Sedating antihistamines mechanism of action
This chapter focuses on the H They are very useful drugs, because approximately 10% to 20% of the general population is sensitive to various environmental allergens.Histamine is a major inflammatory mediator in many allergic disorders, such as allergic rhinitis (e.g., hay fever and mold, dust allergies), anaphylaxis, angioedema, drug fevers, insect bite reactions, and urticaria (itching).
Because some preparations have a high alcohol content, they may cause acetaldehyde syndrome in patients taking disulfiram (Antabuse) to prevent alcohol abuse (see Chapter 17).
Histamine 1 (H) receptors mediate acceleration of the heart rate and gastric acid secretion.
The release of excessive amounts of histamine can lead to anaphylaxis and severe allergic symptoms and may result in any or all of the following physiologic changes: Echinacea has been shown in clinical trials to reduce cold symptoms and recovery time when taken early in the illness.
Treatment of the common symptoms of URI involves the combined use of antihistamines, nasal decongestants, antitussives, and expectorants. This followed numerous case reports of symptoms such as oversedation, seizures, tachycardia, and even death in toddlers.
There is also evidence that such medications are simply not effective in small children, and parents are advised to consult their pediatrician on the best ways to manage these illnesses.