Omeprazole Towa Pharmaceutical Europe (Omeprazole)

Omeprazole is a proton pump inhibitor that acts on the gastric acid secretion pathway. It is indicated for several acid‑related disorders:

• Gastro‑esophageal reflux disease (GERD): provides symptomatic relief and promotes healing of erosive esophagitis.
• Peptic ulcer disease: supports ulcer healing and reduces recurrence risk.
• Zollinger‑Ellison syndrome: controls gastric acid hypersecretion associated with gastrin‑producing tumors.
• Helicobacter pylori eradication regimens (as part of combination therapy): enhances eradication rates when used with antibiotics.
• NSA‑induced gastropathy prophylaxis: lowers risk of ulcer formation in patients requiring chronic NSAID therapy.

• Omeprazole irreversibly binds to the H+/K+‑ATPase enzyme (the gastric proton pump) on the secretory surface of parietal cells. By inhibiting this final step of acid production, it markedly reduces both basal and stimulated gastric acid secretion, allowing the gastric mucosa to heal and decreasing acidity in the stomach and duodenum.

Omeprazole is generally well tolerated, but adverse reactions can occur.

Common Side Effects

• Headache: mild to moderate intensity.
• Diarrhea: usually self‑limiting.
• Nausea or abdominal discomfort: transient gastrointestinal upset.
• Flatulence: excess gas production.
• Constipation: occasional bowel habit change.
• Dry mouth: reduced salivation.

Serious or Rare Side Effects

• Severe allergic reactions (anaphylaxis, angioedema): require immediate medical attention.
• Clostridioides difficile‑associated colitis: may present with watery diarrhea and abdominal pain.
• Low magnesium levels (hypomagnesemia): can cause muscle cramps, arrhythmias, or seizures.
• Bone fractures: increased risk with long‑term use.
• Acute interstitial nephritis: renal inflammation presenting with reduced urine output.
• Liver enzyme elevations: may indicate hepatic stress.

Omeprazole should be used with consideration of the following precautions:

• Assess renal and hepatic function: adjust use in severe impairment.
• Review long‑term therapy need: limit duration when possible to reduce fracture risk.
• Monitor for vitamin B12 deficiency: prolonged use may impair absorption.
• Evaluate for potential drug‑interaction risks: especially with antiplatelet or anticoagulant agents.
• Pregnancy and lactation: use only if clearly needed after risk‑benefit assessment.
• Store below 25°C: keep in the original container, protect from moisture and direct sunlight.

Omeprazole may affect the pharmacokinetics of several co‑administered medicines.

Major Interactions (Avoid)

• Clopidogrel: reduced antiplatelet effect, may increase cardiovascular event risk.
• Atazanavir or other protease inhibitors: decreased antiviral efficacy due to reduced gastric acidity.
• Warfarin: potential increase in INR, requiring closer monitoring.

Moderate Interactions (Monitor Closely)

• Methotrexate: increased serum levels, especially with high‑dose regimens.
• Digoxin: higher plasma concentrations may occur.
• Diazepam: enhanced sedation and respiratory depression risk.
• Ketoconazole and other azole antifungals: reduced absorption and efficacy.
• Iron supplements: decreased iron absorption; separate dosing times.