EDROPHONIUM FOR THE ANTAGONISM OF NEUROMUSCULAR BLOCKADE IN DOGS

Neuromuscular, electrocardiographic and autonomic nervous changes were studied when edrophonium and four combinations of edrophonium and atr opine were used to antagonise vecuronium-induced neuromuscular blockad e in 87 dogs anaesthetised with halothane. Edrophonium (500 mu g/kg bo dyweight) was given alone, or with atropine (40 mu g/kg) or one minute after a dose of 600 mu g of atropine, and a lower dose of edrophonium (250 mu g/kg) was used with high (40 mu g/kg) and low (20 mu g/kg) do ses of atropine. The neuromuscular blockade was antagonised when some recovery was present. The reversal was rapid and complete in 75 cases, but the remaining 12 dogs which received the low dose of edrophonium required a second injection. Trials with the high dose of edrophonium alone were discontinued because cardiac arrest occurred in one dog and bronchosecretion with profuse salivation in another. The heart rate i ncreased with the low dose of edrophonium and the high dose of atropin e, and increased and then decreased when edrophonium was followed by 6 00 mu g of atropine. The heart rate was stable when the high and low d oses of atropine and edrophonium were matched. All the treatments caus ed atrioventricular blockade. Non-cardiac autonomic changes (salivatio n and bronchosecretion) occurred in only two of the 87 dogs.