Omeprazole dose and indications
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Now I have comprehensive information from both a pharmacology textbook (Goodman & Gilman's) and a pediatric handbook (Harriet Lane). Let me compile the answer.
Omeprazole — Dose & Indications
Class: Proton pump inhibitor (PPI) — irreversibly inhibits gastric H⁺/K⁺-ATPase, reducing basal and stimulated acid secretion by 80–95%.
Indications & Adult Doses
| Indication | Dose |
|---|---|
| Duodenal ulcer / GERD | 20–40 mg PO once daily × 4–8 weeks |
| Erosive esophagitis | 20–40 mg PO once daily × up to 12 weeks |
| Gastric ulcer | 20–40 mg PO once daily–BID × 4–8 weeks |
| Pathologic hypersecretory conditions (e.g., Zollinger-Ellison) | Start 60 mg PO once daily; may increase to 120 mg/day in divided doses (TID if >80 mg/day) |
| H. pylori eradication | Used in combination with clarithromycin + amoxicillin (triple therapy) |
| NSAID-induced ulcer prophylaxis | 20 mg once daily (comparable to misoprostol in trials) |
| Acute upper GI bleeding | IV 80 mg bolus (single dose), then maintenance per protocol |
| OTC heartburn (self-treatment) | 20 mg PO once daily (FDA-approved at full dose) |
Pediatric Doses
| Age/Weight | Dose |
|---|---|
| 3–<5 kg | 2.5 mg PO once daily |
| 5–<10 kg | 5 mg PO once daily |
| 10–<20 kg | 10 mg PO once daily |
| ≥20 kg | 20 mg PO once daily |
| General (GERD/esophagitis/ulcers) | 1 mg/kg/day PO once daily–BID (max 20 mg/day); range 0.7–4 mg/kg/day |
Children 1–6 years may need higher doses due to enhanced drug clearance.
Formulations
- Delayed-release capsules: 10, 20, 40 mg (may contain magnesium)
- Delayed-release tablets: 20 mg (OTC)
- Oral suspension: 2 mg/mL; granule packets: 2.5 mg and 10 mg
- With sodium bicarbonate (Zegerid): 20 mg, 40 mg (immediate-release formulation)
Key Pharmacology Points
- Administer 30–60 min before the first meal of the day — fasting increases H⁺/K⁺-ATPase density, and PPIs require acid activation in the canaliculi
- Once-daily dosing sufficient for most; a second dose before the evening meal can be added if needed
- Effect is prolonged (24–48 h) despite short plasma t½ (~0.5–3 h), because new pump synthesis is required for acid recovery
- Full therapeutic effect takes 3–5 days (steady state)
Drug Interactions (CYP450)
- Substrate and inhibitor of CYP 2C19; induces CYP 1A2
- Reduces efficacy of: clopidogrel, itraconazole, ketoconazole, iron salts, ampicillin esters
- Increases levels of: citalopram, diazepam, phenytoin, warfarin
- St. John's wort and rifampin decrease omeprazole effect
- CYP 2C19 ultrarapid metabolizers: increase usual dose threefold
Notable Adverse Effects
- Common: headache, diarrhea, nausea, vomiting
- Long-term risks: hypomagnesemia, vitamin B12 deficiency, fundic gland polyps, C. difficile diarrhea, rebound acid hypersecretion on discontinuation
- Rare but serious: anaphylaxis, acute interstitial nephritis, severe skin reactions
Special Populations
- Hepatic impairment / Asian descent: increased bioavailability — may require dose reduction
- Do not establish safety/efficacy for GERD in infants <1 month
- Interferes with serum chromogranin A (CgA) testing for neuroendocrine tumors — discontinue ≥14 days before testing
— The Harriet Lane Handbook, 23rd ed. | Goodman & Gilman's Pharmacological Basis of Therapeutics | Sleisenger & Fordtran's GI and Liver Disease
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