bis(5-methoxy -2- [ [(4- methoxy -3,5- dimethyl -2- pyridinyl) methyl] sulfinyl] -1H- benzimidazole-1-yl), Losec ®, Prilosec ®
Web information on Omeprazole
Metabolism & Interactions
Omeprazole can inhibit the metabolism of phenytoin, warfarin and diazepam
- majority metabolised by CYP2C19 system forming hydroxy and desmethyl metabolites
- reminder by CYP3A4 forming sulphone metabolite
Mechanism of Action
Proton pump via the achiral sulphenamide which is produced in the parietal cell.
Other Issues for Omeprazole
Produces inhibition for almost a full day even though plasma half life less than 2 hours
Relevant Clinical Literature
Please read pharmacological data limitations
Medpedia on Omeprazole (Less technical, good quality control)
Wikipedia on Omeprazole (Less technical, ? quality control)
- NSAID associated peptic ulcers and erosions
- Gastro-oesophageal reflux disease (GORD)
- Acid-related dyspepsia
- Helicobacter pylori associated peptic ulcers
- Zollinger-Ellison syndrome
Group Clinical Issues
Group Cautions and Interactions
- There is now epidemiological evidence from two studies that all inhibit the actions of clopidogrel when previously it was hoped the interaction was more specific. However clinically this interaction appears to be only significant for omeprazole and possibly esomeprazole.
- There is to date an unexplained association between use in the frail institutional elderly and mortality. As absolute annual mortality increased from 26.6% to 33.3% this may be due to confounding.
Group Side effects
- Community acquired pneumonia
- Hypomagnesaemic hypoparathyroidism (tetany)
- Associated with increased risk of Clostridium difficile infection.
Don't measure gastrin levels if a patient is on a PPI (or at least do not panic when you get the result back !).
- ↑ MHRA Drug Safety Update July 2009:2;12
- ↑ Rosholm JU, Nybo H, Andersen Ranberg K, Himmelstrup B, Skjelbo E, Christensen K, Gram LF. Hyponatraemia in very old nonhospitalised people: association with drug use. Drugs & aging. 2002; 19(9):685-93.
- ↑ Hauben M, Horn S, Reich L, Younus M. Association between gastric acid suppressants and Clostridium difficile colitis and community-acquired pneumonia: analysis using pharmacovigilance tools. International journal of infectious diseases : IJID : official publication of the International Society for Infectious Diseases. 2007 Sep; 11(5):417-22.(Link to article – subscription may be required.)
- ↑ Epstein M, McGrath S, Law F. Proton-pump inhibitors and hypomagnesemic hypoparathyroidism. The New England journal of medicine. 2006 Oct 26; 355(17):1834-6.(Link to article – subscription may be required.)
- ↑ Cundy T, Dissanayake A. Severe hypomagnesaemia in long-term users of proton-pump inhibitors. . 2008 Jan 23.(Epub ahead of print) (Link to article – subscription may be required.)
- ↑ Anon. Proton pump inhibitors and Clostridium difficile: Clinical bottom line. Bandolier online. Last accessed 9 Oct 2006; based on 2003 review article.
- ↑ Dial S, Delaney JA, Barkun AN, Suissa S. Use of gastric acid-suppressive agents and the risk of community-acquired Clostridium difficile-associated disease. JAMA : the journal of the American Medical Association. 2005;294:2989-95. (Direct link – subscription may be required.)