Alcuronium chloride

Alcuronium chloride (formerly marketed as Alloferin) is a neuromuscular blocking (NMB) agent, alternatively referred to as a skeletal muscle relaxant. It is a semi-synthetic substance prepared from C-toxiferine I, a bis-quaternary alkaloid obtained from Strychnos toxifera. C-toxiferine I itself has been tested for its pharmacological action and noted to be a very long acting neuromuscular blocking agent For a formal definition of the durations of actions associated with NMB agents, see page for gantacurium. The replacement of both the N-methyl groups with N-allyl moieties yielded N,N-diallyl-bis-nortoxiferine, now recognized as alcuronium.

Inclusion of the allylic functions presented an enhanced potential area of biotransformation, and thus alcuronium is observed to have a much shorter duration of neuromuscular blocking action than its parent C-toxiferine I. It also has a more rapid onset of action, and is ~1.5 times as potent as tubocurarine. The pharmacological action of alcuronium is readily reversed by neostigmine, and it produces little histamine release. The major disadvantage of alcuronium is that it elicits a vagolytic effect produced by a selective atropine-like blockade of cardiac muscarinic receptors.

Effects

 * Cardiovascular system: histamine release and blockage of the sympathetic ganglia including adrenal medulla could cause hypotension
 * Respiratory system: apnea due to phrenic blockage but bronchoconstriction can occur from the histamine release
 * Central nervous system: no effect on intraocular pressure
 * Autonomic ganglion blockade can cause a decrease in gut motility

Special points

 * Duration of action prolonged in states of low potassium, calcium and protein, also in states of high magnesium and acidosis.
 * Pharmaceutically incompatible with thiopentone
 * Infusion can cause fixed dilated pupils