Vecuronium

Usage

• Medical Conditions: Vecuronium is primarily used as a skeletal muscle relaxant during surgical procedures and other medical interventions requiring muscle paralysis, such as endotracheal intubation, mechanical ventilation, and in the intensive care unit (ICU).
• Pharmacological Classification: Neuromuscular blocking agent, non-depolarizing type.
• Mechanism of Action: Vecuronium competitively binds to nicotinic acetylcholine receptors at the neuromuscular junction, preventing acetylcholine from binding and thus inhibiting muscle contraction.

Alternate Names

• International/Regional Variations: Vecuronium bromide.
• Brand Names: Norcuron.

How It Works

• Pharmacodynamics: Vecuronium induces skeletal muscle relaxation by competitively antagonizing nicotinic acetylcholine receptors at the neuromuscular junction. This prevents depolarization of the muscle fiber, leading to paralysis. It has minimal cardiovascular effects and doesn’t significantly alter heart rate, blood pressure, or cardiac output. It also exhibits little histamine release.
• Pharmacokinetics:
  • Absorption: Administered intravenously (IV). Intramuscular (IM) administration is not recommended.
  • Distribution: Distributes in extracellular fluid and rapidly reaches the neuromuscular junction. It is 60% to 90% plasma protein-bound. Volume of distribution may be decreased in young children and the elderly.
  • Metabolism: Undergoes hepatic metabolism, with the formation of the active metabolite 3-desacetyl-vecuronium, which also contributes to neuromuscular blockade.
  • Elimination: Excreted primarily in bile and feces. Some elimination occurs via the kidneys. The active metabolite, 3-desacetyl-vecuronium, is cleared by the kidneys.

Dosage

Standard Dosage

Adults:

• Intubation: 0.08-0.1 mg/kg IV bolus over 60 seconds. If following succinylcholine administration, 0.04-0.06 mg/kg IV bolus.
• Maintenance: 0.01-0.015 mg/kg IV every 12-15 minutes as needed, or continuous infusion at 0.8-1.4 mcg/kg/min.

Children:

• 1-10 years: 0.1 mg/kg IV, repeated every hour as needed, or continuous infusion 0.05-0.07 mg/kg/hour IV.
• >7 weeks to <1 year: Similar to adult dosing, but higher doses and frequent maintenance doses are typically not required.
• Neonates (up to 4 weeks): An initial test dose of 10-20 mcg/kg is recommended, followed by incremental doses until the desired level of neuromuscular blockade (90-95% twitch depression) is achieved. The maximum dose in neonates should not exceed 100 mcg/kg.

Special Cases:

• Elderly Patients: Same initial and maintenance doses as younger adults can be used, but duration of action may be prolonged due to pharmacokinetic changes.
• Patients with Renal Impairment: No specific dose adjustment, but the duration of action may be prolonged, particularly with continuous infusion.
• Patients with Hepatic Dysfunction: Caution should be exercised. Prolonged recovery may occur. Dosage adjustments may be necessary based on the degree of impairment.
• Patients with Comorbid Conditions: Vecuronium should be used with caution in patients with cardiovascular disease, obesity, neuromuscular diseases (e.g., myasthenia gravis, Eaton-Lambert syndrome), electrolyte imbalances, and acid-base disturbances.

Clinical Use Cases:

• Intubation: 0.08-0.1 mg/kg IV.
• Surgical Procedures: Initial dose of 0.08-0.1 mg/kg IV, followed by maintenance doses as needed.
• Mechanical Ventilation: Continuous infusion, starting at 0.8-1.4 mcg/kg/min, titrated to response.
• Intensive Care Unit (ICU) Use: Continuous infusion, titrated to maintain desired level of paralysis.
• Emergency Situations: Vecuronium is not typically used in emergency situations requiring rapid sequence intubation.

Dosage Adjustments:

Dose adjustments may be required for patients with renal or hepatic dysfunction, and in those with comorbid conditions, especially those affecting neuromuscular transmission. Neuromuscular monitoring is recommended for all patients receiving vecuronium.

Side Effects

Common Side Effects:

• Muscle weakness
• Redness, irritation, or pain at the injection site
• Flushing

Rare but Serious Side Effects:

• Hypotension
• Bronchospasm
• Prolonged paralysis
• Allergic reactions (rash, hives, itching, swelling of face, lips, or tongue)
• Breathing difficulties

Long-Term Effects:

• Myopathy (rare)

Adverse Drug Reactions (ADR):

• Anaphylaxis (rare)

Contraindications:

• Hypersensitivity to vecuronium or bromides.
• Lack of appropriate ventilatory support.
• Malignant hyperthermia.

Drug Interactions:

Vecuronium interacts with numerous medications, including:

• Inhalational anesthetics: Enhance neuromuscular blockade.
• Aminoglycoside antibiotics: Increase neuromuscular blockade.
• Magnesium salts: Increase neuromuscular blockade.
• Other non-depolarizing neuromuscular blockers: Additive or synergistic effects.
• Certain antiarrhythmics (e.g., quinidine): Prolonged neuromuscular blockade.

Pregnancy and Breastfeeding:

• Pregnancy Safety Category: C (FDA). Use only if clearly needed. It has been used in cesarean sections.
• Breastfeeding: Unknown if excreted in breast milk. Caution advised.

Drug Profile Summary

• Mechanism of Action: Competitively inhibits acetylcholine at nicotinic receptors at the neuromuscular junction.
• Side Effects: Muscle weakness, injection site reactions, flushing, hypotension, prolonged paralysis, allergic reactions.
• Contraindications: Hypersensitivity, lack of ventilatory support, malignant hyperthermia.
• Drug Interactions: Inhalational anesthetics, aminoglycosides, magnesium salts, other neuromuscular blockers.
• Pregnancy & Breastfeeding: Category C; use with caution if benefits outweigh risks. Excretion in breast milk unknown.
• Dosage: See detailed dosage guidelines above.
• Monitoring Parameters: Neuromuscular transmission (train-of-four monitoring), respiratory rate, blood pressure, heart rate.

Popular Combinations:

Vecuronium is often used with inhalational anesthetics and opioids for balanced anesthesia.

Precautions:

Standard anesthetic precautions should be observed. Neuromuscular function should be monitored.

FAQs (Frequently Asked Questions)

Q1: What is the recommended dosage for Vecuronium?

A: See detailed dosage guidelines above.

Q2: How is vecuronium metabolized?

A: Primarily by the liver, with an active metabolite (3-desacetyl-vecuronium) that is renally cleared.

Q3: What are the common side effects of vecuronium?

A: Muscle weakness, injection site reaction, flushing.

Q4: What are the contraindications to using vecuronium?

A: Hypersensitivity, lack of ventilatory support.

Q5: Does vecuronium have any significant drug interactions?

A: Yes, with inhalational anesthetics, aminoglycosides, magnesium salts, and other neuromuscular blockers.

Q6: Can vecuronium be used in pregnant or breastfeeding women?

A: Use with caution if benefits outweigh risks. It has been used in cesarean sections. Excretion in breast milk is unknown.

Q7: How should vecuronium be administered?

A: Intravenously (IV). IM administration is not recommended.

Q8: How is the effect of vecuronium reversed?

A: Reversal can be achieved with sugammadex or neostigmine (in conjunction with an anticholinergic like atropine).

Q9: What is the onset and duration of action of vecuronium?

A: Onset is typically 1-3 minutes and duration of action is around 25-40 minutes, depending on the dose and patient-specific factors.