A patient's medication list includes omeprazole. What class of drug is omeprazole?

Omeprazole (Prilosec) is a proton pump inhibitor (PPI). PPIs irreversibly inhibit the H+/K+ ATPase (proton pump) on the apical surface of gastric parietal cells, reducing gastric acid secretion. They are used to treat GERD, peptic ulcer disease, H. pylori eradication, and Zollinger-Ellison syndrome. Other PPIs include lansoprazole, pantoprazole, esomeprazole, and rabeprazole. Dental relevance: long-term PPI use may be associated with dental erosion (from reduced acid buffering), and some PPIs can interact with antiplatelet drugs like clopidogrel (through CYP2C19 inhibition).