Edrophonium antagonizes combined lidocaine-pancuronium and verapamil-pancuronium neuromuscular blockade in cats.

The effects of lidocaine or verapamil on pancuronium neuromuscular blockade and the ability of anticholinesterase agents to antagonize these combined blockades were studied in 14 cats using a standard peroneal nerve-anterior tibialis muscle preparation. Pancuronium was infused at a constant rate to produce a stable 50% depression of single twitch tension. In nine cats, intravenous lidocaine boluses followed by a constant infusion produced serum lidocaine levels of 5.09 +/- 1.9 micrograms/ml (mean +/- SD) and resulted in an additional 20.0 +/- 5.5% depression of twitch tension. In the other five cats, intravenous injection of 0.15 mg/kg of verapamil produced an additional 12.8 +/- 8.0% twitch depression of pancuronium-induced neuromuscular blockade. For individual animals, edrophonium antagonism of the combined lidocaine-pancuronium-induced neuromuscular blockade or combined verapamil-pancuronium-induced neuromuscular blockade was not significantly different from antagonism of an equivalent twitch depression produced by pancuronium alone. It is concluded that lidocaine and verapamil augment neuromuscular blockade caused by pancuronium and that anticholinesterase antagonism of this augmented blockade can be expected to occur in a normal fashion.