Pharmacology of Gastrointestinal Drugs

Omeprazole is a PPI that works by inhibiting the H+/K+-ATPase pump in the gastric parietal cells, thereby reducing gastric acid secretion.

H2-receptor antagonists, such as ranitidine and cimetidine, work by competitively inhibiting histamine at H2-receptors in the gastric parietal cells, thereby reducing gastric acid secretion.

Antacids, such as sodium bicarbonate, magnesium hydroxide, and aluminum hydroxide, work by neutralizing gastric acid and raising the pH of the stomach contents.

Sucralfate is used to treat peptic ulcer disease, prevent stress ulcers, and treat GERD by forming a protective barrier over the ulcer or eroded mucosa.

Prokinetic agents, such as metoclopramide, domperidone, and erythromycin, work by increasing the motility of the gastrointestinal tract.

Antidiarrheal drugs, such as loperamide and diphenoxylate, work by inhibiting intestinal motility, thereby reducing the frequency and volume of stools.

Laxatives, such as bisacodyl, polyethylene glycol, and lactulose, work by increasing the frequency and volume of stools.

Antiemetics, such as metoclopramide, ondansetron, and promethazine, work by blocking dopamine, serotonin, and histamine receptors in the CTZ, thereby reducing nausea and vomiting.

Cholinergic agonists, such as bethanechol, pilocarpine, and carbachol, work by stimulating muscarinic cholinoreceptors, thereby increasing gastrointestinal motility and secretions.

Anticholinergic drugs, such as atropine, scopolamine, and glycopyrrolate, work by blocking muscarinic cholinoreceptors, thereby reducing gastrointestinal motility and secretions.

5-HT4 receptor agonists, such as prucalopride, tegaserod, and mosapride, work by stimulating 5-HT4 receptors in the gastrointestinal tract, thereby increasing gastrointestinal motility and secretion.

Opioid analgesics, such as morphine and codeine, work by inhibiting intestinal motility, thereby reducing the frequency and volume of stools.

Bile acid sequestrants, such as colestipol, cholestyramine, and ezetimibe, work by binding to bile acids in the intestine, thereby preventing their reabsorption and increasing their excretion in the feces.

HMG-CoA reductase inhibitors, such as simvastatin, atorvastatin, and rosuvastatin, work by inhibiting HMG-CoA reductase, a key enzyme in the cholesterol synthesis pathway, thereby reducing cholesterol synthesis.

Fibrates, such as gemfibrozil, fenofibrate, and bezafibrate, work by activating peroxisome proliferator-activated receptor alpha (PPARα), a nuclear receptor that regulates lipid metabolism, thereby increasing HDL cholesterol levels and reducing triglyceride levels.