Pharmacokinetics of rocuronium bromide in paediatric patients.

Rocuronium 0.8 mg kg-1 was given to 22 children between the ages of 3 months and 8 years during anaesthesia with N2O/O2, 60:40, and halothane. Blood samples were collected for 360 min for determination of rocuronium concentrations. The pharmacokinetics were best described by a two-compartment model. Two models were fitted, one proportional to weight and the other adjusted for age. Using the first model, volumes and clearances were all proportional to weight: in the second model, only the volume of the second compartment and clearance from the central compartment were proportional to age. The results do not support the use of body surface area, rather than weight for the calculation of paediatric doses of rocuronium. In this study, the volume of the central compartment was larger than the figure obtained in an adult population.