Abstract
The potency of ORG 9426, a new nondepolarising muscle relaxant, has been estimated using two different modes of nerve stimulation in patients anaesthetised with thiopentone, nitrous oxide-oxygen and intravenous fentanyl. The force of contraction of adductor pollicis was measured following a single twitch (ST) at 0.1 Hz or a train-of-four (TOF) mode of stimulation at 2 Hz every ten seconds. Dose-response curves were constructed using a single-dose method. The ED50, ED90 and ED95 were 147, 272 and 305 μg · kg−1 respectively using the ST mode and 125, 230 and 257 μg · kg−1 using the TOF mode of stimulation. The ED50s were not significantly different but the differences between ED90s and ED95s were significant (P <0.05) indicating greater sensitivity of the neuromuscular junction using TOF stimulation. The results of this study suggest that the information obtained by single-twitch stimulation is not the same as that obtained from the first response of the TOF stimulation, suggesting apparently increased sensitivity (and apparently greater potency) with the TOF mode of stimulation. Org 9426 appears to be a drug with relatively low potency.
Résumé
La puissance de l’ORG 9426, un nouveau relaxant musculaire non-dépolarisant, a été estimée utilisant deux différents modes de stimulation nerveuse chez les patients anesthésiés au pentothal, protoxyde d’azote-oxygène et fentanyl intraveineux. La force de contraction de l’adducteur de pouce fut mesurée après un « twitch » unique (ST) à 0,1 Hz ou une ondée-de-quatre (train-of-four) (TOF) à 2 Hz chaque dix secondes. Les courbes de dose-réponse furent construites utilisant la méthode de dose unique. Les ED50, ED90 et ED95 furent 147, 272 et 305 μg · kg−1 respectivement utilisant le mode ST et 125, 230 et 257 μg · kg−1 respectivement utilisant le mode TOF. Les ED50s ne furent pas significativement différents mais les différences entre les ED90s et les ED95s furent significatifs (P < 0,05) indiquant une plus grande sensibilité de la jonction neuromusculaire utilisant la stimulation TOF. Les résultats de cette étude suggèrent que l’information obtenue par un « twitch » unique n ’est pas la même que celle obtenue par la stimulation TOF, suggérant apparemment une plus grande sensibilité (et apparemment une plus grande puissance) avec la stimulation TOF. Org 9426 apparaît comme étant une drogue ayant relativement une puissance faible.
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
References
Curran MJ, Donati F, Bevan DR. Onset and recovery of atracurium and suxamethonium-induced neuromuscular blockade with simultaneous train-of-four and single twitch stimulation. Br J Anaesth 1987; 59: 989–94.
Bell PF, Gibson FM, Mirakhur RK, Clarke RSJ. Comparison of single twitch and train-of-four modes of stimulation for measurement of non-depolarizing neuromuscular block. Br J Anaesth 1988; 60: 343P.
Savarese JJ, Kitz RJ. Does clinical anesthesia need new neuromuscular blocking agents? Anesthesiology 1975; 42: 236–9.
Durant NN, Katz RL. Suxamethonium. Br J Anaesth 1982; 54: 195–208.
Muir AW, Houston J, Green KL, Marshall RJ, Bowman WC, Marshall IG. The effects of a new neuromuscular blocking agent (ORG 9426) in anaesthetized cats and pigs and in isolated nerve-muscle preparations. Br J Anaesth 1989; 63: 400–10.
Gibson FM, Mirakhur RK, Lavery GG, Clarke RSJ. Potency of atracurium: a comparison of single-dose and cumulative dose techniques. Anesthesiology 1986; 62: 657–9.
Gibson FM, Mirakhur RK, Clarke RSJ, Lavery GG. Comparison of cumulative and single bolus dose techniques for determining the potency of vecuronium. Br J Anaesth 1985; 57: 1060–2.
Armitage P. Statistical Methods in Medical Research. Oxford: Blackwell Scientific Publications, 1971; 349–61.
Payne JP, Hughes R. Evaluation of atracurium in anaesthetized man. Br J Anaesth 1981; 53: 45–54.
Ali HH, Savarese JJ. Monitoring of neuromuscular function. Anesthesiology 1976; 45: 216–49.
Lee C, Katz RL. Neuromuscular pharmacology. A clinical update and commentary. Br J Anaesth 1980; 52: 173–88.
Ali HH, Savarese JJ. Stimulus frequency and dose-response curve to d-tubocurarine in man. Anesthesiology 1980; 52: 36–9.
Wierda JMKH, de Wit APM,Kuizenga K, Agoston S. Clinical observations on the neuromuscular blocking action of ORG 9426, a new steroidal non-depolarising agent. Br J Anaesth 1990; 64: 521–3.
Nagashima H, Nguyen HD, Kinsey A et al. The human dose-response of Org 9426. Anesthesiology 1989; 71: A773.
Bowman WC, Rodger IW, Houston J, Marshall RJ, McIndewar I. Structure:action relationships among some desacetoxy analogues of pancuronium and vecuronium in anaesthetized cat. Anesthesiology 1988; 69: 57–62.
Author information
Authors and Affiliations
Additional information
Supplies of Org 9426 and financial assistance received from Organon Teknika BV, The Netherlands.
Rights and permissions
About this article
Cite this article
Cooper, R.A., Mirakhur, R.K., Elliott, P. et al. Estimation of the potency of ORG 9426 using two different modes of nerve stimulation. Can J Anaesth 39, 139–142 (1992). https://doi.org/10.1007/BF03008644
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF03008644