Potentiation of neuromuscular blockade by calcium channel blockers.

A significant reduction was noticed in the amount of vecuronium needed to maintain steady neuromuscular blockade at 20% twitch height (T1) in patients given nicardipine intraoperatively. Bolus injection of either nicardipine or diltiazem during constant infusion of vecuronium produced transient depression of T1 and the train-of-four ratio (TOFR). Reversal of neuromuscular blockade with a choline esterase inhibitor (neo-stigmine) was not retarded by previous administration of Ca-channel blockers but concurrent administration of anticholine-esterase agent and Ca-channel blockers caused a delay in recovery from motor blockade. Monitoring of neuromuscular junction activity is strongly recommended whenever a large cumulative dose of Ca-channel blockers is used.