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Posted by on May 11, 2013 in The Treatments |

Histamine Blockade

Histamine Blockade

Do you want to know more about H1-H2 blockers? Head for the forums in The Pharmacy to discuss!

When mast cells degranulate, either spontaneously (for no reason whatsoever) or due to a particular trigger, hundreds of chemical agents are released into the body. One of these chemicals is Histamine. If you are a mastocytosis patient, you will often experience elevated levels of histamine in your tissues as you have an overabundance of trigger-happy mast-cells.

Increased histamine causes irritation and inflammation in various parts of the body. The most common places histamine causes a reaction is in the skin, the nasal passages and the bronchial tubes. It also causes excess stomach acid to be produced, thereby causing heartburn.

In mastocytosis patients, the effect of histamine can be devastating and could even be lethal in some instances.

In order to contain the effects of histamine release, H1 receptor blockers are used to stem the impact of histamine on airways, lungs, nose and mouth. H2 receptor blockers are used to control the amount of stomach acid produced.

How Do H1 Blockers Work?

Watch this 1:21 min snippet to find out.

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How Do H2 Blockers Work?

H2 blockers, which are also called H2-receptor antagonists, are medicines used to reduce the amount of acid the stomach produces. H2 blockers work by blocking the histamine receptors in acid producing cells in the stomach. Parietal cells are cells that are the source of the hydrochloric acid (gastric acid) and most of the water in the stomach's digestive juices. These cells produce hydrochloric acid in response to a combination of three things: histamine (via H2 receptors), gastrin (via gastrin receptors), and acetylcholine (via M3 receptors). H2 blockers can be used to treat acid reflux by blocking the effects of histamine on parietal cells.

Watch this short 7 sec. clip to see the acid producing (parietal) cells and the 3 receptors mentioned above, one of which is the H2 receptor on which histamine binds.

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H2 blockers are used for the treatment of symptoms of gastroesophageal reflux disease, and also for the treatment of diseases like peptic ulcers, gastritis, and esophagitis. H2 blockers act very quickly (the effects are seen after 1 hr) but the do not last very long (about 12 hours).

The H2 blockers that are available are similar in how they work. They can be different in how they interact with other medications you are taking. For this reason you should talk to your doctor about which H2 blocker you can take based on what other medication you are taking. Here are some typical brand names of H2 blockers:

  • Prescription
    • Tagamet (cimetideine)
    • Pepcid (famotidine)
    • Axid (nizatidine)
  • Over-the-counter
    • Tagamet-HB
    • Pepcid-AC
    • Axid AR

There is recent evidence that  prolonged use increases the risk of hip fractures by 18% in individuals already at risk due to other conditions. It does not increase the risk of hip fractures if you do not have an elevated risk already.  (Proton Pump Inhibitors and Histamine-2 Receptor Antagonists Are Associated With Hip Fractures Among At-Risk Patients) so try and be on the lowest effective dose if possible, due to altered calcium absorption.