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1/20/25 High Dose Methotrexate Drug Interaction Alerts
January 20, 2025
Good afternoon,
Due to some recent safety events, we have decided to implement new drug interaction alerts for certain drugs/drug classes that should be avoided with high dose methotrexate due to their ability to inhibit methotrexate clearance. These drug interaction alerts will pop up in the same manner as other interaction alerts currently do now and can be handled by the verifying pharmacist. We put together an informational document with more information regarding these pertinent drug interactions. Within the handout, the drugs/drug classes in red will now result in a drug interaction alert, but we wanted to provide you with an inclusive list of other pertinent interacting drugs. These interaction alerts will only pop up with IVPB doses of methotrexate and will continue to pop up if one of these interacting medications is ordered for up to 4 days following the methotrexate administration to allow for methotrexate clearance. If a pharmacist encounters one of these interactions they should review the profile and interaction information and contact the provider to discontinue the offending drug and/or recommend an alternative agent as appropriate. Below is a blurb from the informational document attached. This document can also be found on the methotrexate FormWeb page as well as the Oncology/Chemotherapy FormWeb page.
Methotrexate doses > 500 mg/m2 are considered “high-dose methotrexate” which requires additional monitoring prior, during, and after administration to prevent toxicity. High doses of methotrexate are cleared from the body at varying rates based on numerous factors, but certain drugs can impact the clearance of methotrexate, increasing the risk of toxicity.
Numerous pertinent drug interactions exist between several classes of medications and high-dose methotrexate. Historically, these interactions have not fired an alert in Cerner at the time of verification. Given reported safety events, numerous drug interactions have been updated to fire an alert to the pharmacist at verification. These drug interaction alerts will only fire when combined with methotrexate given via IVPB and will continue to fire for 4 days post high-dose methotrexate infusion to ensure the patient has had adequate time to clear the drug.
At the time of the alert, the verifying pharmacist should review the patient’s medication profile, review the information regarding the interaction and take appropriate action. More details about the drug interaction can be found by clicking the link in the alert (circled in red below).
I will be presenting this information and the information in the attached document at an upcoming huddle, but please let me know if you have any questions in the mean time. Our planned go-live for this update is 2/3/25.
Thank you,
Amanda
Amanda Ouzts, Pharm.D., BCOP, BCPS
Clinical Pharmacy Specialist, Oncology/Hematology
Program Director, PGY-2 Oncology Pharmacy Residency
Huntsville Hospital
Office: 256-817-4187
Fax: 256-265-3278
amanda.ouzts@hhsys.org