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1. The activities of a new antispasmodic, N, N-di-methylthymy loxyacetamidine hydrochloride and of its diethyl congener have been compared with the corresponding activities of Trasentine, Trasentine-6H, and atropine sulfate in respect to the following: a. Antagonism of a histamine-induced spasm of the ileum of the guinea pig. b. Antagonism of an acetylcholineinduced spasm of the ileum of the guinea pig. c. Antagonism, of a barium chloride-induced spasm of the small intestine of the rabbit. d. Actions on the feline uterus in vitro and in vivo. e. Actions on the nictitating membrane of the cat and on salivation induced by drugs and by stimulation of the chorda tympani nerve. f. Paralysis of the peripheral cut vagus in the cat. g. Antagonism of Mecholyl-induced hypotension in the cat. h. Intravenous LD50 in white rats. i. Chronic toxicological studies in dogs and rats. 2. The effects of Su-198 upon the intestines of dogs with Thiry-Vella loops and upon the bronchioles of the perfused guinea pig’s lung have been described. 3. Some of the problems have been discussed which must be solved before an objective evaluation of an antispasmodic becomes possible.

1. A theoretical explanation for the epinephrine-fast state as a manifestation of imbalance in the histamine-sympathin see-saw is presented (“epinephrine-histamine toxicity”). The experimental observations described lead us to conclude that repeated administrations of epinephrine to such individuals produce an increase in plasma histamine overcoming the effects of the epinephrine. It is theoretically plausible that suitably administered antihistaminic agents might return the see-saw to its normal balance. 2. In eight of a group of ten patients displaying epinephrine-fastness significant improvement followed the use of intravenous tripelennamine hydrochloride or diphenhydramine hydrochloride. Epinephrine, administered subcutaneously or by the aerosol route, appeared to bring relief from acute paroxysmal bronchospasm, whereas previously only the side effects of epinephrine had been observed following its use.