The "PD-depression" study,(1) a large-scale, prospective, double-blind trial, was designed to compare the non-ergot dopamine agonist pramipexole versus placebo for the treatment of PD patients with depressive symptoms and stable motor function. The results confirm the findings from an earlier clinical study where pramipexole had shown an antidepressive effect comparable to that of an SSRI when treating PD-related depressive symptoms,(2) and support data from other trials which suggested that pramipexole may have a positive effect on depressive symptoms and motivation associated with PD.(3-12)

"The wealth of data obtained from earlier trials with pramipexole looking into the treatment of this often overlooked non-motor symptom, along with its known efficacy in treating the motor symptoms of PD, made this drug the optimal choice for this new trial," commented Professor Paolo Barone, Department of Neurological Sciences, University of Napoli-Federico II, Naples, Italy and lead investigator of both the PRODEST and the "PD-depression" studies.

Previously, the PRODEST study(13,14) had shown that up to 40 percent of the studied PD patients continued to experience depressive symptoms in spite of receiving an antidepressant treatment.

"The interpretation of these findings reinforces many experts' view that depressive symptoms in PD patients may require a different treatment approach. Establishing an effective treatment for this non-motor symptom of PD is important for patients, caregivers and for physicians, as it could also mean a reduction in the number of medications needed to effectively manage the spectrum of PD symptoms. This in turn would reduce patients' risk of drug-drug interactions and possible antidepressant drug side effects," added Professor Barone.

About the "PD-Depression" study(1)
The "PD-Depression" study is a large-scale, prospective, randomised, double-blind, placebo controlled trial conducted at 76 centres in 13 countries in Europe and Africa with 296 patients treated. The primary efficacy endpoint of the study was change in depressive symptoms as measured by change in Beck Depression Inventory version 1A (BDI). Results of the study showed a significant improvement of depressive symptoms in the pramipexole group versus the placebo group, as measured by a change from baseline in total BDI.

Results of the study show:

• BDI scores improved by an adjusted mean –5.9 in pramipexole treated patients vs. –4.0 in the placebo group (P=0.01)
• The mean Geriatric Depression Scale (GDS) score had improved by 2.5 in the pramipexole group vs. 1.7 in the placebo group (P=0.03)
• UPDRS motor scores improved by –4.4 with pramipexole vs. –2.2 in the placebo (P=0.003)
• UPDRS activities of daily living (ADL) scores improved by –2.4 with pramipexole vs. –1.2 in the placebo (P=0.003)

About Parkinson's disease (PD)
Parkinson's disease is the second most common chronic neurological disorder in older adults after Alzheimer's. Its worldwide prevalence is estimated to be approximately one to two percent of those over 65 years.(15,16,17,18) Although traditionally PD is associated with motor symptoms (such as tremor, rigidity, slowed motion, imbalance, shuffling gait, loss of facial expression), the non-motor symptoms, including depressive symptoms, pain, cognitive impairment and sleep disorders can be significant. Symptoms can vary from patient to patient, but worsen over time.

About Mirapexin®/Sifrol® (pramipexole)
Pramipexole (known under the trade names Mirapexin®, Sifrol®, Mirapex® and Pexola®) is a compound from Boehringer Ingelheim research first approved in 1997 for the treatment of the signs and symptoms of idiopathic Parkinson's disease, as monotherapy or in combination with levodopa. Pramipexole was approved in 2006 for the symptomatic treatment of moderate to severe idiopathic Restless Legs Syndrome (RLS). Pramipexole is available in over 70 countries across the globe.

The most commonly (= 5%) reported adverse drug reactions in patients with Parkinson's disease treated with pramipexole were nausea, dyskinesia, hypotension, dizziness, somnolence, insomnia, constipation, hallucination, headache and fatigue.

Pramipexole may cause patients, particularly with Parkinson's disease, to fall asleep without any warning even while doing normal daily activities such as driving. When taking pramipexole hallucinations may occur and sometimes patients may feel dizzy, sweaty or nauseated upon standing up.

Patients and caregivers should be aware of the fact that abnormal behaviour (reflecting symptoms of impulse control disorders and compulsive behaviours) such as binge eating, compulsive shopping, hypersexuality and pathological gambling have been reported in patients treated with dopaminergic drugs, including pramipexole. Dose reduction/tapered discontinuation should be considered.

About Boehringer Ingelheim
The Boehringer Ingelheim group is one of the world's 20 leading pharmaceutical companies. Headquartered in Ingelheim, Germany, it operates globally with 138 affiliates in 47 countries and 41,300 employees. Since it was founded in 1885, the family-owned company has been committed to researching, developing, manufacturing and marketing novel products of high therapeutic value for human and veterinary medicine.

In 2008, Boehringer Ingelheim posted net sales of 11.6 billion euro while spending one fifth of net sales in its largest business segment Prescription Medicines on research and development.

References:
1. Barone P et al. Pramipexole ameliorates depression in Parkinson's disease: A randomized double-blind vs placebo trial. Abstract S43.004, presented during scientific session 'Evaluation and Treatment of Parkinson's Disease' on 30 April 2009 at AAN 61st Annual Meeting, Seattle, USA.
2. Barone P et al. Pramipexole versus sertraline in the treatment of depression in Parkinson's disease: a national multicenter parallel-group randomized study. J Neurol. 2006;253(5):601-7.
3. Lemke MR. Depressive symptoms in Parkinson's disease. Eur J Neurol 2008 Apr; 15 Suppl 1:21-5.
4. Möller JC et al. Long-term efficacy and safety of pramipexole in advanced Parkinson`s disease: results from a European multicenter trial. Mov Disord 2005 May; 20(5): 602-10.
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10. Goldberg JF et al. Preliminary randomized, double-blind, placebo-controlled trial of pramipexole added to mood stabilizers for treatment-resistant bipolar depression. Am J Psychiatry 2004 Mar; 161(3): 564-6.
11. Künig G et al. Pramipexole, a nonergot dopamine agonist, is effective against rest tremor in intermediate to advanced Parkinson's disease. Clin Neuropharm 1999; 22: 301-305.
12. Leentjens A et al. The effect of pramipexole on mood and motivational symptoms in Parkinson`s disease: a meta-analysis of placebo-controlled studies. Clin Ther. 2009 Jan;31(1):89-98.
13. Barone P et al. Depression and antidepressant use in Parkinson's disease: Results from the PRODEST-PD study. Abstract P1122 poster presented at 11th Congress of EFNS, Brussels, 26 Aug 2007.
14. Barone P et al. Depressive symptoms in Parkinson's disease: Design and methods of an observational study. Mov Disord. Vol. 21, Suppl. 15, 2006: S476.
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16. de Rijk MC et al. Prevalence of Parkinsonism and Parkinson's disease in Europe: the EUROPARKINSON Collaborative Study. European Community Concerted Action on the Epidemiology of Parkinson's disease. J Neurol Neurosurg Psychiatry. 1997;62:10-5.
17. Parkinson Study Group, Holloway RG et al. Pramipexole vs levodopa as initial treatment for Parkinson disease. Arch Neurol 2004; 61(7): 1044-1053.
18. de Lau LM, Breteler MM. Epidemiology of Parkinson's disease. Lancet Neurol 2006;5:525-35.