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| Clinical data | |
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| Other names | Pyrilamine;N-[2-(dimethylamino)ethyl]-N-[(4-methoxyphenyl)methyl]pyridin-2-amine |
| AHFS/Drugs.com | International Drug Names |
| MedlinePlus | a606008 |
| Routes of administration | By mouth,topical |
| Drug class | First-generation antihistamine |
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| CompTox Dashboard(EPA) | |
| ECHA InfoCard | 100.001.912 |
| Chemical and physical data | |
| Formula | C17H23N3O |
| Molar mass | 285.391 g·mol−1 |
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Mepyramine, also known aspyrilamine, is afirst-generation antihistamine, targeting theH1 receptor as aninverse agonist.[1] Mepyramine rapidly permeates the brain, often causingdrowsiness.[2] It is often sold as amaleate salt,pyrilamine maleate.
The medication has negligibleanticholinergic activity, with 130,000-foldselectivity for thehistamineH1 receptor over themuscarinic acetylcholine receptors (for comparison,diphenhydramine had 20-fold selectivity for the H1 receptor).[3]
It was patented in 1943 and came into medical use in 1949.[4]It was marketed under the names Histadyl, Histalon, Neo-Antergan, Neo-Pyramine, and Nisaval.[5] In the 1960s and 70s it was a very common component in over-the-countersleep aids such as Alva-Tranquil, Dormin, Sedacaps,Sominex, Nytol, and many others.[5] The USFood and Drug Administration (FDA) included it in the list of chemicals and compounds barred from use inover-the-counter (OTC) nighttime sleep aid products in 1989.[6]
It is used in over-the-counter combination products to treat the common cold and menstrual symptoms such asMidol Complete.[7] It is also the active ingredient of the topical antihistamine creams Anthisan[8] and Neoantergan[1] sold for the treatment of insect bites, stings, and nettle rash.