Rocuronium bromide, a nondepolarizing muscle relaxant has been shown t
o have a short onset and intermediate duration of action in adults and
young children. We evaluated onset time, intubating conditions, as we
ll as duration of action of rocuronium in children ages four to 12 yea
rs during nitrous oxide-halothane anaesthesia. Following a stable reco
rding of train-of-four (TOF) impulses at the ulnar nerve, patients wer
e given rocuronium 600 mu g . kg(-1) intravenously. We found that the
time to 90% and 100% neuromuscular (N-M) block of the (TOF) was 51 +/-
18 s and 66 +/- 32 s respectively. Intubation was achieved at 94 +/-
31 s and rated as good or excellent in all cases. Time to recovery of
N-M transmission to 25%, 75% and 90% of control was 29 +/- 8 min, 42 /- 14 min and 46 +/- 16 min respectively. Heart rate increased similar
to 12 BPM after drug injection, while the blood pressure remained unc
hanged. From our data we conclude that, as in other age groups, rocuro
nium has a rapid onset, intermediate duration of action in children 4-
12 years of age, and appears devoid of significant side effects.