💊 Methotrexate (MTX) is 1st-line for RA, often as effective as biologics & safer. Starting at 10-15 mg/wk, escalate by 5 mg every 2-4 wks up to 20-30 mg/wk based on response. Switch to parenteral if needed for intolerance or poor response.
- Monitor 🧪 ALT, AST, creatinine, & CBC every 1-1.5 mos after starting or dose change, then every 1-3 mos. Assess for SEs & risk factors at every visit.
- 🦷 Replace folate (5-7 mg/wk or 1 mg daily) to reduce SEs like mouth sores, nausea, & liver toxicity. No need to worry about folic acid affecting MTX efficacy, even if taken on the same day.
- GI SEs ⚠️ worsen as oral MTX increases—split doses or switch to injectables if needed.
- ❌ Stop MTX if ALT/AST >3x ULN; restart at lower dose after normalization. Adjust dose if ALT/AST persistently elevated <3x ULN. Consider further testing if ALT/AST remains >3x ULN after stopping.
- 🔄 Avoid TMP/SMX & PPIs as they ⬆️ MTX toxicity. Recommend H2-blockers or monitor closely if PPIs must be used. NSAIDs are only an issue with higher doses of MTX (used in cancer).
- 📅 To prevent dosing errors, add the day of the week to the Rx label. MTX can be continued in RA pts undergoing elective surgery but stop 3 mos prior to pregnancy.
References
- Visser K, Katchamart W, Loza E, et al. Multinational evidence-based recommendations for the use of methotrexate in rheumatic disorders with a focus on rheumatoid arthritis: integrating systematic literature research and expert opinion of a broad international panel of rheumatologists in the 3E Initiative. Ann Rheum Dis. 2009;68(7):1086-1093.
- Freeman, J., MD. (2018). RA and Methotrexate: Does Methotrexate Reduce Inflammation? - Rheumatoid Arthritis Support Network. https://www.rheumatoidarthritis.org/treatment/methotrexate.
