Effect of renal function on neuromuscular block induced by continuous infusion of mivacurium

We have studied the effect of renal function on the pharmacodynamics of mivacurium. Sixty patients were allocated to three groups according to creatinine clearance: group C(control), creatinine clearance > 50 ml min^-1; group P(preterminal renal failure), creatinine clearance < 50 ml min^-1 > 20 ml min^-1; group T(terminal renal failure), creatinine clearance < 20 ml min^-1. Neuromuscular transmission (train-of-four) was monitored using electromyography from the hypothenar muscle with stimulation of the ulnar nerve. After an initial bolus, mivacurium was administered continuously to maintain a T1 of 5 (4)% of baseline. The dose of mivacurium necessary to maintain 95% neuromuscular block was similar in patients with normal renal function and patients with different levels of renal impairment. Recovery from neuromuscular block after ceasing mivacurium infusion was significantly prolonged in patients with preterminal venal impairment. There was a close correlation between mivacurium pharmacodynamics and pseudocholinesterase activity, but not creatinine clearance.