Description Tofacitinib is an oral Janus kinase (JAK) inhibitor for the treatment of rheumatoid arthritis and psoriatic arthritis. Tofacitinib inhibits JAK dependent cytokinesignaling. JAKs are intracellular enzymes which transmit signals arising from cytokine or growth factor-receptor interactions on the cellular membrane. JAKsphosphorylate and activate Signal Transducers and Activators of Transcription (STATs) which modulate intracellular activity […]