METHOTREXATE TOXICITY IN A RHEUMATOID ARTHRITIS PATIENT

Background: Methotrexate is the most commonly prescribed disease-modifying antirheumatic drug for rheumatoid arthritis because of its effectiveness and affordability. Despite its therapeutic benefits, methotrexate toxicity may occur due to dosing errors, renal impairment, drug interactions, or inadequate monitoring. Low-dose methotrexate toxicity can result in severe complications including pancytopenia, mucositis, hepatotoxicity, nephrotoxicity, and life-threatening infections. Case Presentation: A 58-year-old female with seropositive rheumatoid arthritis presented with fever, painful oral ulcers, generalized weakness, nausea, vomiting, and skin lesions following accidental daily consumption of methotrexate instead of weekly dosing for 10 consecutive days. Laboratory investigations revealed severe pancytopenia, elevated liver enzymes, hypoalbuminemia, and acute kidney injury. Methotrexate toxicity was diagnosed based on clinical presentation, medication history, and laboratory abnormalities. Methotrexate was immediately discontinued, and the patient was treated with intravenous leucovorin rescue therapy, aggressive hydration, urinary alkalinization, broad-spectrum antibiotics, granulocyte colony-stimulating factor, blood transfusions, and supportive care. Gradual clinical and hematological recovery was observed during hospitalization. Conclusion: Methotrexate toxicity is a preventable but serious adverse drug reaction. Early diagnosis, prompt initiation of leucovorin rescue therapy, intensive supportive management, and regular laboratory monitoring are essential for favorable outcomes. Proper patient counseling regarding once-weekly dosing schedules remains crucial in preventing methotrexate-related medication errors and associated morbidity.

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