A comparative study of the dose-response and time course of action of rocuronium and vecuronium in anesthetized adult patients.
OBJECTIVE
(1) To compare the dose-response relations of rocuronium and vecuronium in healthy adult patients anesthetized with nitrous oxide-oxygen-fentanyl-thiopental; and (2) to evaluate the time-course of action of two drugs following equipotent doses.


METHODS
Prospective, randomized, clinical comparison.


METHODS
Operating room, Plastic Surgery Hospital of the Chinese Academy of Medical Sciences and Peking Union Medical College.


METHODS
60 ASA physical status I patients, aged 17-51 years, scheduled for elective plastic surgery.


METHODS
All patients were randomly assigned to either the rocuronium or vecuronium group. General anesthesia was induced with thiopental 4 to 6 mg/kg and fentanyl 2 to 4 micrograms/kg intravenously (i.v.), and maintained with 60% nitrous oxide (N2O) in oxygen. Further increments of thiopental or fentanyl were given as required. The dose-response relations of rocuronium and vecuronium were determined by the cumulative dose-response technique.


RESULTS
Neuromuscular function was assessed mechanomyographically with train-of-four (TOF) stimulation at the wrist every 12 seconds. The percentage depression of first twitch (T1) was used as the study parameter. The cumulative dose-response curve of vecuronium was shifted to the left in a parallel fashion compared with that of rocuronium. As assessed by linear regression, the potency ratio of vecuronium: rocuronium was 1:7.2. There were significant differences in the ED50, ED90, and ED95 between the two drugs. After i.v. administration of equipotent doses of both drugs (2 x ED90), the duration of peak effect, clinical duration, recovery index, and total duration were not significantly different between the two drugs.


CONCLUSIONS
Compared with vecuronium, rocuronium is a low-potency, nondepolarizing relaxant, and its neuromuscular blocking potency is approximately 15% that of vecuronium in adult patients anesthetized with N2O and fentanyl. Following equipotent doses, the time-course of recovery for rocuronium is similar to that of vecuronium.
Xue
F S
FS
Department of Anesthesia, Plastic Surgery Hospital, Chinese Academy of Medical Sciences, Beijing, the People's Republic of China.
Liao
X
X
Liu
J H
JH
Tong
S Y
SY
Zhang
Y M
YM
Zhang
R J
RJ
An
G
G
Luo
L K
LK
D000293:Adolescent; D000328:Adult; D000732:Androstanols / Q000008:administration & dosage*; D000762:Anesthesia Recovery Period; D000768:Anesthesia, General; D018685:Anesthetics, Inhalation / Q000008:administration & dosage; D018686:Anesthetics, Intravenous / Q000008:administration & dosage; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D005260:Female; D005283:Fentanyl / Q000008:administration & dosage; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D019148:Neuromuscular Blockade; D003473:Neuromuscular Nondepolarizing Agents / Q000008:administration & dosage*; D009609:Nitrous Oxide / Q000008:administration & dosage; D010100:Oxygen / Q000008:administration & dosage; D011446:Prospective Studies; D000077123:Rocuronium; D013874:Thiopental / Q000008:administration & dosage; D013997:Time Factors; D014459:Ulnar Nerve / Q000187:drug effects / Q000502:physiology; D014673:Vecuronium Bromide / Q000008:administration & dosage*
D000732:Androstanols; D018685:Anesthetics, Inhalation; D018686:Anesthetics, Intravenous; D003473:Neuromuscular Nondepolarizing Agents; D014673:Vecuronium Bromide; D013874:Thiopental; D009609:Nitrous Oxide; D010100:Oxygen; D005283:Fentanyl; D000077123:Rocuronium