A comparison of edrophonium and neostigmine for the reversal of mivacurium-induced neuromuscular blockade in sheep.

The rate of reversal of neuromuscular block was compared in 36 sheep receiving either edrophonium (500 microg kg(-1)) and atropine (80 microg kg(-1)), neostigmine (50 microg kg(-1)) and atropine (80 microg kg(-1)) or saline (10 ml), using the train of four count (TO4C) recorded at n. facialis-m. levator nasolabialis. Neuromuscular block was produced with mivacurium (200 microg kg(-1)) followed later by a single incremental dose of 70 microg kg(-1). Antagonists or saline were given when spontaneous recovery from the incremental dose (TO4C = 1) had begun. The TO4C increased from 1 to 4 in all animals, in all treatment groups within 10 minutes of reversal. The TO4C was 4 in all animals five minutes after edrophonium, and seven minutes after neostigmine; differences were not statistically significant. The TO4C was significantly higher with edrophonium two and three minutes after antagonism compared with saline. The data show that spontaneous recovery from mivacurium is rapid in sheep, although reversal is accelerated by anticholinesterase drugs.