A 52-year-old woman with a 3-year history of seropositive rheumatoid arthritis (RF+ and anti-CCP+) presents with persistent joint pain and swelling despite adequate doses of methotrexate monotherapy for 6 months. She has no contraindications to biologics. What is the drug of choice to add to her current regimen?
A. Leflunomide
B. Sulfasalazine
C. Infliximab
D. Hydroxychloroquine
Explanation
First-Line Biologic Therapy in RA
Key Point
TNF-α inhibitors (TNFi) are the preferred first-line biologic agents for RA patients with inadequate response to conventional synthetic DMARDs (csDMARDs) like methotrexate.
High-YieldNEET PG
The treat-to-target strategy in RA recommends adding a biologic (preferably a TNFi) when a patient fails to achieve low disease activity on csDMARD monotherapy within 3–6 months.
Why Infliximab?
Table
Feature
Infliximab
Adalimumab
Etanercept
Type
Chimeric monoclonal Ab
Fully human monoclonal Ab
TNF receptor fusion protein
Administration
IV infusion
SC injection
SC injection
Onset
Rapid (2–4 weeks)
2–4 weeks
2–4 weeks
Efficacy in RA
Excellent
Excellent
Excellent
First-line status
Yes (ACR, EULAR)
Yes (ACR, EULAR)
Yes (ACR, EULAR)
Clinical Pearl
Infliximab is typically given as IV induction (3 mg/kg at weeks 0, 2, 6) followed by maintenance every 8 weeks. It must be combined with methotrexate to reduce immunogenicity and improve efficacy.
Mnemonic: TNFi First — When csDMARD fails, add TNF inhibitor first (infliximab, adalimumab, etanercept, golimumab, certolizumab).
Why Not the Others?
Sulfasalazine & Hydroxychloroquine: These are csDMARDs, not biologics. They are less effective than TNFi for inadequate responders and should not be used as monotherapy add-ons in this scenario.
Leflunomide: Also a csDMARD. While it can be combined with methotrexate, TNFi is preferred first-line biologic therapy per ACR/EULAR guidelines.
Warning
Do NOT confuse TNFi with other biologic classes (IL-6 inhibitors, JAK inhibitors, B-cell depletors). TNFi remains the gold standard initial biologic choice in RA.
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