Omeprazole Absorption and Fasting Gastrinemia After Roux-en-Y Gastric Bypass

Purpose Roux-en-Y gastric bypass (RYGB) is one of the bariatric surgeries most frequently performed worldwide. Since this operation may predispose to the formation of peptic ulcer of the gastrojejunal anastomosis, the use of proton pump inhibitors (PPI) is recommended during the first postoperative year. However, so far, there is no detailed knowledge about the absorption of this medication during the immediate postoperative period and consequently about its effectiveness in blocking acid secretion. The objective was to assess the possible endoscopic peptic changes, the absorption of omeprazole (OME), and the status of fasting gastrinemia before and after RYGB operation. Materials and Methods OME absorption, the production of its metabolites omeprazole sulfone (OMES) and 5-hydroxyomeprazole (HOME), and basal (fasting) gastrinemia were determined in patients submitted to RYGB before and 2 months after the operation. Upper digestive endoscopy (UDE) was also performed before and 6 months after the operation. Results Twenty patients were studied. Preoperatively, all these patients had some peptic changes and 55% tested positive for Helicobacter pylori. Six months after surgery, ten patients still showed endoscopic changes and one patient tested positive for H. pylori. During the postoperative period, there was a reduction of OME absorption and of the production of its metabolites 90 min after administration of the drug, and reduction of serum gastrin levels. Conclusion The standard OME dose (40 mg) administered after bariatric surgery is insufficient to achieve serum levels that can effectively block the production of hydrochloric acid, permitting the formation of peptic injuries in many patients.