Duration of “Good On” time per dose: Immediate-release carbidopa-levodopa vs. extended-release carbidopa-levodopa (IPX203, CREXONT®)

Background: For Parkinson's disease patients with motor fluctuations, the duration of benefit per levodopa dose is a key metric that reflects a patient's clinical response. Objective: Determine the difference in mean durations of “Good On” time per dose of subjects randomized to extended-release carbidopa-levodopa (ER CD-LD; IPX203; CREXONT®) vs. immediate-release (IR) CD-LD in the RISE-PD trial. Methods: “Good On” time per dose was assessed at the end of the IR CD-LD dose adjustment phase (Visit 2/Week 3) and compared to End of Study (Visit 7/EOS) between IPX203 and IR CD-LD groups. In addition, to understand if “Good On” time per dose for IR CD-LD before conversion to IPX203 could impact the magnitude of change in “Good On” time per dose of IPX203 vs. IR CD-LD after conversion, subjects were rank-ordered and divided into quartiles based on their initial “Good On” time per dose optimized IR CD-LD values. Changes in “Good On” time per dose between IPX203 and IR CD-LD groups were then compared for each quartile from Visit 2 to EOS. Results: IPX203 increased “Good On” time per dose compared to IR CD-LD by a mean of 1.6 h (p < 0.0001). The mean differences in “Good On” time per dose between IPX203 and IR CD-LD were 1.53h for quartile one, 1.39h for quartile two, 1.83h for quartile three, and 1.56h for quartile four (p < 0.0001 for all quartiles). Conclusion: IPX203 significantly increased “Good On” time per dose regardless of the duration of “Good On” time per dose observed with IR CD-LD.