Gastrointestinal Diseases and Drug Use for Treatment

Anatomy of the Gastrointestinal Tract

• GI tract extends from mouth to anus, divided into upper and lower sections.

  • Upper GI: mouth, esophagus, stomach, duodenum.

  • Lower GI: small intestine (jejunum, ileum), large intestine (colon), rectum, anus.

Common Gastrointestinal Disorders

• Inflammatory Bowel Disease (IBD): Crohn's disease and ulcerative colitis; chronic digestive tract inflammation.

• Gastroesophageal Reflux Disease (GERD): Stomach acid reflux into esophagus; heartburn and tissue damage.

• Peptic Ulcer Disease: Open sores in stomach or duodenum, often from H. pylori.

• Irritable Bowel Syndrome (IBS): Chronic condition; cramping, abdominal pain, altered bowel habits.

• Constipation: Infrequent bowel movements or difficult stool passage.

• Diarrhea: Frequent, loose, watery stools; abdominal cramps.

• Diverticulitis: Inflammation/infection of small pouches (diverticula) in digestive tract.

• Gallstones: Hardened digestive fluid deposits in gallbladder; pain, inflammation, bile duct blockage.

Gastroesophageal Reflux Disease (GERD)

• Stomach acid flows back into esophagus due to improper closure of the esophageal muscle.

  • Key Symptoms: Heartburn, acid reflux, chest pain, swallowing issues, cough, throat irritation.

  • Risk Factors: Obesity, pregnancy, hiatal hernia, smoking, alcohol, certain medications.

  • Complications: Esophagitis, scarring, esophageal cancer.

GERD Treatment

• Combines lifestyle changes with pharmacological interventions to reduce acid, improve esophageal clearance, and strengthen the lower esophageal sphincter.

  • Proton Pump Inhibitors (PPIs): Block acid secretion (e.g., omeprazole, esomeprazole, pantoprazole).

  • H2 Receptor Antagonists: Moderate acid suppression (e.g., ranitidine, famotidine, cimetidine).

  • Antacids & Alginates: Rapid, short-term relief; neutralize acid and create protective barriers.

  • Antiemetics: For nausea/vomiting; improve gastric emptying and esophageal sphincter tone (e.g., metoclopramide).

GERD Medications: Mechanisms and Side Effects

• Proton Pump Inhibitors (PPIs):

  • Mechanism: Stops acid-producing pumps in stomach cells.

  • Examples: Omeprazole, Esomeprazole, Pantoprazole, Lansoprazole.

  • Common Side Effects: Headache, diarrhea, low vitamin B12, higher risk of bone fractures.

• H2 Receptor Blockers:

  • Mechanism: Blocks signals that trigger stomach acid production.

  • Examples: Ranitidine, Famotidine, Cimetidine, Nizatidine.

  • Common Side Effects: Dizziness, confusion, diarrhea, breast enlargement in men (rare).

• Antacids:

  • Mechanism: Directly neutralize stomach acid.

  • Examples: Aluminum hydroxide, Calcium carbonate, Magnesium hydroxide.

  • Common Side Effects: Constipation (calcium/aluminum), diarrhea (magnesium), mineral imbalances.

• Alginates:

  • Mechanism: Form a protective layer over stomach contents

  • Examples: Gaviscon, Sodium alginate products.

  • Common Side Effects: Generally well-tolerated, occasional constipation.

• Antiemetics:

  • Mechanism: Block certain brain receptors, help stomach empty faster, and strengthen the valve between stomach and esophagus

  • Examples: Metoclopramide, Domperidone, Ondansetron.

  • Common Side Effects: Drowsiness, muscle problems , movement disorders, heart rhythm changes, restlessness.

Peptic Ulcer Disease

• Open sores on stomach (gastric) or small intestine (duodenal) lining.

  • Major Causes: H. pylori infection, NSAIDs, Zollinger-Ellison syndrome.

  • Common Symptoms: Burning stomach pain, fullness, bloating, fatty food intolerance, nausea, weight loss.

Peptic Ulcer Treatment

• Targets underlying cause and provides symptomatic relief.

  • H. pylori Eradication: PPI + two antibiotics (clarithromycin, amoxicillin, or metronidazole) for 14 days.

  • Side Effects: GI disturbances, metallic taste, antibiotic resistance, C. difficile infection risk.

  • Acid Suppression: PPIs for 4-8 weeks.

  • Side Effects: Headache, diarrhea, vitamin B12 malabsorption, increased fracture risk with prolonged use.

  • Cytoprotection: Sucralfate or misoprostol to protect ulcerated tissue.

  • Side Effects: Sucralfate (constipation); misoprostol (diarrhea, abdominal cramping, contraindicated in pregnancy).

Constipation

• Difficulty passing stools or infrequent bowel movements (fewer than three times per week).

  • Key Symptoms: Hard, dry stools; straining; incomplete evacuation; abdominal pain/bloating.

  • Common Causes: Insufficient fiber/fluids, lack of activity, certain medications, ignoring urge to defecate.

  • Potential Complications: Hemorrhoids, anal fissures, fecal impaction, rectal prolapse, bowel obstruction (rare).

Constipation Treatment Options

• Bulk-Forming Laxatives: Absorb water to form soft, bulky stool. Take with plenty of fluids.

• Osmotic Laxatives: Draw water into intestines to soften stool. May cause bloating and electrolyte imbalances.

• Stimulant Laxatives: Trigger intestinal contractions. Use short-term only to prevent dependency.

Diarrhea

• Loose, watery stools occurring more than three times daily; increased intestinal motility, decreased absorption.

  • Key Symptoms: Watery stools, urgency, abdominal cramps, dehydration.

  • Common Causes: Viral/bacterial infection, food intolerances, medications, IBD.

  • Potential Complications: Dehydration, electrolyte imbalances, malnutrition, weakness.

Diarrhea Treatment Options

• Antimotility Agents: Slow intestinal contractions (e.g., loperamide, diphenoxylate).

  • Side effects: Constipation, abdominal discomfort, drowsiness.

• Absorbents: Bind toxins and excess fluid (e.g., bismuth subsalicylate, activated charcoal).

  • Side effects: Black stools, tongue discoloration, constipation.

• Probiotics: Restore gut bacteria balance (e.g., Lactobacillus, Saccharomyces boulardii).

  • Side effects: Minimal (gas, bloating).

• Antibiotics: For bacterial infections (e.g., ciprofloxacin, metronidazole).

  • Side effects: Nausea, headache, possible C. difficile infection.

Irritable Bowel Syndrome (IBS)

• Functional bowel disorder; chronic abdominal pain, altered bowel habits without structural abnormalities.

  • Key Symptoms: Abdominal pain, bloating, gas, irregular bowel movements.

  • Gut-Brain Connection: Heightened sensitivity to gut sensations.

  • Treatment Approach: Dietary modifications, stress management, targeted medications.

IBS Medical Treatment Options

• Antispasmodics: Relax intestinal smooth muscle (e.g., mebeverine, hyoscine).

  • Side effects: Dry mouth, blurred vision, constipation, urinary retention, dizziness.

• Antidepressants: Modify pain signals and gut sensitivity (TCAs, SSRIs).

  • Side effects: Drowsiness, nausea, sexual dysfunction, dry mouth, weight changes.

• Gut-Specific Agents: Target intestine-specific receptors/channels.

  • Prucalopride (for IBS-C): Enhances gut motility.

  • Side effects: Diarrhea or constipation, abdominal pain, flatulence, headaches.

  • Rifaximin (for IBS-D): Non-absorbable antibiotic that modifies gut microbiota.

Key GI Medications

• Proton Pump Inhibitors: Omeprazole, Esomeprazole. Irreversibly inhibit H+/K+ ATPase. GERD, peptic ulcers.

• H2 Blockers: Famotidine, Ranitidine. Block histamine receptors. GERD, peptic ulcers (less potent than PPIs).

• Antacids: Aluminum hydroxide, Calcium carbonate. Neutralize stomach acid. Mild GERD, heartburn.

• Bulk-forming Laxatives: Psyllium, Methylcellulose. Absorb water. Chronic constipation, IBS-C.

• Osmotic Laxatives: Lactulose, Polyethylene glycol. Draw water into intestinal lumen. Constipation.

• Stimulant Laxatives: Bisacodyl, Senna. Stimulate intestinal contractions. Acute constipation.

• Antimotility Agents: Loperamide, Diphenoxylate. Slow intestinal transit. Acute diarrhea.

• Adsorbents: Bismuth subsalicylate, Activated charcoal. Adsorb toxins. Acute diarrhea.

• Probiotics: Lactobacillus, Saccharomyces boulardii. Restore gut bacteria. Antibiotic-associated diarrhea, IBS.

• Antispasmodics: Mebeverine, Hyoscine. Relax intestinal smooth muscle. IBS, abdominal cramping.