Objective:

We used disposable biosensors to measure capillary blood levodopa concentration in Parkinson’s disease (PD) after participants ingested oral carbidopa/levodopa, with the goal of correlating levodopa levels with motor symptoms.

Background:

Individuals with PD often have unpredictable and disabling symptom fluctuations. A crucial need exists to improve symptom management when patients develop a narrow therapeutic window, which requires better management of the levodopa doses according to the levodopa concentrations. Currently, no practical, decentralized, and rapid method exists for measuring levodopa levels. Accordingly, a crucial need exists to better understand the variable responses of PD symptoms to levodopa to improve dose adjustments, which would improve symptom management. We have developed a novel method to measure levodopa levels using capillary fingerstick blood in PD for timely and personalized medication adjustment.

Design/Methods:

We  enrolled participants with Hoehn and Yahr (1) stages I-IV idiopathic PD taking oral carbidopa/levodopa at least 50 years old. Using MDS-UPDRS Part IV, participants were categorized depending on levodopa response as “stable” (score =0) or “fluctuators” (score > 0) (2). During the  study visit, participants arrived "off”  after holding levodopa for at least 12 hours,  then took one dose of oral carbidopa/levodopa. Serial assessments were performed every 10 minutes for 120 minutes total: fingerstick for capillary blood levodopa levels, plasma levodopa levels, vital signs, and an abbreviated version of the MDS-UPDRS Part III for motor performance (3). 

Results:

We  collected pilot data from 11 participants with PD. Results from the capillary blood biosensor showed levodopa peak dose within 30-40 minutes; in most, the best motor symptom improvement occurred around 30-50 minutes.

Conclusions:

The capillary blood showed the expected levodopa pharmacokinetic curve, which corresponded with improvement in motor symptoms. We envision that this technology can eventually guide optimal, individualized therapy for PD in a manner analogous to at-home blood glucose monitoring in diabetes mellitus.