Drugs for indigestion and stomach ache
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I now have enough information to provide a comprehensive answer. Here is a well-structured overview of drugs used for indigestion (dyspepsia) and stomach ache:
Drugs for Indigestion & Stomach Ache (Dyspepsia)
Indigestion/dyspepsia arises when acid, pepsin, NSAIDs, H. pylori, or bile overwhelm the stomach's mucosal defenses. Drugs fall into two broad categories: acid-reducing agents and mucosal protective agents, plus prokinetics for motility-related symptoms.
1. Antacids
First-line for mild, intermittent symptoms — available OTC
Antacids are weak bases that neutralize gastric HCl directly.
| Agent | Examples | Key Notes |
|---|---|---|
| Sodium bicarbonate | Alka-Seltzer, baking soda | Fast-acting; produces CO₂ → belching; risk of metabolic alkalosis; raises sodium load (avoid in heart failure, hypertension) |
| Calcium carbonate | Tums, Os-Cal | Slower than sodium bicarb; also causes belching; excess → hypercalcemia (milk-alkali syndrome) |
| Magnesium hydroxide | Milk of Magnesia | Effective but can cause osmotic diarrhea |
| Aluminum hydroxide | Amphojel | Effective but causes constipation |
| Mg + Al combos | Maalox, Mylanta, Gelusil | Balanced to minimize bowel side effects |
⚠️ Drug interaction: antacids bind tetracyclines, fluoroquinolones, itraconazole, and iron — do not take within 2 hours of these drugs.
2. H₂-Receptor Antagonists (H₂ Blockers)
Reduce acid secretion by blocking histamine H₂ receptors on parietal cells
Three agents remain in use: cimetidine, famotidine, and nizatidine.
(Ranitidine was withdrawn due to NDMA contamination.)
- Famotidine (Pepcid) — most commonly used OTC H₂ blocker today
- Cimetidine — inhibits CYP450 enzymes → multiple drug interactions (warfarin, phenytoin, theophylline, etc.)
- Nizatidine — well-tolerated; minimal drug interactions
Uses: GERD, peptic ulcer disease, nonulcer dyspepsia, stress ulcer prophylaxis in ICU patients (IV form)
3. Proton Pump Inhibitors (PPIs)
Most potent acid suppressors — irreversibly block H⁺/K⁺-ATPase (the "proton pump") on parietal cells
| Drug | Route |
|---|---|
| Omeprazole | Oral (OTC & Rx) |
| Esomeprazole | Oral |
| Lansoprazole | Oral (OTC & Rx) |
| Pantoprazole | Oral & IV |
| Rabeprazole | Oral |
| Dexlansoprazole | Oral (dual-delayed release) |
- Must be taken 30–60 minutes before a meal (active when parietal cells are stimulated by food)
- Full effect takes 3–4 days of regular dosing
- Uses: GERD, peptic ulcer, H. pylori eradication (as part of triple therapy), nonulcer dyspepsia (modest benefit: 10–20% better than placebo), stress ulcer prevention, Zollinger-Ellison syndrome (doses up to 120 mg/day)
Notable adverse effects (long-term):
- ↑ risk of C. difficile and other GI infections
- Hypomagnesemia
- Reduced calcium/iron/B₁₂ absorption
- Possible increased risk of osteoporosis-related fractures
- Potential interstitial nephritis / chronic kidney disease
- Clopidogrel interaction: PPIs (especially omeprazole, esomeprazole) inhibit CYP2C19 and may reduce clopidogrel activation → prefer pantoprazole or rabeprazole in patients on clopidogrel
4. Mucosal Protective Agents
Sucralfate
- A sucrose-aluminum sulfate complex that forms a viscous paste coating ulcers for up to 6 hours
- Binds to the ulcer base and stimulates prostaglandin and bicarbonate secretion
- Dose: 1 g four times daily on an empty stomach
- Virtually no systemic absorption → minimal side effects (constipation in ~2%)
- Used mainly for stress ulcer prevention in ICU; avoid in renal failure (aluminum accumulation)
Bismuth Subsalicylate
- Pepto-Bismol — has cytoprotective, antimicrobial, and mild antacid properties
- Also suppresses H. pylori (used in quadruple therapy)
- Side effect: black tongue/stools (harmless); avoid in salicylate allergy
Misoprostol
- A prostaglandin E₁ analogue that stimulates mucus and bicarbonate secretion and reduces acid secretion
- Used primarily to prevent NSAID-induced ulcers in high-risk patients
- Side effects: diarrhea, abdominal cramping; contraindicated in pregnancy (causes uterine contractions)
5. Prokinetic Agents
For dyspepsia with slow gastric emptying or bloating
Metoclopramide
- Dopamine D₂-receptor antagonist → increases esophageal peristalsis, raises lower esophageal sphincter pressure, accelerates gastric emptying
- Also a potent antiemetic (acts on area postrema)
- Adverse effects: drowsiness, restlessness, tardive dyskinesia with long-term use (FDA black box warning)
Domperidone
- Similar mechanism to metoclopramide but does not cross the blood-brain barrier → fewer CNS side effects
- Not FDA-approved in the US but widely used elsewhere
6. H. pylori Eradication
If dyspepsia is associated with H. pylori infection, antibiotic-based regimens are used:
- Standard triple therapy: PPI + clarithromycin + amoxicillin × 14 days
- Bismuth quadruple therapy: PPI + bismuth + metronidazole + tetracycline (preferred in high-resistance areas)
Quick Decision Guide
| Symptom Pattern | First Choice |
|---|---|
| Mild, occasional heartburn/indigestion | Antacid (e.g., calcium carbonate, Maalox) |
| Frequent heartburn (2×/week+) | H₂ blocker (famotidine) or PPI |
| Peptic ulcer / GERD | PPI |
| NSAID-induced stomach upset | PPI or misoprostol |
| Bloating / slow stomach emptying | Prokinetic (metoclopramide) |
| H. pylori-positive ulcer | PPI + antibiotics (triple/quadruple therapy) |
Sources: Katzung's Basic and Clinical Pharmacology, 16th Edition; Sleisenger and Fordtran's Gastrointestinal and Liver Disease
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