Gourt > Health > Pharmacy > Drugs and Medications > Antihistamines
An antihistamine is a drug which serves to reduce or eliminate effects mediated by histamine, an endogenous chemical mediator released during allergic reactions, through action at the histamine receptor. Only agents where the main therapeutic effect is mediated by negative modulation of histamine receptors are termed antihistamines - other agents may have antihistaminergic action but are not true antihistamines.
In common use, the term antihistamine refers only to H1-receptor antagonists, also known as H1-antihistamines. It has been discovered that these H1-antihistamines are actually inverse agonists at the histamine H1-receptor, rather than antagonists per se. (Leurs, Church & Taglialatela, 2002)
Pharmacology
In allergic reactions an allergen (a type of antigen) 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. More on [ Antihistamine ]
Antihistamines - A brief overview of this group of medicines which help with the symptoms of allergies.
Antihistamines: Are Newer Drugs Always a Better Choice? - Medscape review of the properties and uses of these medications, including discussion of research on sedative side effects, and advice for medical professionals on how to use these drugs in treating allergic patients. [Requires free registration]
Prescription Antihistamine Database - Information about medications available by prescription in the U.S., arranged by drug name.
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