QWhat are the side effects to topical ruxolitinib?

Topical ruxolitinib is a medication FDA-approved for the treatment of atopic dermatitis that inhibits JAK1 and JAK2, mediators of cytokines and growth factors that are important for hematopoiesis and immune function. The package insert for topical ruxolitinib reports the most common adverse reactions (incidence ≥1%) are nasopharyngitis, diarrhea, bronchitis, ear infection, eosinophil count increased, urticaria, folliculitis, tonsillitis, and rhinorrhea.

Although risk with topical application is much lower than with systemic therapy, a black box warning exists for risk for serious infections, major adverse cardiovascular events, thrombosis, cancer, and all-cause mortality for patients taking JAK inhibitors orally.  Ruxolitinib is known to be a substrate for cytochrome (CYP3A4). Therefore, with concomitant use of topical ruloxitinib and strong inhibitors of CYP3A4 there is a potential to increase the systemic exposure of ruxolitinib and subsequent adverse reactions.

Reference:

1. Opelzura: Package Insert. Incyte Corporation 2022.