Methotrexate Pneumonitis After a Low-Dose Medication Error: A Case Report

Area of Science:

• Rheumatology
• Clinical Toxicology
• Pharmacovigilance

Background:

• Methotrexate is a primary drug for rheumatoid arthritis.
• Methotrexate-induced pneumonitis is a rare but severe adverse event.
• Patient education on methotrexate dosing is critical.

Observation:

• A 68-year-old rheumatoid arthritis patient mistakenly took daily methotrexate instead of weekly.
• This led to hepatic, hematological, and pulmonary toxicity.
• Clinical presentation suggested methotrexate-induced pneumonitis, despite no histology.

Findings:

• Toxic dosing, pantoprazole, and hypoalbuminemia may have contributed to adverse events.
• The overdose likely accelerated pulmonary manifestations of methotrexate pneumonitis.
• The case underscores the potential for medication errors in methotrexate therapy.

Implications:

• Highlights the critical need for improved patient education and clear warnings for methotrexate.
• Emphasizes the importance of vigilance for methotrexate-induced pneumonitis in rheumatoid arthritis patients.
• Reinforces the need for careful medication management to prevent severe adverse events.