Mercaptopurine with Ribavirin Interaction Details
Brand Names Associated with Mercaptopurine
- 6-MP
- Mercaptopurine
- Purinethol®
- Purixan®
Brand Names Associated with Ribavirin
- Copegus®
- Moderiba®
- Rebetol®
- Ribasphere®
- Ribavirin
- RTCA
- tribavirin
- Virazole®
Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
Dec 29, 2023
Interaction Effect
An increased risk of azathioprine-induced myelotoxicity
Interaction Summary
Severe pancytopenia developed within 3 to 7 weeks after concomitant use of azathioprine and ribavirin (in combination with pegylated interferon) according to a retrospective review (n=8). Ribavirin is a known inhibitor of inosine monophosphate dehydrogenase, which is involved in azathioprine metabolism. This inhibition can lead to accumulation of an azathioprine metabolite (6-methylthioinosine monophosphate), which can cause myelotoxicity. If concomitant use of azathioprine and ribavirin is necessary, weekly monitoring of complete blood counts, including platelets, is recommended for the first month, with twice-monthly monitoring for the second and third months, then monthly or more frequent monitoring with dosage or therapy changes . Discontinue ribavirin treatment if pancytopenia occurs and do not reintroduce ribavirin while the patient is on concomitant azathioprine .
Severity
Major
Onset
Delayed
Evidence
Probable
How To Manage Interaction
The use of azathioprine and ribavirin (in combination with pegylated interferon) concomitantly has been associated with myelotoxicity. Should it be clinically necessary to coadminister these agents, monitor patients for hematologic abnormalities. Weekly monitoring of complete blood counts, including platelets, is recommended for the first month, followed by twice-monthly monitoring for the second and third months, then monthly or more frequent monitoring with dosage or therapy changes . If pancytopenia occurs, discontinue ribavirin treatment and do not reintroduce ribavirin while the patient is on concomitant azathioprine .
Mechanism Of Interaction
Decrease in azathioprine clearance
Literature Reports
A) A retrospective review of 8 patients demonstrated the development of severe pancytopenia within 3 to 7 weeks after concomitant use of azathioprine and ribavirin. While receiving azathioprine for inflammatory bowel disease, 7 patients experienced bone marrow suppression (mean interval of 4.6 +/- 1.6 weeks) following the addition of ribavirin plus peginterferon alfa for chronic hepatitis C. Mean platelet count at time of pancytopenia was 69.75 +/- 82.8 x 10(-3)/mm(3), with a mean hemoglobin level of 7.75 g/dL +/- 1.3 g/dL, and a mean neutrophil count of 0.45 +/- 0.26 x 10(-3)/mm(3). One patient experienced severe pancytopenia after the introduction of azathioprine while being treated for hepatitis C virus (HCV) with ribavirin and peginterferon alfa. Blood counts returned to normal following withdrawal of azathioprine and HCV therapy (mean duration of 5 +/- 1 weeks). No hematological toxicity occurred following the reinstatement of HCV or azathioprine treatment alone in any of the 8 patients .
Mercaptopurine Overview
-
Mercaptopurine is used alone or with other chemotherapy drugs to treat acute lymphocytic leukemia (ALL; also called acute lymphoblastic leukemia and acute lymphatic leukemia; a type of cancer that begins in the white blood cells). Mercaptopurine is in a class of medications called purine antagonists. It works by stopping the growth of cancer cells.
Ribavirin Overview
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Ribavirin is used with an interferon medication such as peginterferon alfa-2a [Pegasys] or peginterferon alpha-2b [PEG-Intron]) to treat hepatitis C in people who have not been treated with an interferon before. Ribavirin is in a class of antiviral medications called nucleoside analogues. It works by stopping the virus that causes hepatitis C from spreading inside the body. It is not known if treatment that includes ribavirin and another medication cures hepatitis C infection, prevents liver damage that may be caused by hepatitis C, or prevents the spread of hepatitis C to other people.
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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.