Pancuronium bromide is a long-acting, non-depolarizing neuromuscular blocking agent introduced in the 1960s and widely used in anesthesia to facilitate endotracheal intubation and provide skeletal muscle relaxation during surgery and mechanical ventilation. Its history is marked by its effectiveness in producing prolonged muscle paralysis, but also by cardiovascular side effects such as tachycardia and hypertension due to vagolytic activity. Pancuronium works by competitively blocking acetylcholine at nicotinic receptors at the neuromuscular junction, preventing depolarization and resulting in flaccid paralysis. It has been largely replaced in some settings by newer agents with more favourable safety profiles, but remains important in specific anesthetic and intensive care applications.
BRAND NAMES
Pavulon (most widely known brand)
Pancuron (used in some regions)
Pavulon Injection (hospital formulations)
MECHANISM OF ACTION
Pancuronium bromide is a non-depolarizing neuromuscular blocking agent. It works by competitively binding to nicotinic acetylcholine (Nm) receptors at the motor end plate of the neuromuscular junction. By blocking acetylcholine from binding, it prevents depolarization of the muscle membrane, thereby inhibiting neuromuscular transmission.
PHARMACOKINETICS
Absorption:
Pancuronium bromide is administered intravenously, so it has 100% bioavailability. Onset of action occurs within 2–3 minutes after IV injection, making it suitable for rapid muscle relaxation during anesthesia.
Distribution:
Pancuronium has a volume of distribution of about 0.2–0.3 L/kg, indicating limited tissue penetration. It is moderately protein bound (approximately 20–30%). It does not significantly cross the blood-brain barrier or placenta in active form.
Metabolism:
The drug undergoes partial hepatic metabolism, producing 3-hydroxypancuronium, which retains some neuromuscular blocking activity. Hepatic function can influence duration of action.
Elimination:
Pancuronium is eliminated primarily through the kidneys (about 60–80%), with both unchanged drug and metabolites excreted in urine. The remaining fraction is excreted via bile. Its half-life ranges from 1.5 to 2.5 hours, but duration may be prolonged in renal impairment.
PHARMACODYNAMICS
Pancuronium bromide is a non-depolarizing neuromuscular blocker that acts by competitively inhibiting acetylcholine at nicotinic (Nm) receptors at the neuromuscular junction. This prevents depolarization of the motor end plate, resulting in flaccid skeletal muscle paralysis. Its effects do not include analgesia or sedation. The blockade can be reversed using acetylcholinesterase inhibitors such as neostigmine, which increase acetylcholine levels at the synapse.
ADMINISTRATION
Pancuronium bromide is administered intravenously only. It is used in general anesthesia, endotracheal intubation, and mechanical ventilation in intensive care settings. It must be administered by trained healthcare professionals with airway support available.
DOSAGE AND STRENGTH
Typical adult intubating dose is 0.06–0.1 mg/kg IV, with maintenance doses of 0.01–0.02 mg/kg as needed. Effects may last 60–90 minutes or longer, depending on dose and patient condition. Dose adjustment is required in renal impairment.
DRUG INTERACTIONS
Pancuronium’s effects may be potentiated by aminoglycoside antibiotics, magnesium salts, volatile anesthetics, and other neuromuscular blockers. Its action may be reduced by anticholinesterase agents or certain anticonvulsants with chronic use. Careful monitoring is required during combined anesthesia therapy.
CONTRAINDICATIONS
Contraindications include known hypersensitivity to pancuronium and situations where mechanical ventilation is not available. It should be used cautiously in patients with renal impairment, electrolyte imbalance, or neuromuscular disorders.
SIDE EFFECTS
Common and clinically relevant effects include prolonged muscle paralysis, tachycardia, hypertension, and mild histamine-related reactions (rare). It may also cause increased salivation or bronchial secretions in some patients.
OVER DOSAGE
Pancuronium bromide overdose results in excessive and prolonged neuromuscular blockade, leading to severe skeletal muscle paralysis, including the respiratory muscles, which can cause apnea and respiratory failure. Patients remain conscious but are unable to move or breathe without assistance. Cardiovascular effects such as tachycardia and hypertension may also be seen due to its vagolytic action.
TOXICITY
Pancuronium toxicity is primarily related to prolonged or excessive neuromuscular blockade, leading to respiratory muscle paralysis and apnea. Cardiovascular effects such as tachycardia and hypertension may also occur due to vagolytic activity. Treatment involves mechanical ventilation support and reversal with acetylcholinesterase inhibitors (e.g., neostigmine) with anticholinergic protection (e.g., atropine).
