20 mg Capsule
40 mg Capsule




The Cathay Drug Co., Inc.


Each capsule contains

Omeprazole ……………………………. 40 mg




Omeprazole is a proton pump inhibitor and thus prevents secretion of gastric acid. It is rapidly absorbed following oral administration but only to a variable extent. It is not affected by food and is acid labile. The bioavailability of omeprazole is 30 – 40% and increases after repeated administration. In elderly patients and those with impaired hepatic function, the bioavailability of omeprazole may increase, but patients with renal impairment are not markedly affected. Omeprazole is highly bound to plasma proteins about 95%.


Omeprazole is extensively metabolized by the liver. Some metabolites have been identified but they do not have inadequate or no antisecretory activity. The elimination half-life from plasma is about 0.5 to 3 hours while the acid inhibitory effect is much longer that lasts more than 24 hours. When omeprazole is discontinued, the secretory activity returns over 3 to 5 days. Approximately 77% of omeprazole is rapidly eliminated in the urine while the remainder of the dose is excreted in the feces.


Omeprazole (MEPRAZ) is used in the treatment of conditions such as peptic ulcer disease, duodenal ulcer associated with H. pylori infection, gastric ulcer, gastroesophageal reflux disease (GERD), hypersecretory conditions like Zollinger-Ellison Syndrome, reflux esophagitis and dyspepsia. It is also used for the prophylaxis of acid aspiration.


Omeprazole (MEPRAZ) may be given orally before meals. Omeprazole capsules must be swallowed whole with water and should not be opened, crushed or chewed.

For Peptic Ulcer Disease: Omeprazole 20mg once a day. For severe cases, dosage should be increase to Omeprazole 40mg once a day. Healing usually occurs with \in 4 weeks for patients with duodenal ulcer and 8 weeks for patients with gastric ulcer. Omeprazole 20mg or 40mg once a day may be given for maintenance.

For Duodenal Ulcer Disease: Omeprazole 20mg once a day for 4 to 8 weeks. The healing occurs within 4 weeks in most patients. It may require an additional 4 weeks of therapy for some patients.

For Duodenal Ulcer associated with H. pylori infection:

Triple therapy

  • Omeprazole 20mg plus Clarithromycin 500mg plus Amoxicillin 1000mg, each given twice a day for 10 days. If an ulcer is present at the initiation of therapy, continue Omeprazole 20mg for an additional 18 days or
  • Omeprazole 20mg plus Clarithromycin 250mg plus Metronidazole 500mg, each given twice a day for 1 week or
  • Omeprazole 20mg once a day plus Amoxicillin 500mg plus Metronidazole 500mg, to be taken three times a day for 1 week.

Dual therapy

  • Omeprazole 40mg plus Clarithromycin 500mg three times a day for 14 days. If an ulcer is present at the initiation of therapy, continue Omeprazole 20mg for an additional 14 days or
  • Omeprazole 40mg once a day plus amoxicillin 750 mg twice a day for 2 weeks

Gastric Ulcer: Omeprazole 20mg once a day for 4 weeks. For patients with poorly responsive gastric ulcer, increase treatment to Omeprazole 40 mg once a day for 8 weeks.

Gastro-Esophageal Reflux Disease (GERD): Omeprazole 20mg 1-2 capsules once a day, given for 4 to 12 weeks. Maintenance therapy can be continued with Omeprazole 20mg once a day.

Zollinger-Ellison Syndrome: The initial recommended dosage is Omeprazole 60mg once a day but doses up to 120 mg 3x a day have been administered. The majority of patients are effectively controlled by doses of Omeprazole 20 to 120 mg once a day.

Prophylaxis of Acid Aspiration: Omeprazole 40mg in the evening before the surgery and followed by Omeprazole 40mg on the day of surgery, give 1 to 4 hours prior to the procedure.

Reflux Esophagitis: Omeprazole 20mg once a day for 4 weeks. For patients who may not be fully healed, continue Omeprazole 20 mg for an additional 4 weeks.

Omeprazole 40mg once a day is recommended for severe reflux esophagitis given 8 weeks.

Omeprazole 10mg once a day is recommended for the maintenance of patients with healed reflux esophagitis. Increase to Omeprazole 20 – 4-mg once a day if needed.

In children from one year and above with severe reflux esophagitis:

  • The recommended dosage for treatment is Omeprazole 10mg once a day, for children weighing 10-20kg, and
  • Omeprazole 20mg once a day, for children weighing > 20 kg.

Dyspepsia: Omeprazole 10mg once a day could be considered as a starting or initial dose because patients may respond adequately to this dose.

For patients with epigastric pain or discomfort with or without heartburn, Omeprazole 20mg once a day is the recommended dosage for 4 weeks. If symptom relief after 4 weeks of treatment with Omeprazole 20mg once a day has not been achieve, it is recommended for further investigation.

Impaired hepatic function: Some recommend that the maximum daily dose for patients with impaired hepatic function is reduced to 20 mg. omeprazole 10 – 20 mg once a day may be sufficient for patients with impaired hepatic function. For the elderly, dose adjustments is not needed.

Impaired renal function:  in patients with impaired renal function, dose adjustment is needed.

Or as prescribed by the physician.


Patients with known hypersensitivity to omeprazole.


Omeprazole inhibits the metabolism of some drugs metabolized by the hepatic cytochrome P450 enzyme system and may increase plasma concentrations of Diazepam, Phenytoin and Warfarin.

Before giving Mepraz for gastric ulcers, the possibility of malignancy should be excluded because Omeprazole may mask the symptoms and cause a delay the diagnosis.


Omeprazole may interfere with the absorption of drugs like: ketokonazole, ampicillin, iron salts, digoxin, cyanocobalamin where gastric pH is an important determinant of bioavailability.

There are clinical reports of interaction with other drugs like: cyclosporine, disulfiram, benzodiazepines which are metabolized via cytochrome P450 system.

Co-administration of omeprazole and clarithromycin may result in increase in plasma levels.

Omeprazole increases the half-life of diazepam, probably caused by inhibition oxidative metabolism. Plasma levels were also increased and total clearance of diazepam was decreased.
Omeprazole reduced the plasma clearance of phenytoin and increased its half-life caused by inhibition of oxidative metabolism.

Co-administration of omeprazole with sucralfate may delay absorption and reduce omeprazole bioavailability. Therefore, take omeprazole 30 minutes prior to sucralfate.


Most frequently reported adverse effects include diarrhea, skin rashes and headache. Effects on the Central Nervous System include reversible confusional states in severely ill patients.

Other adverse effects reported rarely include: arthralgia and myalgia, blood disorders including leucopenia and thrombocytopenia, interstitial nephritis and hepatotoxicity.


Animal studies show risk but human studies are inadequate or lacking or no studies in humans or animals.

Direct pregnant or lactating women to consult a physician before use.


Omeprazole overdosage has been reported rarely. Doses ranged from 320 to 900 mg (16 to 45 times of the usual recommended dose). Symptoms are transient and no serious clinical outcome has been reported.

Nausea, vomiting, dizziness, abdominal pain, diarrhea, headache, apathy, depression and confusion are reported from omeprazole overdosage. No specific antidote for omeprazole overdosage is known.

Omeprazole is extensively protein bound and is, therefore, not readily dialyzable. In the event of overdosage, treatment should be symptomatic and supportive.


Store at temperatures not exceeding 30°C.


Capsule box of 20’s


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