EVALUATION OF CURARIZING DRUGS IN MAN

I. Potency, Duration of Action, and Effects on Vital Capacity of D-Tubocurarine, Dimethyl-D-Tubocurarine, and Decamethylene-Bis (Trimethylammonium Bromide)

¹ Departments of Pharmacology and Anesthesia, University of Illinois, College of Medicine, Chicago 12, Illinois

Effects of curarizing agents vary in different species to such an extent that conclusions drawn from results in animals do not permit accurate predictions of the quantitative effects of these agents in man. Consequently, a quantitative comparison of the curarizing effects of d-tubocurarine, dimethyl d-tubocurarine and C-10 was attempted in 75 experiments on four unanesthetized normal subjects.

1. Equipotent doses of the three agents, based on depression of grip strength (GD₉₅), and expressed as microgm. of ion/kgm. body weight were: d-tubocurarine, 107; dimethyl d-tubocurarine, 41; and C-10, 20.

2. Duration of action was longest with d-tubocurarine, shortest with C-10; the duration of action of dimethyl d-tubocurarine was intermediate but only slightly longer than that of C-10.

3. Vital capacity was decreased most by C-10, less by d-tubocurarine, and least by dimethyl d-tubocurarine, in equivalent doses.

4. Equipotent doses of C-10 had more pronounced but less persistent effects on ocular motility than either d-tubocurarine or dimethyl d-tubocurarine.

5. The effects of a given dose of either d-tubocurarine or dimethyl d-tubo-curarine in man were predictable with greater accuracy than those of C-10.