| 1. Suxamethonium. Used prior to pancuronium (for endotracheal intubation) enhances the relaxation effect of the pancuronium and the duration of action. Therefore administration of pancuronium should be delayed until suxamethonium shows signs of wearing off.2. Anaesthetics. The following anaesthetics may potentiate the neuromuscular blocking activity of pancuronium: halothane, ether, enflurane, isoflurane, methoxyflurane, cyclopropane, thiopentone, methohexitone, ketamine, fentanyl, gammahydroxybutyrate, etomidate.3. The following drugs may influence the duration of action of pancuronium and the intensity of neuromuscular block.Potentiation: Other non-depolarising muscle relaxants, prior administration of succinylcholine, antibiotics of the polypeptide and aminoglycoside groups, diazepam, propranolol, thiamine (high dose), MAO inhibiting agents, quinidine, magnesium sulphate, protamine, nitroglycerin, narcotic analgesics, diuretics, phenytoin, alpha and beta adrenergic blocking agents, imidazoles, metronidazole, noradrenaline and adrenaline.Decreased effect: Neostigmine, edrophonium, corticosteriods (high dose), noradrenaline, adrenaline, potassium chloride, calcium chloride, sodium chloride, heparin (temporary decrease), azathioprine, theophylline, pyridostigmine, neurolept analgesia and propanidid.Variable effect: Depolarising muscle relaxants given after the administration of pancuronium may produce potentiation or attenuation of the neuromuscular blocking effect.The non-depolarising drug increases resistance towards the neuromuscular blocking effect of the depolarising drug. Therefore high doses of a depolarising drug are necessary before muscular relaxation can be obtained. These high doses of a depolarising drug may cause endplate desensitisation and prolong post-operative apnoea.Unlike a non-depolarising block, a depolarising block cannot be overcome by, and may even be worsened by an anticholinesterase agent.The duration of action of mivacurium has been found to be significantly increased when given after pancuronium, due to the reduction of plasma cholinesterase activity by pancuronium.Influence on the cardiovascular system: Pancuronium does not intensify the hypotension induced by halothane; in addition the cardiac depression is partly restored. The excessive bradycardia induced by neurolept analgesia and some of the cholinergic effects of morphine derivatives are counteracted by pancuronium. Pancuronium should be given with caution to patients receiving chronic tricyclic antidepressant therapy who are anaesthetised with halothane or any inhalation anaesthetic since this enhances the predisposition to the development of cardiac arrythmias associated with tricyclic antidepressants. Recent evidence suggests that alkylating drugs (nitrogen mustards) should be considered a possible hazard when given to patients during anaesthesia involving the use of muscle relaxants. | |