Pharmacokinetics of Rocuronium After Bolus and Continuous Infusion During Halothane Anaesthesia

Abstract

Comment Intermediate-duration neuromuscular blocking drugs such as vecuronium and atracurium may be administered by IV infusion during long operations or in intensive care settings. The pharmacokinetics of vecuronium and atracurium infusions have been described previously. This investigation characterized the pharmacokinetics of rocuronium when administered by an infusion after a bolus intubating dose. Rather than administering a standardized infusion rate, these investigators targeted the infusion rate to a specific clinical endpoint: maintenance of T1 at 10% of control values. Thus, not only do we obtain a clinically applicable “typical” infusion rate (0.5 mg/kg/hr), but we can appreciate the interpatient variability in the infusion needs (which were relatively constant at 0.45–0.6 mg/kg/hr). Also of practical importance was the determination of the time required for return of neuromuscular function after cessation of the infusion: 30–36 min for return to 90% of T1 and train-of-four of 0.7. In addition to these clinical guidelines for the use of rocuronium infusions, we find that the pharmacokinetic values for rocuronium were similar after bolus and continuous infusion administration. This should aid individuals in designing infusion regimens for this drug. One caveat should be mentioned, however, in interpreting this investigation. Only eight patients were studied, and only two patients received the rocuronium infusion for more than 60 min. Thus, the pharmacokinetic data are based on a very limited number of patients, and the results may not be applicable to infusions of longer duration, such as in intensive care settings.