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The interaction between two non-depolarizing neuromuscular blocking agents, pancuronium bromide and vecuronium bromide, has been studied at standardized levels of neuromuscular blockade and alternating the sequence of their administration, in 40 surgical patients. The drug administered first appeared invariably to play a dominant role in influencing both the dose requirements and the duration of action of the subsequent neuromuscular blocker. This resulted in reduced dose requirements and significant prolongation of action of vecuronium administered after pancuronium and increased dose requirements and shortening of neuromuscular blocking action of pancuronium given during vecuronium-induced partial neuromuscular blockade. Possible mechanisms of such interaction are discussed.
The pharmacokinetics of pipecuronium bromide was studied in 9 male patients (ASA class 1-2, 20-65 years of age). Following a single intravenous dose of pipecuronium 0.08 mg.kg-1, plasma levels were measured by capillary gas chromatography. Plasma concentration-time curves were evaluated by fitting the data to a bi-exponential equation. The pharmacokinetic parameters of pipecuronium were compared with those of pancuronium (0.08 mg.kg-1) and vecuronium (0.08 mg.kg-1) previously obtained under the same anesthesia (66% N2O, 33% O2 and 1% halothane). With pipecuronium, following pharmacokinetic parameters were obtained; distribution half-life; T1/2 alpha = 3.9 +/- 0.7 min (mean +/- SEM), elimination half-life; T1/2 beta = 102 +/- 12 min, volume of the central compartment; V1 = 95 +/- 13 ml.kg-1, volume of distribution at steady state; Vdss = 264 +/- 41 ml.kg-1, clearance; Cl = 1.8 +/- 0.2 ml.min-1.kg-1. Microconstants of two-compartment open models (k12, k21, k10) were also calculated. Using Mann-Whitney's U-test, these parameters of pipecuronium were compared with those of pancuronium (n = 3) and vecuronium (n = 4). V1 and Vdss of pipecuronium were significantly larger than those of pancuronium (V1; 38 +/- 12 ml.kg-1 and Vdss; 120 +/- 4 ml.kg-1) (both P less than 0.10). Reflecting the larger central volume of pipecuronium, pipecuronium tended to have a larger clearance than that of pancuroniumu (Cl; 1.1 +/- 0.2 ml.min-1.kg-1).(ABSTRACT TRUNCATED AT 250 WORDS)
The drug vecuronium bromide, a short acting, non-depolarising agent with little side-effects, has brought much promise in the field of muscle relaxants. Fifth healthy patients were induced with injection thiopentone sodium 4 mg/kg and vecuronium bromide, 0.1 mg/kg was given IV. The earliest time at which the largest percentage of patients could be intubated satisfactorily was noted. The intubating conditions were estimated by scoring method. The duration of clinical relaxation was decided from the time of IV injection of vecuronium bromide to the return of muscle power of the non-respiratory muscles requiring repeat dose of the drug. The ideal intubating condition was achieved at 120 seconds and the duration of clinical relaxation ranged from 11-15 minutes.
BACKGROUND: Efficacy and safety of Org 9426 were compared with those of vecuronium bromide in Japanese patients. METHODS: We studied 88 Japanese patients undergoing surgery requiring general anesthesia. Patients were allocated randomly to receive intubation dose of 0.6 mg x kg(-1), 0.9 mg x kg(-1) of Org 9426 or 0.1mg x kg(-1) of vecuronium. Following an intubation dose, patients received maintenance doses of 0.1, 0.15 or 0.2 mg x kg(-1) of Org 9426 or 0.025 mg x kg(-1) of vecuronium. The neuromuscular block was monitored with acceleromyography using TOF stimuli. Sevoflurane was administered to all treatment groups after intubation. RESULTS: The onset times of the 0.6 and 0.9 mg x kg(-1) of Org 9426 groups were 84.6 and 77.1 sec respectively, which showed statistical difference between the onset time of 0.1 mg x kg(-1) of vecuronium, 125.7 sec. The intubation condition was similar among three treatment groups. The clinical durations of 0.6 and 0.9 mg x kg(-1) of Org 9426 and 0.1 mg x kg(-1) of vecuronium were 53.4, 73.4 and 59.9 min, respectively. Clinical duration and spontaneous recovery time of maintenance dose of 0.15 mg x kg(-1) of Org 9426 were similar to those of 0.025 mg x kg(-1) of vecuronium. CONCLUSIONS: Org 9426 showed more rapid onset time than that of vecuronium and similar clinical duration and recovery times to those of vecuronium in Japanese patients.
The neuromuscular and cardiac vagus blocking actions of pancuronium, vecuronium (Org NC45) and their respective potential hydroxy metabolites have been studied in the chloralose-anaesthetized cat. Pancuronium was three times more potent as a neuromuscular blocker than its 3-hydroxy derivative, 20 times more potent than the 17-hydroxy derivative and 45 times more potent than the 3,17-dihydroxy derivative. The vagal:neuromuscular block ratios measured at 50% inhibition for these compounds were pancuronium 3.0, 3-hydroxy derivative 6.4, 17-hydroxy derivative 1.1 and 3,17-dihydroxy derivative 0.36 (a value greater than unity indicated greater potency at the neuromuscular junction). Vecuronium was 1.4 times more potent than its 3-hydroxy derivative, 24 times more potent than the 17-hydroxy derivative and 72 times more potent than the 3,17-dihydroxy derivative as a neuromuscular blocker. The vagal:neuromuscular block ratios were vecuronium 79.8, 3-hydroxy derivative 40.4, 17-hydroxy derivative 0.85 and 3,17-dihydroxy derivative 0.15. The 3-hydroxy derivative of vecuronium, the most likely first metabolite of vecuronium, thus possessed only slightly less neuromuscular blocking potency than vecuronium, coupled with a high safety margin between neuromuscular and vagal blocking doses. In addition, the time-course of its action was not different from that of vecuronium. Thus, it is concluded that this potential metabolite is unlikely to give rise to tachycardia in man. It is unlikely that the 17-hydroxy and 3,17-dihydroxy derivatives of vecuronium would be produced in sufficiently great quantities by metabolism from vecuronium to result in either tachycardia or residual neuromuscular blockade.
Vecuronium bromide 1mg was injected intravenously for priming or precurarization in 42 cases. Apparent dyspnea was observed in 2 cases. The doses of vecuronium bromide in these 2 cases, 0.018 and 0.016 mg.kg-1, respectively were the same and less than those in the other 40 cases (0.018 +/- 0.003 mg.kg-1, mean +/- SD). Although respiratory sparing effect of vecuronium bromide is expected, intensive respiratory assist should be taken at the time of priming or precurarization with the drug.
Vecuronium bromide 70 micrograms kg-1 was used to facilitate tracheal intubation and provide neuromuscular blockade in 52 patients undergoing laparoscopic sterilization. Anaesthesia was maintained with 67% nitrous oxide in oxygen. Patients were monitored clinically and by tactile assessment of the evoked response of the adductor pollicis to a supramaximal train-of-four stimulation. Intubating conditions were assessed at 90 s in the first 33 patients, and were poor. They improved significantly in the subsequent 19 patients when intubation was delayed until 150 s (P less than 0.05). Operating conditions were good in all except two patients. Residual neuromuscular blockade was antagonized rapidly at completion of surgery by neostigmine 2.5 mg i.v., which was administered provided there was at least one twitch response. The mean duration of the procedure was 14.3 min (SD 2.5 min). The mean time from injection of neostigmine to satisfactory spontaneous breathing and neuromuscular recovery was 1.6 min (SD 0.7 min).
The disposition of vecuronium bromide has been investigated in six normal cats (group I) and in six cats with ligated renal pedicles (group II). A combined fluorimetric and chromatographic technique was used to determine the concentrations of vecuronium and its metabolites in biological material. After i.v. injection of 0.6 mg kg-1, vecuronium disappeared rapidly from the plasma of the normal cat. Concentrations decreased bi-exponentially with half-lives of 4.6 and 31 min, respectively. The steady state volume of distribution was 0.23 litre kg-1 and the clearance 11 ml min-1 kg-1. Seventy percent of an i.v. dose of vecuronium (or its metabolites) was recovered: 15% in the urine, 40% in the bile and 15% in the liver. Only 3.8% of this consisted of the 3-hydroxy metabolite. There were no significant differences in pharmacokinetic data or in the amounts of vecuronium and its metabolites recovered in cats with ligated renal pedicles. The 15% of vecuronium normally excreted by the kidney was compensated for by increased hepatic and biliary concentration of vecuronium.
Topical vecuronium bromide (Norcuron) and combinations with atropine and phenylephrine, were evaluated as mydriatics in juvenile double-crested cormorants (Phalacrocorax auritus). Nine cormorants were treated with each of four protocols: 1% atropine; 4 mg/mL vecuronium bromide (total 0.16 mg/eye); atropine with vecuronium; and atropine, 2.5% phenylephrine, followed by vecuronium. Drugs were applied topically at 15-min intervals (0.01 mL/drop). Pupil diameter was measured manually every 15 min with a pupil gauge calibrated to the nearest 0.5 mm. No effect was observed with atropine alone. Average +/- SD peak pupil diameter for vecuronium, atropine/vecuronium, and atropine/phenylephrine/vecuronium were 5.4 +/- 1.1 mm, 5.7 +/- 0.8 mm and 6.2 +/- 0.4 mm, respectively; and duration of peak diameters were 38 +/- 28 min, 79 +/- 71 min and 103 +/- 58 min, respectively. The combined atropine, phenylephrine and vecuronium provided the most consistent dilation with larger average pupil size and longer average duration. No side-effects from vecuronium were observed in these birds.
The muscle-relaxation reactions of Ca-antagonist (nifedipine) pretreated patients and a control group (5 in each group) were observed after administration of vecuronium bromide using the "priming principle." Twitch depression induced by the "priming dose" of vecuronium bromide (20 micrograms/kg body weight and T4/T1 ratio in the Ca-antagonist-treated patients (35 +/- 13% and 0.42 +/- 0.14%, respectively), was significantly different (P less than 0.01) when compared with the control group (1.2 +/- 2.7% and 0.75 +/- 0.15%). Similarly, the onset time to maximum blockade after the intubating dose of vecuronium bromide (60 micrograms/kg body wt.) was significantly shorter in the nifedipine group (40 +/- 21 s) when compared with the controls (100 +/- 17 s). The duration of the effect observed clinically (until 25% recovery) in the nifedipine group 32.9 +/- 7.3 min versus 25 +/- 8.15 min was enhanced; however, the difference between the treated group and the control group was not significant.
The authors describe a technique of vecuronium bromide perfusion at constant flow used to obtain curarisation during 50 renal transplantations. The muscular effects of the drug were monitored through an electromyographical recorder, so as to adjust the perfusion rate. The dose of vecuronium bromide was 47.7 +/- 0.74 micrograms X kg-1 X h-1 (mean +/- SEM), this being lower than the dose recommended by D'Hollander (60 micrograms X kg-1 X h-1) for patients with normal renal function. Furthermore, no recurarisation was observed. Therefore, vecuronium can be considered as a satisfactory muscle relaxant in patients with renal failure, but neuromuscular monitoring appears to be a most important safety factor.
The pharmacokinetics and pharmacodynamics of vecuronium bromide were studied in patients under general anesthesia of enflurane and nitrous oxide in oxygen. Eighteen patients were randomly divided into two groups which received either 0.05 mg.kg(-1) (low dose group) or 0.20 mg.kg(-1) (high dose group) of vecuronium intravenously. The plasma concentration of vecuronium was determined by high performance liquid chromatography. The neuromuscular blocking effect was assessed by measuring the twitch tension of the adductor pollicis muscle elicited by supramaximal electrical stimulation. Pharmacokinetic analysis was carried out using a two compartment model. The relationship between the T4/T1 and T1/ control T1 ratios differed during onset and spontaneous offset of the blockade; the T4/T1 ratios were significantly higher during onset than during offset, although there were large variations of fade in the train-of-four response in each patient during offset. These results suggest that it is difficult to estimate the T1/control T1 ratio by the T4/T1 ratio during offset. Pharmacokinetic analysis revealed that the high dose group had a shorter elimination half-life than did the low dose group. A shorter elimination half-life at a high dose may be to some extent due to hepatic clearance. The pharmacokinetic parameters bore no fixed relationship to the pharmacodynamics in each patient.
The neuromuscular blocking effects of vecuronium 10 mg preparation under enflurane anesthesia have been investigated in 22 patients having elective surgeries. The effect on cardiovascular system in man and laboratory examinations were also investigated. The results are as follows; 1. Onset time (time from end of injection until maximal blockade) after the dose of 0.08 or 0.1 mg.kg-1 of vecuronium bromide was about 2.6 minutes and 1.9 minutes, respectively. 2. Clinical duration of action (time from end of injection until 25% recovery of twitch) in the 0.1 mg.kg-1 group (about 50.1 minutes) was significantly longer than that in the 0.08 mg.kg-1 group (about 35.6 minutes). 3. Recovery time (time elapsing between 25 and 75% recovery of twitch) with neostigmine was 5.3 minutes (0.08 mg.kg-1) and 4.2 minutes (0.1 mg.kg-1). 4. Blood pressure was stable before and after the injection of vecuronium and no abnormal change related to the test drug was observed in the laboratory examinations. These data show that the efficacy and safety of the vecuronium 10 mg preparation are the same as those of the 4 mg preparation reported previously. In conclusion, it is considered that vecuronium 10 mg preparation is clinically useful because it is unnecessary to dissolve the drug frequently with injectable water.
OBJECTIVE: To analyze electromyographic response and clinical effects after precurarization with vecuronium bromide (0.01 mg/Kg), also noting intubation conditions and the presence or not of fasciculations after administration of succinylcholine (1.5 mg/Kg). PATIENTS AND METHODS: A single precurarization dose of vecuronium was administered to 20 patients 5 minutes before anesthetic induction for general surgery. During this period we monitored neuromuscular transmission of the cubital nerve in the wrist by electromyography with a series of 4 stimuli, expressing each as the percentage of the first response and of the ratio T4/T1. We also recorded clinical repercussions. General anesthesia was then induced; after administration of succinylcholine, the presence or not of fasciculations was noted and intubation conditions were evaluated. RESULTS: The electromyographic response after precurarization was highly variable, as 4 different responses were recorded. We found potentiation phenomena in 20% of our patients, diminished response in 60%, fatigue phenomena in 15% and no change in 5%. Clinical signs noted were blurred vision and heavy eyelids. Fasciculations disappeared in 95% of the patients and intubation conditions were excellent. CONCLUSIONS: Vecuronium at a precurarization dose produces highly varied but well-tolerated electromyographic responses. The drug is effective in eliminating fasciculations produced by succinylcholine and does not affect intubation conditions.
Effects of vecuronium bromide, an analog of pancuronium, on the cholinergic and glutamatergic neuromuscular junction were investigated. Vecuronium depressed the postsynaptic response of the frog end-plate at lower concentrations than 10(-6) g/ml without affecting the presynaptic events. Vecuronium decreased the amplitude of the double ACh potential, but the second potential was more markedly reduced than the first. In analogy with d-tubocurarine, this suggests that vecuronium may act in part as an open channel blocker at the frog end-plate. Vecuronium depressed both the glutamate response and the excitatory junctional potential at the crayfish neuromuscular junction, although high concentrations were required. The drug increased the decay rate of extracellularly recorded excitatory junctional potentials at the crayfish neuromuscular junction. The reduction of the crayfish synaptic response caused by vecuronium can be explained by the open channel blocking action at this junctional site. The problem that cholinergic antagonists possess a property of channel blocking at the other transmitter system was discussed.
The new nondepolarizing muscle relaxant vecuronium bromide (Norcurone) was applied to 30 patients in the course of general balanced anesthesia for abdominal operations. The advantages of Norcurone over other similar nondepolarizing muscle relaxants used so far are pointed out. The fact that Norcurone has no adverse effect on the hemodynamics is considered essential advantage for its acceptance in anesthesiologic practice.
We studied the usefulness of the 10 mg presentation of vecuronium bromide (NC45-10) for endotracheal intubation. Subjects were ASA type I-II patients between 20-65 years of age scheduled for various kinds of surgery who consented to participate in this study. After the entrance of patients into the operating room, we set up monitors and intravenously injected a priming dosage of NC45-10, 0.015 mg.kg-1. Next, we administered thiopental 5 mg.kg-1 and injected initial dosage of either 0.065 mg.kg-1 or 0.1 mg.kg-1 of NC45-10 intravenously 5 minutes after the administration of priming dose. One minute later, we attempted endotracheal intubation. We evaluated the muscle relaxation by the reaction to endotracheal intubation and graded it by the score of 0-3. Satisfactory muscle relaxation on endotracheal intubation was obtained in 80% of the patients with no significant difference between the 2 groups of initial dosage. No side effect or cardiovascular action was observed. It is concluded that this preparation is clinically safe and useful.