Baricitinib

What is baricitinib?

Baricitinib is an orally administered first-generation selective inhibitor of the tyrosine kinase receptors JAK 1 and JAK 2 approved for use in the treatment of rheumatoid arthritis and atopic dermatitis.

What is baricitinib used for in dermatology?

Baricitinib is currently approved only for moderate to severe atopic dermatitis in adults who are candidates for systemic therapy (as at July 2021). It can be used in combination with topical steroids and/or topical calcineurin inhibitors. Clinical trials have reported 60% of patients taking 4 mg/d achieve EASI 50 after 16 weeks.

Clinical trials in progress are demonstrating efficacy in the treatment of chronic plaque psoriasis, alopecia areata, and systemic lupus erythematosus.

What are the contraindications with baricitinib?

• Other medications — biologic immunomodulators, ciclosporin, or other potent immunosuppressants
• Pregnancy and lactation — the safety of baricitinib has not been studied in human clinical trials. In animal models, teratogenic effects have been noted with extremely high doses. It is recommended baricitinib be ceased at least one month prior to conception and effective contraception used when taking baricitinib.
• Severe and end-stage renal failure (stages 4 & 5)
• Severe hepatic impairment
• Past history of thromboembolism (eg, deep venous thrombosis, pulmonary embolism) or increased risk of thromboembolism (eg, obesity, prolonged immobilisation)
• Active infections — including tuberculosis, hepatitis B, and hepatitis C
• Hypersensitivity to baricitinib or any of the excipients in the product

Caution should be used when treating the elderly (>65 years of age), patients with Stage 3 renal impairment, or diabetics.

Tell me more about baricitinib.

Baricitinib is a novel small molecule inhibitor of tyrosine kinase receptors. It has anti-inflammatory effects by reducing expression of pro-inflammatory cytokines including interleukin (IL)-6, IL-12, IL-17, IL-22, IL-23, and interferon-gamma.

Baricitinib is available as 2 mg and 4 mg film-coated tablets which are taken orally with or without food. The usual starting dose for treating atopic dermatitis is 2 mg/d, increasing to 4 mg/d if disease activity is not controlled. Treatment should be ceased after 8 weeks of 4 mg/d if there has been no clinical improvement.

Before starting baricitinib, investigations should include:

• Full blood count
• Kidney function tests
• Liver function tests
• Fasting lipids
• Screening for tuberculosis, hepatitis B, and hepatitis C
• Pregnancy test if indicated.

Monitoring during baricitinib treatment should include full blood count, liver function tests, and lipids. Treatment should be interrupted if haemoglobin falls below 8 g/dL, lymphocyte count below 500 cells/mm³, neutrophil count below 1000 cells/mm³, or liver transaminases increase.

What are the benefits of baricitinib?

• Rapid onset of action
• Relief from itch
• Improves sleep

What are the disadvantages of baricitinib?

• Drug interactions including immunosuppressants and OAT3 inhibitors such as probenicid
• Immunisations with live vaccines should be performed before starting baricitinib

What are the side effects and risks of baricitinib?

Baricitinib is generally well-tolerated and clinical trials have extended out to 52 weeks of use.

Common side effects

• Headache
• Nausea
• Hypercholesterolaemia
• Nasopharyngitis

Uncommon side effects

• Reactivation of infections such as herpes zoster
• Opportunistic and serious infections
• Haematological derangements — anaemia, lymphopenia, neutropenia
• Liver damage
• Hypertriglyeridaemia
• Vomiting
• Thromboembolism

Mucocutaneous side effects

• Acne
• Paradoxical flare of psoriasis

In 2021, the FDA issued new and updated black box warnings for baricitinib in line with warnings in place for tofacitinib. Although large safety trials have not been conducted with baricitinib, their similar mechanisms of action raise concerns regarding a possible increased risk of serious heart events, blood clots, and death.