H 2 receptor antagonists

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H 2 -receptor antagonists are antihistamines used to inhibit gastric acid secretion . They are used to treat peptic ulcers, gastric acid hypersecretion and secondary syndromes (reflux).

effect

During digestion, enterochromaffin-like cells in the gastric mucosa release histamine , which stimulates the production of gastric acid in parietal cells of the gastric mucosa. The secretion of histamine is controlled by the vagus nerve acetylcholine -mediated. H 2 antagonists block the uptake of histamine by the H 2 receptor of parietal cells and thus inhibit gastric acid secretion . The degree of inhibition of secretion is lower than with proton pump inhibitors . H 2 -antagonists inhibit the basal (nocturnal) acid secretion by up to 90%, the stimulated secretion - z. B. through food intake - but only by about 50%.

Active ingredients

H 2 antagonists are modeled after the lead substance histamine. They generally have a plasma half-life of about two to three hours; the oral bioavailability is variable, from 40% ( famotidine ) to 90% ( nizatidine ). The first effective preparation was cimetidine , which came on the market in the 1970s.

unwanted effects

Rarely (<1%) headache, tiredness, dizziness, diarrhea and constipation can occur.

The active ingredient cimetidine has an antiandrogenic effect. It also inhibits several cytochrome P450 isoenzymes and can thus influence the metabolism of other medicinal products. This does not apply to the other H 2 antagonists.

Others

In Germany, after proton pump inhibitors, H 2 antagonists are the most widely prescribed drugs for the treatment of peptic ulcers.

The causes of the underlying disorder should be analyzed before use. The most common causes of ulcer disease are Helicobacter pylori infection and use of NSAIDs .

literature

Web links

  • KF Sewing, W. Beil, H. Hannemann: Comparative pharmacology of histamine H2-receptor antagonists. In: Drugs. 35 Suppl 3, 1988, pp. 25-29. PMID 2905246
  • H. Yamagishi, T. Koike, S. Ohara, T. Horii, R. Kikuchi, S. Kobayashi, Y. Abe, K. Iijima, A. Imatani, K. Suzuki, T. Hishinuma, J. Goto, T. Shimosegawa: Stronger inhibition of gastric acid secretion by lafutidine, a novel H2 receptor antagonist, than by the proton pump inhibitor lansoprazole. In: World J Gastroenterol. 14 (15), 2008 Apr 21, pp. 2406-2410. PMID 18416470

See also