Methapyrilene hydrochloride is N,N-dimethyl-N′-(2-pyridyl)-N′-(2-thenyl) ethylenediamine hydrochloride (thenylene hydrochloride®, Abbott) and is an antihistaminic drug.
Since the antihistaminic drugs have become available to the members of the medical profession, both the lay press and many physicians have hailed these preparations as practically nontoxic and as the solution to most allergic problems. That present indiscriminate use of these antihistaminic agents needs a critical review is evidenced in the literature. Although we have found no report of a fatality, there have been serious reactions.
Roth and co-workers1 from the Abbott Laboratories reported the pharmacologic properties of methapyrilene. On isolated portions of ileum in the guinea pig and rabbits, they demonstrated that this drug definitely prevented or abolished the spasmproducing activity of histamine. They also demonstrated its inhibitory action on anaphalaxis in the serum-sensitized guinea pig. The authors, in discussing acute toxicity in experimental animals, noted excitation followed by convulsions. In cats and
RIVES HF, WARD BB, HICKS ML. A FATAL REACTION TO METHAPYRILENE (THENYLENE®). JAMA. 1949;140(12):1022–1024. doi:10.1001/jama.1949.82900470008007
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