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Omeprazole



         



Omeprazole

di-5-methoxy-2-[[(4-methoxy-3,5-dimethyl-2-pyridinyl) methyl]sulfinyl]-1H-benzimidazole

Empirical formula C34H36N6O6S2
Molecular weight 688.8
Bioavailability (Oral) 35-60%
Metabolism hepatic CYP2C19, CYP3A4
Elimination half life (Oral) 0.5-1 hour
Excretion 80% renal, 20% faecal
Pregnancy category B3 (Australia)

Omeprazole is a proton pump inhibitor used in the treatment of dyspepsia, peptic ulcer disease (PUD), GORD and Zollinger-Ellison syndrome. Omeprazole magnesium is marketed by AstraZeneca under the tradename Losec®, which is one of the most prescribed drugs in the United Kingdom and internationally.

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Use in Helicobacter pylori eradication

Omeprazole is combined with the antibiotics clarithromycin and amoxicillin (or metronidazole in penicillin-hypersensitive patients) in the one week eradication triple therapy for Helicobacter pylori. Infection by H. pylori is the causative factor in the majority of peptic and duodenal ulcers.

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Multiple-unit pellet system

It is interesting to note that the Losec® tablets are formulated as a "multiple-unit pellet system". Essentially, the tablet consists of enteric-coated granules (pellets) of the omeprazole formulation inside an outer shell. When the tablet is swallowed, the contents swell from water absorption, bursting the shell - releasing the tablet contents. The multiple-unit pellet system is often demonstrated to pharmacists and doctors by AstraZeneca sales representatives despite having little advantage, pharmacodynamically, over a regular enteric-coated tablet.

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Adverse effects

Adverse effects associated with omeprazole therapy are similar to those of the other proton pump inhibitors (cf. proton pump inhibitor page for full details).






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