Immunomodulatory therapies and emerging drug associations with microscopic colitis: A global pharmacovigilance analysis

BACKGROUND: Microscopic colitis (MC) is presumably mediated by immune dysregulation, with drug exposure being a substantial risk factor. This study aims to identify contemporary MC-drug associations. METHODS: A pharmacovigilance study of the FDA adverse event reporting system (FAERS) between July 2014 and June 2024. Disproportionate reporting of MC was assessed using reporting odds ratios (RORs), adjusted for age, sex, and concomitant medications. RESULTS: Of 12,109,491 safety reports, 2648 cases of MC were identified and associated with 55 different medications. Several biologic immunosuppressants showed increased MC reporting, including tocilizumab (ROR = 4.93 [95% CI 3.85-6.31]), interleukin-17 inhibitors (ROR = 3.14 [2.47-3.98]), anti-CD20 agents (ROR = 3.03 [2.46-3.74]), and abatacept (ROR = 2.00 [1.44-2.78]). Synthetic immunosuppressants, particularly leflunomide (ROR = 9.89 [7.30-13.39]), methotrexate (ROR = 2.42 [1.63-3.58]), and mycophenolate (ROR = 2.31 [1.41-3.78]), were also implicated. Immune checkpoint inhibitors showed disproportionate MC reporting (ROR = 3.03 [2.49-3.69]), with the strongest associations for ipilimumab and the ipilimumab-nivolumab combination. Traditional MC-related agents (PPIs, SSRIs, NSAIDs) were corroborated. Additional non-immunomodulatory classes (SNRIs, ARBs, ACE inhibitors, statins, and dopaminergic therapies) also emerged. Concomitant exposure to multiple agents increased MC reporting. CONCLUSIONS: This comprehensive pharmacovigilance study mapped drug-MC associations, suggesting potential novel safety signals while corroborating previously reported agents. Immunomodulatory drugs emerged as substantial risk factors. These findings provide practical insights for clinicians managing patients with MC.