Major
Established
Descripción
Aspirin reduces methotrexate clearance by competing for renal tubular secretion, raising plasma methotrexate levels and toxicity risk.
Mecanismo
Salicylates compete with methotrexate for organic anion transporter-mediated renal excretion; they may also displace methotrexate from plasma proteins, transiently increasing free drug concentrations.
Relevancia clínica
Methotrexate toxicity (bone marrow suppression, mucositis, nephrotoxicity) has been reported when NSAIDs/aspirin are added; high-dose MTX regimens carry the greatest risk.
Manejo clínico
Avoid combination with high-dose MTX; monitor CBC and renal function with low-dose rheumatology regimens; withhold aspirin for 48 h around weekly MTX dose.