How the interaction occurs:
The cause of the interaction is not known. The effect of methotrexate may decrease.
What might happen:
The methotrexate therapy may not be effective when given after asparaginase. This is not a problem if the asparaginase is given after methotrexate therapy.
What you should do about this interaction:
Your healthcare professionals (e.g. doctor or pharmacist) may already be aware of this drug interaction and may be monitoring you for it. Do not start, stop, or change the dosage of any medicine before checking with them first.
1.Capizzi RL. Asparaginase-methotrexate in combination chemotherapy: schedule- dependent differential effects on normal versus neoplastic cells. Cancer Treat Rep 1981;65 Suppl 4:115-21.
2.Elspar (asparaginase) US prescribing information. Merck & Co., Inc. July, 2006.