Gastrointestinal Drugs Quiz

Gastrointestinal Drugs

• Gastroesophageal Reflux Disease (GERD) occurs when stomach acid and pepsin flow back into the esophagus, often called heartburn.
• Causes of GERD include overproduction of acid/pepsin and over-relaxation of the lower esophageal sphincter (LES).
• Peptic Ulcer Disease is a benign lesion of the gastric or duodenal mucosa.
• Causes of PUD include excess acid production and an intrinsic defect in the mucosal defense barrier.
• Helicobacter pylori (H. pylori) infection is a significant cause of peptic ulcers.
• Not all individuals infected with H. pylori develop ulcers.
• H. pylori can weaken the mucosal defense system, leading to ulcer development.
• Nonsteroidal anti-inflammatory drugs (NSAIDs) can contribute to PUD by blocking COX enzymes and decreasing prostaglandins.
• Gastrinoma (Zollinger-Ellison Syndrome) involves tumors in the duodenum or pancreas, secreting excessive gastrin, which stimulates gastric acid.
• Stress ulcers result from physical trauma like severe burns.

Strategies for Protecting Gastric Mucosa from Acid Exposure

• Mechanisms to protect the gastric mucosa from acid exposure include inhibiting acid secretion, preventing direct contact with acid, and neutralizing the acid.
• Medications like cimetidine, omeprazole, prostaglandin antagonists, and muscarinic antagonists target acid secretion.
• Sucralfate forms a protective barrier by adhering to the gastric mucosa. Antacids neutralize the acid.
• Multiple mechanisms, including hormonal (gastrin), paracrine (histamine), and neural (acetylcholine), regulate gastric acid production.
• Gastrin, histamine, and acetylcholine stimulate gastric acid secretion, utilizing specific pathways.

Strategies for Inhibiting Parietal Cell Acid Secretion

• Gastrin antagonists, histamine antagonists, and muscarinic antagonists inhibit acid secretion mediated by different pathways.
• These drugs decrease the stimulation for Parietal cells to produce acid.
• Proton pump inhibitors (PPIs) like omeprazole irreversibly inhibit the H+, K+-ATPase, the enzyme responsible for transporting hydrogen ions into the stomach.
• Omeprazole needs a low pH to be active.
• It leads to profound acid suppression, significantly raising gastric pH.
• Omeprazole is highly protein-bound and metabolized by specific enzymes (CYP2C & CYP3A).
• Esomeprazole, a derivative of omeprazole, is an effective H+, K+-ATPase inhibitor.
• Different forms of H+, K+-ATPase inhibitors exist (e.g., rabeprazole, lansoprazole, pantoprazole).
• Pantoprazole is acid-stable and can be administered intravenously.
• PPIs are well-tolerated, although potential side effects include hypergastrinemia and, rarely, nausea, headaches, or skin rashes.

Histamine H₂ Antagonists

• Cimetidine, ranitidine, famotidine, and nizatidine are examples of histamine H₂ antagonists.
• These drugs reduce acid secretion.

Antacids

• Antacids are weak bases that neutralize stomach acid (HCl).
• Common antacids include magnesium hydroxide, magnesium trisilicate, magnesium-aluminum mixtures, calcium carbonate, and sodium bicarbonate.
• Antacids differ in their onset and duration of action.
• Some may cause systemic alkalosis.

Sucralfate

• Sucralfate is an aluminum salt of sucrose octasulfate.
• In acidic environments, it forms a protective layer on the gastric and duodenal mucosa.
• This黏附黏稠物質 helps protect against further damage, especially to damaged areas of the GI tract.

Role of H. pylori in Peptic Ulcer Disease

• If H. pylori infection is identified, treatment focuses on eradicating the bacteria and inhibiting acid production.
• A common treatment approach includes combining Omeprazole with Amoxicillin.

Functional Disorders of the GI Tract

• Primary functional disorders are due to infection, inflammation, or congenital issues in neuronal/muscular activity.
• Secondary disorders are associated with metabolism issues (e.g., hypo-hyperparathyroidism, hypercalcemia), neurologic disorders (e.g., diabetes mellitus), nerve damage, or other factors (e.g., MS, heavy metal toxicity, or carcinoma).

Prokinetic Drugs

• Used to improve GI motility, assisting materials through the GI tract.
• They boost neuro-muscular signaling and promote transit.
• Common indications include GERD, gastroparesis, nighttime heartburn, and severe refractory constipation.
• Drugs like Metoclopramide and Domperidone are often used.
• Metoclopramide is an antiemetic that enhances gastric emptying but has a potential for side effects.
• Metoclopramide can increase nervous activity and potentially cross the blood–brain barrier.
• Domperidone also enhances gastric emptying, but it lacks efficacy in specific situations like GERD and may have side effects.
• Domperidone largely stays in the digestive tract, minimizing crossing to the brain.

Anti-emetics

• Address nausea and vomiting.
• These medications work at specific receptor sites to reduce nausea and vomiting signals.
• Classified as prokinetics, 5-HT3 antagonists, antimuscarinics, H1 antihistamines, or neuroleptics.
• Specific drugs for motion sickness, cancer-related vomiting, and post-operative conditions.

Laxatives

• Used for constipation relief.
• Types include osmotic, stimulant, and bulk-forming laxatives or cathartics.
• Bulk-forming laxatives add bulk to stools, promoting easier passage.
• Other types act on bowel muscles to increase contractions.

Diarrhea

• Characterized by three or more loose stools per day.
• Often caused by infection with viruses, bacteria, or parasites (gastroenteritis).
• Can be caused from food or water contaminated with fecal material.
• Treatment often involves replacing lost fluids and electrolytes, using oral rehydration salts (ORS).
• Antidiarrheal medications reduce bowel movements.
• These can include antimotility drugs (e.g., codeine, diphenoxylate, loperamide) or agents targeting certain specific receptors and mechanisms (e.g., bismuth subsalicylate, cholestyramine).

Test your knowledge on gastrointestinal disorders such as GERD and Peptic Ulcer Disease. This quiz covers causes, significant pathogens like H. pylori, and the role of NSAIDs in ulcer development. Challenge yourself and learn more about the medications used to treat these conditions.