Dose-response relation for atracurium, ORG NC 45 and pancuronium.

The potencies of atracurium, Org NC 45 and pancuronium were determined using cumulative dose-response curves. The effective doses producing 95% twitch depression were 279 microgram kg-1, 56 microgram kg-1 and 64 microgram kg-1 respectively, the relative potency being 1:5.0:4.3. The calculated log-probit dose-response curves showed the steepest slope for pancuronium, although the slopes did not deviate significantly from the parallel. The three drugs provided equal and generally good intubating conditions at approximately 95% twitch depression. Greater arterial pressure and heart rate were seen with pancuronium than with atracurium and Org NC 45.