How safe and effective are long-acting dopamine agonists for Parkinson’s disease?

This study examined the safety and effectiveness of long-acting non-ergot dopamine agonists in the treatment of Parkinson’s disease. This study concluded that these treatments helped reduce Parkinson’s disease symptoms but were associated with side effects.

Dopamine agonists have been used for both early and advanced stages of Parkinson’s disease. These treatments mimic dopamine in the brain. Non-ergot dopamine agonists (NEDA) may be used as first-line treatments in some patients.

Standard NEDA therapies are administered three times a day. Newer long-acting NEDAs are delivered once a day. Previous studies have shown that long-acting NEDA formulas help keep dopamine levels stable. The safety and effectiveness of these therapies are still under investigation.

This study analyzed the results of nine other studies, including 2,857 patients, comparing long-acting NEDA to placebo (substance with no active effect) in patients with PD. Four studies included patients with early Parkinson’s who had not received prior levodopa treatment. Four studies involved patients with advanced Parkinson’s already treated with levodopa. One study included a mix of patients. Therapies included a rotigotine (Neupro) patch, long-acting pramipexole (Mirapex), and extended-release ropinirole (Requip XL). The average study length was 23.78 weeks.

Overall, NEDA therapy improved motor symptoms and daily living compared to placebo. NEDA therapy also reduced the average amount of “off” time (increase in symptoms when medications are not working well) and increased the amount of “on” time.

10.19% (NEDA) and 5.52% (placebo) of patients stopped treatment due to side effects. NEDA was associated with a 76% higher risk of stopping treatment due to side effects compared to placebo.

In patients with early Parkinson’s disease, NEDA therapy was associated with higher risks of dizziness (58%), sleepiness (84%), constipation (2.71-fold), vomiting (5.18-fold), and insomnia (79%). In patients with advanced Parkinson's disease, NEDA therapy was associated with a 2.85-fold higher risk of dyskinesia (involuntary movements) and a 5.24-fold higher risk of hallucinations.

This study concluded that long-acting NEDA helped reduce Parkinson’s disease symptoms but with associated side effects.

The majority of the studies analyzed here had short durations. The occurrence of side effects may be underestimated. Further studies with longer periods are needed to confirm these results.