Pharmacology Omeprazole belongs to a class of antisecretory compounds, the substituted benzimidazoles, that suppress gastric acid secretion by specific inhibition of the H+/K+ ATPase enzyme system at the secretory surface of the gastric parietal cell. Because this enzyme system is regarded as the acid (proton) pump within the gastric mucosa, omeprazole has been characterized as a gastric acid-pump inhibitor, in that it blocks the final step of acid production. This effect is dose-related and leads to inhibition of both basal and stimulated acid secretion irrespective of the stimulus.
Oral- Duodenal Ulcer: 20 mg once daily for 4 weeks. In severe cases, 40 mg once daily for 4 weeks. Gastric Ulcer: 20 mg once daily for 8 weeks. In severe cases, 40 mg once daily for 8 weeks. Erosive Reflux Oesophagitis: 20 mg once daily for 4 weeks. For those not fully healed, to be continued for 4 more weeks. Refractory Reflux Oesophagitis: 40 mg once daily for 8 weeks. Zollinger-Ellison Syndrome: 60 mg once daily, adjusted individually and continued as long as necessary. Most patients will be effectively controlled with 20-120 mg daily. Dosage above 80 mg should be divided and given twice daily. Long-term maintenance treatment with Omeprazole is not recommended. Impaired Renal or Hepatic Function: Adjustment is not required. Patients with severe liver disease should not require more than 20 mg Omeprazole daily. Administration Powder for suspension: Should be taken on an empty stomach. Take at least 1 hr before a meal. Capsule or Tablet: Should be taken with food. Take immediately before a meal. Patients should be cautioned that the capsules should not be opened, chewed or crushed and should be swallowed whole. Delayed release Capsule or Tablet: Should be taken on an empty stomach. Take at least 1 hr before meals. Swallow whole, do not chewithcrush. For patients with difficulty swallowing, cap may be carefully opened & entire contents sprinkled in a spoonful of applesauce. Swallow drug/food mixt witho chewing immediately after prep. Drug/food mixt should not be stored for future use. Interaction Omeprazole can delay the elimination of Diazepam, Phenytoin and Warfarin. Monitoring of patients receiving Warfarin or Phenytoin is recommended and a reduction of Warfarin or Phenytoin dose may be necessary when Omeprazole is added to treatment. Omeprazole does not interfere with Theophylline or Propranolol metabolism. Contraindications Omeprazole is contraindicated in patients with known hypersensitivity to any component of the formulation. Side Effects Side effects reported with Omeprazole in clinical studies have included nausea, diarrhoea, constipation, flatulence, abdominal colic, paresthesia, dizziness and headache but are rare. Skin rashes, leukopenia and transient elevation of plasma activation of hepatic amino-transferases have been observed occasionally in few patients and there has been no consistent relationship with treatment.