Methotrexate with Mercaptopurine Interaction Details

Brand Names Associated with Methotrexate

Brand Names Associated with Mercaptopurine

Medical Content Editor Dr. Brian Staiger, PharmD
Last updated Dec 29, 2023

Interaction Effect

Mercaptopurine toxicity, increased methotrexate exposure, an increased risk of methotrexate-related severe adverse reactions, reduced active metabolite formation and possibly reduced methotrexate efficacy

Interaction Summary

Coadministration of methotrexate with hepatotoxic agents like mercaptopurine may increase methotrexate plasma concentrations, which may increase the risk of methotrexate severe adverse reactions. In some cases, the coadministration of methotrexate with mercaptopurine may also subsequently reduce active metabolite formation, which may decrease the clinical effectiveness of methotrexate. If coadministration cannot be avoided, monitor closely for methotrexate adverse reactions. Increased organ specific adverse reactions may also occur when methotrexate is coadministered with hepatotoxic products. Concomitant administration of oral mercaptopurine (75 mg/m(2)) and oral methotrexate (20 mg/m(2)) was reported to result in significant increases in area under the concentration-time curve (AUC) and peak mercaptopurine serum levels (31% and 26%, respectively). This interaction is probably not significant with standard low oral doses of methotrexate .

Severity

Major

Onset

Delayed

Evidence

Probable

How To Manage Interaction

Coadministration of methotrexate with hepatotoxic agents like mercaptopurine may increase methotrexate plasma concentrations, which may increase the risk of methotrexate severe adverse reactions. In some cases, the coadministration of methotrexate with mercaptopurine may also subsequently reduce active metabolite formation, which may decrease the clinical effectiveness of methotrexate. If coadministration cannot be avoided, monitor closely for methotrexate adverse reactions. Increased organ specific adverse reactions may also occur when methotrexate is coadministered with hepatotoxic products.

Mechanism Of Interaction

Decreased xanthine oxidase metabolism; additive hepatotoxicity; reduced methotrexate absorption

Literature Reports

A) Concomitant administration of oral mercaptopurine (75 mg/m(2)) and oral methotrexate (20 mg/m(2)) was reported to result in significant increases in area under the concentration-time curve (AUC) and peak mercaptopurine serum levels (31% and 26%, respectively). This interaction is probably not significant with standard low oral doses of methotrexate .

Methotrexate Overview

• Methotrexate is used to treat severe psoriasis (a skin disease in which red, scaly patches form on some areas of the body) that cannot be controlled by other treatments. Methotrexate is also used along with rest, physical therapy, and sometimes other medications to treat severe active rheumatoid arthritis (RA; a condition in which the body attacks its own joints, causing pain, swelling, and loss of function) that cannot be controlled by certain other medications. Methotrexate is also used to treat certain types of cancer including cancers that begin in the tissues that form around a fertilized egg in the uterus, breast cancer, lung cancer, certain cancers of the head and neck, certain types of lymphoma, and leukemia (cancer that begins in the white blood cells). Methotrexate is in a class of medications called antimetabolites. Methotrexate treats cancer by slowing the growth of cancer cells. Methotrexate treats psoriasis by slowing the growth of skin cells to stop scales from forming. Methotrexate may treat rheumatoid arthritis by decreasing the activity of the immune system.

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.

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.