Baricitinib (Olumiant®) is an oral, targeted synthetic DMARD that inhibits JAK1 
and JAK2, which are implicated in the pathogenesis of rheumatoid arthritis (RA). 
This novel, small molecule is approved for use as monotherapy, or in combination 
with methotrexate, for the treatment of adults with moderate to severe active RA 
who responded inadequately to or were intolerant of ≥ 1 DMARD. In pivotal 
multinational trials, once-daily baricitinib 4 mg, with/without methotrexate 
(± another csDMARD), improved the signs and symptoms of RA, disease activity and 
physical function in DMARD-naive patients and in patients with an inadequate 
response to methotrexate, csDMARDs or TNF inhibitors; baricitinib treatment also 
slowed structural joint damage in DMARD-naive patients and in those with an 
inadequate response to methotrexate and csDMARDs. Baricitinib plus methotrexate 
was more effective than adalimumab plus methotrexate in patients with an 
inadequate response to methotrexate. The onset of these benefits was generally 
rapid and sustained over time. Baricitinib was generally well tolerated during 
up to 5.5 years' treatment; the most commonly reported adverse drug reactions 
were upper respiratory tract infections, increased LDL cholesterol, nausea and 
thrombocytosis. Thus, once-daily baricitinib, as monotherapy or in combination 
with methotrexate, is an effective and generally well tolerated emerging 
treatment for patients with moderate to severe active RA who have responded 
inadequately to or are intolerant of ≥ 1 DMARD, and extends the options 
available for this population.