Pharmacology of Vecuronium

Vecuronium is a non-depolarizing neuromuscular blocking agent utilized for muscle relaxation during surgical procedures or as an adjunct in general anesthesia. Here’s a detailed breakdown of its pharmacology:

Classification

• Vecuronium is a non-depolarizing neuromuscular blocking agent, which implies it competes with acetylcholine for receptor binding at the motor end-plate without causing depolarization​¹​.

Mechanism of Action:

• Vecuronium achieves muscle paralysis by competitively binding to nicotinic cholinergic receptors at the neuromuscular junction, specifically the postjunctional membrane of the motor endplate. By doing so, it prevents acetylcholine from binding to these receptors, inhibiting depolarization, and subsequently blocking muscle contraction. This mechanism is central to its muscle relaxant effects typically employed as an adjunct to general anesthesia​^2, ​​^3, ​​⁴​.

Pharmacokinetics

• Distribution: The volume of distribution is reported to be between 0.3 to 0.4 L/kg​⁵​.
• Metabolism: Vecuronium’s metabolism is not very well elucidated, but it’s noted that it has an active metabolite, 3-desacetyl vecuronium, which possesses about half the activity of the parent drug​⁵​.
• Excretion: Between 40-75% of Vecuronium is excreted in feces and around 30% is excreted in the urine as unchanged drug and metabolites​⁴​.
• Half-life: Vecuronium has a half-life ranging from 51 to 80 minutes, which allows for a relatively short duration of action, making it suitable for surgical procedures​⁴​.

Indications

• Vecuronium is primarily used for muscle relaxation during surgery or while on a breathing machine. It’s also employed as an adjunct in general anesthesia, facilitating small bowel intubation, and inducing smooth muscle relaxation prior to radiological procedures​^1, ​​⁶​.

Adverse Effects

• Hives
• Difficulty breathing
• Swelling in the face, lips, tongue, or throat
• Weak or shallow breathing
• Ongoing muscle weakness
• Loss of movement in any part of the body
• Dizziness
• Fever
• Unusually fast or slow heart rate
• Low blood pressure
• Prolonged paralysis
• Inflammation of the skin due to an allergy
• Blood circulation failure due to serious heart condition
• Apnea, a breathing interruption
• A significant type of allergic reaction called anaphylaxis
• Fast heartbeat
• These effects are greatest at about 4 minutes and last for up to an hour. Allergic reactions are rare. It is unclear if use in pregnancy is safe for the baby. Other side effects may include skeletal muscle weakness, hypersensitivity, anaphylactic reaction, anaphylactoid reaction, anaphylactic shock, anaphylactoid shock, and flaccid paralysis, muscular weakness, steroid myopathy⁷.

Drug Interactions

• Detailed drug interactions were not available in the cited references, but like other neuromuscular blocking agents, Vecuronium may interact with other drugs affecting the central nervous system and cardiovascular activities.

Special Populations

• Information on the use of Vecuronium in special populations such as pregnant or breastfeeding women, and individuals with liver or kidney disease was not available in the cited references.

This thorough analysis of Vecuronium’s pharmacology underscores its mechanism of action, pharmacokinetics, clinical uses, and other aspects crucial for medical practitioners and researchers in understanding its application and effects.