Indomethacin inhibits duodenal mucosal bicarbonate secretion and endogenous prostaglandin E2 output in human subjects.

Nonsteroidal anti-inflammatory drugs are a frequent cause of gastric and duodenal mucosal injury. We examined the effect of indomethacin on duodenal mucosal bicarbonate secretion and prostaglandin output in healthy subjects. Subjects received either 50 mg of indomethacin or placebo orally 13 hours and 1 hour before study. A 4-cm segment of proximal (the duodenal bulb) or distal (10 to 14 cm beyond the pylorus) duodenum was isolated and perfused with 154 mM NaCl containing a nonabsorbable marker. In the proximal duodenum indomethacin reduced both basal and acid-stimulated bicarbonate secretion by approximately 65% (p less than 0.01); in the distal duodenum indomethacin decreased basal and acid-stimulated bicarbonate output by approximately 45% (p less than 0.01). Oral indomethacin inhibited basal and acid-stimulated duodenal prostaglandin E2 output in both the proximal and distal duodenum. We conclude that, by decreasing duodenal mucosal bicarbonate production and prostaglandin output in humans, oral indomethacin, in two doses of 50 mg each, impairs an important duodenal defense mechanism.