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Structural formula
Structure of omeprazole
( S ) shape (top) and ( R ) shape (bottom)
Non-proprietary name Omeprazole
other names
  • ( RS ) -5-Methoxy-2 - [(4-methoxy-3,5-dimethylpyridin-2-yl) methanesulfinyl] -1 H -benzimidazole
  • Omeprazolum ( Latin )
Molecular formula C 17 H 19 N 3 O 3 S
Brief description

white to almost white, polymorphic and hygroscopic powder

External identifiers / databases
CAS number 73590-58-6
EC number 615-996-8
ECHA InfoCard 100.122.967
PubChem 4594
ChemSpider 4433
DrugBank DB00338
Wikidata Q422210
Drug information
ATC code

A02 BC01

Drug class

Proton pump inhibitors , ulcer therapeutics

Mechanism of action

Inhibitor of the proton-potassium pump

Molar mass 345.42 g · mol -1
Physical state


Melting point

156 ° C


very sparingly soluble in water (82.3 mg · l −1 at 25 ° C); soluble in methanol , ethanol , dichloromethane ; decomposes in dilute alkali metal hydroxide solutions

safety instructions
Please note the exemption from the labeling requirement for drugs, medical devices, cosmetics, food and animal feed
GHS labeling of hazardous substances
07 - Warning


H and P phrases H: 315-319-335
P: 261-305 + 351 + 338
Toxicological data

2210 mg kg −1 ( LD 50ratoral )

As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Omeprazole is a drug from the group of proton pump inhibitors that is used to treat gastric and duodenal ulcers, as well as reflux esophagitis .

Clinical information

Omeprazole is usually administered as an enteric tablet or capsule , more rarely as an infusion solution .

Mechanism of irreversible inhibition

application areas

type of application

The treatment of acute forms of the diseases mentioned in the Indications section (duodenal ulcer, gastric ulcer, reflux disease and the esophagitis caused by it) is carried out with gastrointestinal omeprazole tablets or capsules; infusion is also possible if necessary .

To eliminate Helicobacter pylori , omeprazole is only combined with antibiotics such as clarithromycin and amoxicillin or metronidazole (so-called eradication therapy ).

Only peroral dosage forms are used in eradication therapy and long-term treatment.


Hypersensitivity to active ingredient or excipient. Combination with atazanavir . Combination with clarithromycin and simultaneous use of terfenadine , astemizole , cisapride or carbamazepine . According to current recommendations, if possible no administration should take place in combination with clopidogrel (switch to H2-receptor antagonist).

Drug interactions

Omeprazole is metabolized in the liver via cytochrome P450 , mainly via the variant CYP2C19 (also cytochrome P450 1A2 ). The cytochrome CYP2C19 is inhibited by omeprazole. However, clinically relevant drug interactions are very rare. The activity of the enzyme CYP2C19 with the breakdown of omeprazole can lead to the temporary accumulation of another active substance or its precursor in the same breakdown pathway. This accumulation can increase the effectiveness of an active ingredient and decrease the effectiveness of a precursor (since one precursor is less converted to the active form). The most common interaction is with vitamin K antagonists. According to data from the Food and Drug Administration, the risk of such an interaction is 0.09 per million prescribed packs of the drug. Interactions with phenytoin or benzodiazepines were even rarer . A mutation of CYP2C19 is also known, which leads to a slower breakdown of all proton pump inhibitors. The mutation occurs in Asia with a frequency of around 20%. There is an interaction with the anticoagulant clopidogrel , which is metabolized by the same enzyme. Since CYP2C19 is inhibited by omeprazole, the conversion of clopidogrel to the active metabolite decreases. This interaction is less common with pantoprazole . The European Medicines Agency advises against simultaneous use .

Use during pregnancy and breastfeeding

Omeprazole is the drug of second choice during pregnancy when antacids or ranitidine or cimetidine are no longer sufficient. If possible, the drug should not be used during pregnancy and breastfeeding unless the doctor deems it absolutely necessary.

unwanted effects

Gastrointestinal disorders, increased liver values , skin reactions, fatigue, sleep disorders, dizziness , joint problems, headaches, hair loss, visual, hearing and taste disorders and polyneuropathy were observed as side effects . In addition, therapy with omeprazole leads to a reduced availability of the intrinsic factor , which in turn leads to an insufficient absorption of vitamin B12 . Very rare but dangerous are pancreatitis , hepatitis , changes in the blood count , Stevens-Johnson syndrome , and visual disturbances . According to a 2009 study, the use of proton pump inhibitors could potentially lead to dependence. According to a 2016 study in Bonn, older people who took pantoprazole or omeprazole for a long time had an increased risk of dementia. An investigation of suspected cases to the FDA found a massive increase in the risk of severe kidney disease for proton pump blockers compared to H 2 acid blockers . In 1992, cases of impotence and gynecomastia (breast enlargement) were reported as undesirable side effects of omeprazole.

Use in animals

In cats, omeprazole must be administered twice daily to achieve a significant increase in gastric pH.

In horses, omeprazole must be administered once daily at a dose of 4 mg / kg body weight for the treatment of gastric ulcers ( equine gastric ulcer syndrome ).

Mechanism of action

Omeprazole is a prodrug and is converted at its site of action, the acid-producing parietal cells of the stomach , into the actually active metabolite (a sulfenamide), which irreversibly inhibits the proton potassium ATPase (the “proton pump”) in these cells . This inhibition is triggered by the formation of adducts, since the metabolite adds to the protein with the formation of a disulfide bridge. This leads to a decrease in acid production in the stomach and the pH of the gastric juice increases.

Absorption and distribution in the body

Omeprazole is acid-sensitive and is therefore administered in an enteric dosage form. The maximum plasma concentration is reached after 1–3 hours. The plasma half-life is 40 minutes. 80% of it is excreted in the urine after metabolism in the liver.

The bioavailability is 35% and increases to 60% with repeated administration.



Omeprazole has a stereocenter on the sulfur atom and is used in the form of its magnesium salt both as a racemate [1: 1 mixture of the ( S ) enantiomer and the ( R ) enantiomer] and as a pure ( S ) enantiomer ( esomeprazole ) as Drug.

Development history

Omeprazole was the first proton pump inhibitor to be introduced into therapy and, as a well-tolerated gastric drug, became a blockbuster for the British-Swedish pharmaceutical company AstraZeneca in the 1990s . Its omeprazole preparations Antra and Prilosec had annual sales of more than 5 billion euros. Shortly before the patent expiry of omeprazole, AstraZeneca launched a new dosage form in 1998 (it is believed to strengthen its own market position with regard to the expected competition with generic market launches) : the Multiple Unit Pellet System (MUPS). Antra MUPS tablets are compressed from small, enteric coated pellets , which disintegrate rapidly on contact with liquid. This should enable particularly good bioavailability . A therapeutic superiority of the MUPS compared to conventional omeprazole film-coated tablets or capsules has not been proven, but the pellets are easy to use in patients who are fed by tube or who are otherwise unable to swallow tablets. After the patent expiry of omeprazole in 1999, AstraZeneca came onto the market in 2000 with its ( S ) enantiomer ( esomeprazole , Nexium ). Since esomeprazole is metabolized more via CYP2A19 and thus more slowly than racemic omeprazole, the result is a slower lowering of the plasma level and thus better bioavailability compared to the racemate . Due to the mechanism of action of the proton pump inhibitors, the therapeutic relevance is questionable.

One innovation was omeprazole sodium hydrogen carbonate formulations ( Zegerid ) from the US company Santarus in 2004, which do not require an enteric coating and allow additional dosage forms and should release the active ingredient particularly quickly. The combination is available as an oral suspension and as capsules.

Trade names

Antra MUPS (D), Ecomep (CH), Gastracid (D), Gastrobene (A), Gastroplex (A), Losec (A), Medoprazol (A), Novec (A), Omec (A), Omep (D ), Omeprax (CH), Omezol (CH), Oprazol (CH), Ulcozol (D), Ulnor (D), Progastim (PL), and other generics.

GastroGard (D, A), Pepticure (D), Peptizole (A), Ulcergold (NL)

Web links

Individual evidence

  1. a b European Pharmacopoeia Commission (Ed.): European Pharmacopoeia 6th Edition . tape 6.0 , 2008.
  2. a b c Entry on omeprazole in the ChemIDplus database of the United States National Library of Medicine (NLM)
  3. a b Datasheet Omeprazole> from Sigma-Aldrich , accessed on April 16, 2011 ( PDF ).
  4. Torsten Kratz, Albert Diefenbacher: Psychopharmacotherapy in old age. Avoidance of drug interactions and polypharmacy. In: Deutsches Ärzteblatt. Volume 116, Issue 29 f. (22 July) 2019, pp. 508-517, pp. 510 f.
  5. a b c d Technical information Antra MUPS, status 08/2006.
  6. a b Heinz Lüllmann, Klaus Mohr, Lutz Hein: Pharmacology and Toxicology: Understanding drug effects . Ed .: Gustav Kuschinsky. 17th, completely revised. Edition. Thieme, Stuttgart 2010, ISBN 978-3-13-193507-6 .
  7. Jump up ↑ J. Labenz, KU Petersen, W. Rösch, HR Koelz: A summary of Food and Drug Administration-reported adverse events and drug interactions occurring during therapy with omeprazole, lansoprazole and pantoprazole. In: Aliment Pharmacol Ther . 17 (8), Apr 2003, pp. 1015-1019. PMID 12694083 .
  8. J. Labenz, K. Petersen, W. Rösch, H. Koelz: Selection of proton pump inhibitors. In: Deutsches Ärzteblatt. Vol. 99, Issue 37, September 13, 2002, pp. 2425-2429.
  9. European Medicines Agency: Public statement EMEA / 328956/2009 (PDF; 20 kB), May 29, 2009; Retrieved July 15, 2009.
  10. C. Reimer, B. Søndergaard, L. Hilsted, P. Bytzer: Proton-pump inhibitor therapy induces acid-related symptoms in healthy volunteers after withdrawal of therapy. In: Gastroenterology. Volume 137, number 1, July 2009, pp. 80-7, 87.e1, doi: 10.1053 / j.gastro.2009.03.058 . PMID 19362552 .
  11. Apotheke Adhoc (ed.): Dementia through omeprazole . February 18, 2016 ( [accessed October 9, 2017]).
  12. T. Makunts, IV Cohen, L. Awdishu, R. Abagyan: Analysis of post-marketing safety data for proton-pump inhibitors Reveals Increased propensity for renal injury, electrolyte abnormalities, and nephrolithiasis. In: Nature Scientific Report. 9, 2019, p. 2282, Published online 2019 Feb 19, doi: 10.1038 / s41598-019-39335-7 . PMID 30783195 .
  13. M. Lindquist, R. Edwards: Endocrine adverse effects of omeprazole. In: BMJ. Volume 305, 1992, pp. 451-452.
  14. S. Šutalo, M. Ruetten, S. Hartnack, CE Reusch, PH Kook: The effect of orally administered ranitidine and once-daily or twice-daily orally administered omeprazole on intragastric pH in cats. In: Journal of veterinary internal medicine / American College of Veterinary Internal Medicine. Volume 29, number 3, May-Jun 2015, pp. 840-846, doi: 10.1111 / jvim.12580 . PMID 25966746 .
  15. ^ BW Sykes, M. Hewetson, RJ Hepburn, N. Luthersson, Y. Tamazali: ECEIM Consensus Paper - Equine Gastric Ulcer Syndrome in adult horses. (PDF) Journal of Veterinary Internal Medicine, 2015, accessed April 19, 2018 .
  16. Ernst Mutschler, Monika Schäfer-Korting: Textbook of Pharmacology and Toxicology. 8th, completely revised and expanded edition. Wissenschaftliche Verlagsgesellschaft, Stuttgart 2001, ISBN 3-8047-1763-2 , p. 640.
  17. ^ J. Terblanche, JH Potgieter, U. Luft, U. Thyroff-Friesinger: Omeprazole - No correlation between release and effectiveness . In: Pharmaceutical newspaper . 01/2002.
  18. Notes on the indication and therapeutic benefit. Proton pump inhibitors (PPIs) in the treatment of esophagitis . (PDF; 255 kB) Scientific evaluation of the Institute for Clinical Pharmacology, published by the AOK, January 2008.
  19. Lars Olbe, Enar Carlsson, Per Lindberg: A proton-pump inhibitor expedition: the case histories of omeprazole and esomeprazole . In: Nature Reviews Drug Discovery . tape 2 , no. 2 , 2003, p. 132-139 , doi : 10.1038 / nrd1010 , PMID 12563304 .
  20. Pure enantiomeric drugs. ( Memento from March 1, 2009 in the Internet Archive )