Baricitinib (Olumiant)
Oral JAK1/2 inhibitor for alopecia areata and severe atopic dermatitis
About This Treatment
Baricitinib is a selective inhibitor of Janus kinase (JAK) types 1 and 2 (JAK1/2), blocking critical intracellular signaling junctions and serving as an oral immunomodulatory agent. In alopecia areata, it controls autoimmune T cell infiltration around hair follicles and suppresses hair matrix attacks, promoting hair regeneration. In severe atopic dermatitis, it suppresses Th2 inflammation, reducing production of IL-4, IL-6, TNF-α and other cytokines. As an oral medication, it offers high patient convenience and expanded treatment options for moderate-to-severe refractory disease patients.
Mechanism of Action
JAK1/2 inhibition blocks upstream cytokine receptor signaling (particularly IL-2, IL-4, IL-6 receptors). In alopecia areata, IFN-γ and IL-2 produced by Th1/Tc1 cells drive hair follicle infiltrating lymphocytes; JAK1/2 inhibition blocks this signal, suppressing autoreactive T cell differentiation and activation. In atopic dermatitis, IL-4 (Th2 activation) and IL-6 (inflammation amplification) are suppressed while regulatory T cell (Treg) function is promoted. Since JAK1/2 represents a crossroads of multiple immune signals, multidirectional inflammation suppression is achievable.
Indications
Expected Results
In alopecia areata, hair regrowth evident by 12 weeks; ~50-60% of patients achieve >80% scalp coverage by 6 months. In atopic dermatitis, EASI improvement by 4-8 weeks with marked improvement by 16 weeks. Long-term treatment enables remission maintenance.
Clinical Evidence
Risks & Side Effects
Increased infection risk (especially TB, viral infections) requires pre-treatment screening. LDL-C and CPK elevation may occur requiring regular blood tests. Thromboembolic risk increase reported but relatively rare. Avoid in patients planning pregnancy.
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