Major
Methotrexate × Pantoprazole
Antimetabolites, folic acid analogues×Proton pump inhibitors
Mechanism
Proton pump inhibitors block the renal BCRP transporter, reducing methotrexate clearance. At high oncologic doses: risk of severe delayed toxicity.
Symptoms
Mouth ulcers (mucositis), nausea, diarrhoea, hair loss. Blood counts fall: leukocytes, platelets, erythrocytes. Severe cases: fatal pancytopenia, nephrotoxicity.
Management
At oncologic methotrexate doses, stop pantoprazole 5 days before and resume 5 days after dosing. Alternative: famotidine (H2-blocker, no BCRP effect). At low rheumatologic doses, pantoprazole is acceptable.
Check the full regimen, not just this pair
Opens the checker with these two drugs prefilled. Add the rest of the regimen and recompute additive risks.