The effect of pramipexole on mood and motivational symptoms in Parkinson's disease: a meta-analysis of placebo-controlled studies.

BACKGROUND: Mood and motivational symptoms have been reported in up to 35% and 51%, respectively, of patients with Parkinson's disease (PD). Preliminary evidence indicates that pramipexole may have a positive effect on these symptoms. OBJECTIVE: This analysis was conducted to evaluate the effects of pramipexole on mood and motivational symptoms in patients with PD. METHODS: Data for the meta-analysis were extracted from all randomized, double-blind, placebo-controlled trials of pramipexole in the manufacturer's database that included part I of the Unified Parkinson's Disease Rating Scale (UPDRS) as an outcome measure. Only patients with baseline scores >0 (range, 0-4) on item 3 (mood) and item 4 (motivation) were included. Separate analyses were performed for mood and motivational symptoms. The outcome of interest was improvement in scores, with no improvement including both unchanged and increased scores. Odds ratios (ORs), 95% CIs, and Cochran-Mantel-Haenszel tests were calculated to compare rates of improvement and no improvement, stratified by trial. RESULTS: Fourteen randomized, double-blind, placebo-controlled trials of pramipexole were identified, all employing the severity of motor symptoms of PD as a primary outcome. Seven of these trials (N = 1296) employed part I of the UPDRS as a secondary outcome measure and were included in the meta-analysis; no other measure of mood or motivational symptoms was used in any of the 14 studies. Six of the 7 studies included patients with motor fluctuations due to levodo-pa treatment, and the remaining study included patients who did not yet require levodopa. Six studies were published in peer-reviewed journals, and all 7 were included in the New Drug Application for pramipexole. The published study reports were usually limited to motor symptoms; only 1 reported on mood and motivation. However, for the purpose of this meta-analysis, the authors had access to data that were not reported in the original publications. In the pooled data set, 480 patients (59.8% male; mean age, 63.3 years) had a baseline score >0 on item 3 (mood). These mood symptoms improved in 64.7% of patients treated with pramipexole and 43.4% of those receiving placebo (OR weighted by trial = 2.41; P < 0.001). Five hundred seventy patients (64.9% male; mean age, 64.1 years) had a baseline score >0 on item 4 (motivation). These motivational symptoms improved in 63.2% of patients treated with pramipexole and 45.0% of those receiving placebo (OR weighted by trial = 2.06; P < 0.001). CONCLUSIONS: This meta-analysis of 7 randomized controlled trials suggests that pramipexole had a beneficial effect on mood and motivational symptoms in PD patients who did not have major depressive disorder. The clinical value of pramipexole in the treatment of depressive and apathetic syndromes requires further investigation.

Receptor-binding and pharmacokinetic properties of dopaminergic agonists.

This review describes symptoms and pathophysiology of Parkinson's diseases (PD) and restless legs syndrome (RLS), and discusses the relationship between clinical outcome of DA agonists and their receptor-binding and pharmacokinetics. Oral DA agonists are divided into 2 classes; the ergots and the non-ergots. Both classes are in general equally effective against PD motor symptoms. Ergots (apart from bromocriptine) stimulate the DA D(1) subreceptor and increase dyskinesia. Furthermore, valvular heart disease (VHD) and pulmonary and retroperitoneal fibrosis appear to represent a class effect of 8beta-aminoergolines as cabergoline and pergolide The side effects profile therefore seems more beneficial for non-ergots than ergots. The main improvement of motor functions by DA agonists is related to D(2) agonism. However, in monotheraphy, the selective D(2)-receptor DA agonist sumanirole seemed less effective than ropinirole which is selective for D(2)-like DA-receptors (D(2), D(3) and D(4)). Given as adjunctive to L-dopa both drugs had equal efficacy on motor-symptoms, indicating that D(2)-receptor activity must be accompanied with stimulation of other DA receptors for optimizing the efficacy on motor symptoms. Striatal D(3) receptor loss may be more important than D(2) receptor loss for reduced response to dopaminergic treatment. D(3) stimulation may also be beneficial for the non-motor symptom depression/mood in PD and for neuron-protection. This makes D(3)-receptors a potential therapeutic target in PD. 5-HT(1A)-receptor agonism and alpha(2) adrenergic antagonism may contribute to prevention of dyskinesia. However, 5-HT-receptor activity is also associated with side effects. 5-HT(2B) agonism (and possibly 5-HT(1B) agonism) is associated with fibrotic reactions, and valvular heart disease (VHD). By interfering with the CYP450 system DA agonists may contribute to drug-drug interactions. Lack of CYP2D6 activity is also suggested as important for etiology and CNS-symptoms of PD. Based on current knowledge D2-like receptor activities (preferences for the D(3) receptor) seem most beneficial. 5-HT(1A)-receptor agonism (prevention of dyskinesia), 5-HT(2B) antagonism or no 5-HT(2B)-receptor activity also seems beneficial. Development of DA agonists containing these properties, without interfering with CYP2D6 may be beneficial.