PH6.1 | PH6.1 | Acid Peptic Disease Pharmacotherapy — SDL Guide — Summary & Reflection

KEY TAKEAWAYS

Acid Peptic Disease Pharmacotherapy — Key Points:

Pathophysiology: Imbalance between aggressive factors (acid, pepsin, H. pylori, NSAIDs) and defensive factors (mucus, bicarbonate, prostaglandins). PH6.1 requires both understanding the drugs AND constructing a management plan.

Two-pillar taxonomy:
- Acid suppression: PPIs (irreversible H⁺/K⁺-ATPase blockade — most potent) > H2RAs (reversible H₂ block — less potent, prone to tolerance) > Antacids (rapid, short-lived neutralisation).
- Mucosal protection: Sucralfate (physical barrier, needs acidic pH, do not combine with PPIs), Bismuth (anti-H. pylori, used in quadruple therapy), Misoprostol (PGE₁ analogue — NSAID ulcer prevention; contraindicated in pregnancy).

PPIs — critical pharmacology:
- Irreversible inhibitors; activated in the acidic canaliculus; take 30–60 min before meals.
- ADRs with long-term use: hypomagnesaemia, C. difficile, iron/B₁₂ malabsorption, fractures, rebound hypersecretion.
- Clopidogrel interaction: avoid omeprazole/esomeprazole → use pantoprazole or rabeprazole.

H2RAs: Famotidine (prototype; ranitidine WITHDRAWN); cimetidine has CYP450 inhibition and antiandrogenic effects; tolerance develops with regular use.

H. pylori management: Triple therapy (PPI + amoxicillin + clarithromycin × 14 days) is first-line; quadruple therapy (+ bismuth) for resistant strains. Confirm eradication with urea breath test ≥4 weeks post-antibiotics + post-PPI.

REFLECT

Consider this clinical scenario: You are an intern on call, and a 55-year-old patient with unstable angina on clopidogrel asks you to continue his omeprazole (prescribed by another doctor) for longstanding heartburn. What would you do, and why? Think through: (a) the mechanism of the clopidogrel–omeprazole interaction and its clinical consequence; (b) whether his heartburn genuinely requires a PPI or could be managed differently; (c) what you would prescribe instead, and what you would tell the patient. Reflect on how pharmacological knowledge — not just drug-by-name pattern recognition — directly influences a prescribing decision that could affect his cardiac outcome.