Pipecuronium-induced prolongation of vecuronium neuromuscular block

We have examined the prolongation of a maintenance dose of vecuronium after an intubating dose of pipecuronium in 45 patients who received either pipecuronium 70 micrograms kg-1 or vecuronium 200 micrograms kg-1 i.v. for tracheal intubation, followed by either pipecuronium 10 micrograms kg-1 or vecuronium 15 micrograms kg-1 for maintenance of neuromuscular block. The duration of the vecuronium maintenance dose was greater after pipecuronium (40 (SD 12) min) than after vecuronium (29 (9) min) (P = 0.02). The duration of pipecuronium after pipecuronium (49 (15) min) was similar to that of vecuronium after pipecuronium. We conclude that the duration of action of vecuronium is prolonged by prior administration of pipecuronium.