COMPARISON OF VECURONIUM WITH ORG-9487 AND THEIR INTERACTION

Purpose: To compare the pharmacodynamic behaviour of vecuronium with t hat of ORG 9487, we measured the time-course of action of equipotent d oses of ORG 9487 and vecuronium and investigated their mutual interact ion when given in succession. Methods: Sixty ASA I-II patients were an aesthetized with thiopentone, fentanyl, halothane and nitrous oxide an d assigned randomly to four groups. Each patient received an initial d ose (ID) of either vecuronium (V) or OPG 9487 (O) followed by maintena nce doses (MDn) of either V or O (ID/MD: O/O, V/O, O/V and V/V. The ti me course oi action was measured mechanomyographically, determining th e duration until 25% recovery of the single twitch (DUR25). Results: T he onset time of an ID of ORG 9487 was shorter than that of an ID of v ecuronium (96 vs 203 sec, P < 0.001). The DUR25 of the ID of ORG 9487 was less than half that of vecuronium (10.7 +/- 2.8 vs 28.8 +/- 6.1 mi n, P < 0.001). The DUR25 of MD1 and MD2 of ORG 9487 were shorter than those of vecuronium (O/O: 7.3 +/- 2.8 and 8.5 +/- 2.4 min; V/O: 12.7 /- 3.3 and 11.5 +/- 3.5 min, vs O/V: 16.4 +/- 4.5 and 20.6 +/- 4.7 min ; V/V: 8.8 +/- 3.0 and 20.1 +/- 3.8 min, respectively, P < 0.05). An I D of vecuronium prolonged the DUR25 of MD1 and MD2 of ORG 9487 (P < 0. 05). Conclusion: ORG 9487 is a muscle relaxant with a shorter duration of action than vecuronium. Maintenance doses of ORG 9487 are also sho rter acting than roughly equipotent maintenance doses of vecuronium, i rrespective of which relaxant is given initially.