Search results
Results from the WOW.Com Content Network
Type I hypersensitivity (or immediate hypersensitivity), in the Gell and Coombs classification of allergic reactions, is an allergic reaction provoked by re-exposure to a specific type of antigen referred to as an allergen. [1] Type I is distinct from type II, type III and type IV hypersensitivities. The relevance of the Gell and Coombs ...
They block mast cell degranulation, stabilizing the cell and thereby preventing the release of histamine and related mediators. One suspected pharmacodynamic mechanism is the blocking of IgE-regulated calcium channels. Without intracellular calcium, the histamine vesicles cannot fuse to the cell membrane and degranulate. [1]
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.
Anti-allergic agents are medications used to treat allergic reactions. Anti-allergic agents have existed since 3000 B.C in countries such as China and Egypt.It was not until 1933 when antihistamines, the first type of anti-allergic agents, were developed. [1]
A-fragments form distinct structural domains of approximately 76 amino acids, coded for by a single exon within the complement protein gene. 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]
Histamine release in the brain triggers secondary release of excitatory neurotransmitters such as glutamate and acetylcholine via stimulation of H 1 receptors in the cerebral cortex. Consequently, unlike the H 1 -antihistamines which are sedating, H 3 -antihistamines have stimulant and cognition-modulating effects.
Bilastine is an antihistamine medication used to treat hives (), allergic rhinitis and itchy inflamed eyes (allergic conjunctivitis) caused by an allergy. [6] It is a second-generation antihistamine and takes effect by selectively inhibiting the histamine H 1 receptor, preventing these allergic reactions. [7]
Chloropyramine is known as a competitive reversible H 1 receptor antagonist (also known as an H 1 inverse agonist), meaning that it exerts its pharmacological action by competing with histamine for the H 1 subtype histamine receptor. By blocking the effects of histamine, the drug inhibits the vasodilation, increased vascular permeability, and ...