DOSE-RANGING STUDY IN YOUNGER ADULT AND ELDERLY PATIENTS OF ORG-9487,A NEW, RAPID-ONSET, SHORT-DURATION MUSCLE-RELAXANT

The purpose of this multicenter, randomized, assessor-blind placebo-co ntrolled study was to determine which of five doses of the new, rapid- onset neuromuscular relaxant, ORG 9487, provided both good to excellen t tracheal intubating conditions 60 s after administration and a clini cal duration of action <20 min in 120 younger (aged 18-64 yr) and 61 e lderly (aged 65-85 yr) adult patients. Anesthesia was induced with fen tanyl (2-5 mu g/kg) and thiopental (3-6 mg/kg) and maintained with N2O /O-2 and a propofol infusion (50-300 mu g.kg(-1).min(-1)). Neuromuscul ar train-of-four (TOF) monitoring by electromyography (Datex Relaxogra ph) commenced immediately after anesthetic induction and was followed, within 30 s, by one of five doses of ORG 9487 (0.5, 1.0, 1.5, 2.0, 2. 5 mg/kg) or a placebo. Tracheal intubation was attempted at 60 s and a gain, in the case of failure, at 90 s. Conditions were assessed with a 4-point scale. Maximum block, clinical duration (time to 25% T1 recov ery), and recovery (TOF greater than or equal to 0.7) were measured. D ose-dependent changes were observed in tracheal intubating conditions and neuromuscular block. Good to excellent intubating conditions at 60 s were present in most younger adult (52 of 60) and elderly (26 of 31 ) patients administered doses greater than or equal to 1.5 mg/kg. Mean clinical durations <20 min were observed in adult patients at doses u p to 2.0 mg/kg and in geriatric patients up to 1.5 mg/kg. Thus, doses of 1.5-2.0 mg/kg ORG 9487 enabled both rapid tracheal intubation and a short clinical duration of action in adult and elderly patients.