Antihistamines are drugs that counteract the effects of histamine released from mast cells in the body, helping to prevent reactions triggered by stress, inflammation, or allergy. They work by binding to histamine receptor sites in tissues, blocking histamine’s effects. Certain antihistamines can also treat motion sickness and vomiting.
What are the most common antihistamines used in equine medicine?
Unfortunately, information on the most common antihistamines specifically used in equine medicine is not available in the search results. However, the search results do discuss common antihistamines in general. The first antihistamines introduced were H1 receptor antagonists, which counteract histamine’s effects, excluding those on gastric secretion. Examples of H1 receptor antagonists include diphenhydramine, chlorpheniramine, promethazine, and loratidine.
How do antihistamines work?
Antihistamines work by replacing histamine at its receptor sites, preventing histamine from binding and triggering reactions in susceptible tissues. This action helps alleviate symptoms associated with allergies, inflammation, and other conditions related to histamine release.
What conditions do antihistamines treat?
H1 antihistamines can alleviate symptoms of allergic conditions like seasonal hay fever, relieving sneezing, runny nose, and itching. They are more effective in controlling acute conditions, such as the beginning of hay-fever season, and can also treat acute urticarial rashes and insect bites. However, they have limited value for perennial vasomotor rhinitis and are not typically effective for asthma.
What are the side effects of antihistamines?
H1 antihistamines are generally safe, with the most common side effect being drowsiness. Newer H1 antihistamines are designed to minimize this effect by not crossing the blood-brain barrier. Some antihistamines, like diphenhydramine and promethazine, can prevent and treat motion sickness due to their effects on the central nervous system. However, these can impair performance while driving and enhance the effects of alcohol and other depressants.
What are H1 receptor antagonists?
H1 receptor antagonists are a type of antihistamine that binds to H1 receptor sites, selectively opposing the pharmacological effects of histamine, except for those on gastric secretion. These were developed starting around 1937, with the discovery of compounds that protect against the lethal effects of histamine and anaphylactic shock. Examples include diphenhydramine, chlorpheniramine, promethazine, and loratidine.
While the search results do not specify the most common antihistamines in equine medicine, they provide a general overview of how antihistamines work, what they treat, and their potential side effects.
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