Neuromuscular block with doxacurium (BW A938U) in patients with normal or absent renal function

The characteristics of neuromuscular block induced by doxacurium were compared in patients with and without renal function. Seventeen patients with end stage chronic renal failure and 18 patients with normal renal function were anaesthetized with 0.5% halothane and nitrous oxide in oxygen and received doxacurium in an initial dose of 25 micrograms kg-1 (estimated from available data as an ED95 dose), with incremental doses of 5 micrograms kg-1. At the end of surgery, residual neuromuscular block was antagonized with either edrophonium 1.0 mg kg-1 or neostigmine 0.08 mg kg-1. There was no significant difference between the mean maximum blocks achieved with doxacurium: 17.4% (renal failure group) and 11.6% (control group) of control twitch heights, or between the mean times to achieve maximum block (10.9 min and 10.8 min, respectively). The mean duration of action of doxacurium, indicated by the time for twitch height to recover to 25% of control, was longer in the renal failure group (120.8 min vs 66.7 min in the control group) (ns). Similarly, the mean duration of action of increments was longer in the renal failure group (27.4 min vs 20.5 min in the control group). The rate of spontaneous recovery from doxacurium as indicated by the time for twitch height to recover from 0 to 5%, 5 to 10% and 10 to 25%, was not significantly different in the two groups. Antagonism of doxacurium was achieved more reliably with neostigmine than with edrophonium in both groups. The administration of doxacurium was associated with minimal cardiovascular effects.