THERE IS ample evidence to warrant a change of our clinical practice with regard to levodopa therapy in patients with Parkinson disease (PD), although considerable confusion has clouded the issue of the rationale underlying this change. Concerns regarding "levodopa toxicity" initially emanated from a number of basic science reports suggesting that levodopa has the potential to hasten injury and death of the nigral neuron. However, over time, the distinction between in vitro data and clinical observation blurred, and both clinicians and patients began to erroneously merge the pressing problems of clinical management in advanced PD (eg, motor fluctuations, dyskinesia) with the concept of levodopa toxicity. The need for an accurate definition of levodopa toxicity lies at the heart of this issue.
Shulman LM. Levodopa Toxicity in Parkinson Disease: Reality or Myth?Reality—Practice Patterns Should Change. Arch Neurol. 2000;57(3):406-408. doi:10.1001/archneur.57.3.406