Omeprazole

Omeprazole is a proton pump inhibitor (PPI). It inhibits stomach acid production and is used for heartburn, gastroesophageal reflux disease (GERD), gastric and duodenal ulcers, and as stomach protection when taking certain medications.

Omeprazole is available under the brand name Antra MUPS® as well as numerous generics. Without a prescription, omeprazole 20 mg is only available for adults to treat reflux symptoms (e.g. heartburn, acid regurgitation), once daily for 14 days. Other strengths and indications as well as long-term use are prescription-only.

The effect does not set in immediately – full acid suppression is reached after 2-5 days.

Omeprazole irreversibly inhibits the proton pump (H+/K+-ATPase) in the parietal cells of the stomach:

Mechanism of action:

• Omeprazole is a prodrug – it is only activated in the acidic environment of the parietal cell
• Binds irreversibly to the proton pump
• Blocks the final step of stomach acid production
• Reduces stomach acid by up to 90%

Onset of action:

• First improvement within 1-2 hours
• Full effect after 2-5 days of regular use
• New proton pumps first have to be formed again

Duration of action: After stopping, acid production returns to normal within 3-5 days, as new proton pumps are regenerated.

Omeprazole is suitable for:

• Gastroesophageal reflux disease (GERD)
• Heartburn and acid regurgitation
• Reflux esophagitis (inflammation of the esophagus)
• Gastric and duodenal ulcers
• Eradication therapy for Helicobacter pylori (in combination with antibiotics)
• Stomach protection during NSAID use (ibuprofen, diclofenac)
• Zollinger-Ellison syndrome

Not suitable as a permanent solution for:

• Occasional heartburn (antacids may be sufficient)
• Unexplained upper abdominal complaints without a diagnostic workup

Available strengths:

• 10 mg (prescription-only)
• 20 mg (non-prescription only for adults with reflux symptoms for 14 days, otherwise prescription-only)
• 40 mg (prescription-only)

Usual dosages:

• Heartburn/mild reflux: 20 mg 1x daily
• Reflux esophagitis: 20-40 mg 1x daily for 4-8 weeks
• Gastric ulcer: 20 mg 1x daily for 4-8 weeks
• Stomach protection with NSAIDs: 20 mg 1x daily
• Helicobacter eradication: 20 mg 2x daily (7-14 days, with antibiotics)

How to take:

• In the morning, 30 minutes before breakfast
• Swallow the capsule/tablet whole with water, without chewing
• MUPS tablets can be dissolved in water

Important notes:

• Take regularly, not only when symptoms occur
• Do not stop abruptly after long-term therapy (rebound effect possible)
• Long-term use (>8 weeks) only under medical supervision
• Regular review of whether the therapy is still necessary

Omeprazole must not be taken in cases of:

• Hypersensitivity to omeprazole or other PPIs
• Concomitant use of nelfinavir (HIV medication)

Caution with:

• Hepatic impairment (dose adjustment, max. 20 mg)
• Long-term use (be aware of the risks)
• Suspected stomach cancer (symptoms may be masked!)

Pregnancy/breastfeeding: Omeprazole can be used during pregnancy if the benefit outweighs the risk. It passes into breast milk in small amounts.

Common (1-10%):

• Headache
• Abdominal pain
• Diarrhea
• Constipation
• Nausea
• Flatulence

Uncommon:

• Dizziness
• Sleep disturbances
• Skin rash

With long-term use (>1 year):

• Increased risk of bone fractures (hip, wrist)
• Magnesium deficiency
• Vitamin B12 deficiency
• Possibly increased risk of Clostridium difficile infections
• Possibly increased risk of kidney disease

Rebound effect: After stopping, more stomach acid may temporarily be produced. Tapering off is recommended.

Contraindicated:

• Nelfinavir (HIV) – loss of efficacy

Reduced effect of:

• Clopidogrel (Plavix®) – omeprazole inhibits CYP2C19 and can impair the activation of clopidogrel. Alternative: pantoprazole

Altered absorption due to pH change:

• Ketoconazole, itraconazole – reduced absorption
• Iron preparations – reduced absorption
• Vitamin B12 – reduced absorption with long-term use

Omeprazole inhibits CYP2C19:

• Diazepam – slowed breakdown
• Phenytoin – increased levels possible