Generic
Omeprazole
270 brands available in the market
At a glance
Omeprazole is a proton pump inhibitor (PPI) that reduces stomach acid production. It is used for heartburn, acid reflux, peptic ulcer disease, Zollinger-Ellison syndrome and H. pylori infection.
Description
Omeprazole is a substituted benzimidazole that inhibits gastric acid secretion by blocking the H+/K+ ATPase enzyme system in the gastric parietal cell. It reduces stomach acid production, providing relief from acid-related indigestion and heartburn and helping heal the esophageal and gastric lining. It is used for gastric and duodenal ulcers, GERD, Zollinger-Ellison syndrome and H. pylori-associated peptic ulcers.
Indications
Gastric and duodenal ulcer, NSAID-associated duodenal and gastric ulcer, prophylaxis in patients with history of NSAID-associated ulcers, gastro-esophageal reflux disease (GERD), long-term management of acid reflux disease, acid-related dyspepsia, severe ulcerating reflux esophagitis, prophylaxis of acid aspiration during general anesthesia, Zollinger-Ellison syndrome, H. pylori-induced peptic ulcer.
Therapeutic class
Proton Pump Inhibitor
Pharmacological class
Substituted benzimidazole
Pharmacology
Omeprazole inhibits the final step of gastric acid secretion by blocking the H+/K+ ATPase enzyme system in gastric parietal cells. It inhibits both basal and stimulated acid secretion. Onset occurs within 1 hour, maximum effect within 2 hours, and inhibition lasts up to 72 hours. Secretary activity returns gradually over 3-5 days after discontinuation.
Mechanism of action
Omeprazole irreversibly blocks the H+/K+-ATPase enzyme (proton pump) in gastric parietal cells, stopping the final step of gastric acid secretion. This reduces stomach acid production, providing relief from acid reflux, heartburn and peptic ulcers and helping heal the esophageal and gastric lining.
Dosage
Oral:
- Benign gastric and duodenal ulcer: 20 mg once daily for 4 weeks (duodenal) or 8 weeks (gastric); severe/recurrent: 40 mg/day; maintenance: 20 mg once daily; relapse prevention: 10-20 mg/day.
- NSAID-associated ulcers: 20 mg once daily for 4 weeks; continue for further 4 weeks if not fully healed. Prophylaxis: 20 mg once daily.
- GERD: 20 mg once daily for 4 weeks; continue for further 4-8 weeks if not healed; refractory cases: 40 mg once daily for 8 weeks; maintenance: 20 mg once daily.
- Long-term management of acid reflux: 10-20 mg/day.
- Acid-related dyspepsia: 10-20 mg once daily for 2-4 weeks.
- Acid aspiration prophylaxis: 40 mg on preceding evening, then 40 mg 2-6 hours before surgery.
- Zollinger-Ellison syndrome: Initially 60 mg once daily; range 20-120 mg/day (doses >80 mg divided).
- H. pylori eradication: 20 mg twice daily + antibiotics (amoxicillin 500mg + metronidazole 400mg both tid for 1 week, OR clarithromycin 250mg + metronidazole 400mg both bid for 1 week, OR amoxicillin 1g + clarithromycin 500mg both bid for 1 week).
- Pediatric (severe reflux esophagitis >1 year): 10-20 kg: 10-20 mg once daily for 4-12 weeks; >20 kg: 20-40 mg once daily for 4-12 weeks.
IV Injection/Infusion:
- Acid aspiration prophylaxis: 40 mg slow IV injection (5 min) 1 hour before surgery.
- Duodenal ulcer, gastric ulcer, reflux esophagitis (when oral not possible): 40 mg IV once daily.
- Zollinger-Ellison syndrome: Initially 60 mg/day IV; doses >60 mg/day divided.
- Special Populations: Elderly: No dose adjustment; severe hepatic impairment: 10-20 mg/day; renal impairment: No dose adjustment.
Administration
Oral: Take capsule whole on an empty stomach 1 hour before breakfast, do not chew or crush.
IV Injection: Reconstitute each 40 mg vial with 10 mL water for injection, give slow IV injection over 2-5 minutes (max 4 mL/min). Use within 4 hours of reconstitution.
IV Infusion: Dissolve in 100 mL saline or 5% dextrose, infuse over 20-30 minutes. Use within 12 hours (saline) or 6 hours (dextrose). Do not mix with other drugs.
Missed dose
If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and continue with your regular schedule. Do not double the dose.
Side effects
Common side effects: Diarrhea, flatulence, headache, nausea, stomach pain, vomiting, constipation.
Rare side effects: Skin rash, urticaria, pruritus, photosensitivity, bullous eruption, erythema multiforme, angioedema, alopecia, dry mouth, stomatitis, candidiasis, paresthesia, dizziness, somnolence, insomnia, vertigo, reversible mental confusion, agitation, depression, hallucinations (predominantly in severely ill patients), arthritic and myalgic symptoms, blurred vision, taste disturbance, peripheral edema, increased sweating, gynecomastia, leukopenia, thrombocytopenia, agranulocytosis, pancytopenia, anaphylactic shock, malaise, fever, bronchospasm, encephalopathy (in pre-existing severe liver disease), hepatitis with or without jaundice, interstitial nephritis, hepatic failure.
Precautions & warnings
Long-term use may cause magnesium deficiency and increased fracture risk. Take calcium and magnesium supplements. Avoid concomitant use with clopidogrel. Inform your doctor if you experience watery diarrhea, fever or persistent stomach pain. Consult doctor if no improvement within 14 days. Inform doctor immediately if decreased urination, edema, back pain, fatigue, rash or fever occur (signs of kidney problems). Caution in pregnancy and lactation.
Contraindications
Hypersensitivity to any component. When gastric ulcer is suspected, malignancy should be excluded before treatment (treatment may alleviate symptoms and delay diagnosis).
Drug interactions
Clopidogrel: Reduced antiplatelet effect – avoid concomitant use. Rilpivirine, atazanavir, nelfinavir: Decreased plasma concentrations – potentially fatal. Warfarin: Increased INR and prothrombin time. Digoxin: Increased bioavailability (10%) due to pH change – risk of cardiotoxicity. Diuretics: Increased risk of hypomagnesemia. Benzodiazepines (diazepam), phenytoin, cilostazol, cyclosporine: Delayed elimination. Ketoconazole, itraconazole, posaconazole, dasatinib, iron salts: Decreased absorption. Methotrexate: Increased toxicity. No interaction with: Amoxicillin, antacids, propranolol, metoprolol, caffeine, theophylline.
Food interactions
Caution advised when consuming alcohol as it may increase stomach acid production and worsen symptoms. Omeprazole absorption is not affected by alcohol or food.
Use in pregnancy
Pregnancy: Three prospective epidemiological studies showed no adverse effects on pregnancy or fetal/newborn health. Omeprazole can be used during pregnancy. Animal studies have shown harmful effects on the fetus. Consult your doctor.
Pregnancy Category: C — always consult a doctor before taking during pregnancy.
Use in lactation
There is no information on passage of omeprazole into breast milk or effects on neonate. Breast-feeding should be discontinued if use is considered essential.
Pediatric use
Safety and efficacy not established in children under 18 years (except severe reflux esophagitis >1 year).
Geriatric use
No dosage adjustment generally required for elderly patients.
Renal / hepatic impairment
Safe in kidney disease; no dose adjustment needed. Caution in severe liver disease; dose adjustment may be needed (lower dose for long-term use).
Overdose effects
Symptoms: confusion, drowsiness, blurred vision, tachycardia, nausea. No specific antidote; symptomatic treatment.
Storage conditions
Store in a dry place away from light and heat. Keep out of reach of children.
Chemical structure
5-methoxy-2-[[(4-methoxy-3,5-dimethylpyridin-2-yl)methyl]sulfinyl]-1H-benzimidazole