Comparison of the Pharmacology of Vecuronium and Atracurium with That of Other Currently Available Muscle Relaxants

Abstract

The search for new muscle relaxants is an attempt to improve on the undesirable pharmacologic properties of currently available nondepolarizing muscle relaxants. Ideally, new muscle relaxants would exhibit fewer cardiovascular hemodynamic side effects, have fewer cumulative effects, possess rapid onset of and shorter durations of action, and be less dependent on hepatic and/or renal function for metabolism and excretion. Furthermore, drug metabolites should be pharmacologically inactive. Two new nondepolarizing muscle relaxants, vecuronium (Norcuron) and atracurium (BW 33A), are examples of drugs approaching these ideal muscle-relaxant characteristics. Currently, these drugs are used clinically in Europe and are undergoing clinical trials in this country.

Reappearance of the Train-of-Four After Neuromuscular Blockade Induced With Tubocurarine, Vecuronium or Atracurium

“…The times to the onset of blockade and to recovery to 90% blockade (the time to reappearance of T3 in our study) are similar to previously reported values (Watts and Dillon, 1968;Hilgenberg, 1983;Bencini and Newton, 1984;Hunter, Jones and Utting, 1984;Miller et al, 1984).…”

New Neuromuscular Blocking Drugs

“…The alternative was to administer bolus doses of succinylcholine repeatedly, which had the disadvantage of resulting in a widely variable degree of blockade and an increased risk of side effects. The shorter duration of action of atracurium and vecuronium makes them more suitable for brief procedures, 58 although if the operation lasts less than 15 minutes, even these agents are too long-acting ( Table 1). The introduction of mivacurium has proved useful in this respect.…”

“…Atracurium and vecuronium have no direct cardiovascular effects. 58 The newer agents have been developed with the aim of avoiding these side effects, but rocuronium may have a slight vagolytic effect. 19 Although the absence of cardiovascular effects is considered advantageous, it may allow the effects of other anesthetic agents to become manifest (e.g., bradycardia with opioid analgesic drugs).…”

Adverse Effects of Neuromuscular Blocking Drugs

“…Of the neuromuscular blocking agents, tubocurarine is the most potent in this respect: the free hydroxyl groups on the molecule are thought to enhance histamine release. Atracurium (Hilgenberg, 1983), alcuronium and gallamine have only about one-third of the histamine releasing potency of tubocurarine. However, several severe anaphylactic reactions to all these agents have now been described (Salem, Kim and El Etr, 1968;Fisher, 1978;Fisher, Hallowes and Wilson, 1978;Mercer, 1984).…”