Omeprazole with St John's Wort Interaction Details
Brand Names Associated with Omeprazole
- Omeprazole
- Prilosec®
- Prilosec® OTC
- Talicia (as a combination product containing Amoxicillin, Omeprazole, Rifabutin)
- Zegerid® (as a combination product containing Omeprazole, Sodium Bicarbonate)
- Zegerid® OTC (as a combination product containing Omeprazole, Sodium Bicarbonate)
Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
Nov 05, 2023
Interaction Effect
Reduced omeprazole exposure
Interaction Summary
Omeprazole is extensively metabolized by CYP2C19 and CYP3A4. The concomitant use of omeprazole with St John's wort (a CYP3A4 inducer) may cause substantially decreased omeprazole plasma concentrations. In a crossover study in healthy males, the coadministration of St John's wort with omeprazole decreased omeprazole Cmax and AUC. In another study, coadministration significantly reduced the serum concentration of omeprazole in healthy Chinese subjects with known CYP2C19 genotype. The response to omeprazole exposure during long-term use of St John's Wort was affected by the CYP2C19 genotype allelic variants of the study participants . The coadministration of omeprazole with St John's wort should be avoided .
Severity
Major
Onset
Unspecified
Evidence
Probable
How To Manage Interaction
Concomitant use of omeprazole with St.John's wort can substantially decrease the plasma concentrations of omeprazole. The concomitant use of omeprazole with St John's wort should be avoided .
Mechanism Of Interaction
Induction of CYP3A4-mediated metabolism of omeprazole by St John's wort; induction of CYP2C19-mediated metabolism of omeprazole by St John's wort
Literature Reports
A) Coadministration of St John's Wort and omeprazole significantly reduced the serum concentration of omeprazole, in a manner dependent on predominant variant of each subject's CYP2C19 genotype. In a randomized, placebo-controlled crossover trial, healthy Chinese subjects with known CYP2C19 genotype (n=12) received a 14-day oral regimen of placebo or St John's Wort 300 mg 3 times daily. Six subjects carried the 'wild-type' allele for CYP2C19-genotype (extensive metabolizer phenotype) and 6 carried 'mutant' CYP2C19 alleles with 'poor metabolizer' phenotypes. On day 15, each subject received a single oral dose of omeprazole 20 mg, after which blood samples were analyzed over the next 12 hours for omeprazole with its metabolites 5-hydroxyomeprazole (5-HO; CYP2C19-dependent) and omeprazole sulfone (OS; CYP3A4-dependent). Study subjects then crossed over to the opposite study arm after a 5-week washout period. Compared with placebo, coadministration of St John's Wort in extensive metabolizers significantly reduced the mean Cmax from 1.64 mcmol/L to 0.76 mcmol/L and AUC from 3.19 mcmol x hour/L to 1.63 mcmol x hour/L of omeprazole (-49.6% and 43.9%, respectively; p=0.017 and p=0.011, respectively). Serum mean maximum concentrations of 5-HO and OS were 38.1% and 155.5% higher, respectively, after exposure to St John's wort (p=0.028 and p=0.001, respectively). Omeprazole Cmax was also reduced in poor metabolizers receiving co-treatment with St John's Wort (-37.5% compared with placebo group; p less than 0.001), yet serum mean maximum concentrations of 5-HO were notably lower in poor metabolizers compared with extensive metabolizers (0.26 mcmol/L versus 1.21 mcmol/L; p less than 0.001) after exposure to St John's Wort .
B) In a crossover study, the coadministration of St John's wort (300 mg 3 times a day for 14 days) with omeprazole in 12 healthy male subjects decreased omeprazole Cmax and AUC by 37.5% and 37.9%, respectively in CYP2C19 poor metabolizers, and by 49.6% and 43.9%, respectively in extensive metabolizers .
Omeprazole Overview
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Prescription omeprazole is used alone or with other medications to treat the symptoms of gastroesophageal reflux disease (GERD), a condition in which backward flow of acid from the stomach causes heartburn and possible injury of the esophagus (the tube between the throat and stomach) in adults and children 1 year of age and older. Prescription omeprazole is used to treat damage from GERD in adults and children 1 month of age and older. Prescription omeprazole is used to allow the esophagus to heal and prevent further damage to the esophagus in adults and children 1 year of age and older with GERD. Prescription omeprazole is also used to treat conditions in which the stomach produces too much acid such as Zollinger-Ellison syndrome in adults. Prescription omeprazole is also used to treat ulcers (sores in the lining of the stomach or intestine) and it is also used with other medications to treat and prevent the return of ulcers caused by a certain type of bacteria (H. pylori) in adults. Nonprescription (over-the-counter) omeprazole is used to treat frequent heartburn (heartburn that occurs at least 2 or more days a week) in adults. Omeprazole is in a class of medications called proton-pump inhibitors. It works by decreasing the amount of acid made in the stomach.
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Definitions
Severity Categories
Contraindicated
These drugs, generally, should not be used together simultaneously due to the high risk of severe adverse effects. Combining these medications can lead to dangerous health outcomes and should be strictly avoided unless otherwise instructed by your provider.
Major
This interaction could result in very serious and potentially life-threatening consequences. If you are taking this drug combination, it is very important to be under close medical supervision to minimize severe side effects and ensure your safety. It may be necessary to change a medication or dosage to prevent harm.
Moderate
This interaction has the potential to worsen your medical condition or alter the effectiveness of your treatment. It's important that you are monitored closely and you potentially may need to make adjustments in your treatment plan or drug dosage to maintain optimal health.
Minor
While this interaction is unlikely to cause significant problems, it could intensify side effects or reduce the effectiveness of one or both medications. Monitoring for changes in symptoms and your condition is recommended, and adjustments may be made if needed to manage any increased or more pronounced side effects.
Onset
Rapid: Onset of drug interaction typically occurs within 24 hours of co-administration.
Delayed: Onset of drug interaction typically occurs more than 24 hours after co-administration.
Evidence
Level of documentation of the interaction.
Established: The interaction is documented and substantiated in peer-reviewed medical literature.
Theoretical: This interaction is not fully supported by current medical evidence or well-documented sources, but it is based on known drug mechanisms, drug effects, and other relevant information.
How To Manage The Interaction
Provides a detailed discussion on how patients and clinicians can approach the identified drug interaction as well as offers guidance on what to expect and strategies to potentially mitigate the effects of the interaction. This may include recommendations on adjusting medication dosages, altering the timing of drug administration, or closely monitoring for specific symptoms.
It's important to note that all medical situations are unique, and management approaches should be tailored to individual circumstances. Patients should always consult their healthcare provider for personalized advice and guidance on managing drug interactions effectively.
Mechanism Of Interaction
The theorized or clinically determined reason (i.e., mechanism) why the drug-drug interaction occurs.
Disclaimer: The information provided on this page is for informational purposes only and should not be considered medical advice. Always consult with a qualified healthcare professional regarding your specific circumstances and medical conditions.
Where Does Our Information Come From?
Information for our drug interactions is compiled from several drug compendia, including:
The prescribing information for each drug, as published on DailyMED, is also used.
Individual drug-drug interaction detail pages contain references specific to that interaction. You can click on the reference number within brackets '[]' to see what reference was utilized.
The information posted is fact-checked by HelloPharmacist clinicians and reviewed quarterly.