Disposition kinetics of pancuronium bromide in patients with total biliary obstruction

Plasma concentrations of pancuronium were measured in nine patients undergoing surgery because of total biliary obstruction. When compared with the averaged model-independent pharmacokinetic parameters obtained for normal patients, the terminal half-life of 270 min was more than twice normal (132 min, P less than 0.001); the plasma clearance of 59 ml min-1 was less than half the normal rate for pancuronium (123 ml min-1, P less than 0.003). These significant alterations to the pharmacokinetics of pancuronium were associated with prolongation of neuromuscular blockade. Following a bolus injection of pancuronium 6 mg, there was a mean time of 114 min (normals 70 min, P less than 0.05) before the evoked twitch response had returned to 5% of the control value. The pattern of urinary excretion of the drug and its metabolites did not differ from that of normal patients. To avoid excessive dosage during prolonged surgery for total biliary obstruction, it is recommended that supramaximal nerve stimulation be used to indicate the need for the administration of further doses of pancuronium.