Cholestyramine with Valproic Acid Interaction Details

Brand Names Associated with Cholestyramine

Brand Names Associated with Valproic Acid

Medical Content Editor Dr. Brian Staiger, PharmD
Last updated Feb 28, 2024

Interaction Effect

Decreased serum valproic acid concentrations

Interaction Summary

A controlled study observed that the concurrent administration of valproic acid and cholestyramine resulted in significantly reduced valproic acid area under the concentration-time curve (AUC) and maximum concentration (Cmax) values. However, administration of valproic acid three hours before taking cholestyramine resulted in no significant pharmacokinetic changes[1].

Severity

Moderate

Onset

Rapid

Evidence

Probable

How To Manage Interaction

Clinicians should be aware that valproic acid taken concurrently with cholestyramine may decrease serum valproic acid concentrations. If these drugs are to be given together, administer cholestyramine at least three hours after valproic acid, and monitor patients for valproic acid therapeutic efficacy.

Mechanism Of Interaction

Decreased absorption of valproic acid

Literature Reports

A) In an open-label, three-way crossover study, the effects of cholestyramine on the plasma concentrations of valproic acid were investigated in six healthy volunteers. Subjects participated in three treatment phases, with a minimum one-week washout period between phases. During phase 1, the subjects received a single dose of valproic acid 250 mg. During phase 2, subjects received cholestyramine 4 g twice daily for one day, followed by valproic acid 250 mg with the morning dose of cholestyramine. Phase 3 was identical to phase 2 except that the valproic acid 250 mg was taken three hours before the morning dose of cholestyramine. When valproic acid was given concurrently with cholestyramine, the valproic acid area under the concentration-time curve (AUC) decreased by 21% and the valproic acid maximum concentration (Cmax) decreased by 15% compared to valproic acid alone. When valproic acid was given three hours before cholestyramine, no significant changes in AUC or Cmax were observed. Based on this data, decreases in valproic acid concentrations can be partially avoided by taking the cholestyramine three hours after valproic acid [1].

References

1 ) Malloy MJ, Ravis WR, Pennell AT, et al: Effect of cholestyramine resin on single dose valproate pharmacokinetics. Int J Clin Pharmacol Ther 1996; 34:208-211.

Cholestyramine Overview

• Cholestyramine is used with diet changes (restriction of cholesterol and fat intake) to reduce the amount of cholesterol and certain fatty substances in your blood. Accumulation of cholesterol and fats along the walls of your arteries (a process known as atherosclerosis) decreases blood flow and, therefore, the oxygen supply to your heart, brain, and other parts of your body. Lowering your blood level of cholesterol and fats may help to prevent heart disease, angina (chest pain), strokes, and heart attacks.

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

Valproic Acid Overview

• Valproic acid is used alone or with other medications to treat certain types of seizures. Valproic acid is also used to treat mania (episodes of frenzied, abnormally excited mood) in people with bipolar disorder (manic-depressive disorder; a disease that causes episodes of depression, episodes of mania, and other abnormal moods). It is also used to prevent migraine headaches but not to relieve headaches that have already begun. Valproic acid is in a class of medications called anticonvulsants. It works by increasing the amount of a certain natural substance 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.