1. Clinical Overview
This is a fixed-dose combination (FDC) therapy primarily indicated for the eradication of Helicobacter pylori (H. pylori) infection in patients with peptic ulcer disease (PUD) and gastritis. It combines a broad-spectrum penicillin antibiotic (Amoxycillin), a macrolide antibiotic (Clarithromycin), and a proton pump inhibitor (Omeprazole). This triple therapy is a standard first-line regimen in India for H. pylori eradication, as per the Indian Society of Gastroenterology (ISG) and Maastricht VI/Florence consensus guidelines.
| Onset | Duration | Bioavailability |
|---|---|---|
| Omeprazole: Gastric acid suppression begins within 1 hour, with peak effect at 2 hours. Amoxycillin & Clarithromycin: Antibacterial action begins upon reaching effective tissue concentrations, typically within 1-2 hours of administration. | Omeprazole: Acid suppression lasts up to 24 hours. Amoxycillin: 6-8 hours (dose-dependent). Clarithromycin: 12 hours. | Amoxycillin: ~80% (oral). Omeprazole: ~35-60% (oral, increased to ~90% with enteric coating). Clarithromycin: ~50% (oral). |
2. Mechanism of Action
This combination acts synergistically to eradicate H. pylori. Omeprazole irreversibly inhibits the H+/K+ ATPase enzyme system (proton pump) in gastric parietal cells, profoundly suppressing gastric acid secretion. This elevated gastric pH creates a more favorable environment for the antibiotics to work, increases the stability of amoxicillin, and may inhibit bacterial growth. Amoxycillin inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs). Clarithromycin inhibits bacterial protein synthesis by binding to the 50S ribosomal subunit. Together, they achieve bactericidal action against H. pylori.
3. Indications & Uses
- Eradication of Helicobacter pylori infection in patients with: Active Duodenal Ulcer
- Active Gastric Ulcer
- Symptomatic Gastritis (Non-ulcer Dyspepsia with H. pylori positivity)
4. Dosage & Administration
Adult Dosage: One kit (containing Amoxycillin 750mg + Omeprazole 20mg + Clarithromycin 250mg) TWICE daily, for 10 to 14 days. Omeprazole is typically taken 30-60 minutes before breakfast and dinner. The antibiotics can be taken with or after food to improve tolerance, but the entire kit is often recommended before meals for optimal omeprazole effect.
Administration: Take Omeprazole capsule whole, with a full glass of water, 30-60 minutes before a meal (breakfast and dinner). Do not crush, chew, or break the enteric-coated pellet. Amoxycillin and Clarithromycin tablets can be taken at the same time, with or immediately after food to minimize GI upset. Complete the full course (10-14 days) even if symptoms improve earlier.
5. Side Effects
Common side effects may include:
- Diarrhea / Loose stools
- Nausea
- Abdominal pain
- Headache
- Taste perversion (metallic taste - Clarithromycin)
- Vomiting
- Flatulence
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Warfarin / Acenocoumarol | Increased anticoagulant effect (Omeprazole inhibits CYP2C19; Clarithromycin inhibits warfarin metabolism). Risk of bleeding. | Major |
| Clopidogrel | Omeprazole (especially high dose) may reduce antiplatelet efficacy of Clopidogrel by inhibiting CYP2C19 conversion to active metabolite. Consider alternative PPI like Pantoprazole or Ranitidine. | Major |
| Atorvastatin, Simvastatin, Lovastatin | Clarithromycin (CYP3A4 inhibitor) dramatically increases statin levels, high risk of myopathy/rhabdomyolysis. Withhold statin or use Pravastatin/Rosuvastatin. | Major |
| Midazolam, Triazolam | Clarithromycin increases levels of these benzodiazepines, causing excessive sedation and respiratory depression. | Major |
| Digoxin | Clarithromycin increases Digoxin bioavailability (gut bacteria inhibition), leading to toxicity (nausea, arrhythmia). | Major |
| Carbamazepine, Phenytoin | Clarithromycin increases levels of these anticonvulsants, leading to toxicity (dizziness, ataxia, nystagmus). | Major |
| Rifampicin | Reduces levels of all three components by inducing CYP enzymes. Can lead to treatment failure. | Major |
| Methotrexate | Omeprazole may reduce renal clearance of methotrexate, increasing toxicity (myelosuppression). | Major |
| HIV Protease Inhibitors (Ritonavir, Saquinavir) | Clarithromycin increases their levels;他们也 increase clarithromycin levels. Mutual inhibition. Requires dose adjustment. | Major |
| Sildenafil, Tadalafil | Clarithromycin increases their levels, risk of hypotension, priapism. | Moderate |
| Oral Contraceptives | Antibiotics may reduce efficacy. Use additional barrier method during and 7 days after therapy. | Moderate |
| Potassium-Competitive Acid Blockers (Vonoprazan) | Therapeutic duplication. Avoid concomitant use. | Moderate |
7. Patient Counselling
- DO complete the entire course of 10-14 days, even if you feel better.
- DO take the Omeprazole capsule 30-60 minutes BEFORE breakfast and dinner.
- DO take the full kit (all medicines) at the same time, as directed.
- DO inform your doctor if you are taking any other medicines, especially blood thinners, heart medicines, or cholesterol pills.
- DO use additional contraception (condoms) if you are on oral contraceptive pills.
- DON'T crush, chew, or break the Omeprazole capsule.
- DON'T take antacids within 2 hours of taking this medicine.
- DON'T consume alcohol during the treatment.
- DON'T share this medicine with anyone else.
8. Toxicology & Storage
Overdose: Amoxycillin: Crystalluria, renal toxicity, seizures (high doses). Omeprazole: Blurred vision, confusion, drowsiness, dry mouth, flushing, headache, nausea, tachycardia. Clarithromycin: Severe GI symptoms (nausea, vomiting, diarrhea), QT prolongation leading to arrhythmias, hearing loss, hepatic dysfunction.
Storage: Store in a cool, dry place, below 25°C. Protect from light and moisture. Keep out of reach of children. Do not use after the expiry date printed on the pack.