tofacitinib
Xeljanz (tofacitinib) is an oral Janus kinase inhibitor from Pfizer that calms overactive immune signalling. After TNF blockers have not worked, it treats rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis, ulcerative colitis, and certain childhood arthritis forms.
This page is based on FDA prescribing information and the EMA medicine record for tofacitinib, cross-checked with MedlinePlus and the National Cancer Institute dictionary; the mechanism is explained in plain language, and analogies are used only where they stay accurate.
How it works
Explains what the medicine does in the body, not dosing, side effects, or safety.
An analogy
Immune signals arrive at cells like letters, and Janus kinases are the clerks who carry each letter to the nucleus to be read. In rheumatoid arthritis and colitis the mailbox is flooded with inflammatory letters. Tofacitinib sends the clerks home, so fewer inflammatory messages get through, and the swollen joints and inflamed gut gradually quiet down.
In simple terms
Tofacitinib is taken by mouth and belongs to the Janus kinase inhibitor class. It binds JAK enzymes and prevents activation of the JAK-STAT signalling pathway, which many inflammatory cytokines use. This decreases the production of pro-inflammatory signals and lowers immune system activity that attacks joints in arthritis or the colon in ulcerative colitis. It is used after TNF blocker therapy has not worked well enough.
In depth
Tofacitinib is an orally available inhibitor of Janus kinases (JAK) with immunomodulatory and anti-inflammatory activities. Upon administration it binds JAK and prevents activation of the JAK-signal transducers and activators of transcription (STAT) signalling pathway. This may decrease the production of pro-inflammatory cytokines such as interleukin-6, -7, -15, and -21, and interferons, preventing both inflammatory responses and inflammation-induced damage. JAK kinases are intracellular enzymes involved in signalling pathways affecting haematopoiesis, immunity, and inflammation. Combination with biologic DMARDs or potent immunosuppressants such as azathioprine and cyclosporine is not recommended.
See it in motion
A schematic animation of the mechanism — simplified for clarity, not drawn to scale.
How tofacitinib inhibits Janus kinases to quiet the JAK-STAT pathway
- Immune signals arrive at cells like letters, and Janus kinases are the clerks who carry each letter to the nucleus to be read.
- Tofacitinib is an orally available inhibitor of Janus kinases (JAK) with immunomodulatory and anti-inflammatory activities.
- Upon administration it binds JAK and prevents activation of the JAK-signal transducers and activators of transcription (STAT) signalling pathway.
- This may decrease the production of pro-inflammatory cytokines such as interleukin-6, -7, -15, and -21, and interferons, preventing both inflammatory responses and inflammation-induced damage.
Target: Janus kinases (JAK)
Intracellular enzymes that relay cytokine signals from cell surface receptors to the nucleus via the JAK-STAT pathway; blocking them reduces the production of pro-inflammatory cytokines that drive arthritis and colitis.
Approved uses
Approved uses differ by country and change over time. Always follow your local prescribing information.
Approved uses in United States
FDA- For the treatment of adults with moderately to severely active rheumatoid arthritis who have had an inadequate response or intolerance to one or more TNF blockers
- For the treatment of adults with active psoriatic arthritis who have had an inadequate response or intolerance to one or more TNF blockers
- For the treatment of adults with active ankylosing spondylitis who have had an inadequate response or intolerance to one or more TNF blockers
- For the treatment of adults with moderately to severely active ulcerative colitis who have had an inadequate response or intolerance to one or more TNF blockers
- For the treatment of pediatric patients 2 years of age and older with active psoriatic arthritis who have had an inadequate response or intolerance to one or more TNF blockers
- For the treatment of pediatric patients 2 years of age and older with active polyarticular course juvenile idiopathic arthritis who have had an inadequate response or intolerance to one or more TNF blockers
Approved uses in European Union
EMA- In combination with methotrexate, for the treatment of moderate to severe active rheumatoid arthritis in adults who have responded inadequately to, or are intolerant to, one or more disease-modifying antirheumatic drugs (DMARDs), with monotherapy possible in case of methotrexate intolerance or when methotrexate treatment is inappropriate
- In combination with methotrexate, for the treatment of active psoriatic arthritis in adults who have had an inadequate response or intolerance to prior DMARD therapy
- For the treatment of adults with moderately to severely active ulcerative colitis who have had an inadequate response, lost response, or were intolerant to either conventional therapy or a biologic agent
- For the treatment of active polyarticular juvenile idiopathic arthritis and juvenile psoriatic arthritis in patients 2 years of age and older who have responded inadequately to previous DMARD therapy, in combination with methotrexate or as monotherapy when methotrexate is inappropriate
Official sources
The statements on this page trace back to these records.
- Xeljanz (tofacitinib) — Summary of product characteristics and package leaflet, English version
European Medicines Agency
- U.S. Food and Drug Administration: tofacitinib prescribing information
U.S. Food and Drug Administration
- MedlinePlus: tofacitinib
MedlinePlus, U.S. National Library of Medicine
- National Cancer Institute: tofacitinib
National Cancer Institute
This page explains how the medicine works — it isn’t the patient leaflet. For anything that applies to you, read the leaflet that came with your medicine or ask your pharmacist.
MedUnfold provides educational content and is not medical advice. Always follow your local prescribing information and healthcare professional.