How can meloxicam increase the toxicity of methotrexate?

Meloxicam may increase methotrexate toxicity by reducing its renal tubular secretion and raising blood levels, particularly with impaired kidney function or dosing within three days, and may amplify blood toxicity even though methotrexate pharmacokinetics at 15 mg/week were not relevantly affected by concomitant meloxicam.