Management overview for methotrexate poisoning

Methotrexate toxicity from oral poisoning is uncommon and usually involves dosing interval errors or a patient with impaired kidney function. Dosing interval errors most commonly involve a weekly dose being inadvertently administered daily.

If methotrexate poisoning is suspected, contact a clinical toxicologist or poisons information centre (13 11 26). All cases of deliberate self-poisoning should be assessed in hospital. Calcium folinate is the only useful antidote for methotrexate toxicity. Glucarpidase has no role following acute or chronic ingestions.

High-dose intravenous methotrexate and intrathecal methotrexate are used in cancer chemotherapy. High-dose intravenous methotrexate can cause acute kidney injury and life-threatening toxicity. Inadvertent intrathecal methotrexate administration also causes severe and life-threatening central nervous system toxicity. Glucarpidase may be indicated to reduce toxicity in these scenarios, but detailed advice about this treatment is beyond the scope of these guidelines—seek advice from a medical oncologist.