Mepyramine

Mepyramine, also known as pyrilamine, is a first generation antihistamine, targeting the H₁ receptor as an inverse agonist.^[1] Mepyramine rapidly permeates the brain, often causing drowsiness.^[2] It is often sold as a maleate salt, pyrilamine maleate.

Mepyramine

Clinical data
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	oral, topical,
ATC code	R06AC01 (WHO) D04AA02 (WHO)
Legal status
Legal status	In general: Over-the-counter (OTC)
Identifiers
IUPAC name N-(4-methoxybenzyl)-N',N'-dimethyl-N-pyridin-2-ylethane-1,2-diamine
CAS Number	91-84-9 Y 59-33-6 (maleate)
PubChem CID	4992
IUPHAR/BPS	1227
DrugBank	DB06691 N
ChemSpider	4818 Y
UNII	HPE317O9TL
KEGG	D08183 Y
ChEBI	CHEBI:6762 N
ChEMBL	ChEMBL511 Y
CompTox Dashboard (EPA)	DTXSID9023542
ECHA InfoCard	100.001.912
Chemical and physical data
Formula	C17H23N3O
Molar mass	285.391 g·mol−1
3D model (JSmol)	Interactive image
SMILES O(c1ccc(cc1)CN(c2ncccc2)CCN(C)C)C
InChI InChI=1S/C17H23N3O/c1-19(2)12-13-20(17-6-4-5-11-18-17)14-15-7-9-16(21-3)10-8-15/h4-11H,12-14H2,1-3H3 Y Key:YECBIJXISLIIDS-UHFFFAOYSA-N Y
NY (what is this?)  (verify)

The medication has negligible anticholinergic activity, with 130,000-fold selectivity for the histamine H₁ receptor over the muscarinic 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-counter sleep aids such as Alva-Tranquil, Dormin, Sedacaps, Sominex, Nytol, and many others.^[5] The US FDA included it in the list of chemicals and compounds barred from use in over-the-counter 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 as Midol 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.

See also

• Chloropyramine (chloro instead of methoxy)

References

1. Parsons ME, Ganellin CR (January 2006). "Histamine and its receptors". British Journal of Pharmacology. 147 (Suppl 1) (published 2 February 2009): S127–S135. doi:10.1038/sj.bjp.0706440. PMC 1760721. PMID 16402096.
2. "Mepyramine". drugbank.com. Retrieved 8 May 2021.
3. Kubo N, Shirakawa O, Kuno T, Tanaka C (March 1987). "Antimuscarinic effects of antihistamines: quantitative evaluation by receptor-binding assay". Japanese Journal of Pharmacology. 43 (3): 277–282. doi:10.1254/jjp.43.277. PMID 2884340.
4. Fischer J, Gannelin CR, eds. (2006). Analogue-based Drug Discovery. John Wiley & Sons. p. 545. ISBN 9783527607495.
5. Thornton WE (September 1977). "Sleep aids and sedatives". Journal of the American College of Emergency Physicians (JACEP). 6 (9): 408–412. doi:10.1016/S0361-1124(77)80006-3. PMID 330911.
6. 54 FR 6826
7. "Active Ingredients for Midol Complete". Bayer HealthCare LLC. Archived from the original on 2 December 2009. Retrieved 8 December 2009.
8. "Anthisan Cream - Patient Information Leaflet (PIL)". Medicines.org.