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H 1 antagonists, also called H 1 blockers, are a class of medications that block the action of histamine at the H 1 receptor, helping to relieve allergic reactions. Agents where the main therapeutic effect is mediated by negative modulation of histamine receptors are termed antihistamines ; other agents may have antihistaminergic action but are ...
They are the most potent inhibitors of acid secretion available. The group followed and has largely superseded another group of pharmaceuticals with similar effects, but a different mode of action, called H 2-receptor antagonists. These drugs are among the most widely sold drugs in the world, and are generally considered effective. [3]
Ball-and-stick model of cimetidine, the prototypical H 2 receptor antagonist. H 2 antagonists, sometimes referred to as H2RAs [1] and also called H 2 blockers, are a class of medications that block the action of histamine at the histamine H 2 receptors of the parietal cells in the stomach. This decreases the production of stomach acid.
There are four main types: H1, H2, H3, and H4. H1 receptors are linked to allergic responses, H2 to gastric acid regulation, H3 to neurotransmitter release modulation, and H4 to immune system function. There are four known histamine receptors: H 1 receptor H1 Receptors: These receptors are primarily located on smooth muscle cells, endothelial ...
A study from 2019 showed that PPI use alone and together with histamine H2-receptor antagonists was associated with an increased bone fracture hazard, which was amplified by days of use and earlier initiation of therapy. [38] The reason is not clear; increased bone break down by osteoclasts has been suggested. [39]
Drug interactions can be of three kinds: additive (the result is what you expect when you add together the effect of each drug taken independently), synergistic (combining the drugs leads to a larger effect than expected), or; antagonistic (combining the drugs leads to a smaller effect than expected). [3]
The action of drugs on the human body (or any other organism's body) is called pharmacodynamics, and the body's response to drugs is called pharmacokinetics. The drugs that enter an individual tend to stimulate certain receptors, ion channels, act on enzymes or transport proteins. As a result, they cause the human body to react in a specific way.
Hydroxyzine can also be used for the treatment of allergic conditions, such as chronic urticaria, atopic or contact dermatoses, and histamine-mediated pruritus. [ medical citation needed ] These have also been confirmed in both recent and past studies to have no adverse effects on the liver, blood, nervous system, or urinary tract.