Extended-release levodopa treatment increases the ON time of patients with Parkinson’s disease

This study investigated the duration of ON time in patients with Parkinson’s disease treated with levodopa-carbidopa (LD-CD). Researchers suggested that LD-CL extended-release (ER) capsules (Rytary) increased ON time in these patients.

Parkinson’s disease affects brain cells. These cells lose their ability to control body functions which causes physical and mental symptoms. The standard treatment is levodopa alone or in combination with carbidopa (LD-CD). Immediate-release (IR) LD-CD capsules are commonly used. However, long-term treatment with levodopa is associated with wearing-off symptoms. Wearing-off happens when Parkinson’s symptoms come back before the next dose of treatment.

After dosing with LD-CD ER capsules, the drug peaks in the bloodstream at around 1 hour which is maintained for about 4 to 5 hours. Prior studies in patients with Parkinson’s disease suggested that LD-CD ER capsules reduce OFF times when compared with LD-CD IR. However, the average duration of benefit from LD-CD ER is still not clear. 

This study included information about 393 patients with Parkinson’s disease. Before the study, patients took an average of 775.8 mg LD-CD divided into 5 doses per day. During the study, patients received either ER LD-CD (201) or IR LD-CD (192). The main outcome was the average ON time per dose from the start to the end of the treatment.

The IR group had an increase in average ON time per dose from 2.24 to 2.38 hours. On the other hand, patients receiving ER had an increase in average ON time from 2.17 to 3.55 hours. LD-CD ER increased ON time per dose by 1.21 hours more than LD-CD IR.

In patients with troublesome dyskinesia (uncontrolled, involuntary movements after long-term use of LC-CD), the ER capsules increased ON time by 1.6 hours more than the IR capsules.

This study concluded that LD-CD ER capsules significantly increased ON time per dose compared to LD-CD IR capsules.

This study included only patients with at least 2.5 hours of OFF time per day and did not have severe wearing-OFF symptoms. The results of this study may not apply beyond this population. Further studies with a more varied population are necessary.