Noninvasive monitoring of plasma L-dopa concentrations using sweat samples in Parkinson's disease.
BACKGROUND
L-dopa (l-3,4-dihydroxyphenylalanine) is commonly used for treating Parkinson's disease (PD). However, regardless of its prominent effect, therapeutic range of L-dopa narrows down with disease progression, which leads to development of motor complications including wearing off and dyskinesias. In addition, intestinal absorption of L-dopa is inversely correlated with the amount of oral protein intake, and shows intra- and inter-day variability. Hence, frequent monitoring of plasma L-dopa concentrations is beneficial, but frequent venipuncture imposes physical and psychological burdens on patients with PD.


METHODS
We investigated the usefulness of sweat samples instead of plasma samples for monitoring L-dopa concentrations. With a monolithic silica disk-packed spin column and the high-performance liquid chromatography-electrochemical detection system, L-dopa in sweat samples was successfully quantified and analyzed in 23 PD patients.


RESULTS
We found that the Pearson's correlation coefficient of the plasma and sweat l-dopa concentrations was 0.678. Although the disease durations and severities were not correlated with the deviation of the actual sweat L-dopa concentrations from the fitted line, acquisition of the sweat samples under a stable condition was technically difficult in severely affected patients. The deviations may also be partly accounted for by skin permeability of L-dopa.


CONCLUSIONS
Measuring L-dopa concentrations in sweat is suitable to get further insights into the L-dopa metabolism.
['Tsunoda|Makoto|M|', 'Hirayama|Masaaki|M|', 'Tsuda|Takao|T|', 'Ohno|Kinji|K|']
D001774:Blood Chemical Analysis D006801:Humans D007980:Levodopa D010300:Parkinson Disease D013542:Sweat
Plasma l-dopa Parkinson's disease Sweat l-dopa