Effects of eight-week treatment with histamine H2-antagonists or an antacid on plasma levels of histamine and serotonin in duodenal ulcer patients.

The effects of 8-week treatment with oral histamine H2-antagonists (ranitidine or cimetidine) or an antacid on plasma levels of histamine and serotonin were studied in duodenal ulcer patients. Histamine H2-antagonists significantly elevated plasma histamine levels, however, they markedly decreased serotonin concentrations by the 4th week of treatment. Antacid treatment similarly increased histamine levels without significantly affecting blood serotonin. It is concluded that changes in intragastric or intraduodenal acidity affect histamine release, as reflected by increased blood levels; serotonin secretion could be influenced by blocking histamine H2-receptors, possibly those located mainly in the gastrointestinal tract.