Proton pump inhibitors
ATC code: A02BC01 (Omeprazole)
Brand names
Prilosec, Zegerid
Irreversibly inhibits the H+/K+-ATPase in gastric parietal cells — the final step of gastric acid secretion. Converted to its active form in the acidic environment of parietal cell canaliculi, where it binds the enzyme covalently. The effect persists until new H+/K+-ATPase molecules are synthesized (about 24 hours).
First line
PPIs are first-line for GERD in adults per 2022 and CG184. Standard dose: omeprazole 20 mg once daily for 4–8 weeks in non-erosive disease, 40 mg in erosive disease. If the response is inadequate, assess adherence, timing, functional heartburn, and alternative diagnoses. Long-term maintenance uses the lowest effective dose.
First line
A component of H. pylori eradication regimens per Maastricht VI/Florence Consensus 2022. In triple therapy: omeprazole 20 mg BID with amoxicillin and clarithromycin. In bismuth quadruple therapy: with tetracycline and metronidazole. Course duration 14 days. PPI is continued at least 4 more weeks after antibiotics for mucosal healing.
First line
Gastroprotection is indicated in long-term NSAID users with risk factors: age over 65, prior peptic ulcer or GI bleeding, concomitant anticoagulants, antiplatelet drugs, or glucocorticoids, and high NSAID doses. Routine gastroprotection in low-risk patients is not recommended.
First line
Standard therapy for peptic ulcer disease: omeprazole 20–40 mg once or twice daily for 4–8 weeks depending on ulcer location. In H. pylori-positive patients, as part of an eradication regimen. Maintenance therapy is used in recurrent ulcers, H. pylori-negative ulcers, and chronic NSAID users.
6 pairs found. Sorted from critical to minor.
Mechanism
Omeprazole weakly inhibits CYP3A4 – atorvastatin exposure rises modestly (10–20 %). Clinically meaningful additional myopathy is rare.
Management
Routine dose adjustment is not required. If muscle pain develops, check CK and reconsider the statin.
Sources
FDA category C. Large cohort studies have not shown a significant increase in birth defects. Used when clinically necessary and benefits outweigh risks.
Passes into milk in minimal amounts. Considered compatible with breastfeeding in infants over 1 month old.
omeprazole is evaluated for the following indications with varying evidence strength: Gastroesophageal reflux disease (evidence tier A), Peptic ulcer disease (evidence tier A), Helicobacter pylori infection (evidence tier A). See the full indication matrix with dosing and citations above on this page.
Common side effects of omeprazole (≥ 1 in 100): Headache, Diarrhea or constipation, Nausea, flatulence, Abdominal pain. See the Safety section for uncommon and serious reactions.
FDA category C. FDA category C. Large cohort studies have not shown a significant increase in birth defects. Used when clinically necessary and benefits outweigh risks.
Passes into milk in minimal amounts. Considered compatible with breastfeeding in infants over 1 month old.
omeprazole is contraindicated in: Hypersensitivity to any component; Concomitant use with rilpivirine and nelfinavir. Full list in the Safety section.
long-term use is associated with hypomagnesemia, vitamin B12 deficiency, increased fracture risk, acute interstitial nephritis, C. difficile infection, and community-acquired pneumonia. Prescribing should be justified and periodically reviewed.
Mechanism
Ciprofloxacin is better absorbed in an acidic gastric environment. Omeprazole raises gastric pH – ciprofloxacin bioavailability falls by roughly 20–30 %. Additionally, Al/Mg-containing antacids (often used concurrently) chelate ciprofloxacin and reduce absorption further.
Management
If a PPI is necessary, take ciprofloxacin 2 hours before or 6 hours after the PPI and any antacids/calcium/iron products. For severe infections, consider IV ciprofloxacin.
Mechanism
Omeprazole is a potent CYP2C19 inhibitor, the key enzyme for clopidogrel bioactivation. The active thiol metabolite concentration drops, weakening the antiplatelet effect. The issued a black-box warning in 2010 about increased cardiovascular events on dual antiplatelet therapy.
Management
Avoid the combination. If gastric protection is needed, choose pantoprazole or rabeprazole (less CYP2C19 inhibition) or an H2-blocker (famotidine). Esomeprazole is as risky as omeprazole.
Sources
Mechanism
Levothyroxine sodium requires gastric acidity to dissolve. Omeprazole raises gastric pH – thyroxine absorption falls by 20–30 %. Clinically this presents as rising TSH and failure to achieve targets in some patients.
Management
Take levothyroxine strictly on an empty stomach, 30–60 minutes before food and other drugs. Take the PPI 2 hours later or in the evening. Check TSH at 6–8 weeks after starting omeprazole and, if needed, increase the levothyroxine dose by 12.5–25 µg.
Sources
Mechanism
Omeprazole inhibits CYP2C19 – sertraline concentration rises by roughly 40 %. Clinically, side effects may intensify: nausea, diarrhea, insomnia, agitation, QT prolongation.
Management
With concurrent use in CYP2C19 poor metabolizers, start sertraline at the lowest dose (25 mg) and titrate more slowly. Obtain an ECG when QT-prolongation risk factors are present.
Sources
Mechanism
Omeprazole inhibits intestinal OCT1 – metformin absorption rises slightly. Clinical significance is minimal and no additional hypoglycemia occurs.
Management
No dose adjustment is required.
Sources
many patients do well with lifestyle changes (weight, meals, sleep position) and a short PPI course. Lifelong therapy is justified in severe erosive esophagitis, Barrett esophagus, or Zollinger-Ellison syndrome.