Methapyrilene
Encyclopedia
Methapyrilene is a 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. 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. All of these products were reformulated in the late 1970s because methapyrilene was demonstrated to cause liver cancer
in rats when given chronically.
Antihistamine
An H1 antagonist is a histamine antagonist of the H1 receptor that serves to reduce or eliminate effects mediated by histamine, an endogenous chemical mediator released during allergic reactions...
and anticholinergic
Anticholinergic
An anticholinergic agent is a substance that blocks the neurotransmitter acetylcholine in the central and the peripheral nervous system. An example of an anticholinergic is dicycloverine, and the classic example is atropine....
of the pyridine
Pyridine
Pyridine is a basic heterocyclic organic compound with the chemical formula C5H5N. It is structurally related to benzene, with one C-H group replaced by a nitrogen atom...
chemical class which was developed in the early 1950s. It was sold under the trade names Co-Pyronil and Histadyl EC. It has relatively strong sedative
Sedative
A sedative or tranquilizer is a substance that induces sedation by reducing irritability or excitement....
effects, to the extent that its primary use was as a medication for insomnia
Insomnia
Insomnia is most often defined by an individual's report of sleeping difficulties. While the term is sometimes used in sleep literature to describe a disorder demonstrated by polysomnographic evidence of disturbed sleep, insomnia is often defined as a positive response to either of two questions:...
rather than for its antihistamine action. Together with scopolamine
Scopolamine
Scopolamine, also known as levo-duboisine, and hyoscine, is a tropane alkaloid drug with muscarinic antagonist effects. It is among the secondary metabolites of plants from Solanaceae family of plants, such as henbane, jimson weed and Angel's Trumpets , and corkwood...
, it was the main ingredient in Sominex, Nytol, and Sleep-Eze. It also provided the sedative component of Excedrin PM. All of these products were reformulated in the late 1970s because methapyrilene was demonstrated to cause liver cancer
Liver cancer
Liver tumors or hepatic tumors are tumors or growths on or in the liver . Several distinct types of tumors can develop in the liver because the liver is made up of various cell types. These growths can be benign or malignant...
in rats when given chronically.