Major
celecoxib × Methotrexate
Selective COX-2 inhibitor (coxib)×Antimetabolites, folic acid analogues
Mechanism
NSAIDs reduce renal methotrexate clearance (both selective and non-selective COX inhibitors).
Symptoms
Mouth ulcers (mucositis), nausea, diarrhoea, hair loss. Blood counts fall: leukocytes, platelets, erythrocytes. Severe cases: fatal pancytopenia, nephrotoxicity.
Management
At oncologic methotrexate doses, the combination is not prescribed. At low rheumatologic doses, celecoxib is acceptable with full blood count and creatinine monitoring every 1–3 months.