II. Indications
III. Contraindications
- Live Vaccines (see Drug Interactions below)
IV. Mechanism
- 
                          Janus Kinase (JAK) and the JAK/STAT Pathway- Janus Kinase (JAK) is a family of intracellular Tyrosine Kinases that trigger a signaling cascade of Cytokines
- JAK acts on STAT transcription factors, triggering gene transcription related to inflammation
- Janus Kinase (JAK) is named for its Protein's 2 phosphate-Transferring domains
 
- Janus Kinase Inhibitor- JAK Inhibitors are small molecule agents that interfere with Cytokine signalling by blocking their receptor binding
 
V. Medications
- Ruxolitinib or Jakafi (JAK1 and JAK2 Inhibitor)- Indicated in Rheumatoid Arthritis and Myelofibrosis (including Polycythemia Vera)
 
- 
                          Baricitinib or Olumiant (JAK1 and JAK2 inhibitor)- Indicated in Rheumatoid Arthritis and Alopecia Areata
 
- 
                          Upadacitinib or Rinvoq (JAK1 inhibitor)- Indicated in Rheumatoid Arthritis
 
- 
                          Tofacitinib or Xeljanz (JAK3 Inhibitor)- Indicated in Rheumatoid Arthritis and Psoriatic Arthritis
 
VI. Adverse Effects
- Venous Thromboembolism
- Sudden cardiovascular death (associated with Tofacitinib)- FDA black box warning for major cardiovascular event risk
 
- 
                          Immunosuppression
                          - Tuberculosis reactivation risk (test for Latent Tb before starting)
- Increased risk of opportunistic infection (e.g. invasive Fungal Infections, Pneumonia, Shingles)
- Malignancy risk (e.g. Lymphoma)
 
VII. Drug Interactions
- 
                          Live Vaccines- Hold JAK Inhibitors for 1 week before and 4 weeks after Live Vaccines
 
VIII. References
- (2019) Presc Lett 26(10): 58
