H2 antagonist

H ₂ - receptor antagonists are anti-histamines for inhibiting gastric acid secretion. They are used to treat peptic ulcers, gastric acid hypersecretion and subsequent syndromes ( gastroesophageal reflux disease).

Effect

During digestion give off enterochromaffinartige cells of the gastric mucosa histamine, which stimulates the production of stomach acid in the 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 gastric parietal cells and thus inhibit gastric acid secretion. The extent of inhibition of secretion is less than that of the proton pump inhibitors. H ₂ antagonists inhibit the basal ( nocturnal) acid secretion though up to 90 %, the stimulated secretion, for example by ingestion, but only by about 50%.

Agents

H ₂ antagonists are modeled after the lead compound histamine. They generally have a plasma half -life of approximately 2-3 hours, the oral bioavailability is variable by 40% ( famotidine ) to 90 % ( nizatidine ). The first effective drug was cimetidine, which came on the market in the 1970s.

  • Cimetidine
  • Ranitidine
  • Famotidine
  • Nizatidine
  • Roxatidine
  • Lafutidin

Adverse effects

Rare ( <1%) are headache, fatigue, dizziness, diarrhea and constipation.

The drug cimetidine has an antiandrogenic effect. It inhibits beyond several cytochrome P450 isoenzymes, and thus affect the metabolism of other drugs. On the other H ₂ antagonists is not true.

Others

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

Before applying the causes of the underlying disorder should be analyzed. The most common causes of peptic ulcer disease are infection with Helicobacter pylori and the intake of NSAIDs.

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