We compared the cardiovascular and neuromuscular effects of Org NC 45 with those of pancuronium, metocurine, and d-tubocurarine in six dogs anesthetized with halothane. The ED90 (dose of drug which produced a 90% depression of twitch tension) of Org NC 45, pancuronium, metocurine, and d-tubocurarine was 14 ± 3, 22 ± 3, 63 ± 19, and 130 ± 19 μg/kg, respectively. All subsequent neuromuscular and cardiovascular effects were determined from a dose equal to 3 times the ED90 of muscle relaxant. Org NC 45, pancuronium, metocurine, and d-tubocurarine produced a neuromuscular blockade with a duration (time from relaxant administration until recovery of 50% of the original twitch tension) of 42 ± 2, 108 ± 10, 109 ± 21, and 100 ± 19 minutes, respectively. Org NC 45 caused no significant cardiovascular changes. Pancuronium increased heart rate, mean arterial blood pressure, cardiac output, and pulmonary wedge pressure, and it decreased systemic vascular resistance (p < 0.05). Although metocurine also increased heart rate and cardiac output (p < 0.05), mean arterial blood pressure and pulmonary wedge pressure did not change. d-Tubocurarine decreased all cardiovascular parameters except heart rate which increased significantly (p < 0.05). We conclude that Org NC 45 produces a neuromuscular blockade of shorter duration with fewer cardiovascular changes than that of pancuronium, metocurine, or d-tubocurarine.
Supported by the Netherlands Organization for the Advancement of Pure Research (Z.W.O.)-NATO Grant; Organon, Inc, Oss, Netherlands; and the Anesthesia-Pharmacology Research Foundation.
© 1980 International Anesthesia Research Society