Chronic Urticaria Explained: BTK Inhibitors & Remibrutinib

In this episode of the Science of Skin Podcast, Dr. Ted Lain sits down with Dr. Sarina Elmariah, MD, PhD, professor of dermatology at UC San Francisco and director of the UCSF Center for Itch and Neurosensory Disorders, for a deep dive into chronic spontaneous urticaria (CSU).

Dr. Elmariah breaks down the role of Bruton's tyrosine kinase (BTK) in mast cell degranulation and explains how it sits at the center of the histamine release cascade. The conversation covers the difference between Type I (auto-allergic) and Type IIb (autoimmune) CSU pathways, available diagnostic tools like autologous serum skin testing and basophil activation testing, and why BTK appears to be a common thread across nearly all CSU mechanisms — including many inducible urticarias.

The two also discuss remibrutinib (brand name Rhapsido), a BTK inhibitor newly FDA-approved for CSU, and what makes its binding mechanism distinct from earlier BTK inhibitors. They close with a look beyond histamine at the other inflammatory mediators — proteases, leukotrienes, prostaglandins, and cytokines — that help explain why so many CSU patients don't respond to antihistamines alone, and why angioedema tends to linger longer than a typical urticarial wheel.

This episode is sponsored by Novartis with content independently created by the Science of Skin podcast.

⚠️ This content is for educational and informational purposes only and reflects the personal research findings and opinions of the speakers. It is not medical advice. The discussion involves animal studies and experimental research; consult a licensed healthcare provider for questions about your own health.

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