Mepyramine

{{short description|First generation antihistamine}}

{{Use dmy dates|date=April 2024}}

{{cs1 config|name-list-style=vanc|display-authors=6}}

{{Drugbox

| Verifiedfields = changed

| class = First-generation antihistamine

| verifiedrevid = 408591350

| IUPAC_name = N-(4-methoxybenzyl)-N',N'-dimethyl-N-pyridin-2-ylethane-1,2-diamine

| image = Mepyramine.svg

| tradename =

| Drugs.com = {{drugs.com|international|mepyramine}}

| MedlinePlus = a606008

| pregnancy_category =

| legal_status = OTC

| routes_of_administration = By mouth, topical

| bioavailability =

| protein_bound =

| metabolism =

| elimination_half-life =

| excretion =

| CAS_number_Ref = {{cascite|correct|??}}

| CAS_number = 91-84-9

| CAS_supplemental =
{{CAS|59-33-6}} (maleate)

| ATC_prefix = R06

| ATC_suffix = AC01

| ATC_supplemental = {{ATC|D04|AA02}}

| PubChem = 4992

| IUPHAR_ligand = 1227

| DrugBank_Ref = {{drugbankcite|changed|drugbank}}

| DrugBank = DB06691

| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}

| ChemSpiderID = 4818

| UNII_Ref = {{fdacite|correct|FDA}}

| UNII = HPE317O9TL

| KEGG_Ref = {{keggcite|correct|kegg}}

| KEGG = D08183

| ChEBI_Ref = {{ebicite|changed|EBI}}

| ChEBI = 6762

| ChEMBL_Ref = {{ebicite|correct|EBI}}

| ChEMBL = 511

| synonyms = Pyrilamine; N-[2-(dimethylamino)ethyl]-N-[(4-methoxyphenyl)methyl]pyridin-2-amine

| C = 17

| H = 23

| N = 3

| O = 1

| SMILES = O(c1ccc(cc1)CN(c2ncccc2)CCN(C)C)C

| StdInChI_Ref = {{stdinchicite|correct|chemspider}}

| StdInChI = 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

| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}

| StdInChIKey = YECBIJXISLIIDS-UHFFFAOYSA-N

}}

Mepyramine, also known as pyrilamine, is a first-generation antihistamine, targeting the H₁ receptor as an inverse agonist. Mepyramine rapidly permeates the brain, often causing drowsiness.

{{cite web

|url= https://go.drugbank.com/drugs/DB06691

|title =Mepyramine

|access-date = 8 May 2021

|website=drugbank.com

}}

It is often sold as a maleate salt, pyrilamine maleate.

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).{{cite journal | vauthors = Kubo N, Shirakawa O, Kuno T, Tanaka C | title = Antimuscarinic effects of antihistamines: quantitative evaluation by receptor-binding assay | journal = Japanese Journal of Pharmacology | volume = 43 | issue = 3 | pages = 277–282 | date = March 1987 | pmid = 2884340 | doi = 10.1254/jjp.43.277 | doi-access = free }}

It was patented in 1943 and came into medical use in 1949.{{cite book | veditors = Fischer J, Gannelin CR |title=Analogue-based Drug Discovery |date=2006 |publisher=John Wiley & Sons |isbn=9783527607495 |page=545 |url=https://books.google.com/books?id=FjKfqkaKkAAC&pg=PA545 |language=en}}

It was marketed under the names Histadyl, Histalon, Neo-Antergan, Neo-Pyramine, and Nisaval.{{cite journal | vauthors = Thornton WE | title = Sleep aids and sedatives | journal = Journal of the American College of Emergency Physicians | volume = 6 | issue = 9 | pages = 408–412 | date = September 1977 | pmid = 330911 | doi = 10.1016/S0361-1124(77)80006-3 }} 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. The US Food and Drug Administration (FDA) included it in the list of chemicals and compounds barred from use in over-the-counter (OTC) nighttime sleep aid products in 1989.{{Federal Register|54|6826}}

It is used in over-the-counter combination products to treat the common cold and menstrual symptoms such as Midol Complete.{{Cite web |url=http://midol.com/menstrual_complete_caps.html#q1 |title=Active Ingredients for Midol Complete |access-date=2009-12-08 |archive-url=https://web.archive.org/web/20091202030735/http://www.midol.com/menstrual_complete_caps.html#q1 |work=Bayer HealthCare LLC |archive-date=2009-12-02 |url-status=dead}} It is also the active ingredient of the topical antihistamine creams Anthisan{{Cite web |url=https://www.medicines.org.uk/emc/product/1618/pil |title=Anthisan Cream - Patient Information Leaflet (PIL) |website=Medicines.org}} and Neoantergan{{cite journal | vauthors = Parsons ME, Ganellin CR | title = Histamine and its receptors | journal = British Journal of Pharmacology | volume = 147 | issue = Suppl 1 | pages = S127–S135 | date = January 2006 | pmid = 16402096 | pmc = 1760721 | doi = 10.1038/sj.bjp.0706440 | publication-date = 2009-02-02 }} sold for the treatment of insect bites, stings, and nettle rash.