Pharmacodynamics Of Rocuronium Research Articles

Pharmacodynamics of rocuronium with and without prior administration of succinylcholine

Study Objectives: To compare succinylcholine (S) and rocuronium (R) used for endotracheal intubation, and to assess the possible action of S on subsequently administered R. Design: Double-blind, randomized, phase III study. Setting: University Medical Center. Patients: 24 ASA physical status I and II patients, ages 28 to 65, undergoing general anesthesia for abdominal procedures. Intervention: Double-blind administration of R 600 mcg/kg (Group A) or S 1 mg/kg (Group B) was given for endotracheal intubation. Maintenance of muscle relaxation was achieved with open label R 150 mcg/kg. Standardized general anesthetic technique with sodium thiopental, fentanyl, and nitrous oxide in oxygen was administered. Measurements and Main Results: Neuromuscular junction was tested by ulnar nerve stimulation and mechanomyograph. Intubation was attempted at 80% first twitch depression of train-of-four. Heart rate and blood pressure were recorded throughout. Onset times were 74 ± 37 seconds for S and 130 ± 46 seconds for R. Intubation times were 76 ± 29 seconds for S and 85 ± 23 seconds for R (no significant difference). Good to excellent intubation conditions were achieved in both groups. S given prior to R decreased onset time and increased duration of R, when compared with R given alone. No drug related cardiovascular events were noted. Conclusion: Rapid intubation conditions can be obtained after both S and R. Given its overall safety profile, R can be used when S is contraindicated, or in healthy patients with no apparent difficult airway, when procedures are expected to last more than 25 minutes.

The pharmacodynamics of rocuronium in pediatric patients anesthetized with halothane

The aim of this study was to determine the neuromuscular blocking potency of rocuronium (ORG 9426) in 4-to 14-year old children anesthetized with halothane. After induction of anesthesia, the ulnar nerve was stimulated with electrical impulses of 0.2 ms duration every 12 s and the force of contraction of the thumb (P) was continuously recorded. Doses of 0.12, 0.16, 0.20, and 0.24 mg·kg(-1) rocuronium were administered, in a randomized fashion, to 4 groups of 12 patients each. The ED50, ED90, and ED95 of rocuronium determined from the log dose-probit regression lines were 0.18, 0.34, and 0.40 mg·kg(-1), respectively. To facilitate tracheal intubation, after the development of the maximal effect of the first dose, a variable second dose of rocuronium was administered to increase the total dose to 0.3 mg·kg(-1). If after the second dose P was greater than 10% of control, additional 0.025-0.1 mg·kg(-1) increments of rocuronium were administered until P became less than 10% of control. At this time the trachea was intubated. Muscular relaxation was maintained with 0.075, 0.1, or 0.125 mg·kg(-1) rocuronium, administered whenever P recovered to 25% of control. The clinical duration of these doses was 6.9±2.8, 6.1±0.4, and 8.1±0.6 min, respectively. On repeated administration of three 0.1 or 0.125 mg·kg(-1) doses, rocuronium showed little cumulative tendency. Time for spontaneous recovery of P from 25% to 75%, 8.4±0.39 min and from 10% to 90%, 16.19±0.15 min, of control, were relatively short. When at termination of anesthesia T4/T1 ratios were lower than 0.75, the residual neuromuscular block could be antagonized with 0.5 mg·kg(-1) edrophonium in 2 min. Rocuronium, 0.3 mg·kg(-1) caused a 13.5% increase of heart rate but had no effect on blood pressure. In conclusion, in 4 to 14-year-old children, rocuronium appears to have a more rapid onset and shorter duration of action than other steroid-type muscle relaxants.

Pharmacodynamics of Rocuronium and Succinylcholine and Their Effects on Blood Pressure, Heart Rate, and Intraocular Pressure

Pharmacodynamics of Rocuronium and Succinylcholine and Their Effects on Blood Pressure, Heart Rate, and Intraocular Pressure

The pharmacodynamics of rocuronium in pediatric patients anesthetized with halothane

The pharmacodynamics of rocuronium in pediatric patients anesthetized with halothane

Pharmacokinetics and pharmacodynamics of rocuronium in patients with cirrhosis.

Rocuronium, like other steroidal nondepolarizing muscle relaxants, may in part be eliminated by the liver. To determine the influence of liver disease on its neuromuscular blocking effect, we studied the pharmacokinetics and pharmacodynamics of rocuronium in patients with cirrhosis. Eighteen patients undergoing elective surgery, 10 with cirrhosis and 8 with normal liver function, were studied. Anesthesia was induced with intravenous thiopental 5-7 mg.kg-1 and maintained with 60% nitrous oxide in oxygen and repeated doses of fentanyl 2 micrograms.kg-1. The force of thumb adduction in response to supramaximal ulnar nerve stimulation was monitored and recorded. An intravenous bolus of rocuronium 0.6 mg.kg-1 was administered and venous blood sampled at frequent intervals for 6 h. Plasma concentrations of rocuronium was measured by high-pressure liquid chromatography. Data were fitted to both a pharmacokinetic and a pharmacodynamic model by using a two-compartment open model and an effect compartment model. Data were analyzed by least-squares regression. The onset of neuromuscular blockade was longer (P < 0.01) in patients with cirrhosis (158 +/- 56 s) than in normal patients (108 +/- 33 s). Recovery of the thumb twitch to 75 and 90% of its control value was 77 +/- 25 and 88 +/- 29 min in cirrhotic patients versus 57 +/- 11 and 64 +/- 13 min, respectively, in normal patients (P < 0.05). The central volume of distribution of rocuronium was 104 +/- 21 in cirrhotic patients and 78 +/- 24 ml.kg-1 in normal patients (P < 0.05). No significant difference in elimination kinetics was observed between the two groups. The elimination half-life was 87.5 +/- 17.5 min in normal patients and 96.0 +/- 36.8 min in cirrhotic patients (difference not significant). This increased onset time was linearly correlated to the increased central volume of distribution of rocuronium in cirrhosis. Rocuronium onset time is longer in cirrhotic patients than in those with normal liver function; this can be explained by an increase in the volume in which rocuronium initially distributes. Although elimination kinetics are unchanged in patients with cirrhosis, rocuronium recovery time is prolonged in cirrhotic patients.