Parkinson's Disease is a major neurodegenerative disorder in which there is a progressive loss of dopamine-containing neurons. The understanding that PD is a syndrome of dopamine (DA) deficiency led to the introduction in the clinical practice of L-dopa, a precursor of DA that crosses the blood brain barrier, and also to the use of selective inhibitors of MAO-B, the major DA metabolising enzyme in man.

Safinamide is an inhibitor of MAO-B. This is a phase III trial to evaluate the efficacy and safety of safinamide (50 and 100 mg p.o. q.a.m.) compared to placebo as add-on therapy to a stable dose to levodopa in subjects with advance idiopathic Parkinson's Disease.

The principal efficacy measure is the increase in mean daily "on" time during the 18-hr diary recording period.

Inclusion Criteria:

Male and female between the ages of 30 to 80 years with diagnosis of idiopathic Parkinson's Disease of more than 5 years duration, with a Hoehn and Yahr stage of I-IV during an "off" phase.

Be levodopa-responsive and have been receiving treatment with a stable dose of levodopa for at least 4 weeks.

Have motor fluctuations, with >1.5 hours "off" time during the day. Be able to maintain an accurate and complete diary (18-hour)

Exclusion Criteria:

Patients with medical conditions and/or taking concomitant medications that would have put them at risk, interfered with the study evaluations, or made them unable to complete the requirements of the study;.

Be in a late stage of Parkinson's Disease, and experiencing severe, disabling peak-dose or biphasic dyskinesia and/or unpredictable or widely swinging fluctuations in their symptoms.

Current diagnosis of substance abuse or history of alcohol or drug abuse in the past 3 months.

Have received treatment with safinamide previously. History of, or current depression psychosis (e.g. schizophrenia or psychotic depression) Evidence of dementia or cognitive dysfunction. History of allergic response to anticonvulsants, levodopa, or other anti-Parkinsonian agents.

Hypersensitivity or contraindications to MAO-B inhibitors. Ophthalmologic history including any of the following conditions: albino subjects, family history of hereditary retinal disease, progressive and/or severe diminution of visual acuity (i.e., 20/70), retinitis pigmentosa, retinal pigmentation due to any cause, any active retinopathy or ocular inflammation (uveitis), or diabetic retinopathy.