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H2 Receptor Antagonists

H2 receptor antagonists are drugs which are used to try and reduce the acid production in the stomach. They were originally launched in the 1970s, and have a long history of use. In general they are very safe but they can cause occasional side effects.


H2 receptor antagonists work by blocking a type of histamine receptor (the H2 receptor). There are at least four different types of histamine receptor within human cells and each type is responsible for different functions. Anti histamine used for allergy and hay fever block H1 receptors. H3 receptors are involved in chemical messaging within the central nervous system, H4 receptors are involved in the mediation of allergic reactions via their effect on mast cells, whereas H2 receptors stimulate an intracellular chemical called cyclic adenosine monophosphate (cAMP), this then binds to an acid pump in the stomach lining stimulating the production of acid. H2 receptor antagonists block the receptor thus preventing the release and subsequent effects of cAMP.


Usually H2 receptor antagonists like ranitidine are used in patients with reflux, either who do not tolerate PPIs, or to try and confer additional benefit. They are effective in relieving symptoms in approximately 6/10 patients. Side effects include nausea, headache and abdominal bloating.

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