Indication
Omeprazole is indicated for the treatment of-
Gastric and duodenal ulcer
NSAID-associated duodenal and gastric ulcer
As prophylaxis in patients with a history of NSAID-associated duodenal and gastric ulcer
Gastro-esophageal reflux disease
Long-term management of acid reflux disease
Acid-related dyspepsia
Severe ulcerating reflux esophagitis
Prophylaxis of acid aspiration during general anesthesia
Zollinger-Ellison syndrome
Helicobacter pylori-induced peptic ulcer.
Pharmacology
Omeprazole, a substituted benzimidazole, is an inhibitor of gastric acid secretion. It inhibits gastric acid secretion by blocking hydrogen-potassium-adenosine triphosphatase (H+/K+ ATPase) enzyme system in the gastric parietal cell. After oral administration, the onset of the antisecretory effect occurs within one hour, with the maximum effect occurring within two hours and inhibition of secretion lasts up to 72 hours. When the drug is discontinued, secretory activity returns gradually, over 3 to 5 days.
Dosage
Oral-
Benign gastric and duodenal ulcer: 20 mg once daily for 4 weeks in duodenal ulceration, 8 weeks in gastric ulceration; in severe or recurrent cases, dose to be increased to 40 mg daily; maintenance dose for recurrent duodenal ulcer, 20 mg once daily; in prevention of relapse in duodenal ulcer, 10-20 mg daily.
NSAID-associated duodenal or gastric ulcer: 20 mg once daily for 4 weeks, continued for further 4 weeks, if not fully healed. 20 mg once daily is used as prophylaxis in patients with a history of NSAID-associated duodenal or gastric ulcers.
Gastro-esophageal reflux disease: 20 mg once daily for 4 weeks, continued for further 4-8 weeks, if not fully healed; 40 mg once daily has been given for 8 weeks in gastro-esophageal reflux disease, refractory to other treatment; maintenance dose is 20 mg once daily.
Long-term management of acid reflux disease: 10-20 mg daily.
Acid-related dyspepsia: 10-20 mg once daily for 2-4 weeks.
Prophylaxis of acid aspiration: 40 mg on the preceding evening, then 40 mg 2-6 hours before surgery.
Zollinger-Ellison syndrome: Initially 60 mg once daily; usual range 20-120 mg daily (If daily dose is more than 80 mg, 2 divided dose should be used).
Helicobacter pylori eradication regimen in peptic ulcer disease: Omeprazole is recommended at a dose of 20 mg twice daily in association with antimicrobial agents as detailed below: Amoxicillin 500 mg and Metronidazole 400 mg both three times a day for one week, or Clarithromycin 250 mg and Metronidazole 400 mg both twice a day for one week, or Amoxicillin 1 g and Clarithromycin 500 mg both twice a day for one week.
Paeditaric use in severe ulcerating reflux esophagitis (Child>1 year): If body-weight 10-20 kg, 10-20 -mg once daily for 4-12 weeks; if body-weight over 20 kg, 20-40 mg once daily for 4-12 weeks.
IV Injection-
Prophylaxis of acid aspiration: Omeprazole 40 mg to be given slowly (over a period of 5 minutes) as an intravenous injection, one hour before surgery.
Duodenal ulcer, gastric ulcer or reflux oesophagitis: In patients with duodenal ulcer, gastric ulcer or reflux oesophagitis where oral medication is inappropriate, Omeprazole IV 40 mg once daily is recommended.
Zollinger- Ellison syndrome (ZES): In patients with Zollinger-Ellison Syndrome the recommended initial dose of Omeprazole given intravenously is 60 mg daily. Higher daily doses may be required and the dose should be adjusted individually. When doses exceed 60 mg daily, the dose should be divided & given twice daily.
Interaction
Omeprazole can prolong the elimination of diazepam, warfarin and phenytoin. So, reduction of warfarin or phenytoin dose may be necessary when Omeprazole is added to the treatment. There is no evidence of an interaction of Omeprazole with theophylline, propranolol or antacids.
Contradiction
Omeprazole is contraindicated in patients with known hypersensitivity to any of the components of the formulation.
Side Effect
Omeprazole is generally well tolerated. Nausea, abdominal colic, paresthesia, dizziness and headache have been stated to be generally mild and transient and not requiring a reduction in dosage.
Pregnancy
US FDA pregnancy category of Omeprazole is C. However, results from three prospective epidemiological studies indicate no adverse effects of Omeprazole on pregnancy or on the health of the fetus/newborn child. There is no information available on the passage of Omeprazole into breast milk or its effects on the neonate. Breast-feeding should, therefore, be discontinued, if the use of Omeprazole is considered essential.
Precaution
When gastric ulcer is suspected, the possibility of gastric malignancy should be excluded before treatment with Omeprazole is instituted, as treatment may alleviate the symptoms and delay diagnosis.
Overdose
Storage
Keep in a dry place away from light and heat. Keep out of the reach of children.