Gut microbes eat levodopa: COMT inhibitors backfire in Parkinson’s treatment

A Yale-led study shows that COMT inhibitors, used with levodopa to treat Parkinson’s, disrupt the gut microbiome and promote Enterococcus faecalis, which metabolizes levodopa in the gut and prevents it from reaching the brain. This microbiome-mediated drug interaction helps explain why identical doses can variably affect patients and suggests clinicians should consider gut bacteria when evaluating co-prescribed drugs; the finding could extend to other disease-drug combinations.