Omeprazole

Omeprazole is a proton pump inhibitor (PPI) which inhibits gastric acid production by the gastric parietal cells.Following endoscopic treatment of bleeding peptic ulcers, omeprazole given intravenous for 72 hours has been shown to reduce the risk of rebleeding N Engl J Med 2000; 343: 310–6). PPIs are often overused in the ICU and there is emerging data linking PPI use with Clostridium difficile infection (Dial S, et al. CMAJ 2004; 171: 33–8.

Uses
Bleeding peptic ulcers, after endoscopic treatment of bleeding (unlicensed)
Continuation of PPI therapy when the PO/NG route is unavailable.
Helicobacter pylori eradication.

Administration
• Bleeding peptic ulcers, after endoscopic treatment of bleeding
IV: Initial 80 mg IV loading dose given over 1 hour, followed by 8 mg/h
IV infusion for 72 hours
Reconstitute with either sodium chloride 0.9% or glucose 5%

• Continuation of PPI therapy when the PO/NG route is unavailable
IV bolus: 40 mg daily. Reconstitute 40 mg vial with the solvent provided and administer over 5 min

• Eradication of Helicobacter pylori
See monograph on metronidazole

Adverse effects
GI disturbances (nausea, vomiting, abdominal pain, diarrhoea and constipation)
Paraesthesia
Agitation
Liver dysfunction
Hyponatraemia
Leukopenia and thrombocytopenia rarely

Cautions
Severe hepatic disease (risk of encephalopathy)
Pregnancy (toxic in animal studies)
May mask symptoms of gastric cancer
Omeprazole may enhance anticoagulant effect ofwarfarin – monitor INR
and may increase phenytoin levels
Omeprazole may reduce the effectiveness of clopidogrel

Organ failure
Hepatic: reduce dose