Neostigmine and Edrophonium Antagonism of Varying Intensity Neuromuscular Blockade Induced by Atracurium, Pancuronium, or Vecuronium

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Abstract
To compare the time course of neostigmine and edrophonium antagonism of varying intensity neuromuscular blockade induced by atracurium, pancuronium, or vecuronium, the authors studied 98 patients anesthetized with nitrous oxide (60%) and halothane or enflurane. Neuromuscular blockade, as monitored by single stimulus-induced twitch tension (TT), was antagonized at varying degrees of spontaneous recovery (2-80% of control TT). Time to antagonism (time from injection of neostigmine or edrophonium to 90% recovery of control TT) was not different between edrophonium, 0.5 mg/kg, and neostigmine, 0.04 mg/kg, when spontaneous recovery had been allowed to occur to at least 11% of control TT prior to antagonist administration (P > 0.05). For profound neuromuscular blockade (TT .ltoreq. 10% of control) induced by pancuronium or vecuronium, time (mean .+-. SD) to antagonism with neostigmine, 0.04 mg/kg, was 7.0 .+-. 2.2 min and 5.6 .+-. 1.7 min, respectively, while the same for edrophonium, 0. 5mg/kg, was 20.0 .+-. 8.0 min and 15.0 .+-. 12.5 min, respectively (P < 0.05). Time to antagonism of profound atracurium-induced neuromuscular blockade was 8.5 .+-. 3.3 min for neostigmine, 0.04 mg/kg, and 9.8 .+-. 7.0 min for edrophonium, 0.5 mg/kg, (P > 0.05). For profound vecuronium- and pancuronium-induced neuromuscular blockade, time to antagonism by edrophonium, 1.0 mg/kg, was 4.6 .+-. 3.0 min and 3.9 .+-. 1.6 min respectively. The authors conclude that neostigmine, 0.04 mg/kg, antagonizes neuromuscular blockade within 12 min when TT is greater than 2% of control at time of reversal. When TT is greater than 10% of control, edrophonium, 0.5 mg/kg, produces similar time to antagonism. However, when TT is 2-10% of control, the dose of edrophonium dose should be at least 1.0 mg/kg to be as rapid as neostigmine, 0.04 mg/kg.