Mercaptopurine with Olsalazine Interaction Details
Brand Names Associated with Mercaptopurine
- 6-MP
- Mercaptopurine
- Purinethol®
- Purixan®
Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
Dec 29, 2023
Interaction Effect
An increased risk of bone marrow suppression
Interaction Summary
Coadministration of olsalazine, an aminosalicylate derivative, and mercaptopurine may inhibit the thiopurine methyltransferase enzyme (TPMT) and increase the risk of bone marrow suppression (anemia, leukopenia, thrombocytopenia, or any combination) caused by mercaptopurine. In a case report, a 16-year old female diagnosed with Crohn's disease given both drugs developed hematopoietic toxicity . If coadministering, use the lowest effective doses of each drug and closely monitor CBC for signs of bone marrow suppression .
Severity
Major
Onset
Delayed
Evidence
Probable
How To Manage Interaction
Coadministration of olsalazine, an aminosalicylate derivative, and mercaptopurine may inhibit the thiopurine methyltransferase enzyme (TPMT) and increase the risk of bone marrow suppression (anemia, leukopenia, thrombocytopenia, or any combination) caused by mercaptopurine. If coadministering, use the lowest effective doses of each drug and closely monitor CBC for signs of bone marrow suppression.
Mechanism Of Interaction
Inhibition of thiopurine methyltransferase (TPMT) by olsalazine
Literature Reports
A) A 16-year old white female diagnosed with Crohn's disease was started on 6-mercaptopurine 50 mg daily, olsalazine 500 mg daily, and prednisone 5 mg daily. At this time, her WBC count was 8.8 X 10(9)/L. One month later, when olsalazine and 6-mercaptopurine were increased to 1000 mg and 75 mg daily, respectively, her WBC count had decreased to 4.9 X 10(9)/L. Another month later, she developed leukopenia with a WBC count of 1.7 X 10(9)/L. Her 6-mercaptopurine dose was reduced to 50 mg daily, and two weeks later her WBC remained the same. The 6-mercaptopurine dose was then decreased to 25 mg daily, and her WBC count stabilized at 5.2 X 10(9)/L. Because of the continuing exacerbations of her disease, her drug regimen was changed to olsalazine 1750 mg daily, 6-mercaptopurine 50 mg daily, and prednisone 50 mg daily. Approximately one month later, her WBC count had fallen to 1.3 X 10(9)/L, and the 6-mercaptopurine dose was discontinued. Her WBC recovered to 4.4 X 10(9)/L in one month, and due to the difficulty in controlling the Crohn's disease with steroids alone, 6-mercaptopurine was again initiated at 12.5 mg daily. While taking this reduced dose, she experienced no further hematopoietic toxicity and her disease was controlled .
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.
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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.
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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.
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