Infectious side effects of baricitinib: a big data analysis based on VigiBase

Background: and aim baricitinib is an inhibitor of Janus-associated kinase (JAK) subtypes 1 and 2 with various effects on intracellular signaling pathways. Approved for rheumatoid arthritis (RA), and recently used for severe COVID-19, the prevalence of infections associated with baricitinib treatment has not been widely reported. We aimed to analyze the prevalence of infectious side effects in patients treated with baricitinib. Methods: : using the WHO global pharmacovigilance database (VigiBase), we carried out an extensive data analysis of approximately 300 patients treated with baricitinib. The prevalence of infectious side effects was our main focus. Patients treated with baricitinib for the indication of severe COVID-19 were excluded. Results: the most prevalent infectious side effect of baricitinib was oral herpes (IC025 of 4.36) and herpes zoster infection (IC025 of 4.159). On the contrary, gastrointestinal viral infections, infectious pleural effusions and various viral pneumonias had low prevalence rates (IC025 values of 0.173; 0.093; and 0.188, respectively). Conclusion: based on a big data analysis, baricitinib was associated with infectious complications where oral herpes and herpes zoster infections shown to be more prevalent than previously reported. The immunomodulatory effect of baricitinib including cytokine effects on immune cells and the inhibition of numerous growth factors and cytokines such as IL-2, suppressing both innate and adaptive immune responses, are the most comprehensive mechanisms behind such side effects. Given the clinical indications for baricitinib (RA) and the current use in severe COVID-19, cautious approach should be taken before introducing baricitinib particularly in immunosuppressed patients.