Revised SPC: Maxtrex (methotrexate) 2.5 and 10 mg Tablets

SPC updated to warn use of nitrous oxide potentiates the effect of methotrexate on folate metabolism, resulting in increased toxicity and whilst this effect can be reduced by administering calcium folinate, the concomitant use of nitrous oxide and methotrexate should be avoided.

Source:

electronic Medicines compendium