Vandetanib with Phenytoin Interaction Details
Brand Names Associated with Vandetanib
- Caprelsa®
- Vandetanib
Brand Names Associated with Phenytoin
- Dilantin®
- Phenytek®
- Phenytoin
Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
Dec 22, 2023
Interaction Effect
Decreased vandetanib exposure
Interaction Summary
Avoid coadministration of vandetanib (a CYP3A4 substrate) with phenytoin (a strong CYP3A4 inducer). Although the interaction between phenytoin and vandetanib has not been studied, coadministration of rifampicin (also a strong CYP3A4 inducer) and vandetanib resulted in decreased vandetanib AUC in healthy volunteers . Therefore, if coadministration is required, monitor for a reduction in vandetanib efficacy.
Severity
Major
Onset
Unspecified
Evidence
Theoretical
How To Manage Interaction
Coadministration of vandetanib with a strong CYP3A4 inducer, such as phenytoin, should be avoided as this may decrease vandetanib exposure and reduce the efficacy of vandetanib. If coadministration is required, monitor for a reduction in vandetanib efficacy.
Mechanism Of Interaction
Induction of CYP3A4-mediated vandetanib metabolism by phenytoin
Literature Reports
A) During a crossover study of 12 healthy volunteers, coadministration of vandetanib 300 mg (on day 1 and day 10) and rifampicin 600 mg (on days 1 through 31) resulted in a 40% decrease in vandetanib AUC compared with vandetanib alone. There was no clinically meaningful change in vandetanib Cmax .
Vandetanib Overview
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Vandetanib is used to treat a certain type of thyroid cancer that cannot be treated by surgery or that has spread to other parts of the body. Vandetanib is in a class of medications called kinase inhibitors. It works by blocking the action of an abnormal protein that signals cancer cells to multiply. This helps slow or stop the spread of cancer cells.
Phenytoin Overview
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Phenytoin is used to control certain type of seizures, and to treat and prevent seizures that may begin during or after surgery to the brain or nervous system. Phenytoin is in a class of medications called anticonvulsants. It works by decreasing 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:
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.