Gastric Physiology and Pharmacology Quiz

Gastrointestinal Drugs: Peptic Ulcer Disease

• This chapter covers drugs used to treat peptic ulcer disease.
• Learning objectives include reviewing GI physiology, understanding the effect of hydrochloric acid, and distinguishing between different medication classes such as antacids, H2 antagonists, proton pump inhibitors, and miscellaneous acid-control agents.
• The objectives also include describing the mechanism of action, indications, contraindications, interactions, and adverse effects of various drug classes.
• Identifying a prototype medication, its related information, and pharmacokinetic details are included in the objectives.
• Understanding client care implications is another objective.
• Stomach secretions involve hydrochloric acid (HCl) from parietal cells and pepsinogen from chief cells.
• Other components in the stomach include mucus, bicarbonate, and prostaglandins.

Stomach Cell Types

• Parietal cells produce and secrete HCl, keeping the stomach at a pH of 1 to 2.
• They are the primary target for acid-controller drugs.
• ECL cells secrete histamine, stimulating parietal cells.

Stomach Acid-Related Diseases

• Acidity affects the integrity of the digestive tract.
• Common stomach problems include indigestion, heartburn, and acid stomach.
• Peptic ulcer disease (PUD) and gastroesophageal reflux disease (GERD) are mentioned.
• Common locations of gastric and duodenal ulcers are illustrated.

Factors in Peptic Ulcer Disease

• Aggressive factors such as H. pylori infection, NSAIDs, acid, pepsin, and smoking contribute to ulcers.
• Defensive factors such as mucus, bicarbonate, blood flow, and prostaglandins protect the stomach lining.

Drug Therapies for H. Pylori

• Eradication of H. pylori, reduction of gastric acidity, and enhancement of mucosal defenses are important aspects of treatment.
• Antibacterials like amoxicillin and clarithromycin are used in triple therapy for H. pylori eradication along with a proton pump inhibitor like omeprazole. This regimen is typically for seven to 14 days.

Inhibitors of Gastric Acid Secretion/Action

• H2 antagonists, proton pump inhibitors, and antacids are discussed.
• Different types of antacids include magnesium salts, calcium salts, sodium bicarbonate, and aluminum salts.
• Other agents, such as sucralfate and misoprostol, protect the mucosa.

H2 Antagonists:

• Reduce acid secretion, and are available in OTC lower dosages.
• Cimetidine (Tagamet), famotidine (Pepcid), ranitidine (Zantac), and nizatidine (Axid) are examples.
• Cimetidine may interact with other drugs, affecting their metabolism.
• Care is needed in patients with impaired renal or liver function, confusion, disorientation, or in the elderly.
• H2 antagonists block histamine H2 receptors that stimulate acid-producing parietal cells.
• Indications include GERD, PUD, adjunct therapy for upper GI bleeding and hypersecretory conditions.
• Adverse effects are infrequent but cimetidine can cause impotence and gynecomastia. Older patients may experience CNS depression (e.g., lethargy) or confusion.

Proton Pump Inhibitors (PPIs):

• Inhibit the pump that moves H+ into the stomach lumen, making them more effective than H2 antagonists.
• Omeprazole (Losec or Prilosec), lansoprazole, rabeprazole, pantoprazole (Pantoloc), and esomeprazole are examples.
• PPIs irreversibly bind to the H+/K+ ATPase enzyme.
• They are used for GERD maintenance therapy, erosive esophagitis, short-term treatment of active duodenal and benign gastric ulcers, and Zollinger-Ellison syndrome.
• PPIs are generally safe for short-term use (4-8 weeks). Headaches, GI problems (nausea, vomiting, diarrhea) are uncommon side effects. Caution is advised in patients with liver disease.

Antacids:

• Chemically neutralize stomach acid; they do not prevent acid production.
• Common forms include capsules, tablets, powders, and suspensions.
• Types of antacids include aluminum, magnesium, calcium salts, and sodium bicarbonate.
• Aluminum salts can cause constipation; Magnesium salts often cause diarrhea; calcium salts can cause constipation and possible kidney stones.
• Sodium bicarbonate is highly soluble but short-lasting and may cause metabolic alkalosis, so it is not recommended to clients with fluid imbalances, hypertension, HF, renal insufficiency and preexisiting conditions.
• Antacids may reduce the absorption of other medications if taken close to each other.
• Patients with allergies, fluid imbalances, renal issues, pregnancy, or GI obstructions should be evaluated carefully before taking antacids.
• Patients should follow instructions on timing relative to other medications.

Other Agents to Protect the Mucosa:

• Sucralfate binds directly to ulcer surfaces, forming a protective barrier and inhibiting pepsin.
• Sucralfate may have minimal absorption, but can cause constipation, nausea, and dry mouth. It may also impair the absorption of other drugs, such as tetracycline and digoxin, or it might interfere with phosphate levels.
• Misoprostol is a synthetic prostaglandin used to reduce gastric effects of NSAIDs; it may cause abdominal cramps and diarrhea.

Client Care Guidelines:

• Patient history is imperative for proper treatment planning. Assessment for allergies and pre-existing conditions such as fluid imbalances, renal or liver disease, HF, pregnancy, and GI obstructions must be considered.
• Clients with heart failure (HF) or hypertension should consider low-sodium antacids.
• Medications are often best taken one to two hours after antacids to prevent drug interactions.
• Chewable tablets should be chewed completely.
• Patients taking omeprazole should be instructed not to crush, chew, or open the capsule.
• Antacids may be taken with water to enhance dispersion but not if rapid-dissolving forms are utilized.
• Caffeine, alcohol, harsh spices, and black pepper may worsen underlying GI conditions.
• Inform clients that treatment duration is often limited to a short term, for example several weeks rather than a long term or permanent solution.

Test your knowledge on the primary functions of gastric cells and the medications used to manage acidity. This quiz covers key concepts such as the role of parietal cells, common organisms linked to peptic ulcers, and the action of H2 antagonists. Improve your understanding of gastric physiology and pharmacology.