Description: Tofacitinib is a medication that belongs to a class of drugs called Janus kinase (JAK) inhibitors. It is an oral drug that works by slowing down an overactive immune system to decrease inflammation. It is often used when other medications, such as methotrexate or TNF blockers, have not been effective or cannot be tolerated by the patient.

Indication: Tofacitinib is used to treat a variety of autoimmune and inflammatory conditions, including:

• Moderately to severely active rheumatoid arthritis (RA)
• Active psoriatic arthritis (PsA)
• Active ankylosing spondylitis (AS)
• Moderately to severely active ulcerative colitis (UC)
• Active polyarticular course juvenile idiopathic arthritis (pcJIA) in patients 2 years of age and older

Mechanism of Action: Tofacitinib’s primary mechanism of action is the inhibition of Janus kinases (JAKs). JAKs are intracellular enzymes that play a critical role in the signaling pathways of various cytokines and growth factors involved in the immune and inflammatory responses. Tofacitinib primarily inhibits JAK1 and JAK3, and to a lesser extent, JAK2. By blocking these JAKs, tofacitinib prevents the phosphorylation of signal transducers and activators of transcription (STATs). This disruption of the JAK-STAT signaling pathway hinders the movement of STATs to the cell nucleus, which in turn reduces the expression of genes that produce inflammatory mediators. This ultimately leads to a reduction in the inflammatory response and helps to control the symptoms of autoimmune diseases.