ChlorpheniraminePhenylephrineHistamine H1 AntagonistsReceptors, Histamine H1ButyrophenonesDimethindeneHistamine AntagonistsHistamineTriprolidineReceptors, Histamine H2DimapritMetiamideReceptors, HistamineBurimamideHistamine H2 AntagonistsHydroxyzineClemastineKetotifenCimetidineMethylhistaminesHistamine AgonistsPyrilamineDiphenhydramineAdrenergic alpha-AgonistsImpromidineStereoisomerismGuinea PigsAdrenergic alpha-1 Receptor Agonists