Background: Cabergoline is an ergotic dopamine agonist with D2 receptor activity and a very long half-life. This pharmacological profile may result in clinically different effects. Small clinical trials indicate that overnight switching from 1 agonist to another can be performed safely.
Objective: To determine safety and efficacy of overnight switching from dopamine agonists to cabergoline in patients with advanced Parkinson disease (PD).
Methods: Patients with advanced PD and motor complications not optimally controlled by levodopa and a stable dose of bromocriptine, pergolide, pramipexole, and ropinirole were converted to cabergoline overnight. Patients were assessed by using an on-off diary, Unified Parkinson Disease Rating Scale (subscales I-IV), Parkinson's Disease Quality of Life 8 (PDQ-8), an ad hoc sleep questionnaire and an ad hoc off-period severity questionnaire. All rating scales were administered just before conversion and after 2, 6, and 12 weeks of treatment, when patients were on an optimal dose of cabergoline. Adverse effects were assessed at every visit following a check list.
Results: One hundred twenty-eight patients were included in the trial. Forty were on pergolide (mean dose, 2.8 mg/d), 38 on pramipexole (mean dose, 2.1 mg/d), and 32 on ropinirole (mean dose, 8.1 mg/d). Patients on bromocriptine (n = 18) were excluded from the analysis because of the small sample size. Three patients reported serious side effects (respiratory arrest, dyskinesias, and face edema and abdominal pain). Twenty-eight patients reported 41 adverse events. Twelve patients were withdrawn due to adverse effects (hallucinations [n = 5], dyspnea [n = 1], dizziness [n = 4], and vascular problems [n = 2]). A significant improvement in assessed parameters was obtained (P < 0.0001). Mean levodopa dose remained unchanged. After 12 weeks, the mean dose of cabergoline was 3.2 mg, and 25% of patients were taking the drug twice a day.
Conclusions: Switching from pergolide, ropinirole, and pramipexole to cabergoline in an overnight schedule is safe. The observed clinical improvement may be related to a placebo effect, to the use of low doses of dopamine agonists, or to a direct effect of cabergoline.