Atracurium, one of the newly developed nondepolarizing muscle relaxants, is remarkable due to the intermediate duration of action from the other previously known nondepolarizing agents and the broad safety margin in patients with renal or liver disease. There have been many reports suggesting that the pharmacologic effects of the nondepolarizing muscle relaxants are influenced by dosage. In this study, we attempted to identify the specific mechanism of muscle relaxation of atracurium. Particular attention was paid to the actually delivered atracurium dose and to the degree of muscle relaxation in rabbits. The results were as follows; 1) In the atracurium 0.4 mg/kg group, the onset of action was shortened and in the atracurium 0.6 mg/kg group, it was shortened more significantly. 2) The duration of action was increased with the increase of dose: the mean duration was 895 seconds in the atracurium 0.1 mg/kg group, 1,113.7 seconds in the 0.2 mg/kg group, and 1,199.3 second is in the 0.4 mg/kg group. It was prolonged to 1,730 seconds in the atracurium 0.6mg/kg group. 3) The spontaneous recovery index showed no differences in the atracurium 0.1 mg/kg group, 0.2 mg/kg group and 0.4 mg/kg group (196.7 sec., 195.0 sec, 202.7 sec. each). But in the atracurium 0.6 mg/ kg group, it was markedly prolonged to 334 seconds. In conclusion, atracurium, like other nondepolarizing agents, produces a dose related duration of action in muscle relaxation.
Atracurium* ; Humans ; Liver Diseases ; Muscle Relaxation* ; Rabbits*

The interaction between succinylcholine(SCC) and non-depolarizer; atracurium or vecuronium, was investigated in 36 cats of either sex using the sciatic nerve-anterior tibialis muscle preparation. And also, its relation to the pseudocholinesterase activity was examined. The duration of action of vecuronium(6.5+/-1.3 to 7.3+/-2.2 minutes) in cats pretreated with SCC was greater than those(2.0+/-0.6 minutes) in non-pretreated cats. However, SCC had no influence on the duration of atracurium. The serum pseudocholinesterase activity was decreased after the injection of atracurium or neostigmine in contrast to vecuronium. The authors conclude that the prior administration of SCC prolongs the duration of vecuronium but not that of atracurium, and pseudocholinesterase activity is not related to the prolonging effect of SCC.
Animals ; Atracurium* ; Cats* ; Neostigmine ; Pseudocholinesterase ; Succinylcholine* ; Vecuronium Bromide*

A major goal in pharmacokinetic-pharmacodynamic (PK/PD) modeling of neuromuscular blockade (NMB) is to quantitatively estimate the dose-response relationship.Our PK/PD model consists of three submodels:PK, link kinetics, and PD.A virtual effect compartment in which the drug concentration is in equilibrium with the observed concentration is used to extract the kinetic component (keo) from the pharmacodynamic data alone.Parameters of this model are keo, Ce(50), and gamma.The underlying structural pharmacokinetics and pharmacodynamics for NMB have been well understood, and new novel PK/PD models have been substituted for the gold standard PK/PD model for NMB.The purpose of this review was to describe progress in the field of PK/PD modeling of NMB from the first model, a simultaneous PK/PD model developed by Sheiner et al in the 1970s, to some of the more complicated models.Specific PK/PD models, which accurately described the behaviors of rocuronium, mivacurium, atracurium, and cisatracurium, include the recirculatory model, the peripheral link model, the peripheral elimination model, and a nonparametric model for link kinetics.
Aluminum Hydroxide ; Androstanols ; Atracurium ; Carbonates ; Isoquinolines ; Kinetics ; Neuromuscular Blockade

BACKGROUND: Atracurium, a nondepolarizing muscle relaxant, is eliminated by Hofmann elimination and not affected by pseudocholinesterase(pChe). Many reports show fall in pChe activity during pregnancy and our measurement failed to prove it. However, the authors found previously the infusion rate of mivacurium, which is metabolized by pChe, to achieve surgical relaxation is decreased. So, we compared the difference in the infusion rate of atracurium between full-term pregnant and nonpregnant women. METHODS: Muscle relaxation of full-term pregnant women(C group, n=10) and nonpregnant women (Non-C group, n=10) was maintained by continuous infusion of atracurium to keep 1st response of TOF at 5 1%. After discontinuance of infusion, recovery index was measured without reversals using the accelerograph. RESULTS: There was no significant difference in infusion rate of atracurium to maintain 1st twitch response of TOF at 5 1% and recovery index between two groups. There was little correlation between the total infusion time and infusion rate, or between the total infusion time and recovery index. CONCLUSION: The atracurium infusion rate in parturients to maintain muscle relaxation was not different from that in non-parturients. For Cesarean section, the usual infusion rate of atracurium is recommended to achieve the adequate surgical relaxation.
Atracurium* ; Cesarean Section* ; Female ; Humans ; Muscle Relaxation ; Obstetrics ; Pregnancy ; Relaxation

BACKGROUND: The train-of-four(TOF) fade known as expression of prejuntional receptor binding was useful for evaluating the residual neuromuscular blockade(NMB). The present study was undertaken to investigate the effect of the neostigmine(Neo) on TOF ratio during the recovery from vecuronium(V) or atracurium(A) induced NMB under the general anesthesia. METHODS: Forty healthy adult patients were randomly divided into 4 groups as follows; spontaneous recovery from V-induced NMB(V-C group) or A-induced NMB(A-C group), reversed recovery with Neo at 20% recovery of control first twitch height(T) from V-induced NMB(V-R group) or A-induced NMB(A-R group). TOF ratio at 25 and 75% recovery of T and recovery index(RI) defined as time from 25 to 75% recovery of T were measured. RESULTS: TOF ratios at 25 and 75% recovery of T were 3.7 & 35.8%(V-C group), 8.4 & 46.9%(A-C group), 3.7 & 48.7%(V-R group) and 15.2 & 55.6%(A-R group) respectively(P>0.05). RI were 19.2 min(V-C group), 19.5 min(A-C group), 3.5 min(V-R group), and 5.6 min(A-R group) respectively (P<0.05). CONCLUSIONS: RI were significantly shortened in reversed recovery groups with Neo than spontaneous recovery groups (P<0.05). However TOF ratio at 75% recovery of T1 were not significantly different between spontaneous recovery and reversed recovery groups.
Adult ; Anesthesia, General ; Atracurium ; Humans ; Neostigmine* ; Neuromuscular Blockade* ; Vecuronium Bromide

The usefulness of nondepolarizing muscle relaxants for intubation is limited by a relatively slow onset of neuromuscular block compared to that achived with succinylcholine. But, authors have reported that larger doses of nondepolarizing muscle relaxants produce a more rapid onset of maximal neuromuscular block and conditions conductive to endotracheal intubation and recent reports support the use of the "priming principle in the clinical practice of anesthesiology. This phenomenon may apply to all nondepolarizing relaxants: it is reported to facilitated neuromuscular blockade and tracheal intubation when used with atracurium, vecurouium, alcuronium or pancuronium. In this study, administering a small subclinical dose of atracurium (75ug/kg) Smin. prior to the remainder of an intubating doae of atracurium (250ug/kg) had no different on grade of block for intubation compared to single IV bolus of atracurium (500ug/kg).
Alcuronium ; Anesthesiology ; Atracurium* ; Intubation ; Intubation, Intratracheal* ; Neuromuscular Blockade ; Pancuronium ; Succinylcholine

The usefulness of nondepolarizing muscle relaxants for intubation is limited by a relatively slow onset of neuromuscular block compared to that achived with succinylcholine. But, authors have reported that larger doses of nondepolarizing muscle relaxants produce a more rapid onset of maximal neuromuscular block and conditions conductive to endotracheal intubation and recent reports support the use of the "priming principle in the clinical practice of anesthesiology. This phenomenon may apply to all nondepolarizing relaxants: it is reported to facilitated neuromuscular blockade and tracheal intubation when used with atracurium, vecurouium, alcuronium or pancuronium. In this study, administering a small subclinical dose of atracurium (75ug/kg) Smin. prior to the remainder of an intubating doae of atracurium (250ug/kg) had no different on grade of block for intubation compared to single IV bolus of atracurium (500ug/kg).
Alcuronium ; Anesthesiology ; Atracurium* ; Intubation ; Intubation, Intratracheal* ; Neuromuscular Blockade ; Pancuronium ; Succinylcholine

Subparalyzing dose of nodepolarizing relaxants prior to injection of succinylcholine has been used to prevent various adverse effects induced after succinylcholine. For investigating interactions between succinylcholine and small doses of four non-depolar-izing agents, the 112 subjects that were ASA class 1-2 and no existing neuromuscular conduction system disorder were divided into 5 groups that were control group(only succinylcholine 1 mg/kg) and pretreated group d-tubocurarine 0.5 mg/kg, atracurium 0.08 mg/kg, vecuronium 0.01 mg/kg and pancuronium 0.01 mg/kg. In each group, the plasma concentration of K+ and PChE before and after use of succinylcholine, fasciculation, onset and recovery time of succinylcholine block and intubating conditon were observed. The results are as follows; In the pretreated group, there were no significant changes of plasma concentration of K+ and plasma cholinesterase(Table 3) but diminished the incidence of fascieulation, delayed the onset time and shorted the recovery time of succinylcholine block(Table 4), and worse in intubating condition(Table 5) except pancuronium treated group. It was concluded that these seem to make worse condition of intubation, while small doses of nondepolarizing muscle relaxants except pancuronium antagonize depolarizing muscle relaxant.
Atracurium ; Fasciculation ; Incidence ; Intubation ; Pancuronium ; Plasma ; Succinylcholine* ; Tubocurarine ; Vecuronium Bromide

Subparalyzing dose of nodepolarizing relaxants prior to injection of succinylcholine has been used to prevent various adverse effects induced after succinylcholine. For investigating interactions between succinylcholine and small doses of four non-depolar-izing agents, the 112 subjects that were ASA class 1-2 and no existing neuromuscular conduction system disorder were divided into 5 groups that were control group(only succinylcholine 1 mg/kg) and pretreated group d-tubocurarine 0.5 mg/kg, atracurium 0.08 mg/kg, vecuronium 0.01 mg/kg and pancuronium 0.01 mg/kg. In each group, the plasma concentration of K+ and PChE before and after use of succinylcholine, fasciculation, onset and recovery time of succinylcholine block and intubating conditon were observed. The results are as follows; In the pretreated group, there were no significant changes of plasma concentration of K+ and plasma cholinesterase(Table 3) but diminished the incidence of fascieulation, delayed the onset time and shorted the recovery time of succinylcholine block(Table 4), and worse in intubating condition(Table 5) except pancuronium treated group. It was concluded that these seem to make worse condition of intubation, while small doses of nondepolarizing muscle relaxants except pancuronium antagonize depolarizing muscle relaxant.
Atracurium ; Fasciculation ; Incidence ; Intubation ; Pancuronium ; Plasma ; Succinylcholine* ; Tubocurarine ; Vecuronium Bromide

Epidural administration of opioid and/or local anesthetics during general anesthesia is widespread method for postoperative pain control. Despite of its availability, inadvertent administration of non-epidural medications into epidural space can be associated with serious neurologic sequelae. We report a case of accidental epidural atracurium injection.
Anesthesia, General ; Anesthetics, Local ; Atracurium* ; Epidural Space ; Lidocaine* ; Pain, Postoperative