Background: The purpose of this study was to investigate the interaction of anesthetic agents with Org 9426 (rocuronium bromide) infused continuously. The effect of intubation dose of Org 9426 on its infusion rate was also investigated.
Methods: Total of 38 Japanese patients were randomly allocated either to receive intubation dose of 0.6 or 0.9 mg x kg(-1) of Org 9426. These patient groups were anesthetized with either sevoflurane or propofol. Infusion of Org 9426 was started with the initial infusion rate of 7 microg x kg(-1) x min(-1) when T1 reappeared after the intubation dose. The infusion rate was adjusted to keep the height of T1 between 3-10% of the control value.
Results: The rates of infusion 90 min after the start of infusion were 3.4, 7.5, 3.9 and 7.7 microg x kg(-1) x min(-1) for the 0.6 mg x kg(-1)-sevoflurane, 0.6 mg x kg(-1) propofol, 0.9 mg x kg(-1)-sevoflurane and 0.9 mg x kg(-1) propofol groups, respectively. Sevoflurane significantly reduced the infusion rate with both intubation doses. The mean infusion rates of 0.9 mg x kg(-1) groups were slower than those of 0.6 mg x kg(-1) groups up to 60 min after the start of infusion. Mean clearance of Org 9426 during infusion was not different between sevoflurane and propofol anesthesia.
Conclusions: Patients receiving sevoflurane anesthesia required a markedly lower Org9426 infusion rate compared with patients receiving propofol anesthesia.