title: Pharmacodynamic effects of 51W89, an isomer of atracurium, in children during halothane anaesthesia.
abstract: 51W89 is one of the 10 stereoisomers of atracurium with less propensity to release histamine than atracurium. We evaluated dose-response data and neuromuscular effects of 2 x ED95 dose and maintenance doses of 51W89 during halothane anaesthesia in 68 children, 2-12 yr old. Neuromuscular function was monitored by evoked adductor pollicis EMG. Log-probit, single-dose, dose-response data gave ED50 and ED95 values of 23 and 41 micrograms kg-1, respectively, for 51W89. Twice the ED95 dose (80 micrograms kg-1) had an onset time (time from administration to maximum effect) of 2.5 (SD 0.8) min, a clinical duration (time to 25% EMG recovery) of 31 (7) min and a recovery index (time from 25 to 75% EMG recovery) of 11.1 (1.7) min. Seventy-nine incremental doses of 51W89 of 94 (19) micrograms kg-1. Duration of effect of incremental doses remained constant within individuals reflecting non-cumulative properties. There were insignificant changes in arterial pressure and heart rate after 51W89 and no side effects were observed. We regard 51W89 as a promising, non-cumulative, intermediate-acting neuromuscular blocking agent the effects of which can be antagonized easily by neostigmine.
authors.affiliation: Department of Anaesthesiology, Children's Hospital University of Helsinki, Finland.
authors.forename: O A
authors.initials: OA
authors.lastname: Meretoja
authors.forename: T
authors.initials: T
authors.lastname: Taivainen
authors.forename: K
authors.initials: K
authors.lastname: Wirtavuori
mesh_terms: D000769:Anesthesia, Inhalation; D001279:Atracurium / Q000031:analogs & derivatives / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects; D002648:Child; D002675:Child, Preschool; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D004576:Electromyography; D006221:Halothane; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007536:Isomerism; D009388:Neostigmine / Q000494:pharmacology; D009466:Neuromuscular Blocking Agents
chemical_list: D009466:Neuromuscular Blocking Agents; D001279:Atracurium; D009388:Neostigmine; D006221:Halothane