Gut microbes metabolize Parkinson's disease drug

A gut bacterial pathway that degrades the drug levodopa is identified and can be inhibited The trillions of microorganisms that form the gut microbiota contain a treasure trove of enzymes. These directly modify and metabolize dietary components, drugs, and toxins that humans ingest. Although this is often beneficial, the gut microbiota can modify drug bioavailability and efficacy (1, 2). Levodopa (l-dopa), the major drug treatment for Parkinson's disease, displays highly variable and interindividual responses with reduced efficacy over time. On page 1055 of this issue, Maini Rekdal et al. (3) identify a two-step gut microbial enzymatic pathway that degrades l-dopa to dopamine and then to m-tyramine, thus potentially limiting drug availability in patients. Moreover, they identify a small molecule that blocks this l-dopa–metabolizing bacterial pathway, with the aim of increasing l-dopa availability in Parkinson's disease patients.