Plasma binding of pancuronium: effects of age, sex, and disease

The extent of pancuronium binding in plasma in controversial due to a lack of definitive studies in human plasma. The degree of pancuronium binding in human plasma and the concomitant effects of age, sex, and renal disease on drug binding were determined by equilibrium dialysis using [3H]pancuronium. The free fraction of pancuronium was 93.2 +/- 1.6% in male subjects and 88.9 +/- 2.5% in adult nonpregnant female subjects, indicating that pancuronium is not highly protein bound. The free fraction in newborns and their mothers was 91.0 +/- 1.8% and 89 +/- 1.3%, respectively. There were no significant differences between the plasma binding of pancuronium in men, nonpregnant women (whether on oral contraceptives or not), pregnant women, or neonates. The free fraction of pancuronium was unaltered (90.7 +/- 2.1%) in patients with severe renal disease. We therefore conclude that the binding of pancuronium in human plasma is very low and that age, sex, oral contraceptives, pregnancy, and renal disease do not influence the plasma binding of this drug.