MCQs on antihistamines | medicinal chemistry | by pharmacy infoline

Antihistamines are drugs which treat rhinitis and other allergies. Typically people take antihistamines as a cheap , generic, over-the-counter medicine which will provide relief from nasal congestion, sneezing, or hives caused by pollen, dust mites, or animal allergy with few side effects. Antihistamines are usually for short-term treatment. Chronic allergies increase the danger of health problems which antihistamines won’t treat, including asthma, sinusitis, and lower tract infection. Consultation of a medical professional is suggested for those that shall take antihistamines for longer-term use. Although people typically use the word “antihistamine” to explain drugs for treating allergies, doctors and scientists use the term to explain a category of drug that opposes the activity of histamine receptors within the body. during this sense of the word, antihistamines are subclassified consistent with the histamine receptor that they influence . The 2 largest classes of antihistamines are H1-antihistamines and H2-antihistamines. H1-antihistamines work by binding to histamine H1 receptors in mast cells, smooth muscle, and endothelium within the body also as within the tuberomammillary nucleus within the brain. 

Antihistamines that focus on the histamine H1-receptor are wont to treat allergies within the nose (e.g., itching, runny nose, and sneezing). additionally , they’ll be wont to treat insomnia, kinetosis , or vertigo caused by problems with the internal ear. 

H2-antihistamines bind to histamine H2 receptors within the upper alimentary canal , primarily within the stomach. 

Antihistamines that focus on the histamine H2-receptor are wont to treat gastric acid conditions (e.g., peptic ulcers and acid reflux). Histamine receptors exhibit constitutive activity, so antihistamines can function as either a neutral receptor antagonist or an inverse agonist at histamine receptors. Only a couple of currently marketed H1-antihistamines are known to function as inverse agonists.

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