Parkinson's Disease - Medications

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Amantadine

Amantadine (Symadine, Symmetrel) stimulates the release of dopamine and may be used for patients with early mild symptoms. It has some benefit against muscle rigidity and slowness and may help some patients in advanced stages who are unresponsive to other drugs. It is less powerful than levodopa and may lose its effectiveness after 6 months. It may also reduce motor fluctuations brought on by levodopa, however, and these benefits appear to persist for at least a year. Large, well-conducted studies are still needed to determine its true benefits and safety.

Side Effects. Side effects are similar to those of anticholinergic drugs and also may include swollen ankles and mottled skin. It can also cause visual hallucinations. Overdose can cause serious and even life-threatening toxicity. Patients with Parkinson's should not withdraw from this drug abruptly. In rare instances, it can cause acute delirium or a life-threatening condition called neuroleptic malignant syndrome. Pregnant or nursing women should not use this drug.

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Investigative Drugs

Dopamine Agonists. A rotigotine transdermal patch (Neupro) is showing promise in late-stage (Phase III) trials. Piribedil (Trivastal) is also progressing in clinical trials.

Cholinesterase Inhibitors. The Alzheimer’s drug rivastigmine (Exelon) is being investigated for treatment of dementia in Parkinson’s patients. Initial results show moderate improvement but side effects include nausea, vomiting, and tremors.

Coenzyme Q10 (Ubiquinone). Coenzyme Q10 (also called ubiquinone) is an antioxidant that is being studied for Parkinson's disease. This enzyme is important for cellular energy, which may be impaired in PD. In one study, patients who took coenzyme Q10 experienced slower decline in daily activities and mental and motor skills compared to patients on placebo. This is available as a supplement in health food stores, but such products are not necessarily those used in clinical studies. Patients should check with their doctor about taking this supplement.