Clinical data
ATC code
  • N,N-dimethyl-N'-pyridin-2-yl-N'-(2-thienylmethyl)ethane-1,2-diamine
CAS Number
PubChem CID
CompTox Dashboard (EPA)
Chemical and physical data
Molar mass261.39 g·mol−1
3D model (JSmol)
  • n1ccccc1N(CCN(C)C)Cc2sccc2
  • InChI=1S/C14H19N3S/c1-16(2)9-10-17(12-13-6-5-11-18-13)14-7-3-4-8-15-14/h3-8,11H,9-10,12H2,1-2H3 checkY

Methapyrilene is an antihistamine and anticholinergic of the pyridine chemical class which was developed in the early 1950s. It was sold under the trade names Co-Pyronil and Histadyl EC in the UK.[1] It has relatively strong sedative effects, to the extent that its primary use was as a medication for insomnia rather than for its antihistamine action. Together with scopolamine, it was the main ingredient in Sominex, Nytol, and Sleep-Eze. It also provided the sedative component of Excedrin PM.[2] All of these products were reformulated in the late 1970s[3] when methapyrilene was demonstrated to cause liver cancer in rats when given chronically.[4]

See also


  1. ^ "Archive". Birmingham Post. July 1979 – via The Free Library.
  2. ^ "FDA Seeks Restrictions On Sleeping Aid Drugs". Daily Press. Vol. 83, no. 164. 1978-06-13. p. 1 – via
  3. ^ Cook C (1979-06-28). "Sleep aids back with new drug | Critics assail 'human testing'". The Minneapolis Star. pp. 1A, 6A – via
  4. ^ Lijinsky W, Reuber MD, Blackwell BN (August 1980). "Liver tumors induced in rats by oral administration of the antihistaminic methapyrilene hydrochloride". Science. 209 (4458): 817–819. Bibcode:1980Sci...209..817L. doi:10.1126/science.7403848. PMID 7403848.