Histamine H2-receptor antagonists.

In summary, histamine initiates acid secretion by stimulating the H2 subtype histamine receptor on parietal cells. Cimetidine, rantidine, famotidine, and nizantidine are histamine H2-receptor antagonists that block this action of histamine, reducing gastric acid output and concentration under both basal and stimulated conditions. These agents are used for treatment and prevention of peptic and stress ulcers as well as for hypersecretory states. Because of their effectiveness and low incidence of side effects, H2-antagonists have largely replaced more traditional antiulcer regimens.