An H1 antagonist is a histamine antagonist of the H1 receptor that serves to reduce or eliminate effects mediated by histamine, an endogenous chemical mediator released during allergic reactions. 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 on...
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Antihistamine
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