Alcuronium kinetics and plasma concentration–effect relationship

Abstract

The kinetics and dynamics of the neuromuscular blocker alcuronium were investigated in 12 surgical patients who received bolus and infusion regimens. In 6 patients the duration of the infusion was sufficiently long so that a steady-state alcuronium plasma concentration was reached (mean, 0.80 .+-. 0.23 .mu.g/ml). In the remaining 6 patients a steady state was not reached but the alcuronium concentration at the end of the infusion was 0.91 .+-. 0.39 .mu.g/ml. Alcuronium kinetic parameters did not differ between the 2 groups or from those obtained previously after bolus doses. In 6 patients for whom sufficient alcuronium concentration-time response data were available over the 0-100% response range, various mathematic models were used to characterize the concentration-effect relationship. A dynamic model incorporating a separate effect compartment connected to the central compartment was most appropriate. The mean rate constant for equilibration of alcuronium concentration and effect was 0.24 .+-. 0.11/min, whereas the steady-state concentration required to induce 95% paralysis was 0.91 .+-. 0.35 .mu.g/ml (mean).