CONGESTAL 20 TABS

Description A histamine H1 antagonist used in allergic reactions hay fever rhinitis urticaria and asthma. Indication For the treatment of rhinitis urticaria allergy common cold asthma and hay fever. Pharmacodynamics In allergic reactions an allergen interacts with and cross-links surface IgE antibodies on mast cells and basophils. Once the mast cell-antibody-antigen complex is formed a complex series of events occurs that eventually leads to cell-degranulation and the release of histamine (and other chemical mediators) from the mast cell or basophil. Once released histamine can react with local or widespread tissues through histamine receptors. Histamine acting on H1-receptors produces pruritis vasodilatation hypotension flushing headache tachycardia and bronchoconstriction. Histamine also increases vascular permeability and potentiates pain. Chlorpheniramine is a histamine H1 antagonist (or more correctly an inverse histamine agonist) of the alkylamine class.