Pharmacodynamics and pharmacokinetics of rocuronium following continuous infusion in patients during intravenous anaesthesia.

After an initial bolus dose (0.6 mg kg-1), 10 patients received a continuous infusion of rocuronium, initially at 0.5 mg kg-1h-1, and then adjusted to maintain 90% twitch depression. Blood samples were analysed for 420 min after switching off the infusion. The dose required to maintain the block was 595 +/- 146 micrograms kg-1h-1, 7-9 times that reported for vecuronium under similar conditions. The pharmacokinetic parameters (volume of distribution at steady state, 309 +/- 80 ml kg-1, plasma clearance 4.5 +/- 1.96 ml kg-1 min-1, and elimination half-life 107 +/- 37 min) were similar to those previously reported after a large single bolus.