Omeprazole with Carbamazepine Interaction Details

Brand Names Associated with Omeprazole

Brand Names Associated with Carbamazepine

Medical Content Editor Dr. Brian Staiger, PharmD
Last updated Nov 25, 2023

Interaction Effect

An increased risk of carbamazepine toxicity

Interaction Summary

Omeprazole has been reported to increase the elimination half-life, increase the area under the concentration-time curve (AUC), and decrease the clearance of a single-dose of carbamazepine. Conversely,  described a patient who had no alteration in the carbamazepine plasma level during concurrent therapy with omeprazole for helicobacter pylori gastritis. One of the reasons for the conflicting results may be that carbamazepine induces its own metabolism, thereby possibly causing different interactions between single-dose and multiple-dose therapy with carbamazepine.

Severity

Moderate

Onset

Delayed

Evidence

Probable

How To Manage Interaction

Monitor patients receiving concurrent carbamazepine and omeprazole therapy for signs of carbamazepine toxicity (ataxia, nystagmus, diplopia, headache, vomiting, apnea, seizures, coma). Also monitor carbamazepine serum levels. Doses of carbamazepine may need to be reduced.

Mechanism Of Interaction

Inhibition of carbamazepine metabolism

Literature Reports

A) The administration of a single dose of carbamazepine to nine patients receiving omeprazole therapy resulted in a prolongation of the carbamazepine half-life (17.2 hours vs. 37.3 hours) and an increase in the AUC from 382 mcg/hr/mL to 668 mcg/hr/mL. The clearance of carbamazepine decreased from 20.7 mL/hr/kg to 12.5 mL/hr/kg. These results show that any adjuvant therapy of omeprazole has the potential to interact with carbamazepine concentrations, and should only be administered with close monitoring of the carbamazepine serum levels .

B) An epileptic patient stabilized on carbamazepine (900 mg daily) therapy, had a serum level of 7.5 mg/L. One day after the addition of clarithromycin (500 mg three times daily) and omeprazole (20 mg twice daily), the carbamazepine level had risen to 14 mg/L. Despite carbamazepine dose reductions of 200 mg daily, the plasma level reached 20.8 mg/L. The clarithromycin was then discontinued, and metronidazole and bismuth subsalicylate were substituted. The plasma levels of carbamazepine returned to normal, even though therapy with omeprazole was continued. Omeprazole is an inducer of hepatic microsomal cytochrome P450 2C enzymes, whereas carbamazepine is metabolized by and induces CYP 3A4. The different metabolic pathways between omeprazole and carbamazepine suggest that in this patient, clarithromycin was solely responsible for the increased carbamazepine serum levels and no drug interaction exists between omeprazole and carbamazepine .

Omeprazole Overview

• 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.

Carbamazepine Overview

• Carbamazepine is used alone or in combination with other medications to control certain types of seizures in people with epilepsy. It is also used to treat trigeminal neuralgia (a condition that causes facial nerve pain). Carbamazepine extended-release capsules (Equetro brand only) are also used to treat episodes of mania (frenzied, abnormally excited or irritated mood) or mixed episodes (symptoms of mania and depression that happen at the same time) in patients with bipolar I disorder (manic-depressive disorder; a disease that causes episodes of depression, episodes of mania, and other abnormal moods). Carbamazepine is in a class of medications called anticonvulsants. It works by reducing abnormal electrical activity in the brain.

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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:

• Gold Standard Drug Database
• Micromedex
• Lexicomp
• DrugBank

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.