Adverse effects of nondepolarising neuromuscular blocking agents. Incidence, prevention and management.

Nondepolarising muscle relaxants block neuromuscular transmission, acting as antagonists of the nicotinic receptors at the neuromuscular junction. Their undesired effects are frequently caused by interaction with acetylcholine receptors outside this junction, and autonomic cardiovascular effects may result. Other adverse effects include anaphylactic or anaphylactoid reactions, and histamine release. Various disease states may present specific considerations in the use of nondepolarising muscle relaxants. Although many complications of these drugs (such as prolonged block or resistance) are easily treated, others may necessitate immediate intervention and vigorous therapy. Careful selection of an appropriate relaxant for a particular patient will usually prevent the occurrence of complications.

New developments in nondepolarizing muscle relaxants.

Anesthesiologists perceive that the ideal muscle relaxant is not yet available, particularly the nondepolarizing one with a rapid onset and a short duration of action. There is also a need for relaxants with different durations of action but which would be free from side effects. During the process of this development several new compounds have been tested and four have reached an advanced state of study; three of these, doxacurium, pipecuronium, and mivacurium are already licensed and rocuronium is likely to be licensed in the near future. Doxacurium and pipecuronium are slow onset and long duration of action compounds but singularly free from cardiovascular side effects. Mivacurium has an onset comparable to that of atracurium and vecuronium but with a duration of action which is intermediate in duration between these drugs and succinylcholine. Rocuronium is a drug with a fast onset of action capable of being used in place of succinylcholine but with a duration of action which is similar to that of vecuronium.