A histamine antagonist is an agent that serves to inhibit the release or action of histamine. Antihistamine can be used to describe any histamine antagonist, but it is usually reserved for the classical antihistamines that act upon the H1 histamine receptor.
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antihistamine (drug) -- Britannica Online Encyclopedia
... online encyclopedia article on antihistamine (drug), any of a ... BLOG. LOG IN. Skip this Advertisement. Encyclopædia Britannica. Audio / Video. Contributors ...www.britannica.com/EBchecked/topic/28127/antihistamineAntihistamines: Soothe Your Sinuses on Yahoo! Health
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For sniffles and sneezing bouts brought about by hay fever or allergies ... Parenting a Child with Food Allergy (Blog) Revolution Health- Child Food Allergies ...www.allergizer.com/50226711/whats_your_preferred_antihistami...Allergies and Asthma: The Best Antihistamines for Sneezing and Nasal ...
The Allergies and Asthma blog has now been retired. ... To determine which is best antihistamine, I read the most recent studies, which ...blogs.webmd.com/allergies-and-asthma/2008/04/best-antihistam...A histamine antagonist is an agent that serves to inhibit the release or action of histamine. Antihistamine can be used to describe any histamine antagonist, but it is usually reserved for the classical antihistamines that act upon the H1 histamine receptor.
Antihistamines are used as treatment for allergies. Allergies are caused by an excessive response of the body to allergens, such as the pollen released by grasses and trees. An allergic reaction indicates an excessive release, by the body, of histamines.
H1-receptor antagonists
main: l1=H1 antagonist
In common use, the term antihistamine refers only to H1 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. Clinically, H1 antagonists are used to treat allergic reactions.
Examples:
- Diphenhydramine
- Loratadine
- Desloratadine
- Meclizine
- Quetiapine (this is a side-effect of a drug usually used as an antipsychotic)
- Fexofenadine
- Pheniramine
- Cetirizine
- Promethazine
- Chlorpheniramine
H2-receptor antagonists
main: l1=H2 antagonist
H2 antagonists, like H1 antagonists, are also inverse agonists and not true antagonists. H2 histamine receptors are found principally in the parietal cells of the gastric mucosa. H2 antagonists are used to reduce the secretion of gastric acid, treating gastrointestinal conditions including peptic ulcers and gastroesophageal reflux disease.
Examples:
- Cimetidine
- Famotidine
- Ranitidine
- Nizatidine
- Roxatidine
- Lafutidine
Experimental: H3- and H4-receptor antagonists
These are experimental agents and do not yet have a defined clinical use, although a number of drugs are currently in human trials. H3-antagonists have a stimulant and nootropic effect, and are being investigated for the treatment of conditions such as ADHD, Alzheimer's Disease, and schizophrenia, whereas H4-antagonists appear to have an immunomodulatory role and are being investigated as antiinflammatory and analgesic drugs.
H3-receptor antagonists
main: l1=H3 antagonist Examples:
- A-349,821
- ABT-239
- Ciproxifan
- Clobenpropit
- Thioperamide
H4-receptor antagonists
Examples:
- Thioperamide
- JNJ 7777120
- VUF-6002
Inhibitors of histamine release
These agents (mast cell stabilizers) appear to stabilize the mast cells to prevent degranulation and mediator release.


























