Omeprazole-induced changes in gastric mucus secretion.

The influence of omeprazole treatment on gastric mucus secretion in man was examined in two separate studies. 24 outpatients with endoscopic duodenitis but normal gastric mucosa were treated under double-blind conditions with either omeprazole 20 mg o.m. or placebo for four weeks. Omeprazole was found to induce a significant reduction (p less than 0.001) in the amount of neutral and total mucoproteins into the gastric juice and in the viscous and protective properties of mucus as assessed by a Mucoprotective Index. In a subsequent study 12 omeprazole-treated patients were re-examined either 10 days (6 patients) or 15 days (6 patients) after the drug withdrawal. A trend towards normalization of mucus secretion was detectable already after 10 days, but only at 15 days did gastric mucus fully revert to normal. The results suggest that the decrease in the quantity and quality of mucus secretion observed with omeprazole is a transient phenomenon, secondary to the sustained acid suppression induced by the drug and clinically irrelevant.