Pyoderma gangrenosum adverse event with Rituximab use: A postmarketing pharmacovigilance analysis

Rituximab is a monoclonal antibody that is used for the treatment of certain malignancies and autoimmune conditions. Pyoderma gangrenosum is a rare painful ulcer that can be fatal in some cases and can also reoccur after treatment. The objective of this paper was to analyze whether a statistically significant signal exists between Rituximab and pyoderma gangrenosum in the Food and Drug Administration Adverse Event Reporting System (FAERS). A disproportionality analysis was carried out on cases from January 1, 2004 to March 31, 2019 in the FAERS. Frequentist methods of relative reporting ratio, reporting odds ratio (ROR), and proportional reporting ratio (PRR) and the Bayesian-based IC₀₂₅ metric were used in order to assess the adverse event signal. Thirty-two cases were found in FAERS in which the drug Rituximab was administered and pyoderma gangrenosum was reported as an adverse event. The lower 95% CI of the information component was 0.97, the lower 95% CI of ROR was 2.18, the PRR was 3.09 and Chi-squared was 42.16, which indicates a statistically significant signal. The signal is supported by six case reports in the literature that describe a total of 14 patients who developed pyoderma gangrenosum after Rituximab administration. When administering Rituximab, clinicians should monitor for the occurrence of symptoms representing pyoderma gangrenosum.