Anti-ulcer drugs are a category of medications used for the prevention and treatment of stomach and duodenal ulcers, including proton pump inhibitors (such as omeprazole), H2 receptor antagonists (such as ranitidine), and antacids. These drugs primarily act on the gastric mucosa by reducing gastric acid secretion or neutralizing stomach acid, thereby lowering the pH level in the stomach to promote ulcer healing and alleviate symptoms. They achieve therapeutic effects by intervening in key signaling pathways of gastric acid secretion, such as inhibiting the H+/K+ ATPase in gastric gland cells or blocking histamine H2 receptors. The efficacy and side effects of these medications may vary among individuals due to genetic differences, such as variations in the genes for metabolic enzymes, affecting drug efficacy and side effects.