Omeprazole Accord Healthcare Ireland (Omeprazole)

Omeprazole is a proton pump inhibitor that acts on gastric acid secretion pathways.

• Gastro‑oesophageal reflux disease (GERD): provides symptomatic relief and promotes healing of the oesophageal lining.
• Peptic ulcer disease: facilitates ulcer healing by maintaining a less acidic gastric environment.
• Zollinger‑Ellison syndrome: controls excessive gastric acid secretion associated with gastrin‑producing tumours.
• Erosive esophagitis: aids healing of erosive damage to the oesophagus.
• Helicobacter pylori eradication regimens: used as an adjunct in combination therapy to improve eradication rates.

• Omeprazole selectively and irreversibly binds to the H+/K+‑ATPase enzyme (the gastric proton pump) on the secretory surface of parietal cells, inhibiting the final step of acid secretion. This suppression of gastric acid production raises gastric pH, allowing mucosal healing and symptom relief in acid‑related disorders.

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

Common Side Effects

• Headache: mild and transient.
• Diarrhoea: loose stools without blood.
• Nausea: occasional feeling of queasiness.
• Abdominal pain: mild cramping or discomfort.
• Flatulence: increased intestinal gas.
• Constipation: infrequent bowel movements.

Serious or Rare Side Effects

• Clostridioides difficile infection: severe colitis presenting with watery diarrhoea.
• Fracture risk: decreased calcium absorption may increase risk of hip, wrist or spine fractures with long‑term use.
• Vitamin B12 deficiency: malabsorption leading to neuropathy or anaemia.
• Acute interstitial nephritis: kidney inflammation presenting with reduced urine output.
• Severe skin reactions: such as Stevens‑Johnson syndrome or toxic epidermal necrolysis.

When using Omeprazole, consider the following precautions:

• Assess renal function: adjust use in severe renal impairment.
• Review concomitant medications: potential for altered absorption of drugs requiring acidic pH.
• Evaluate long‑term use: monitor for bone density loss and vitamin B12 levels.
• Pregnancy and lactation: weigh benefits against potential risks; use only if clearly needed.
• Store at below 25°C: keep in the original packaging, protect from moisture and direct sunlight.

Omeprazole may interact with several medicines; monitoring is advised.

Major Interactions (Avoid)

• Clopidogrel: reduced antiplatelet effect, increasing cardiovascular risk.
• Atazanavir: decreased absorption leading to sub‑therapeutic levels.
• Methotrexate (high dose): increased serum concentrations and toxicity.

Moderate Interactions (Monitor Closely)

• Warfarin: potential increase in INR, requiring more frequent coagulation monitoring.
• Digoxin: elevated serum levels may occur, necessitating dose adjustment.
• Phenytoin: reduced plasma concentrations, possibly diminishing seizure control.