Gastrointestinal Pharmacology – Peptic Ulcer Disease, GERD & Bowel Drugs

Vocabulary flashcards covering key GI pharmacology terms, mechanisms, uses, side effects, and nursing considerations from the lecture notes.

Peptic Ulcer Disease (PUD)

Upper GI disorder involving erosion of the gut wall, most often caused by Helicobacter pylori or chronic NSAID use.

Aggravating factors for PUD

Smoking, NSAID use, and other gastric irritants that worsen ulcer formation or delay healing.

Helicobacter pylori (H. pylori)

Spiral-shaped bacterium that colonizes the stomach and is a primary cause of PUD; requires antibiotic eradication therapy.

Gastroesophageal Reflux Disease (GERD)

Condition in which stomach acid refluxes into the esophagus, producing heartburn; H. pylori is not involved so antibiotics are unnecessary.

Proton Pump Inhibitors (PPIs)-prazole

block gastric H⁺/K⁺-ATPase, profoundly reducing stomach acid.

Long-term PPI risks

↓Calcium, ↓Magnesium, ↓Vitamin B12 & iron absorption, osteoporosis, renal injury, pneumonia, C. difficile infection.

PPI administration

Take once daily 30-60 min before a meal

For PPIs, DON’T

crush pill but capsule contents may be sprinkled on soft food if swallowed whole.

Lansoprazole (Prevacid), Pantoprazole (Protonix), Esomeprazole (Nexium), Omeprazole (Prilosec)

PPIs that reduce HCI in stomach

Talicia

Fixed-dose capsule containing amoxicillin, rifabutin and omeprazole; taken 4 capsules TID x 14 days to eradicate H. pylori.

H2 Receptor Antagonists (H2 blockers)-toxins MOA

inhibit histamine H₂ receptors on parietal cells, lowering gastric acid secretion.

Famotidine (Pepcid)

Preferred H2 blocker for GERD/PUD; minimal drug interactions and lower CNS effects than cimetidine.

Ranitidine (Zantac)

H2 blocker withdrawn in many markets due to NDMA impurity concerns; previously used for mild-to-moderate GERD/PUD.

Cimetidine (Tagamet)

Older H2 blocker that crosses BBB causing confusion, especially in elderly; numerous CYP-450 drug interactions.

H2 blocker counseling

Take 30-60 min before meals or at bedtime; avoid smoking; separate from antacids by at least 30 min to 1 h.

Antacids

OTC agents (calcium carbonate, magnesium/aluminum hydroxide) that neutralize existing stomach acid for rapid symptom relief.

Calcium Carbonate (Tums)

Antacid that neutralizes gastric acid; can cause rebound acid hypersecretion and constipation if overused.

Magnesium Hydroxide (Milk of Magnesia)

Acts as both antacid and osmotic laxative; side effect = diarrhea.

Aluminum Hydroxide

Antacid that can cause constipation; often combined with magnesium hydroxide to balance bowel effects (e.g., Mylanta).

Mylanta

Combination magnesium/aluminum antacid providing balanced GI effects (limits diarrhea & constipation).

Sodium load with antacids

Many liquid/effervescent antacids contain significant sodium; monitor in heart-failure or hypertensive patients.

Sucralfate

Mucosal protectant that forms a viscous barrier over ulcers; must be taken on an empty stomach (1 h before or 2 h after meals).

Bismuth Subsalicylate (Pepto-Bismol)

OTC mucosal protectant with mild antimicrobial activity; coats stomach lining and provides symptomatic relief.

Bulk-forming laxatives

Agents such as psyllium that absorb water, swell, and soften stool; first-line for chronic constipation; onset 1-3 days.

Psyllium (Metamucil)

Natural fiber supplement; mix with at least 8 oz water; may take 24-72 hours for effect.

Surfactant (stool softener) laxatives

Docusate sodium facilitates water & fat penetration into stool; used to prevent straining.

Stimulant laxatives

Bisacodyl & senna increase intestinal motility and fluid secretion; produce semi-fluid stool in 6-12 h; risk of dependence.

Bisacodyl (Dulcolax)

Oral or suppository stimulant laxative; avoid concomitant milk or antacids which dissolve enteric coating prematurely.

Senna (Senokot)

Plant-derived stimulant laxative; chronic use can cause melanosis coli (brown pigmentation of colonic mucosa).

Osmotic laxatives

Polyethylene glycol or magnesium salts draw water into bowel producing watery stool in 2-6 h (higher doses) or 6-12 h (lower).

Polyethylene Glycol (PEG 3350)

Non-absorbable osmotic laxative used either daily for constipation or in high volumes for bowel prep.

Laxative Groups

Group 3: soft stool in 1-3 days (bulk, surfactant); Group 2: semi-fluid stool in 6-12 h (stimulant, low-dose osmotic); Group 1: watery stool in 2-6 h (high-dose osmotic, PEG prep).

Mineral Oil Enema

Lubricant laxative instilled rectally to ease stool passage; adverse effect: anal leakage.

Loperamide (Imodium)

Peripheral µ-opioid receptor agonist that slows intestinal transit to treat diarrhea; can cause dizziness, dry mouth, and dehydration.

Loperamide dosing

2 mg after first loose stool, then 2 mg after each subsequent loose stool, not exceeding 8 mg OTC or 16 mg Rx in 24 h.

Loperamide precautions

Avoid combining with sedating antihistamines; high doses may cross BBB causing euphoria or respiratory depression.

PPI vs. H2 blocker in GERD

PPIs provide more powerful, longer-lasting acid suppression for severe GERD; H2 blockers relieve mild, intermittent heartburn more rapidly.

Beers List consideration

Cimetidine (H2 blocker) and many antispasmodics carry higher risk of confusion and anticholinergic burden in older adults.