Resolution of Levodopa/Dopa‐Decarboxylase Inhibitor—Associated Microscopic Colitis with Subcutaneous Foslevodopa/Foscarbidopa: A Case Series and Review of the Literature

BACKGROUND: Microscopic colitis (MC) typically presents with chronic, non-bloody watery diarrhea. Diagnosis requires endoscopy with colonic mucosal biopsies. The etiology is multifactorial, with several medications implicated, although only a few cases have been attributed to oral levodopa/dopa-decarboxylase inhibitor (LDDCI) therapy. CASES: We present two people with Parkinson's disease (PD; PwP) who developed MC on LDDCI therapy. Symptoms of MC resolved following the transition from oral LDDCI therapy to continuous subcutaneous foslevodopa/foscarbidopa infusion (CSFLI). LITERATURE REVIEW: A review of the literature identified 21 reported cases of parkinsonism patients who developed MC during LDDCI therapy across three articles. Diarrheal symptoms improved after treatment modification, either by switching the LDDCI formulation or by discontinuing the therapy. CONCLUSION: In PwP presenting with LDDCI-associated MC, CSFLI represents an effective alternative that maintains dopaminergic efficacy while bypassing the gastrointestinal tract. Early recognition and timely switching to parenteral levodopa formulations may prevent prolonged symptoms and complications of MC in PwP. Microscopic colitis, a rare adverse effect of LDDCI therapy, may resolve completely with CSFLI.