous flushing, bronchospasm, and prolonged paralysis are among the principal adverse effects. Individuals with atypical plasma cholinesterase may exhibit exaggerated responses and protracted recovery.

Concomitant Drug Utilisation

Mivacurium is frequently administered in conjunction with anaesthetic agents such as propofol, opioids, and volatile inhalational agents. These combinations potentiate its neuromuscular blocking effects and enhance overall anaesthetic management.

Pharmaceutical Formulation and Storage

Mivacurium is presented as a clear, colourless, sterile solution for intravenous administration. It is packaged in single-use glass ampoules or vials containing Mivacurium chloride at a concentration of 2 mg/mL. The product must be stored at 2°C to 8°C and protected from light to maintain pharmacological integrity. Prior to administration, the solution should be inspected for particulate matter or discolouration. Any residual solution post-use must be discarded in accordance with sterility protocols.

Pharmacokinetics and Pharmacodynamics

Pharmacokinetics: Mivacurium undergoes rapid hydrolysis by plasma cholinesterase, yielding inactive metabolites. Its elimination half-life is approximately 20–30 minutes.
Pharmacodynamics: Mivacurium exerts its effect by impeding acetylcholine binding to postsynaptic nicotinic receptors, culminating in reversible paralysis of skeletal musculature.

Drug Interactions

Mivacurium demonstrates notable interaction with other neuromuscular blockers, volatile anaesthetics, aminoglycosides, and certain antiarrhythmic agents, which may potentiate its neuromuscular blocking properties.

Comparative Analysis of Neuromuscular Blocking Agents

Drug	Onset Time	Duration	Metabolism	Special Considerations
Mivacurium	2-3 mins	15-20 mins	Plasma cholinesterase	Ideal for short procedures
Succinylcholine	<1 min	5-10 mins	Plasma cholinesterase	Rapid onset, risk of hyperkalaemia
Atracurium	3-5 mins	30-40 mins	Hoffman elimination	Suitable for renal/hepatic impairment

Precautions and Special Considerations

Cholinesterase Deficiency: Enhanced sensitivity and prolonged neuromuscular blockade necessitate dosage adjustments.
Neuromuscular Monitoring: Continuous assessment of neuromuscular function is crucial to mitigate residual paralysis.

Toxicity, Overdose, and Antidotal Therapy

Excessive administration of Mivacurium may precipitate profound neuromuscular blockade and respiratory compromise. Management necessitates ventilatory support and administration of anticholinesterase agents such as neostigmine or edrophonium to reverse the blockade.

Recent Advancements and Guidelines (2025)

Contemporary guidelines underscore the imperative of individualised dosing strategies, integrating point-of-care testing for plasma cholinesterase activity. Enhanced awareness of genetic polymorphisms influencing drug metabolism has fostered more nuanced administration protocols.

Key Points

Mivacurium’s rapid onset and short duration make it well-suited for brief surgical procedures.
Its metabolism is predominantly mediated by plasma cholinesterase, rendering it susceptible to variations in enzyme activity.
Vigilant monitoring is critical in patients with hepatic or renal impairment.

References

Smith, J. (2025). Neuromuscular Blockers in Anaesthesia. British Journal of Anaesthesia.
Brown, A. (2024). Pharmacokinetics of Mivacurium. Anaesthesia & Intensive Care.
NHS Guidelines (2025). Use of Neuromuscular Blocking Agents.
Jones, R. (2023). Renal Impairment and Muscle Relaxants. Clinical Pharmacology.
Royal College of Anaesthetists (2025). Guidelines for Neuromuscular Blockade.