How do proton pump inhibitors like omeprazole reduce gastric acid secretion?

Proton pump inhibitors (PPIs) such as omeprazole work by irreversibly binding to and inhibiting the H+/K+ ATPase enzyme, which is often referred to as the proton pump. This enzyme is located in the luminal surface of the parietal cells in the gastric epithelium and is responsible for secreting hydrogen ions (protons) in exchange for potassium ions. When this enzyme is inhibited, the secretion of gastric acid into the stomach is significantly reduced.

The irreversibility of this binding means that the effect lasts until new proton pumps are synthesized by the parietal cells, which typically takes several days. This makes PPIs highly effective for conditions like peptic ulcer disease and gastroesophageal reflux disease (GERD), where excessive gastric acid secretion is problematic.

The other options pertain to different mechanisms: inhibiting Na+/K+/2Cl- reabsorption relates to diuretics, beta-adrenergic receptor inhibition is associated with certain cardiovascular drugs, and reducing thromboxane A2 production pertains to antiplatelet medications. None of these mechanisms directly affect the proton pumps responsible for gastric acid secretion, which underscores why the binding to the H+/K+ ATPase is