Objective: To determine if altered transit time in the various segments of the gastrointestinal (GI) tract relates to the variability of clinical responses and serum levodopa level in patients with Parkinson’s disease (PD).

Background: Motility dysfunction has been studied in PD, but no studies have measured Whole Gut Transit Time(WGTT) in these patients.Simultaneous measurement of regional and WGTT along with levodopa level will be a crucial step in understanding the effect of motility disorders and their location on changes to response to levodopa.

Method:
10 PD patients with typical levodopa response (predictable fluctuations) and 10 erratic responders (sudden “ON”/”OFFs”, delayed time to “ON”, or response failure) will ingest SmartPill, a wireless motility capsule that measures transit time in GI tract. Serum levodopa levels every 30 minutes and serial finger tapping for the first three hours of SmartPill and their first dose of Levodopa ingestion will be used to study the correlation between changes in GI motility and response and T-max of levodopa. The presence or absence of small intestinal bacterial overgrowth (SIBO) will be documented by a glucose breath test.

Results: Fifteen patients (9 women, 6 men; mean age 68), including 8 erratic and 7 typical responders, have completed the study. Serum levodopa level in erratic responders had more than one peak whereas typical responders had their highest serum levodopa level at 30 minutes after taking their morning dose with a subsequent gradual decrease in their level. It took 120 minutes for >80% of the erratic responders to feel ON compared with 60 minutes for the same percentage of typical responders to feel ON. No SIBO negative patient had abnormal Small Bowel Transit Time (SBTT), while 60% of SIBO positive patients had abnormal SBTT. Two erratic responders had abnormally long SBTT and one typical responder had abnormally short SBTT.

Conclusion: Erratic responders displayed an erratic pattern in serum levodopa levels and delayed onset of feeling ON, whereas typical responders had one early peak and a gradual decrease in their level and an earlier onset of ON time. SmartPill is a feasible technology to assess transit time in PD patients.
The preliminary data from this study has been presented in other non motor features of Parkinson’s Disease working group virtual meeting of PSG on January 19th,  2021.

References: This abstract has also been submitted to IAPRD XXVI World Congress for Parkinson’s Disease. Data from this study has not previously been published.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/comparison-of-gastrointestinal-transit-times-in-typical-and-erratic-levodopa-responders-in-patients-with-parkinsons-disease/