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Omeprazole is a proton pump inhibitors. it decreases the amount of acid produced in the stomach by inhibition of H+/K+ ATPase located in the luminal membrane of gastric parietal cells


  • Treatment of Gastroesophageal reflux disease (GERD)
  • Treatment of duodenal and gastric ulcers
  • H. Pylori bacteria eradication to reduce recurrence of Duodenal Ulcer
  • Zollinger-Ellison syndrome

[edit] DOSAGE

  • Gastroesophageal Reflux Disease:
    • Adults: 20mg/day for 4-8 weeks
    • 1-16 Year Olds:
      • 5-10 kg, 5 mg once daily
      • 10-20 kg, 10 mg once daily
      • More than 20 kg, 20 mg once daily
  • Treatment of duodenal ulcer: 20 mg once daily for 4-8 weeks
  • Treatment of gastric ulcer: 40 mg once daily for 4-8 weeks
  • H. pylori Eradication (Triple Therapy): Omeprazole (20 mg) twice daily + Amoxicillin (1000 mg) Twice Daily + Clarithromycin (500 mg) Twice Daily, for 10-14 days
  • Zollinger-Ellison syndrome: 60 mg once daily


  • Known hypersensitivity to Omeprazole


  • Symptomatic response to therapy with Omeprazole does not preclude the presence of gastric malignancy
  • Proton pump inhibitor (PPI) therapy may be associated with increased risk of Clostridium difficile associated diarrhea.
  • Avoid concomitant use of Omeprazole with clopidogrel
  • Long-term and multiple daily dose PPI therapy may be associated with an increased risk for osteoporosis-related fractures of the hip, wrist, or spine.
  • Hypomagnesemia has been reported rarely with prolonged treatment with PPIs
  • Avoid concomitant use of Omeprazole with St John’s Wort or rifampin due to the potential reduction in omeprazole concentrations.


  • Drugs for which gastric pH can affect bioavailability (e.g.,ketoconazole, Itraconazole, ampicillin esters, iron salts, and digoxin): Omeprazole may interfere with absorption due to inhibition of gastric acid secretion.
  • Drugs metabolized by cytochrome P450 (e.g., diazepam, warfarin, phenytoin, cyclosporine, disulfiram, benzodiazepines): omeprazole can prolong their elimination. Monitor to determine the need for possible dose adjustments when taken with Omeprazole.
  • Patients treated with proton pump inhibitors and warfarin concomitantly may need to be monitored for increases in INR and prothrombin time
  • Atazanavir and Nelfinavir: Omeprazole reduces plasma levels of Atazanavir and Nelfinavir. Concomitant use is not recommended
  • Saquinavir: Omeprazole increases plasma levels of saquinavir
  • Voriconazole: Voriconazole, a combined inhibitor of CYP2C19 and CYP3A4, may increase plasma levels of omeprazole
  • Clopidogrel: Omeprazole decreases exposure to the active metabolite of clopidogrel
  • Tacrolimus: Omeprazole may increase serum levels of tacrolimus
  • Methotrexate: Omeprazole may increase serum level of methotrexate


  • Pregnancy Category C (US). Omeprazole should be used during pregnancy only if clearly needed.
  • Nursing mothers: A decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.


Most common adverse reactions in adults are: diarrhea, headache, flatulence, abdominal pain, nausea, constipation and dizziness/vertigo




Heartburn/Gastritis/Gastric ulcer/Duodenal ulcer/Gastroesophageal reflux
H2 antagonists Famotidine   Nizatidine   Ranitidine (Zantac)
Proton-pump inhibitors Dexlansoprazole (Dexilant)   Esomeprazole (Nexium)   Lansoprazole (Prevacid)   Omeprazole (Losec, Prilosec)   Omeprazole/Sodium bicarbonate (Zegerid)   Pantoprazole (Controloc, Pantecta, Pantoloc, Protonix) (  Rabeprazole (Aciphex, Pariet)
Prostaglandins Misoprostol (Cytotec)
Other drugs Alginic acid   Magaldrate   Sucralfate
Combination Regimens Bismuth Subcitrate Potassium/Metronidazole/Tetracycline (Pylera)   Lansoprazole/Amoxicillin/Clarithromycin (Prevpac)