Levodopa Challenge Test

It can be difficult to accurately differentiate PD from other forms of parkinsonism, especially during the early stages of disease. Levodopa administration can be used for diagnostic purposes, as PD patients respond more frequently and robustly to levodopa compared with other forms of parkinsonism. Clarke and Davies (145) reviewed 13 studies that examined whether an acute levodopa or apomorphine challenge test could aid in the diagnosis of PD. Four studies examined de novo patients and nine...

Does Tolerance Develop to Levodopa

The lay literature is replete with information suggesting that levodopa loses its effect after about five years. This leads to some trepidation on the part of the patient and physician in initiating therapy. If that were the case, it would indicate that tolerance is a possible concern and would argue for delaying treatment. It is conceivable that, when all nigrostriatal cells are depleted, levodopa would lose all effectiveness since these are the cells that convert levodopa and release...