Ruxolitinib with Phenytoin Interaction Details
Brand Names Associated with Ruxolitinib
- Jakafi
- Ruxolitinib
Brand Names Associated with Phenytoin
- Dilantin®
- Phenytek®
- Phenytoin
Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
Dec 27, 2023
Interaction Effect
Decreased ruxolitinib exposure and increased exposure of the active metabolite
Interaction Summary
Use caution with coadministration of ruxolitinib (a CYP3A4 substrate), with strong CYP3A4 inducers, as reduced ruxolitinib plasma concentrations may occur. When coadministered with rifampin, a strong CYP3A4 inducer, exposure of ruxolitinib active metabolites increased by about 100% while ruxolitinib Cmax and AUC decreased by 32% and 61%, respectively (n=12). If concurrent use is necessary, monitor patients frequently, and adjust the ruxolitinib dose as needed during treatment.
Severity
Major
Onset
Unspecified
Evidence
Theoretical
How To Manage Interaction
Use caution with coadministration of ruxolitinib with strong CYP3A4 inducers, as reduced ruxolitinib plasma concentrations may occur. If concurrent use is necessary, monitor patients frequently, and adjust the ruxolitinib dose as needed during treatment.
Mechanism Of Interaction
Induction of CYP3A4-mediated ruxolitinib metabolism
Literature Reports
A) Active metabolite exposure of ruxolitinib increased by about 100%, while ruxolitinib Cmax and AUC decreased by 32% and 61%, respectively, when a single ruxolitinib 50 mg dose was added to an established rifampin 600 mg/day regimen in healthy volunteers (n=12). Rifampin is a strong CYP3A4 inducer .
Ruxolitinib Overview
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Ruxolitinib is used to treat myelofibrosis (a cancer of the bone marrow in which the bone marrow is replaced by scar tissue and causes decreased blood cell production). It is also used to treat polycythemia vera (PV; a slow growing cancer of the blood in which the bone marrow makes too many red blood cells) in people who were not able to be treated successfully with hydroxyurea. Ruxolitinib is also used to treat acute graft versus host disease (aGVHD; a complication of hematopoietic stem-cell transplant [HSCT; a procedure that replaces diseased bone marrow with healthy bone marrow] that usually develops within the first months after HSCT) in adults and children 12 years of age and older who were treated unsuccessfully with steroid medications. It is also used to treat chronic GVHD (cGVHD; a complication of HSCT that usually develops at least 3 months after HSCT) in adults and children 12 years of age and older who were treated unsuccessfully with 1 or 2 other treatments. Ruxolitinib is in a class of medications called kinase inhibitors. It works to treat myelofibrosis and PV by blocking the signals that cause cancer cells to multiply. This helps to stop the spread of cancer cells. It works to treat GVHD by blocking the signals of the cells that cause GVHD.
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.