Methotrexate with Triamterene Interaction Details
Brand Names Associated with Methotrexate
- Amethopterin
- Methotrexate
- MTX
- Rheumatrex®
- Trexall®
Brand Names Associated with Triamterene
- Dyrenium®
- Triamterene
Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
Nov 17, 2023
Interaction Effect
Bone marrow suppression
Interaction Summary
A case of bone marrow suppression in a 57-year old woman taking triamterene and methotrexate has been reported. The proposed mechanism was an additive inhibitory effect on dihydrofolate reductase (DHFR). Further case reports or controlled studies are necessary to confirm the extent of this interaction.
Severity
Major
Onset
Delayed
Evidence
Probable
How To Manage Interaction
Concurrent therapy with triamterene and methotrexate should be avoided. If coadministration of these agents is necessary, regular monitoring of the patient's complete blood count, renal function, and hepatic function should be undertaken.
Mechanism Of Interaction
Additive effects on folate disposition
Literature Reports
A) A case of a 57-year old woman who developed a possible interaction between methotrexate and triamterene has been reported . The patient had been taking triamterene-hydrochlorothiazide 50 mg/25 mg per day in addition to atenolol and diclofenac for rheumatoid arthritis and hypertension. Methotrexate 5 mg per week was added to the patient's regimen for active rheumatoid arthritis. After one month of therapy, the patient's hemoglobin count decreased from 10.1 g/dL to 8.0 g/dL and her white cell count was 3.6 x 10(9)/L. The patient developed mouth ulcers, dyspnea, and bruised easily. The patient later developed pancytopenia with renal impairment and was treated for bone marrow suppression. The authors proposed that triamterene may have the ability to inhibit dihydrofolate reductase (DHFR), and that the addition of methotrexate resulted in a synergistic suppression of DHFR. The authors suggested that complete blood count, renal function, and liver function should be monitored carefully whenever methotrexate therapy is initiated.
Methotrexate Overview
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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.
Triamterene Overview
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Triamterene is used alone or with other medications to treat edema (fluid retention; excess fluid held in body tissues) caused by various conditions, including liver and heart disease. Triamterene is in a class of medications called diuretics ('water pills'). It causes the kidneys to eliminate unneeded water and sodium from the body into the urine, but reduces the loss of potassium.
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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.