Tofacitinib is an oral Janus Kinase Inhibitor. Because of its unique and novel mechanism of action, it is one of the potent JAK Inhibitors.
It was approved by the FDA in 2012. It is available in two formulations:
- Immediate Release as Xeljanz, and
- The Extended Release Oral Tablets as Xeljanz XR
Tofacitinib is a Janus kinase inhibitor sold in the market under the name “Xeljanz”.
It is used to inhibit the functioning of Janus kinase, and thus controls the immune system of our body by suppressing it.
As a result of slowing down the immune system, our body is prevented from many autoimmune diseases such as:
- Rheumatoid arthritis,
- Moderately-to-severely active ulcerative colitis, and
- Psoriatic arthritis.
Tofacitinib Mechanism of action (Xeljanz MOA)
Rheumatoid arthritis is an autoimmune disorder characterized by fatigue, loss of appetite, weakness, and swelling, followed by joint pain and eventually complete or partial destruction of them.
In it, the immune cells enter the affected synovium and cause the release of inflammation-causing cytokines and degradation-causing mediators which in turn damages the joint.
Cytokines form complex networks which play a key feature in signaling to different kinase pathways working inside the cell.
These pathways are involved in the functioning and activation of cells working in the immune system.
So our main aim is to target these kinase pathways such as the Janus kinase pathway which is the main pathway controlling this complex network of cytokines.
Tofacitinib is thus a drug that controls the cytokines responsible for the inflammatory response caused by the immune system.
It is a reversible and partial inhibitor of JAK which stops its functioning by preventing the activation and phosphorylation of Signal Transducers and Activators of Transcription called as STATs.
This JAK-STAT pathway is involved in the immune function and formation of blood cells.
So Tofacitinib (Xeljanz) acts by inhibiting this pathway, stopping the formation of excess unnecessary blood cells and immune system damaging one’s body.
It decreases the inflammatory response and hence proves to be very effective in the treatment of rheumatoid arthritis.
Tofacitinib inhibits the formation of proinflammatory cytokines that are directly involved in the pathogenesis of Rheumatoid arthritis and other inflammatory conditions.
Because of its targeted action, it is more effective compared to conventional DMARDS.