Which medication is a Jak inhibitor used in RA?

• A. Infliximab
• B. Etanercept
• C. Tofacitinib
• D. Rituximab

Answer: (C)

Rheumatoid arthritis responds to therapies that interrupt cytokine signaling, and the Jak inhibitors do just that by blocking the JAK-STAT pathway inside cells. Tofacitinib is a small-molecule Jak inhibitor taken orally that mainly inhibits JAK1 and JAK3 (with some JAK2 activity), which prevents phosphorylation of STATs and reduces transcription of inflammatory genes. This dampens the broad range of cytokine signals driving joint inflammation in RA.

The other agents listed work differently: infliximab and etanercept are biologic drugs that neutralize TNF, a specific pro-inflammatory cytokine; rituximab targets CD20 on B cells to deplete them. Jak inhibitors are part of targeted synthetic DMARDs, offering an oral alternative to injectable biologics. Keep in mind the infection risk and potential blood and liver test changes with Jak inhibitors.