Capsules, sustained release*: 10 mg, 20 mg, 40 mg
*Also available in a 20 mg nonprescription formulation
Short-term treatment of active duodenal ulcer: 20 mg daily for 4-8 weeks.
Short-term treatment of erosive esophagitis or poorly responsive gastroesophageal reflux disease: 20 mg daily for 4-8 weeks.
Pathological hypersecretory conditions including Zollinger-Ellison syndrome, multiple endocrine adenomas, and systemic mastocytosis: Initial dose is 60 mg once a day. Doses up to 120 mg given three times a day have been administered. Some patients have been treated continuously for more than 5 years.
Maintenance therapy of healing erosive esophagitis: 20 mg given once daily.
To maintain the healing of erosive esophagitis and gastric ulcers: 20 mg given once daily.
For the treatment of GERD or other acid-related disorders in pediatric patients over the age of 2 years: For patients <20 kg give 10 mg daily. For patients >20kg give 20 mg daily.
As an adjunct in the treatment of H. pylori infection:
Dual Therapy: Omeprazole 40 mg once daily with clarithromycin 500 mg given 3 times a day for 14 days. If an ulcer was present at initiation of treatment, follow with omeprazole 20 mg once a day for 14 days.
Triple Therapy: Omeprazole 20 mg with clarithromycin 500 mg plus amoxicillin 1000 mg given twice daily for 10 days. If an ulcer was present at initiation of therapy, follow with omeprazole 20 mg once a day for 18 days.
Pharmacology/Pharmacokinetics:
Omeprazole is a proton-pump inhibitor (PPI) that suppresses the H+/K+ ATPase enzyme system at the secretory surface of the gastric parietal cell. The enzyme system is involved in the movement and production of gastric acid. Omeprazole is acid-labile and is formulated as enteric-coated granules. Onset after oral administration occurs within 1 hour and reached a maximum at 2 hours. The binding to the (H+/K+)-ATPase results in antisecretory activity that lasts for more than 72 hours.
Drug Interactions:
Increases plasma levels of diazepam, phenytoin, and warfarin by inhibiting oxidative metabolism. May also interact with other drugs metabolized via the cytochrome P450 system (cyclosporine, disulfiram, benzodiazepine). Since the pharmacological effect of omeprazole increases gastric pH, absorption of drugs in which bioavailability is determined by gastric pH may be changed. This would include ketoconazole, digoxin, cyanocobalamin, ampicillin esters, and iron salts. Antacids may be used concomitantly. Voriconazole may increase plasma levels. Omeprazole inhibits the metabolism of cilostazol. Omeprazole prevents the conversion of clopidogrel to its active metabolite.
Contraindications/Precautions:
Animal studies have shown a dose-related increased risk for gastric carcinoid tumors with long-term use. The levels of drug needed to produce tumors far exceeded the normal daily dose (up to 352 times the human dose). Pregnancy Category C.
Adverse Effects:
Side effects are rare but may include back pain, cough, constipation, rash, and dizziness.
Take 30 minutes prior to eating.
Antacids may be taken at the same time.
Store in a cool, dry place away from sunlight and children.
If a dose is missed, take it as soon as possible. If it is closer to the time of your next dose than the dose you missed, skip the missed dose and return to your dosing schedule. Do not double doses.
Contact a physician if the above side effects are severe or persistent.
For patients who have difficulty swallowing capsules, the contents of a capsule can be added to one tablespoon of applesauce, swallowed immediately and followed by a glass of cool water. The contents of the capsule should not be crushed or chewed.
