Objective: This quality improvement (QI) project was conducted to evaluate the impact of the conversion from immediate-release (IR) and/or extended-release (ER) levodopa (LD) to mucoadhesive polymer ER carbidopa/LD (IPX203).
Background: IPX203, designed as an IR and ER formulation of carbidopa/LD, was approved by the FDA in August 2024 for Parkinson’s disease (PD). At our institution, patients who experience ongoing motor fluctuations despite adequate PD medications trials are candidates for IPX203. While the manufacturer provides guidance on converting patients from IR and/or ER LD to IPX203, our practitioners may choose to tailor their patient IPX203 dose conversion based upon their clinical judgment.
Method: A retrospective chart review was conducted. Patients with PD were included if they were initiated IPX203 between February to November 2025 and excluded if they lacked follow up. The primary endpoints included: pre- and post-conversion comparisons of wearing off and comparison of initial and stable total LD daily IPX203 dose. Secondary endpoints included tolerability during the conversion and a pre and post conversion of PD-medication pill burden. Data collection included demographics, initial and stable IPX203 total daily LD dose, number of daily PD pills, wearing off symptoms, and side effects. Data were analyzed using descriptive and paired comparative statistics, with two-sided α=0.05 and 95% confidence intervals.
Results: Twelve patients were evaluated. Nine patients were converted from ER LD (mean total daily dose 2097 mg), and 3 were converted from IR and/or sustained acting LD (mean total daily dose 1040 mg). Stable IPX203 dosing showed an average increase of LD dose +338 mg (95% CI −91 to +768; Cohen’s dz=0.50). Dose changes were heterogeneous (median +140 mg-increased (6), decreased (2), and unchanged (4) dosing). Eleven patients reported improved wearing off following conversion. Five patients experienced reduced dyskinesias, while 5 patients had no change in side effects. Newly reported or worsening side effects included hallucinations (n=1), dizziness (n=1), and increased impulsivity (n=1). Average daily pill burden decreased from 12.9 to 8.4 pills.
Conclusion: In this small QI cohort, IPX203 conversion in PD patients was generally well-tolerated and resulted in improved wearing off and decreased pill burden. Further evaluation in larger studies is warranted.
To cite this abstract in AMA style:
L. Poon, A. Lee, D. Lee, T. Chiao, T. Stiep. Evaluating the Conversion of Immediate-Release and/or Extended-Release Levodopa to IPX203 in Patients with Parkinson’s Disease [abstract]. Mov Disord. 2026; 41 (suppl 1). https://www.mdsabstracts.org/abstract/evaluating-the-conversion-of-immediate-release-and-or-extended-release-levodopa-to-ipx203-in-patients-with-parkinsons-disease/. Accessed October 1, 2026.« Back to 2026 International Congress
MDS Abstracts - https://www.mdsabstracts.org/abstract/evaluating-the-conversion-of-immediate-release-and-or-extended-release-levodopa-to-ipx203-in-patients-with-parkinsons-disease/