TOFAJAK 5 mg Tablets TOFAJAK contains Tofacitinib citrate, a selective oral inhibitor of the Janus kinase (JAK) family of enzymes, predominantly inhibiting JAK1 and JAK3. By blocking the JAK-STAT signaling pathway, it prevents the trans-phosphorylation and activation of STAT proteins, thereby suppressing the transcription of proinflammatory cytokines central to autoimmune inflammatory cascades. It is indicated for the treatment of adult patients with moderately to severely active rheumatoid arthritis, active psoriatic arthritis, active ankylosing spondylitis, and moderately to severely active ulcerative colitis.