Table 1.

IC₅₀ and IC₉₀ values for competitive antagonism of human nAChRs by various neuromuscular blocking agents. Macroscopic currents were activated by 300 μM ACh, −50 mV. CE₅₀ values are estimates of the clinical concentrations of the antagonists that decrease muscle tension by 50% based on pharmacokinetic/pharmacodynamic modeling (32,33). They are not corrected for the free fraction of drug after accounting for protein binding which ranges from 0.31 for vecuronium to 0.63 for atracurium (33).

Antagonist	IC50 (nM)	nH	IC90 (nM)	CE50 (nM)	CE50/IC90
(+)-tubocurarine	24 ± 2	1.03 ± 0.07	286 ± 70	606 − 982	1.3 − 2.1
metocurine	18 ± 2	1.04 ± 0.11	149 ± 32
pancuronium	6.3 ± 0.8	0.95 ± 0.08	94 ± 28	154	1.6
vecuronium	15 ± 2	1.03 ± 0.12	129 ± 38	168 − 190	1.3 − 1.5
cisatracurium	10 ± 1	1.02 ± 0.09	88 ± 18	135 − 169	1.5 − 1.9
rocuronium	17 ± 2	0.67 ± 0.05	472 ± 95	1250−1600	2.6 − 3.4
atracurium	17 ± 2	0.56 ± 0.09	744 ± 120