Objective: To examine levels of stomach and small intestine (SI) pH in relation to variable clinical responses to doses of levodopa in Parkinson’s disease (PD) patients.
Background: A relationship between levodopa response and pH throughout the stomach and SI in patients with PD was explored using wireless motility capsules. Establishing a connection will better elucidate the impact of pH on levodopa absorption.
Method: The study included 10 PD patients with typical response to levodopa (time to “ON” within 1 hour) and 10 erratic responders (sudden “ON”/”OFFs”, delayed time to “ON”, response failure). The capsules captured continuous stomach and SI motility and pH data. Dose response was assessed by finger tapping scores and patient reporting every 30 minutes for 3 hours.
Results: Average mean gastric pH was 1.85 for typical responders and 1.77 for erratic responders. Most typical responders had a median stomach pH between 0.5 and 1.5; most erratic responders were between 0.5 and 2.5. Percent of time spent between a gastric pH range of 1.5-3.5 was calculated. Typical responders had an average 17% of time within that range, 63% time below 1.5 and 20% above 3.5. Erratic responders averaged 31% of time within range, 56% time below 1.5, and 13% above 3.5. The pH profile of the SI appeared to be similar between the 2 groups in averages, medians and proportion of time in ideal range. Of typical responders, 9 reported being ON within 1 hour of their first levodopa dose. Only 6 erratic responders reported being ON in 1 hour. At 180 minutes, 8 of the erratic responders reported being ON, but only 2 typical responders reported still feeling ON. Finger tapping scores improved for 90% of typical responders in 1 hour compared to only 50% of erratic responders.
Conclusion: Erratic responders reported more delayed time to ON than typical responders and showed less clinical improvement within 1 hour. In the stomach, erratic responders showed more spread of pH values. Typical responders averaged more time spent at gastric pH levels below 1.5. Further exploration of pH differences throughout the stomach and SI is needed to define an ideal range of pH for levodopa absorption. This could provide crucial information for improving efficacy of doses and clinical outcomes for PD patients1.
References: 1. Rivera-Calimlim L, Dujovne CA, Morgan JP, Lasagna L, Bianchine JR (1970) L-dopa treatment failure: explanation and correction. Br Med J 4:93–94.
To cite this abstract in AMA style:
M. Arena, B. Brumbach, S. Diamond, K. Block, J. Nutt, R. Pfeiffer, D. Safarpour. Effect of differences in stomach and small intestine pH on response to levodopa in patients with Parkinson’s Disease. [abstract]. Mov Disord. 2023; 38 (suppl 1). https://www.mdsabstracts.org/abstract/effect-of-differences-in-stomach-and-small-intestine-ph-on-response-to-levodopa-in-patients-with-parkinsons-disease/. Accessed July 1, 2025.« Back to 2023 International Congress
MDS Abstracts - https://www.mdsabstracts.org/abstract/effect-of-differences-in-stomach-and-small-intestine-ph-on-response-to-levodopa-in-patients-with-parkinsons-disease/