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Pneumonitis complicating low-dose methotrexate therapy in rheumatoid arthritis
Abstract:
Three of 95 patients with rheumatoid arthritis who were being treated with low-dose (5 to 15 mg/wk) methotrexate sodium developed the clinical, radiographic, and pathologic features of methotrexate-associated pulmonary injury. Marked hypoxemia emphasized the severity of illness in our patients; lowest oxygen pressure values for each patient were 35 mm Hg, 42 mm Hg, and 45 mm Hg. The management of our patients with a pulmonary toxic reaction to methotrexate included discontinuing the drug treatment, antibiotic therapy until an infectious cause was excluded, and high-dose methylprednisolone. Two patients recovered and one died. Contrary to an earlier report that suggested that pneumonitis occurred only with methotrexate sodium doses exceeding 15 mg/wk, our three cases demonstrate that a severe pulmonary toxic reaction may also complicate low-dose weekly methotrexate therapy of rheumatoid arthritis.
Insights
Low-dose methotrexate sodium can cause serious lung injury in rheumatoid arthritis patients. This pulmonary complication, marked by severe hypoxemia, can occur even at doses below 15 mg/wk.
Area of Science:
- Rheumatology
- Pulmonology
- Toxicology
Background:
- Methotrexate (MTX) is a common disease-modifying antirheumatic drug (DMARD) used for rheumatoid arthritis (RA).
- Methotrexate-associated pulmonary injury (MAPI) is a rare but serious adverse effect of MTX therapy.
- Previous reports suggested MAPI risk was primarily associated with higher MTX doses.
Observation:
- Three RA patients developed MAPI despite receiving low-dose weekly MTX (5-15 mg/wk).
- Patients presented with clinical, radiographic, and pathological features of pulmonary injury.
- Severe hypoxemia was noted, with lowest recorded oxygen pressure values between 35-45 mm Hg.
Findings:
- MAPI can occur at low MTX doses, challenging previous dose-related assumptions.
- The pulmonary toxic reaction presented with significant respiratory compromise.
- Treatment involved MTX cessation, antibiotics, and high-dose corticosteroids.
Implications:
- Clinicians should maintain a high index of suspicion for MAPI in RA patients on low-dose MTX.
- Early recognition and management are crucial for patient outcomes.
- This finding necessitates a re-evaluation of MAPI risk stratification in RA patients receiving MTX.