Histamine antagonist

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A histamine antagonist is an agent which serves to inhibit the release or action of histamine.

Although the term "antihistamine" could technically be used for any histamine antagonist, in practice the term is reserved for the classical antihistamines which act upon the H1 histamine receptor.

Clinical: H1- and H2-receptor antagonists

H1-receptor antagonists

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. [1]

H2-receptor antagonists

Clinically-relevant histamine H2-receptors are found principally in the parietal cells of the gastric mucosa. H2-receptor "antagonists" are also inverse agonists, rather than true antagonists; and are used to reduce the secretion of gastric acid. Examples include cimetidine, ranitidine, and famotidine.

Experimental: H3- and H4-receptor antagonists

These are experimental agents and do not yet have a defined clinical use.

H3-receptor antagonists

H4-receptor antagonists


Inhibitors of histamine release

These agents (mast cell stabilizers) appear to stabilise the mast cells to prevent degranulation and mediator release.

Other agents with antihistaminergic activity

Many drugs, used for other indications, possess unwanted antihistaminergic activity. These include tricyclic antidepressants, antipsychotics, etc.


  1. Leurs R, Church MK, Taglialatela M (2002). "H1-antihistamines: inverse agonism, anti-inflammatory actions and cardiac effects". Clin Exp Allergy. 32 (4): 489–98. PMID 11972592.

External links

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