Methotrexate and Apixaban Interaction Guidelines

Introduction to Methotrexate and Apixaban Interaction

The hepatitis C treatment guidelines from 2020 provide a comprehensive drug interaction table that shows apixaban (Eliquis) has no clinically significant interaction with methotrexate, according to the guidelines from a reputable medical society 1
The British Association of Dermatologists guidelines mention interactions between methotrexate and several medications, but do not list anticoagulants like apixaban, as stated by the British Association of Dermatologists 2

Methotrexate has several important drug interactions, including with NSAIDs and salicylates, which can reduce renal elimination of methotrexate, potentially increasing toxicity, as noted by the British Association of Dermatologists 2
Other medications, such as probenecid, phenytoin, and certain other drugs, can affect methotrexate levels through various mechanisms, according to the British Association of Dermatologists 2

The following medications may interact with methotrexate:

Medication	Mechanism of Interaction
NSAIDs	Reduced renal elimination
Salicylates	Reduced renal elimination
Probenecid	Reduced renal elimination
Cyclosporine	Reduced renal elimination
Phenytoin	Displacement from protein binding
Sulfonamides	Displacement from protein binding, antifolate effects
Tetracyclines	Displacement from protein binding, reduced intestinal absorption
Barbiturates	Antifolate effects
Nitrofurantoin	Antifolate effects

Strong CYP3A4 inhibitors or inducers can significantly affect apixaban levels, as reported in the Chest guidelines 5
Combining apixaban with other blood thinners increases bleeding risk, according to the American Academy of Otolaryngology-Head and Neck Surgery 6

Regular monitoring of complete blood count (CBC) and liver function tests is required when prescribing both medications together, with careful attention to signs of unusual bleeding or methotrexate toxicity, as recommended by medical guidelines 1
Patient education is crucial, informing patients about signs of methotrexate toxicity and bleeding signs that would require medical attention, as emphasized by medical experts 1
Avoid adding other interacting medications, such as NSAIDs, trimethoprim-containing antibiotics, and strong P-gp inhibitors, to minimize potential interactions, as advised by medical guidelines 2
Renal function and elderly patients require special consideration, with regular monitoring and potential dose adjustments, as recommended by medical guidelines 1

The British Journal of Dermatology recommends avoiding the use of trimethoprim-sulfamethoxazole (co-trimoxazole) and other antifolate antibiotics with methotrexate due to potentially fatal interactions, as these combinations can cause severe bone marrow suppression and potentially fatal pancytopenia in patients 3
Trimethoprim alone has a similar antifolate mechanism as co-trimoxazole and should be used with caution in patients taking methotrexate, as it can increase the risk of toxicity 3
Other sulfonamides can displace methotrexate from protein binding and have antifolate effects, which can increase the risk of toxicity in patients with renal impairment or hypoalbuminemia 3

The following antibiotics may interact with methotrexate:

Antibiotic	Mechanism of Interaction
Penicillins	Reduced renal clearance
Tetracyclines	Displacement from protein binding, reduced intestinal absorption
Fluoroquinolones	Increased methotrexate levels
Chloramphenicol	Unknown

Macrolides, such as azithromycin and erythromycin, and cephalosporins are considered lower-risk options for use with methotrexate, but still require monitoring of methotrexate levels and toxicity in patients 3
Clindamycin is also considered a lower-risk option, but its use with methotrexate should be carefully evaluated in patients with renal impairment or hypoalbuminemia 3

Monitoring for signs of toxicity, such as fever, mouth ulceration, unusual bruising/bleeding, and jaundice, is crucial when using antibiotics with methotrexate, particularly in elderly patients or those with renal impairment 3
Signs of toxicity include:
Sign Description
Fever Elevated body temperature
Mouth ulceration Ulcers in the mouth
Myelosuppression Reduced blood cell counts
Elevated liver enzymes Increased liver enzyme levels
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Sign	Description
Fever	Elevated body temperature
Mouth ulceration	Ulcers in the mouth
Myelosuppression	Reduced blood cell counts
Elevated liver enzymes	Increased liver enzyme levels

Intervention should include:

Intervention	Description
Discontinuation of methotrexate	Stopping methotrexate immediately
Leucovorin rescue	Administering leucovorin to reduce toxicity
Aggressive hydration	Providing fluids to prevent dehydration
Urinary alkalinization	Increasing urine pH to reduce methotrexate toxicity

Discontinuation of methotrexate immediately is recommended if toxicity is suspected, particularly in patients with renal impairment or hypoalbuminemia 3
Consideration of leucovorin rescue is recommended for significant toxicity, particularly in patients with severe renal impairment or hypoalbuminemia 3
Provision of supportive care, including hydration and monitoring of blood counts, is crucial for patients with suspected methotrexate toxicity 3

Complete abstinence from alcohol is advised during methotrexate therapy due to increased hepatotoxicity risk 8
The American Academy of Dermatology recommends obtaining a detailed medication history before initiating methotrexate and identifying high-risk patients, including elderly patients, those with renal impairment, hypoalbuminemia, and a history of alcohol use 4, 8
Enhanced monitoring, including more frequent CBC and liver function tests, close monitoring of renal function, and consideration of temporary methotrexate discontinuation for severe infections requiring antibiotics, is necessary when potentially interacting medications must be used 3, 8
Elderly patients often have reduced renal function, which can increase the risk of methotrexate toxicity when used with antibiotics, and require close monitoring of methotrexate levels and toxicity 3
Patients with renal impairment have reduced methotrexate clearance, which can increase the risk of toxicity when used with antibiotics, and require close monitoring of methotrexate levels and toxicity 3, 4
Patients with hypoalbuminemia have increased free methotrexate levels, which can increase the risk of toxicity when used with antibiotics, and require close monitoring of methotrexate levels and toxicity 3