Histamine-2-receptor antagonists: standard therapy for acid-peptic diseases

Article Abstract:

In a continuation of their article published in a previous issue of The New England Journal of Medicine, the authors discuss the therapeutic use of H2 blockers. This class of drug blocks the type of histamine receptor found on the acid-secreting cells of the stomach. This receptor is distinct from the histamine receptor on mast cells, which is responsible for allergic responses and is called the H1 receptor. The authors discuss four effective H2 blocker drugs, although only two, cimetidine and ranitidine, have been approved for use in the United States. All four drugs are effective in the treatment of duodenal ulcers and gastric ulcers. However, ulcers are generally recurring disorders, and the drugs are not particularly effective in the maintenance of ulcer patients or the prevention of ulcer recurrence. Furthermore, it should be emphasized that the H2 blockers are not approved for this use. Prostaglandin analogues such as misoprostol may prove to be more useful in the prevention of recurrences. The H2 blockers may be somewhat more effective, however, in the prevention of recurring ulcers which are specifically a result of stomach surgery or section of the vagus nerve. H2 blockers can also be effective in the treatment of Zollinger-Ellison syndrome, a condition in which gastric ulcers and hypersecretion of acid are associated with pancreatic tumors. Evidence is mixed on the question of whether H2 blockers are effective in the treatment of gastroesophageal reflux, or heartburn, in which stomach acids back up into the esophagus and damage the tissue. Ranitidine, but not cimetidine, is approved for the treatment of gastroesophageal reflux, but some studies have concluded that the contribution of the drug to healing is small. The stress involved in major physical trauma, such as a serious medical condition or physical injury, may result in some erosion of the stomach lining, known as a stress ulcer. However, H2 blockers are not approved in the United States for the prevention of bleeding from stress ulcers. (Consumer Summary produced by Reliance Medical Information, Inc.)

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Histamine-2-receptor antagonists: standard therapy for acid-peptic diseases

Article Abstract:

H2 blockers are a class of drugs that can be useful in treating acid-peptic disorders, such as peptic ulcer disease. The authors provide and in-depth review of the properties of these drugs, including pharmacokinetics and the possible interactions with other drugs. Currently, four H2 blockers are marketed in the US: cimetidine, ranitidine, famotidine, and nizatidine. These drugs work by blocking the histamine-2 receptor on the parietal cells lining the stomach and reducing the secretion of stomach acid by these cells. Histamine-2 receptors are distinct from histamine-1 receptors, which are blocked by conventional antihistamine drugs. Histamine-2 receptors are also present on T cells, and thus H2 blockers can influence the cellular immune system, but not all H2-blockers affect the immune system equally. Cimetidine augments cellular immune reactions, but ranitidine and famotidine do not exert this effect. Some reports have indicated that this augmentation may be used to therapeutic advantage. The H2 blockers are relatively free from adverse side effects, but serious adverse effects may occur in patients with impaired kidney function, impaired liver function, advanced age, or other risk factors. More common is the frequency of adverse interactions with other drugs. Cimetidine, and to a lesser degree ranitidine, binds to the heme portion of enzymes of the cytochrome P-450 system. The cytochrome P-450 system is a system of liver enzymes responsible for metabolizing many foreign substances and plays a key role in the protection of the body against poisons. However, since many drugs are also metabolized by the P-450 system, any inhibition of this system by cimetidine may radically alter the fate of the drug in the body. At least 41 different drugs have been found to interact with cimetidine; therefore, care must be taken when prescribing other medications to patients receiving cimetidine. (Consumer Summary produced by Reliance Medical Information, Inc.)

Antihistamines

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Misoprostol for the treatment of peptic ulcer and antiinflammatory-drug-induced gastroduodenal ulceration

Article Abstract:

Misoprostol is a drug being examined for the prevention and treatment of peptic ulcers and ulcers caused by nonsteroidal antiinflammatory drugs (NSAID). This drug decreases the secretion of stomach acid in response to food, coffee and other substances. Diarrhea is the most common side effect of misoprostol, and severe diarrhea can cause some patients to discontinue its use. Pregnant women should not take misoprostol because it can cause a miscarriage. Misoprostol may not be more effective than other drugs for the treatment of stomach ulcers or duodenal ulcers, and it may cause a larger number of side effects. Treatment with NSAIDs can cause damage to the gastrointestinal tract. Misoprostol may not be effective for the treatment of ulcers caused by NSAIDs, but it may prevent severe damage to the gastrointestinal tract caused by NSAIDs.

Health aspects, Misoprostol, Duodenal ulcer

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