Omeprazole is the drug of choice to treat ulceration associated with mass cell tumours and gastrinomas. It inhibits the hydrogen-potassium ATPase which prevents hydrogen ion prouction by the parietal cells. | Omeprazole is the drug of choice to treat ulceration associated with mass cell tumours and gastrinomas. It inhibits the hydrogen-potassium ATPase which prevents hydrogen ion prouction by the parietal cells. |