What is histamine antagonist?

Histamine antagonist (histamine antagonist) is a kind of drug that binds the histamine specific receptor of chemical messenger and prevents the chemical from acting in the body Some of these drugs, also known as histamines, reduce vasodilation in response to common allergic symptoms such as runny nose and swelling Early versions of these drugs also had a wide range of neurological effects, including sedation, but later products were more targeted In addition, there is an histamine antagonist that can prevent gastric acid secretion and can be used to treat dyspepsia Histamine is an improved histidine form that increases the permeability of blood vessels to immune system cells, allowing them to reach infection and injury sites Histamine antagonists are chemicals that bind H1 or H2 histamine receptors and block their activity in vivo When it binds to H1 receptor of respiratory epithelium, histamine mediates nasal infection and dyspnea caused by allergy Another type of histamine receptor, H2, releases digestive acid through gastric parietal cells Anaphylaxis is an allergy that induces the release of histamine and regulates the immune cascade of vasodilation Histamine antagonists called antihistamines bind to H1 receptors in the respiratory epithelium This prevents the receptor from causing common allergic symptoms Runny nose and tears associated with allergies are the result of vasodilation blocked by antihistamines Sneezing is partly caused by receptors in the nasal nerve, which antihistamines prevent from being activated Although histamine antagonists block the chemical's activity, they do not prevent the body from producing them The first generation antihistamines, such as diphenhydramine, have sedative side effects and often cause drowsiness Sometimes they are used as over-the-counter drugs to aid sleep and have a mild sedative effect This effect is due to the fact that these drugs are not very selective for H1 receptor, and have a certain range of inhibitory effects on the nervous system, such as inducing sleep Serotonin receptor is a site of antihistamine action Second generation histamine antagonists, such as loratadine, are specially designed for more specific H1 histamine antagonists, with much fewer side effects than early drugs Gastric acid is secreted by gastric parietal cells in response to chemical messengers, including histamine Too much stomach acid is one of the causes of indigestion or heartburn The early antacids had the effect of histamine antagonists, competing with histamine, binding H2 receptor and preventing gastric acid release from gastric parietal cells Cimetidine is an example of an H2 receptor blocker used to treat dyspepsia, sometimes to relieve symptoms of peptic ulcer Another drug for heartburn is proton pump inhibitors, which have been shown to be more effective than histamine antagonists.