[Comparative clinical studies of vecuronium, atracurium and pancuronium]

The new relaxants vecuronium (Norcuron) and atracurium (Tracrium) have been compared with pancuronium (Pavulon) with respect to onset and duration of action and intubating conditions under clinical situations. A variant of the balanced anaesthesia technique with flunitrazepam, fentanyl and N2O/O2 was used. The following doses were considered equipotent (mg/kg body weight): vecuronium 0.07/0.10; atracurium 0.35/0.50; pancuronium 0.08/0.115. The degree of neuromuscular block was assessed in a semiquantitative manner, using the train of four. No difference between the three relaxants in onset of action was found. After the high doses, however, full paralysis developed 60 s earlier. The same is true of intubating conditions. Good or very good intubating conditions were obtained in the majority of cases 3 minutes after injection of the drug. Following the higher dose, good intubating conditions are achieved approximatively 1/2-1 min sooner. Both new relaxants allow for relatively rapid intubation without the inconvenience of a long duration of action. After a low initial dose the following time for recovery to 25% was noted (means +/- S.D., min): vecuronium 20.3 +/- 7.0; atracurium 28.0 +/- 3.1; pancuronium 53.3 +/- 14.8. The early recovery phase (from 5% to 25% recovery) was 6.1 +/- 2.4 after vecuronium, 8.3 +/- 1.7 after atracurium, 17.2 +/- 10.8 after pancuronium. There is a good correlation between our semiquantitative results, using the train of four, and quantitative recordings of muscle contractions reported in the literature. Both drugs show no cumulative effect after five repeated administrations.(ABSTRACT TRUNCATED AT 250 WORDS)