Adults

Typical dose is 20-40 mg once daily, preferably in the morning before breakfast. Duration varies by condition (e.g., GERD 4-8 weeks, Ulcers 2-8 weeks). For Zollinger-Ellison Syndrome, initial dose 60 mg once daily, adjusted based on response.

Elderly

No specific dose adjustment is generally required, but monitor for potential side effects due to age-related physiological changes.

Renal_impairment

No dose adjustment is typically necessary in patients with renal impairment.

Onset

Acid inhibition begins within 2-3 hours; full therapeutic effect achieved within 2-4 days.

Excretion

Approximately 77% excreted in urine, and the remainder in feces via biliary excretion.

Half life

Plasma half-life is 0.5-1 hour, but the duration of action is much longer due to irreversible binding to the proton pump.

Absorption

Rapidly absorbed, bioavailability approximately 30-40% after the first dose, which increases to about 60% with repeated dosing.

Metabolism

Extensively metabolized in the liver primarily by CYP2C19 and to a lesser extent by CYP3A4.

Digoxin

Increased systemic exposure to digoxin. Monitor digoxin levels if co-administered.

Warfarin

Omeprazole may alter the metabolism of warfarin, leading to increased INR and risk of bleeding. Close monitoring of INR is recommended.

Clopidogrel

Omeprazole inhibits CYP2C19, which metabolizes clopidogrel to its active form, potentially reducing clopidogrel's antiplatelet effect. Concurrent use is generally discouraged.

Methotrexate

May increase serum levels of methotrexate, especially in high-dose therapy, leading to potential toxicity. Temporary discontinuation of omeprazole may be considered.