Atracurium after an anticholinesterase. Does prior reversal with edrophonium or neostigmine influence the response to atracurium?

This study documents the response to atracurium (75 micrograms.kg-1) administered 30 min after a pancuronium- or tubocurarine-induced neuromuscular block has been reversed with either neostigmine (50 micrograms.kg-1) or edrophonium (0.5 mg.kg-1). Twenty-one ASA 1 or 2 patients were studied, of whom 11 received neostigmine and 10 edrophonium. The degree of neuromuscular block was measured electromyographically from the first dorsal interosseous muscle of the hand using train-of-four stimulation of the ulnar nerve. When atracrium was administered, the single twitch response compared with control was 100% in all patients and the mean train-of-four ratios were 91% and 65% in the neostigmine and edrophonium groups respectively. After atracurium (75 micrograms.kg-1), minimum values for the single twitch response compared with control were 52% and 66% in the neostigmine and edrophonium groups respectively. Prior administration of atracurium appears to potentiate the neuromuscular blocking effects of atracurium administered 30 min later.