Question

Why do antihistamines not affect the secretion of acid in the stomach?

Answer 1

The action of antihistamines depends on receptors. If there is no favourable receptor found, antihistamine will not do its necessary action.

Complete step by step solution:
-When histamine, a chemical created by your system, overreacts to an allergen like pollen and pet dander, it can cause symptoms like coughing, sneezing and watery eyes. -Antihistamines are medications that help with allergies, and also with stomach problems, cold, anxiety and more
-Antihistamines are a category of medication commonly wont to treat symptoms of allergies. These drugs help treat conditions caused by an excessive amount of histamine, a chemical created by our body’s system. Antihistamines are most typically utilized by those that have sensitivity to pollen and other allergens. they're also want to treat a range of other conditions like stomach problems, colds, anxiety and more.
-Receptors are proteins, usually cell surface receptors, which bind to ligands and cause responses within the system, including cytokine receptors, protein receptors and Fc receptors. Receptors are found in various immune cells like B cells, T cells, NK cells, monocytes and stem cells. A molecule that binds to a receptor is called as a ligand, and may be a peptide, also called short-protein or another small molecule like a neurotransmitter, hormone, pharmaceutical-drug, toxin, or parts of the surface of an outbreak or microbe. When a ligand binds to its corresponding receptor, it does activate or inhibits the receptor's pathway of the biochemical reaction.
-Receptors can induce cell growth, division and death; control membrane channels or regulate cell binding. Receptors play a very important role in signal transduction, immunotherapy and immune responses.
-Receptors are proteins that bind to ligands like hormones and are accountable for mediating the effect of the ligand. For a ligand the various cells have receptors with different characteristics.
-Histamine receptors are of 4 different kinds. H1 receptors are present on air passages, blood vessels while stomach cells express H2 receptors.
-The H2 receptor antagonists (H2RA) are a category of medication which are accustomed to block the action of histamine on parietal cells (specifically the histamine H2 receptors) within the stomach, decreasing the assembly of acid by these cells.

-The common antihistamines block the binding of histamine to H1 receptors but not H2 receptors and thus don't affect the secretion of digestive juice.

Note: Side effects of antihistamines include sleepiness, dizziness, dry nose, upset stomach, weight gain along with some changes in feelings too. Long term usage of antihistamines can contribute to neurodegenerative diseases. Moreover, some old antihistamines can cause memory loss, by crossing the blood brain barrier.