Neostigmine, Pyridostigmine and Edrophonium as Antagonists of Deep Pancuronium Blockade

To compare the ability of equipotent doses of neostigmine, pyridostigmine and edrophonium to antagonize intense pancuronium neuromuscular blockade, one hundred and twenty ASA physical status I or II patients scheduled for elective surgery received 0.06 mg·kg-1 pancuronium during a thiopentone-nitrous oxide-enflurane anaesthetic. Train-of-four stimulation was applied every 12 s and the force of contraction of the adductor pollicis muscle was recorded. In the first 60 patients, spontaneous recovery was allowed until ten per cent of initial first twitch height. Then neostigmine (0.005, 0.01, 0.02 or O.05 mg·kg-1), pyridostigmine (0.02, 0.04, 0.1 or 0.2 mg·kg-1), or edrophonium (0.1, 0.2, 0.4 or 1 mg·kg-1) was injected by random allocation. Dose-response relationships were established from the measurement of first twitch height (T1) ten minutes later. From these, neostigmine, 0.04 and 0.08 mg·kg-1 was found to be equipotent to pyridostigmine, 0.2 and 0.38 mg·kg-1, and edrophonium, 0.54 and 1.15 mg·kg-1, respectively. These doses were given by random allocation to the next 60 patients, but at one per cent spontaneous recovery. Neostigmine, 0.04 mg·kg-1, produced a T1 of 73 ± 4 per cent (mean ± SEM), and a train-of-four ratio (TOF) of 39 ± 3 per cent. This was significantly greater than with pyridostigmine, 0.2 mg·kg-1 (T1 = 50 ± 6 per cent; TOF = 25 ± 3 per cent), and edrophonium, 0.54 mg·kg-1 (T1 = 54 ± 3 per cent; TOF = 17 ± 2 per cent). With the higher doses, neostigmine, 0.08 mg·kg-1, produced more recovery of T1 (83 ± 3 per cent) and TOF (45 ± 3 per cent) than either pyridostigmine, 0.38 mg·kg-1 (T1 = 74 ± 3 per cent) or edrophonium, 1.15 mg·kg-1 (T1 = 71 ± 4 percent; TOF = 30 ± 3 per cent). It is concluded that neostigmine is more effective than the other two agents in the antagonism of deep pancuronium blockade.