BLOQUEADORES NEUROMUSCULARES NO DESPOLARIZANTES PDF

BLOQUEADORES NEUROMUSCULARES • Esses Bloqueadores são análogos estruturais da Ach e atuam como antagonistas(tipo não despolarizante) ou. Bloqueadores neuromusculares em pediatria. Junção neuromuscular. História Farmacologia UTI ped. Charles Waterton Curare Fisiologia Fisiologia Brommage . de cálcio podem interagir com bloqueadores neuromusculares potencializando ca e ausência de ação despolarizante sobre a fibra muscular. Unitermos.

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De a era publicada trimestralmente. The local anesthetic effects on neuromuscular junction and its influence on boqueadores produced by nondepolarizing neuromuscular blockers are still under-investigated; however, this interaction has been described in experimental studies and in humans.

The aim of this study was to evaluate in vitro the interaction between ropivacaine and pancuronium, the influence on transmission and neuromuscular blockade, and the effectiveness of neostigmine and 4-aminopyridine to reverse the blockade. The effects of ropivacaine on membrane potential and miniature endplate potential, the amplitude of diaphragm responses before and 60 min after the addition of ropivacaine degree of neuromuscular blockade with pancuronium and with the sespolarizantes of pancuronium—ropivacaineand the effectiveness of neostigmine and 4-aminopyridine on neuromuscular block reversal were evaluated.

Ropivacaine did not alter the amplitude of muscle response the membrane potentialbut decreased the frequency and amplitude of the miniature endplate potential. Pancuronium blockade was potentiated by ropivacaine, and partially and fully reversed by neostigmine and 4-aminopyridine, respectively. Ropivacaine increased the neuromuscular block produced by pancuronium.

The complete antagonism with 4-aminopyridine suggests presynaptic action of ropivacaine. Local anesthetics, particularly amino amides, are a group of drugs widely administered by different routes, such as topical, subcutaneous infiltration, peripheral nerve block, neuraxial anesthesia alone or combined with general anesthesia.

There is evidence that these drugs may interfere with neuromuscular transmission and increase the effects of neuromuscular blockers.

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The aim of this study was to evaluate in an experimental model the effect of ropivacaine on neuromuscular transmission, its influence on the neuromuscular block produced by pancuronium, and the effectiveness of neostigmine and 4-aminopyridine on blockade reversal.

Male Wistar rats weighing between and g were used. The animals were anesthetized intraperitoneally with urethane 1. Bulbring 11 technique was used to evaluate the effect of ropivacaine on neuromuscular transmission, its influence on blockade produced by pancuronium and the effectiveness of neostigmine and 4-aminopyridine on neuromuscular blockade reversal. The nerve was placed over platinum electrodes connected to a Grass S48 stimulator. The diaphragm was maintained, by its tendinous portion, under constant voltage 5.

In Group III pancuronium—ropivacainepancuronium was added to the preparation 30 min after the addition of ropivacaine. Muscle response to indirect stimulation was recorded for 60 min after addition of the drugs. In the rat diaphragm, the effects of ropivacaine on miniature endplate potentials and membrane potentials were also studied.

Parameters evaluated were 1 extent of diaphragm muscle response to indirect stimulation before and 60 min after ropivacaine addition; 2 extent of diaphragm muscle response to indirect stimulation before and 60 min after pancuronium addition, alone and previously combined with ropivacaine; 3 membrane potentials MP and miniature endplate potentials MEPP ; and 4 effectiveness of neostigmine and 4-aminopyridine on neuromuscular blockade reversal.

Results were expressed as means and standard deviations. Wilcoxon test was used to analyze the membrane potential of muscle fiber and the effectiveness of neuromuscular blockade reversal drugs.

To evaluate the reduction in the extent of muscle response, Student’s t -test normal distribution was used. At the concentration studied and used alone, ropivacaine did not reduce the extent of muscle response to indirect electrical stimulation on rat phrenic nerve-diaphragm.

With pancuronium alone and in preparations previously exposed to ropivacaine, the despolarisantes extent of muscle responses was Amplitude of muscle response to indirect stimulation on phrenic nerve-diaphragm preparation of rats exposed to ropivacaine 5. Degree of blockade with pancuronium alone and in preparation previously exposed to ropivacaine. The neuromuscular blockade caused by pancuronium in despolarizantws exposed to ropivacaine was both partially and fully reversed by neostigmine and 4-aminopyridine, respectively.

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There was no significant effect of ropivacaine on membrane potentials Fig. Effects on miniature endplate potentials MEPP were characterized by a decrease neuromuscularres frequency and extent until complete blockade.

The effects of local anesthetics on neuromuscular junction and its influence on the blockade produced by nondepolarizing neuromuscular blockers are still under-investigated; however, this interaction has been described in experimental and human studies. Although local anesthetics can only produce neuromuscular blockade at high doses, interactions with neuromuscular blockers, particularly non-depolarizing, become clinically relevant, and careful observation is required when using these agents simultaneously, or in situations where the safety margin of neuromuscular transmission is reduced.

Several mechanisms are admitted to explain the interaction between local anesthetics and neuromuscular blockers: The ropivacaine concentration used was established in a pilot study and determined from data presented in studies carried out in Brazil, where other amino-amide local anesthetics with similar characteristics to ropivacaine neuromusculzres used.

Regarding the influence of neuromuscular blockers on the effects local anesthetics, these authors also reported that ineffective concentrations of d-tubocurarine caused a similar decrease of ED50 and increase of local anesthetic potency.

In a clinical trial, Sahin et al. These findings may be explained by the fact that levobupivacaine metabolism, deespolarizantes used in epidural space, only occurs in approximately 30 min when the drug reaches the circulation. The present study showed that ropivacaine, at the concentration studied, administered alone had no effect on neuromuscular junction; however, it potentiated the blockade produced by pancuronium.

These results are similar to those of other authors, who found no clinical impairment in neuromuscular transmission in experimental studies with the isolated use of different local anesthetics. However, a neuromuscularfs potentiation of the effect of various neuromuscular blockers has been described as a result of these drugs combination, an interaction that may be consequential to the true potentiation at different locations of the neuromuscular junction, 1,2,4—7,12,13,20 caused by the action of the two drugs.

It is believed that the greatest degree of neuromuscular blockade caused by pancuronium in rat diaphragm preparations previously exposed to ropivacaine, and evidenced by a greater reduction in the extent of muscle responses to phrenic nerve stimulation, is due to a presynaptic action of ropivacaine and not to the muscular fiber depolarizing action, as it was found in electrophysiological studies that bupivacaine at neurlmusculares concentration used did not modify the membrane potential deepolarizantes muscle fibers.

The presynaptic deapolarizantes was demonstrated by the decrease in the frequency and amplitude of miniature bloqueavores potentials MEPP caused by ropivacaine, being the result of nl in quantal release of acetylcholine. The neuromuscular blockade caused by ropivacaine combined with pancuronium was completely reversed by 4-aminopyridine and, to a lesser extent, with neostigmine. These results were also described by Sahin et al.

In experimental studies, similar results were found regarding reversal of blockade caused by lidocaine—rocuronium combination. By inhibiting the acetylcholinesterase, neostigmine increases the neurotransmitter concentration in the synaptic cleft, competitively displacing the agents causing blockage. The partial antagonism of neostigmine reinforces this finding, as cholinesterase inhibitors are only effective in reversing the postsynaptic block.

The 4-aminopyridine, in addition to its inhibitory effect of endplate nicotinic receptor desensitization, causes increased quantal acetylcholine.

This increase is the result of actions in the membrane of nerve endings, such as potassium channel inhibition, which produces an increase in the duration of the action potential and increased influx of calcium ions to motor nerve endings during membrane depolarization.

Ropivacaine alone did not compromise neuromuscular transmission, but potentiated the blockade produced by pancuronium, which was reversed by neostigmine and 4-aminopyridine. These findings are important for clinical practice because it provides guidance on the need for monitoring, particularly when combined with other drugs. The authors declare no conflicts of interest. Artigo anterior Artigo seguinte. Effect of ropivacaine combined with pancuronium on neuromuscular transmission and effectiveness of neostigmine and 4-aminopyridine for blockade reversal: Under a Creative Commons license.

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Mostrar mais Mostrar menos. Background and objectives The local anesthetic effects on neuromuscular junction and its influence on blockade produced by nondepolarizing neuromuscular blockers are still under-investigated; however, this interaction has been described in experimental studies and in humans.

The aim of this study was to evaluate in vitro the interaction between ropivacaine and pancuronium, the influence on transmission and neuromuscular blockade, and the effectiveness of neostigmine and 4-aminopyridine to reverse the blockade. The effects of ropivacaine on membrane potential and miniature endplate potential, the amplitude of diaphragm responses before and 60 min after the addition of ropivacaine degree of neuromuscular blockade with pancuronium and with the association of pancuronium—ropivacaineand the effectiveness of neostigmine and 4-aminopyridine on neuromuscular block reversal were evaluated.

Results Ropivacaine did not alter the amplitude of muscle response the membrane potentialbut decreased the frequency and amplitude of the miniature endplate potential. Pancuronium blockade was potentiated by ropivacaine, and partially and fully reversed by neostigmine and 4-aminopyridine, respectively.

Conclusions Ropivacaine increased the neuromuscular block produced by pancuronium. The complete antagonism with 4-aminopyridine suggests presynaptic action of ropivacaine. Introduction Local anesthetics, particularly amino amides, are a group of drugs widely administered by different routes, such as topical, subcutaneous infiltration, peripheral nerve block, neuraxial anesthesia alone or combined with general anesthesia. Muscle response to indirect stimulation was recorded for 60 min after addition of the drugs.

Parameters evaluated were 1 extent of diaphragm muscle response to indirect stimulation before and 60 min after ropivacaine addition; 2 extent of diaphragm muscle response to indirect stimulation before and 60 min after pancuronium addition, alone and previously combined with ropivacaine; 3 membrane potentials MP and miniature endplate potentials MEPP ; and 4 effectiveness of neostigmine and 4-aminopyridine on neuromuscular blockade reversal.

Results At the concentration studied and used alone, ropivacaine did not reduce the extent of muscle response to indirect electrical stimulation on rat phrenic nerve-diaphragm. Degree of blockade with pancuronium alone and in preparation previously exposed to ropivacaine.

Effect of epidurally administered bupivacaine on atracurium-induced neuromuscular blockade. Acta Anaesthesiol Scand, 34pp. The effect of epidural bupivacaine on vecuronium-induced neuromuscular blockade in children. Acta Anesthesiol Scand, 38pp.

Epidurally administered mepivacaine delays recovery of train-of-four ratio from vecuronium-induced neuromuscular block. Br J Anaesth, 99pp. Nueromusculares of epidural levobupivacaine on recovery from vecuronium-induced neuromuscular block in patients undergoing lower abdominal surgery.

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Acta Cir Bras, 24pp.

Br J Anaesth, 58pp. Minerva Anestesiol, 71pp. Observation on the isolated phrenic neuromuscupares preparation of the rat.

Br J Pharmacol, 1pp. Rev Bras Anestesiol, 55pp. Interaction of muscle relaxants and local anesthetics at the neuromuscular junction.

Anesth Analg, 57pp. Anesthetic agents, adjuvants, and drug interaction. Clinical anesthesia, 6th ed. Edrophonium antagonize combined lidocaine-pacuronium and verapamil-pancuronium neuromuscular blockade in cats. Anesthesiology, 65pp. Local anesthetics transiently block currents through single acetylcholine-receptor channels.

J Physiol,pp. Rev Bras Anestesiol, 38pp. Investigation of fading responses induced by non-depolarising muscle relaxants in the evoked EMG of the gastrocnemius muscle of the cat. Acta Anaesthesiol Scand, 43pp.