Search results
Results from the WOW.Com Content Network
Antihistamines are drugs which treat allergic rhinitis, common cold, influenza, and other allergies. [1] Typically, people take antihistamines as an inexpensive, generic (not patented) drug that can be bought without a prescription and provides relief from nasal congestion, sneezing, or hives caused by pollen, dust mites, or animal allergy with few side effects. [1]
Mast cell stabilizers inhibit the release of allergic and inflammatory mediators, helping to prevent and treat allergic conditions. They work by blocking a calcium channel which is essential for mast cell degranulation , [ 21 ] inhibiting the release of histamine and other mediators from mast cells.
Histamine is a weak base (a compound able to react with a hydrogen ion to form an acid) that can link with acid groups within the granules of the mast cells. [8] The mechanism of the displacement theory. The crux of this theory lies in the assumption that histamine liberators release histamine by displacing it from cells.
Pain is due to the release of chemicals such as bradykinin and histamine that stimulate nerve endings. [15] Acute inflammation of the lung (usually in response to pneumonia) does not cause pain unless the inflammation involves the parietal pleura, which does have pain-sensitive nerve endings. [15]
An H 3 receptor antagonist is a type of antihistaminic drug used to block the action of histamine at H 3 receptors.. Unlike the H 1 and H 2 receptors which have primarily peripheral actions, but cause sedation if they are blocked in the brain, H 3 receptors are primarily found in the brain and are inhibitory autoreceptors located on histaminergic nerve terminals, which modulate the release of ...
H 1 antagonists, also called H 1 blockers, are a class of medications that block the action of histamine at the H 1 receptor, helping to relieve 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.
The C3a, C4a and C5a components are referred to as anaphylatoxins: [4] [5] they cause smooth muscle contraction, vasodilation, histamine release from mast cells, and enhanced vascular permeability. [5] They also mediate chemotaxis, inflammation, and generation of cytotoxic oxygen radicals. [5]
Other causes are side effects of topical decongestants such as oxymetazoline and phenylephrine. Both of these medications activate alpha-1 adrenergic receptors that result in smooth muscle constriction. Non-selective beta blockers are known to facilitate bronchospasm as well. Beta blockers bind to the β2 receptors and block the action of ...