Objective: To investigate the effectiveness, safety and pharmacokinetics of WD-1603 carbidopa-levodopa controlled-release tablets in subjects with Parkinson’s disease.

Background: The development of drug products that achieve more consistent levodopa plasma concentrations has been a longstanding goal. GiPump® is a proprietary osmotic pump technology designed to release drug content at a constant rate. WD-1603, a controlled-release tablet, utilizes the GiPump® platform to achieve this sustained drug delivery.

Method: We conducted a Phase II randomized, double-blind, parallel-group, placebo-controlled study in subjects with early Parkinson’s disease. Forty eligible subjects were randomly assigned to one of four treatment groups at a 1:1:1:1 ratio: (1) 25/100 mg, (2) 25/150 mg, (3) 2×25/100 mg, or (4) placebo. Subjects received treatment for four weeks, taking WD-1603 or placebo tablets orally three times daily for 28 days. Plasma samples were collected at steady state on Day 28.

Results: On Day 27, the treatment difference, assessed as the least-squares (LS) mean change from baseline in the MDS-UPDRS II+III total score, was -6.7 (p = 0.0388), -8.5 (p = 0.0125), and -13.6 (p = 0.0003) for the low-, medium-, and high-dose WD-1603 groups, respectively, compared to the placebo group. On Day 14, the corresponding treatment differences were -6.0 (p = 0.0395), -8.0 (p = 0.0092), and -11.7 (p = 0.0005). The treatment difference was statistically significant for the medium- and high-dose groups on both Days 14 and 27. At steady state, following the second dose on Day 28, plasma levodopa concentrations in the three WD-1603 dose groups exhibited stable profiles, with a mean fluctuation index (FI) of 1.19 (τ = 5h).

Conclusion: WD-1603 shows promising efficacy in a dose-dependent manner, providing significant improvements in efficacy as early as by Day 14.  An FI of 1.19 indicates minimal peak-to-trough fluctuation in plasma levodopa levels, suggesting that WD-1603 provides a relatively consistent delivery of levodopa over time. This stability could contribute to sustained efficacy and potentially fewer motor fluctuations.  Further investigation, including long-term studies, would be needed to confirm the durability of the effect and evaluate safety in a larger population.

Figure 1. Change in MDS-UPDRS-II+III

Figure 2. Levodopa PK Profile on Day 28

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MDS Abstracts - https://www.mdsabstracts.org/abstract/a-phase-ii-randomized-parallel-double-blind-placebo-controlled-study-of-the-efficacy-and-safety-of-wd-1603-in-subjects-with-parkinsons-disease/