dimetindene dimetindene dimetindene , also sold under the brand name fenistil, is an antihistamine/anticholinergic. it is a first generation selective h1 antagonist. dimetindene is an atypical first generation h1 antagonist as it only minimally passes across the blood–brain barrier. dimetindeneclinical datatrade namesfenistilahfs/drugs.cominternational drug namesroutes ofadministrationoral, topicalatc coded04aa13 (who) r06ab03 (who)legal statuslegal status au: s4 (prescription only) uk: general sales list (gsl, otc) identifiers iupac name n,n-dimethyl-2-ethan-1-amine cas number5636-83-9 y 3614-69-5pubchem cid21855drugbankdb08801 ychemspider20541 yunii661fh77z3pkeggd07853 ychemblchembl22108 ycomptox dashboard (epa)dtxsid9022942 echa infocard100.024.622 chemical and physical dataformulac20h24n2molar mass292.426 g·mol−13d model (jsmol)interactive imagechiralityracemic mixture smiles n1ccccc1c(c=3c2ccccc2cc=3ccn(c)c)c inchi inchi=1s/c20h24n2/c1-15(19-10-6-7-12-21-19)20-17(11-13-22(2)3)14-16-8-4-5-9-18(16)20/h4-10,12,15h,11,13-14h2,1-3h3 ykey:mvmqesmqsyovgv-uhfffaoysa-n y (verify) dimetindene is also an m2 receptor antagonist. it was patented in 1958 and came into medical use in 1960. medical use dimetindene is used orally and topically as an antipruritic. it is used topically to treat skin irritations, such as insect bites. dimetindene is also administered orally to treat allergies, such as hay fever. it is commonly formulated as its maleic acid salt, dimethindene maleate. names it is sold under the brand name fenistil among others.