Atracurium, vecuronium and pancuronium in end-stage renal failure. Dose-response properties and interactions with azathioprine.

Dose-response relations for atracurium, vecuronium and pancuronium were determined in patients in end-stage renal failure for the initial neuromuscular blockade (using three cumulative doses) and for the maintenance of stable 90% response (during continuous infusion). All measurements were during renal transplant surgery, and the interaction of azathioprine on neuromuscular blockade was estimated. Mean ED95 doses were (microgram kg-1): atracurium 375.6, vecuronium 67.2, pancuronium 86.6; the initial blockade required significantly larger doses than in normal patients (37%, 20% and 45%, respectively, using ED50 values). Mean infusion rates for 90% sustained blockade in renal failure were (microgram kg-1 h-1): atracurium 409.4, vecuronium 78.3, pancuronium 14.2. The atracurium dose was not influenced by renal function, whereas vecuronium and pancuronium requirements were significantly reduced by 23.2% and 61.5%, respectively, compared with normal patients (previous study). Azathioprine was injected at the rate of 1 mg kg-1 min-1 for 3 min at stable 90% neuromuscular blockade with constant-rate infusion of the neuromuscular blocking drug. This produced a relatively small and transient antagonism of blockade--probably of negligible clinical significance.