The relative vagolytic potencies of six muscle relaxants in the rabbit

Drane, Sheila E.; Evans, Martin H.

doi:10.1111/j.2042-7158.1979.tb13685.x

Cited by 4 publications

(3 citation statements)

References 8 publications

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“…Second, the degree of twitch blockade required to produce paralysis suitable for surgery or intubation of the trachea is likely to be greater than the degree of vagal block required to produce tachycardia. These problems have been approached by Drane and Evans (1979) who suggested the use of the ratio of the 20% vagal blocking dose to the 80% twitch blocking dose (called the EDayso ratio in this paper). We have used both the ED*) ratio and the ED20/S0 ratio and find that, despite numerical differences between the ratios (tables I and III), when the two ratios for different drugs were compared with that for pancuronium as standard, the relative safety margins of the drugs were similar, no matter which ration was used.…”

Section: Discussionmentioning

confidence: 99%

“…To take account of the different slopes of these dose-inhibition curves, which appear common to most non-depolarizing neuromuscular blocking agents, the results for all compounds have been expressed not only as the ratio of the 50% blocking doses at the cardiac vagus neuroeffector and the neuromuscular junctions, but also as the ratio of the dose producing 20% vagal block to the dose producing 80% neuromuscular blockade. The latter ratio has been regarded as producing a more meaningful guide to the likely occurrence of tachycardia as a result of vagal blockade at muscle paralysing doses (Drane and Evans, 1979). In both cases a vagal: neuromuscular ratio value greater than unity indicates greater neuromuscular blocking potency.…”

Section: Pancuronium Analoguesmentioning

confidence: 99%

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Neuromuscular and Vagal Blocking Actions of Pancuronium Bromide, Its Metabolites, and Vecuronium Bromide (Org Nc 45)and Its Potential Metabolites in the Anaesthetized Cat

Marshall

Gibb

Durant

1983

British Journal of Anaesthesia

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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.

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Section: Discussionmentioning

confidence: 99%

Section: Pancuronium Analoguesmentioning

confidence: 99%

Neuromuscular and Vagal Blocking Actions of Pancuronium Bromide, Its Metabolites, and Vecuronium Bromide (Org Nc 45)and Its Potential Metabolites in the Anaesthetized Cat

Marshall

Gibb

Durant

1983

British Journal of Anaesthesia

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“…The ED50 values for vagal blockade from vecuronium and atracurium were not significantly different and hence the difference in the vagal/neuromuscular blocking EDJO ratios (table I) reflects purely the greater neuromuscular blocking potency of vecuronium-a factor of around 4. We have also used the EDsvso ratio (table I), which compares the dose producing 20% vagal block with that producing 80% neuromuscular block (Drane and Evans, 1979). This value may give a more meaningful indication of the safety margin from autonomic side-effects at degrees of neuromuscular blockade likely to be used for intubation of the trachea in man (Marshall, Gibb and Durant, 1983).…”

Section: Autonomic Effectsmentioning

confidence: 99%

Neuromuscular Blocking and Autonomic Effects of Vecuronium and Atracurium in the Anaesthetized Cat

Sutherland¹,

Squire²,

Gibb³

et al. 1983

British Journal of Anaesthesia

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The effects of vecuronium and atracurium on neuromuscular transmission, on the responses of the heart rate to vagal stimulation and on the responses to preganglionic stimulation of the nictitating membrane were compared in the chloralose-anaesthetized cat. Vecuronium was four times more potent than atracurium as a neuromuscular blocking agent, whereas the two compounds had similar potencies in blocking the effects of stimulation of the cardiac vagus. The vagal/neuromuscular ratios measured at 50% inhibition were 96 for vecuronium and 25 for atracurium. Vecuronium possessed a slightly shorter recovery time than atracurium and shorter duration of action on the soleus muscle. The onset times of the two compounds were not significantly different. Both compounds had longer time-courses of action than suxamethonium. Very large doses of vecuronium decreased the responses of the preganglionic stimulation of the nictitating membrane, suggesting that at high doses the compound possesses ganglion blocking activity. Large doses of atracurium also decrease the nictitating membrane responses and, in some cats, contractions of the nictitating membrane associated with increases in heart rate and arterial pressure were observed.

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Antimuscarinic and Ganglion-Blocking Activity of Neuromuscular Blocking Agents

Харкевич¹,

Shorr²

1986

New Neuromuscular Blocking Agents

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The relative vagolytic potencies of six muscle relaxants in the rabbit

Cited by 4 publications

References 8 publications

Neuromuscular and Vagal Blocking Actions of Pancuronium Bromide, Its Metabolites, and Vecuronium Bromide (Org Nc 45)and Its Potential Metabolites in the Anaesthetized Cat

Neuromuscular and Vagal Blocking Actions of Pancuronium Bromide, Its Metabolites, and Vecuronium Bromide (Org Nc 45)and Its Potential Metabolites in the Anaesthetized Cat

Neuromuscular Blocking and Autonomic Effects of Vecuronium and Atracurium in the Anaesthetized Cat

Antimuscarinic and Ganglion-Blocking Activity of Neuromuscular Blocking Agents

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