Carbamazepine with Psyllium Interaction Details

Brand Names Associated with Carbamazepine

Brand Names Associated with Psyllium

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

Interaction Effect

Decreased absorption and effectiveness of carbamazepine

Interaction Summary

In healthy volunteers, carbamazepine bioavailability was reduced when psyllium was administered concomitantly. If patients are treated with carbamazepine and psyllium, their administration times of should be separated as far as possible, and plasma levels of carbamazepine should be monitored .

Severity

Moderate

Onset

Rapid

Evidence

Probable

How To Manage Interaction

If patients are treated with carbamazepine and psyllium, their administration times should be separated as far as possible, and plasma levels of carbamazepine should be monitored.

Mechanism Of Interaction

Reduced dissolution rate and slowed diffusion of carbamazepine

Literature Reports

A) Decreased absorption, a decreased maximum concentration, and reduced area under the curve (AUC) of carbamazepine were noted after administration with a psyllium product to 4 healthy volunteers. Volunteers did not take any other medications one week prior to and during the study. Carbamazepine 200 mg orally was administered with ispaghula husk (psyllium) suspended in 200 milliliters (mL) of water. Cmax with carbamazepine alone was 2.33 micrograms/hour (mcg/hour), which was reduced to 1.11 mcg/hour when psyllium was added. AUC with carbamazepine alone was 45.43 micrograms/milliliter/hour (mcg/mL/hour), when psyllium was added AUC was reduced to 25.03 mcg/mL/hour. Tmax was increased from 5.52 hours to 24.14 hours with psyllium cotreatment. Bioavailability was reduced to 55% that of carbamazepine alone. Statistical significance values were not provided. The mechanism of interaction was proposed to be due to a decrease in the amount of biological fluid available in the gastrointestinal tract as a result of water-absorption by psyllium, which would reduce the dissolution rate of the drug from the tablet. Diffusion of the drug may be slowed as a result of gel formation by psyllium. Administration times of carbamazepine and psyllium should be separated as far as possible, and plasma levels of carbamazepine should be monitored .

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.

Psyllium Overview

• Psyllium, a bulk-forming laxative, is used to treat constipation. It absorbs liquid in the intestines, swells, and forms a bulky stool, which is easy to pass.

• This medication is sometimes prescribed for other uses; ask your doctor or pharmacist for more information.

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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.