Omeprazole increased small intestinal mucosal injury in two of six disease-free cases evaluated by capsule endoscopy.

Recently, a report showed that proton-pump inhibitors (PPI) exacerbate non-steroidal anti-inflammatory drug-induced small intestinal injury in the rat. In the present report of two human cases, small intestinal injuries were probably induced and/or exacerbated after PPI treatment. Case 1 was a 30-year-old healthy man in whom no small intestinal mucosal break was detected at baseline capsule endoscopy. After 2 weeks of omeprazole given 20 mg once daily, he was found to have two small intestinal mucosal breaks. Case 2 was a 40-year-old healthy man in whom six small intestinal mucosal breaks were detected at baseline capsule endoscopy. After 2 weeks of omeprazole given 20 mg once daily, 12 small intestinal mucosal breaks were detected. Follow-up capsule endoscopy carried out 3 weeks after stopping omeprazole in case 2 showed seven small intestinal mucosal breaks were detected, showing restitution of the small intestinalmucosal injury. These two cases were obtained from a pilot study evaluating the effect of single administration of PPI on small intestinal mucosa in humans. In the pilot study, six healthy male volunteers were given omeprazole 20 mg for a period of 2 weeks. Small intestinal injury was evaluated before and after PPI treatment using capsule endoscopy. In four subjects other than the two above-mentioned cases, no small intestinal mucosal breaks were found at both baseline and post-treatment capsule endoscopy. Considering the two cases with increased or newly detected small intestinal mucosal breaks, omeprazole may exacerbate/induce small intestinal injury.