title: BL-5255, a tetrazolylpyrimidinone with potent oral antiallergy activity in animals.
abstract: BL-5255, 2-(2-n-propoxyphenyl)-5-(5-1 H-tetrazolyl)pyrimidin-4 (3H)-one, effectively inhibited allergic reactions in sensitized rats or guinea pigs when administered by oral or intravenous routes as the water-soluble sodium or ethanolamine monohydrate salts. In the IgE-mediated rat PCA, BL-5255 was 50 times more potent than disodium cromoglycate by intravenous administration. When administered orally in this model, BL-5255 inhibited the PCA reaction by 50% at 0.1 mg/kg. At less than 0.1 mg/kg p.o., the compound protected conscious actively sensitized guinea pigs from aerosolized antigen-induced collapse. In N. brasiliensis-sensitized rats, BL-5255 administered at 0.1--10 mg/kg p.o. inhibited antigen-induced airway constriction in a dose-related manner. BL-5255 is not a histamine or serotonin antagonist but appears to exert its antiallergic effect by inhibiting the release of mediators.
mesh_terms: D000284:Administration, Oral; D000402:Airway Obstruction / Q000188:drug therapy; D000818:Animals; D001393:Azoles / Q000627:therapeutic use*; D004305:Dose-Response Relationship, Drug; D006168:Guinea Pigs; D006634:Histamine H1 Antagonists; D006636:Histamine Release / Q000187:drug effects; D006967:Hypersensitivity / Q000188:drug therapy*; D006969:Hypersensitivity, Immediate / Q000276:immunology; D008297:Male; D010323:Passive Cutaneous Anaphylaxis; D011744:Pyrimidinones / Q000627:therapeutic use*; D051381:Rats; D013777:Tetrazoles / Q000627:therapeutic use*
chemical_list: D001393:Azoles; D006634:Histamine H1 Antagonists; D011744:Pyrimidinones; D013777:Tetrazoles; C021943:BL 5255