31.3 Pepsin Inhibitors and Prostaglandin Analogues

Pepsin Inhibitors and Prostaglandin Analogues

Pepsin inhibitors and prostaglandin analogues protect the stomach lining through two different strategies: one blocks the enzyme that damages the mucosa, while the other strengthens the mucosa's own defenses. Understanding how each class works, their key side effects, and the nursing considerations around them is essential for safe medication administration.

Mechanisms of Action

Pepsin inhibitors work by blocking pepsin, the enzyme responsible for breaking down proteins in the stomach. Pepsin doesn't just digest food proteins; it can also digest the gastric mucosa itself, especially when the protective mucus layer is compromised. By inhibiting pepsin activity, these drugs (e.g., pepstatin, pepsinostreptin) reduce direct enzymatic damage to the stomach lining.

Prostaglandin analogues take a different approach. They mimic the body's natural prostaglandins, which play a protective role in the GI tract. Misoprostol is the most clinically significant drug in this class. It works through several mechanisms:

• Stimulates mucus and bicarbonate secretion, reinforcing the gastric mucosal barrier
• Improves mucosal blood flow, which promotes tissue repair and healing
• Reduces gastric acid secretion to a modest degree
• Has a mild anti-inflammatory effect on the gastric lining

Indications, Side Effects, and Drug Interactions

Pepsin Inhibitors

• Indications: Peptic ulcer disease, GERD, Zollinger-Ellison syndrome
• Common side effects: Nausea, diarrhea, abdominal pain, headache
• Drug interactions: May reduce the absorption of antibiotics and antifungals (because altering the gastric environment can affect how these drugs dissolve and absorb)

Prostaglandin Analogues (Misoprostol)

• Indications: Prevention of NSAID-induced gastric ulcers (this is the primary use), treatment of duodenal ulcers
• Common side effects: Diarrhea (the most frequent complaint), abdominal cramping, nausea
• Serious concern: Misoprostol causes uterine contractions and is absolutely contraindicated in pregnancy due to the risk of miscarriage or premature labor. Women of childbearing age must have a negative pregnancy test before starting therapy.
• Drug interactions: May enhance the effects of anticoagulants, increasing bleeding risk. Monitor closely if the patient is on warfarin or similar drugs.

Nursing Care Plan

Assessment

• Evaluate baseline GI symptoms: location and severity of pain, heartburn, nausea, bloating
• Assess for signs of GI bleeding: black tarry stools (melena), coffee-ground emesis, dropping hemoglobin
• Review the patient's current medication list for potential interactions (antibiotics, antifungals, anticoagulants)
• For women of childbearing age on misoprostol, confirm pregnancy status before administration

Monitoring

• Track symptom improvement over time (pain reduction, decreased heartburn frequency)
• Watch for side effects, especially diarrhea with misoprostol, which can be dose-limiting
• Monitor for signs of drug interactions, particularly increased bruising or bleeding in patients on anticoagulants
• Check adherence at follow-up visits, since these drugs work best with consistent dosing

Interventions

1. Administer medications as prescribed, paying attention to timing relative to meals

2. Educate the patient on proper administration and what to expect

3. Encourage lifestyle modifications that support therapy:

   • Avoid trigger foods (spicy, acidic, or fatty foods; caffeine; alcohol)
   • Eat smaller, more frequent meals
   • Elevate the head of the bed for patients with GERD symptoms

4. Provide reassurance and emotional support, especially for patients dealing with chronic or recurring symptoms

Patient Education Guide

Proper Use

• Take the medication as directed. Timing matters: some pepsin inhibitors are taken before meals, while misoprostol is typically taken with food to reduce diarrhea.
• Do not crush, chew, or break tablets unless specifically instructed.
• Store at room temperature, away from heat, light, and moisture.

Side Effects to Know

• Common side effects include nausea, diarrhea, abdominal pain, and headache. Diarrhea is especially common with misoprostol and often improves after the first few days.
• Report severe or persistent side effects to your healthcare provider.
• For patients on misoprostol: This drug can cause uterine contractions. It must not be taken during pregnancy, and reliable contraception is required during treatment.

Important Precautions

• Tell your healthcare provider about all other medications you're taking, including over-the-counter drugs and supplements, to avoid harmful interactions.
• Avoid taking NSAIDs while on prostaglandin analogues unless specifically directed by your provider, as NSAIDs can counteract the protective effects.
• Seek immediate medical attention if you notice signs of GI bleeding: black or tarry stools, vomiting material that looks like coffee grounds, or unexplained weakness and dizziness.