Prilosec | omeprazole
Medication class: Proton Pump Inhibitor
Manufactured by: AstraZeneca
Approval date: September,1989
What is omeprazole and its mechanism of action?
Omeprazole (Prilosec) belongs to a group of drugs known as Proton Pump Inhibitors (PPIs). Proton pump inhibitors blocks the production of gastric acids by enzymes (proton pump) in the stomach wall. Excessive acid production contributes to development of ulcers. Omeprazole prevents ulcers, reduces symptoms of ulcers (pain, bleeding, burning, weight loss, vomiting) and helps ulcers heal by reducing the production of acid.
What is omeprazole used for treating?
• Duodenal (intestines) ulcers in adults, including eradication of H. pylori when combined with clarithromycin and/or amoxicillin
• Gastric ulcers in adults
• Gastroesophageal Reflux Disease (GERD) in pediatric patients in adults
• Maintenance of healing of Erosive Esophagitis in pediatric patients and adults
• Zollinger-Ellison Syndrome: Hypersecretory conditions in adults
• Occasional heartburn (Prilosec OTC)
How effective is omeprazole?
Active duodenal ulcers: Omeprazole 20 mg administered to adult patients for 2 to 4 weeks was better than placebo in reducing day time and nighttime pain. 75% of omeprazole versus 27% of placebo treated patients healed after 4 weeks. In another study, 82% of omeprazole 20 mg versus 63% of Zantac 300 mg treated patients healed after 4 weeks.
Gastric ulcers: Omeprazole 40 mg administered over 8 weeks healed 82.7% of adult patients compared to 48.1% of patients treated with placebo. Omeprazole 20 mg healed 47.5% patients within 4 weeks and 74.8% patients within 8 weeks compared to 30.8% and 48.1% of patients treated with placebo.
Gastroesophageal Reflux Disease (GERD): Omeprazole 10 or 20 mg administered once daily over 4 weeks was better than placebo in treating heart burn and other symptoms of GERD in adult outpatients. 46%, 31%, and 13% of omeprazole 20 mg, 10 mg, and placebo reported reduced symptoms, respectively.
Erosive Esophagitis: Omeprazole 20 or 40 mg administered once daily for 8 weeks healed 74% and 75% of adult patients, respectively compared to 14% of patients treated with placebo. Omeprazole 20 mg taken once daily or 3 days a week was more effective than placebo in maintaining healing of erosive esophagitis at 6 months. Omeprazole 10 or 20 mg daily was also better than Zantac 300 mg in maintaining remission for 12 months. Remission rates were 58%, 77%, and 46%, respectively.
Zollinger-Ellison Syndrome: Omeprazole 20 mg significantly prevented gastric acid secretions and controlled symptoms of diarrhea, anorexia and pain in adult patients. Omeprazole was well tolerated even at high doses (up to 360 mg per day) for prolonged periods (>5 years in some patients).
What are the interesting facts about omeprazole?
• It is approved for adults and pediatric patients between 1 and 16 years of age.
• Interacts with Plavix (clopidogrel).
• Generic versions are available.
• Over-the-counter formulation is available.
• First PPI that was approved.
What is the dosage for omeprazole?
Omeprazole is available as 10, 20, and 40 mg delayed-release capsules, delayed-release suspension 2.5 or 10 mg, and tablets (OTC) 20 mg. Omeprazole capsules should be swallowed whole. However, patients who have difficulty in swallowing can open the contents of the Omeprazole delayed-response capsules and add them to one table spoon of apple sauce. Suspension should be mixed with 5 or 15 mL of water, left for 2-3 minutes to thicken and taken within 30 minutes.
Active duodenal ulcers: 20 mg for 4 weeks.
Gastric ulcers: 40 mg once daily for 4 to 8 weeks.
GERD: 20 mg once daily for 4 to 8 weeks.
Maintenance of healing of Erosive Esophagitis: 20 mg once daily.
Zollinger-Ellison Syndrome: 60 mg once daily.
Pediatric patients (1 to 16 years of age): The recommended dose for treating GERD and maintenance of healing of Erosive Esophagitis is 5,10, or 20 mg once daily depending on weight.
Heartburn: 20 mg tablet before meals for 2 weeks.
H. pylori eradication: Omeprazole 20 mg, clarithromycin 500 mg, amoxicillin 1000 mg all given twice daily for 10 days or omeprazole 40 mg for 14 days plus clarithromycin 500 mg 3 times daily for 14 days.
What are the side effects of omeprazole?
Common: Headache, abdominal pain, nausea and vomiting, diarrhea and flatulence.
Serious: Allergic reactions, liver dysfunction, pancreatitis, fractures, low magnesium, atrophic gastritis (inflammation of stomach lining), reduced blood cell counts, nephritis (inflammation of the kidney), severe skin reactions.
Omeprazole drug interactions
Drugs for which gastric pH can affect absorption (e.g., ketoconazole, ampicillin, Iron salts): Omeprazole may interfere with absorption of these drugs due to inhibition of gastric acid secretion, thus decreasing their efficacy.
Drugs metabolized by liver enzymes (cytochrome P450) (e.g., diazepam, warfarin, phenytoin, cyclosporine, disulfiram, benzodiazepines): Omeprazole may reduce elimination of these drugs increasing levels of these drugs in the blood. Increased side effects may occur.
Voriconazole: Voricanozole may double blood levels of omeprazole possibly increasing side effects of omeprazole.
St. John’s Wort or rifampin may reduce blood levels of omeprazole. Both drugs increase breakdown of omeprazole in the liver.
Omeprazole reduces conversion of clopidogrel (Plavix) to its active form, reducing the efficacy of clopidogrel even administered 12 hours apart. Avoid combining omeprazole with clopidogrel.
Tacrolimus: Omeprazole may increase serum levels of Tacrolimus.
What is the price of omeprazole
Omeprazole cost $0.69 to $0.89 per capsule for generic formulations and $5 to $10 per capsule for brand name Prilosec.
Reference: Prilosec FDA Prescribing Information and Medication Guide.
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