Pharmacological and certain chemical properties of AH 10407, an unusually short-acting, competitive neuromuscular blocking drug, and some related compounds.

1 1,1′-Azobis[3-methyl-2-phenylbenzimidazolinium]dimethanesulphonate(AH 10407) has an ultrashort, competitive neuromuscular blocking action in the mouse, cat, dog, Cynamolgus monkey and cotton-eared marmoset. 2 AH 10407 is chemically unstable in bicarbonate-containing solutions and is degraded to inactive products. The half-life of AH 10407 in vitro in dog and human whole blood and in Krebs physiological solution is about 1.0 minute. In distilled water and in HCO3-deficient Krebs solution AH 10407 is much more stable. Base catalyzed degradation is shown to be the prime determinant of the duration of action of the drug. 3 Some pharmacological properties of AH 11244 and AH 11056, close analogues of AH 10407, are briefly described and the duration of their neuromuscular blocking actions rationalized by reference to their chemical stabilities.