Omeprazole Omeprazole

Omeprazole - Definition and Overview

Omeprazole chemical structure
Omeprazole

(RS)-5-methoxy-2-[[(4-methoxy-3,5-dimethyl-2-pyridinyl) methyl]sulfinyl]-1H-benzimidazole
CAS number
73590-58-6
ATC code
A02BC01
Chemical formula C34H36N6O6S2
Molecular weight 688.8
Bioavailability 35-60%
Metabolism hepatic CYP2C19, CYP3A4
Elimination half-life 0.5-1 hour
Excretion 80% renal, 20% faecal
Pregnancy category B3 (Australia)
Legal status Schedule 4 (Australia)
POM (UK)
Routes of administration oral, intravenous


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 tradenames Losec and Prilosec, and is one of the most prescribed drugs internationally. Faced with the loss of patent protection, AstraZeneca developed and launched esomeprazole (Nexium), a single enantiomer form of omeprazole.

Clinical use

Main article: Proton pump inhibitor

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.

Multiple-unit pellet system

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, pharmacokinetically, over a regular enteric-coated tablet.

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