GM1 Ganglioside Effects on Parkinson's Disease

Inclusion criteria: * Btwn ages of 39-85 yrs old. * Females: at least 2 years post-menopausal; surgically sterile; or negative pregnancy test by quantitative serum ßHCG, \& follow a reliable method of birth control for at least 2 months prior to entry, agree both to follow a reliable method of birth control, \& to desist from breast feeding during, \& for 1 month following, the study drug administration. * Dx of idiopathic PD 6 months prior to screening. The diagnosis requires: the presence of at least 2 of the 4 cardinal clinical manifestations of the disease, tremor, rigidity, bradykinesia, and disturbances of posture or gait, \& at least 1 must be rigidity or bradykinesia. * Modified Hoehn and Yahr Staging between 1 and 3 as rated during an "off" period of at least 12 hours. * Unified Parkinson's Disease Rating Scale motor component score between 10 and 40 as rated during an "off" period of at least 12 hours and a score of 6 or greater during "on" period. * Antiparkinsonian treatments: stable treatment of l-dopa/carbidopa and/or dopamine agonist for at least 3 months prior to Screening. * Mini Mental State Exam score \> 25. * Beck Depression Inventory score \< 10. * Signed informed consent. Exclusion criteria: * Abrupt onset of Parkinsonism. * Failure of Parkinsonian symptoms to have responded to l-dopa. * Motor symptoms (such as peak dose dyskinesias (UPDRS score \> 3), \& random on-off phenomenon, other than end-of-dose wearing-off, persistently fluctuating over a 6 month or longer period, in response to l-dopa. * Hx of findings of any movement disorder other than idiopathic PD. * A tremor score on the UPDRS motor scale of \>5. Tremor score greater than 3 in an individual limb. * High-dose vitamin E therapy (more than 1000 I.U./day) any time during the period starting 3 months prior baseline. * Transient ischemic attack any time during the period starting 6 months prior baseline. * Hx of 2 or more strokes. Hx of any stroke that resulted in motor deficit, movement disorder, ataxia, cognitive impairment, or a hemi-inattention syndrome. Any stroke with residua at the time of, or within 6 months preceding, study entry. * Previous cerebral infarction, including lacunar infarction, in any area subserving motor function. * Binswanger's disease or hx of hypertensive encephalopathy. * Hx of encephalitis. * Hx of extended exposure to any known neurotoxin that may cause parkinsonism, or chronic or sufficient use or consumption of any non-medicinal substance that could cause risk of developing a movement disorder or disturbance of posture or gait. * Use of the following drugs within 6 months prior to screening: neuroleptics, metoclopramide, clozapine, flunarizine, alpha-methyldopa. * Patients actively taking a medicine that is known to compete with the imaging agent for binding sites on the dopamine terminals. * Hx of medication or drug use that may have caused atypical parkinsonism or history of Substance Use Disorder. * Hx of a metabolic disorder that resulted or could have resulted in movement disorder or disturbance of posture or gait. * Any disease or condition that resulted or could have resulted in a movement disorder or disturbance of posture or gait. * Hx of intracranial hemorrhage, intracranial neoplasm, significant head trauma with loss of consciousness \>24 hrs or other structural brain disease. * Hx or clinical findings suggestive of progressive supranuclear palsy or multiple system atrophy. * Acquired cognitive impairment reasonably possibly due to any cause other than idiopathic PD. * Hx of a hereditary disorder associated with a movement disorder. * Normal or low pressure hydrocephalus. * Any ill-defined neuropathic disease, myelopathy, myopathy or other medical disorder or physical condition by history or clinical examination that could be expected to interfere with the diagnosis, treatment or assessment of PD, or with any of the study assessments. * Hx of Guillain-Barré syndrome, chronic idiopathic polyneuropathy, or relapsing polyneuropathy. * Hx of Axis I or Axis II major psychiatric disorder. * Significant cardiac, pulmonary, hepatic, gastrointestinal, or renal disease. * Any condition that could alter the distribution, accumulation, metabolism, or excretion of the study medication; or result in a life expectancy of less than 2 years. * Any primarily non-neurologic medical condition with a significant risk of secondarily causing neurologic dysfunction. * Myocardial infarction within 6 months prior to screening. * Presence of any medical condition or laboratory test abnormality or use of any licit or illicit substance which could cause unwarranted risk from participation in the study or result in worsening in the patient's medical condition during participation in study. Presence of any of the following laboratory test abnormalities are unwarranted risk: serum transaminase greater than twice the upper limit of normal;serum creatinine greater than 2.0 mg/dl in a man or greater than 1.7 mg/dl in a woman. * Hx of a life-threatening allergic or immune-mediated reaction. * Previous use of any ganglioside preparation. * Use of any experimental drug in the period starting 60 days before Baseline. * Hx of stereotaxic brain surgery for PD.