Receptors, Histamine H3Receptors, Histamine H1HistamineReceptors, Histamine H2Histamine H1 AntagonistsHistamine AgonistsHistamine H2 AntagonistsReceptors, HistamineHistamine AntagonistsHistamine H3 AntagonistsHistamine ReleaseMethylhistaminesChlorpheniramineDimapritCimetidineMetiamideThioureaImpromidineDiphenhydramineFamotidineHistamine N-MethyltransferaseHistamine AgentsPiperidinesRanitidinePyrilamineGuinea PigsBurimamideHistidine DecarboxylaseHistamine H1 Antagonists, Non-SedatingDose-Response Relationship, DrugDoxepinIsothiuroniump-Methoxy-N-methylphenethylamineRadioligand AssayTripelennamineTerfenadineImidazolesReceptors, G-Protein-CoupledGastric AcidTriprolidineMast CellsHormone AntagonistsKetotifenRats, WistarRats, Sprague-DawleyDibenzoxepinsDopamine AntagonistsNeurokinin-1 Receptor AntagonistsExcitatory Amino Acid AntagonistsGuanidinesBinding, CompetitiveBetahistinePruritusNarcotic AntagonistsCetirizineGastric MucosaMuscle, SmoothIndolesPyridinesMuscarinic AntagonistsInterleukin 1 Receptor Antagonist ProteinDibenzazepinesMolecular StructureAnaphylaxisStructure-Activity RelationshipDrug Inverse AgonismCells, CulturedDrug InteractionsPiperazinesAstemizoleCyproheptadineNizatidineMuscle ContractionGABA AntagonistsCyclic AMPLigandsBenzazepinesAnti-Allergic AgentsPurinergic P1 Receptor AntagonistsDimethindeneTime FactorsBasophilsSerotoninIleumGastric JuicePentagastrinNicotinic AntagonistsStomachCricetinaeBiphenyl CompoundsTracheaAdenosine A2 Receptor AntagonistsKineticsPromethazinePheniramineAdrenergic alpha-1 Receptor AntagonistsCHO CellsDogsPurinergic P2 Receptor AntagonistsStereoisomerism