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 Twelve patients were withdrawn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.