Examples

Generic Name	Brand Name
amantadine hydrochloride	Symmetrel

How It Works

Amantadine is a medicine that is used to treat and prevent infection with influenza (flu) viruses. It also is effective in treating some symptoms of Parkinson's disease, although it is not clear how it works. Amantadine may cause greater amounts of dopamine to be released in the brain, and it may block receptors for acetylcholine, a brain chemical that contributes to control of movement. For normal motor or muscle control, acetylcholine and dopamine levels need to be balanced carefully.

Why It Is Used

Amantadine can be used by itself to treat people who are in the early stages of Parkinson's disease. It is best used as short-term therapy (6 to 12 months) for people with early Parkinson's disease who have mild to moderate symptoms.¹

Amantadine also can be used with levodopa in the later stages of Parkinson's disease to reduce dyskinesias, which are a side effect of taking levodopa. Amantadine does not seem to help with the symptoms of Parkinson's disease at this stage.¹

How Well It Works

For people with early Parkinson's disease, amantadine is more effective than anticholinergic agents at improving slow movement (akinesia or bradykinesia) and rigidity but less effective at improving tremor.¹

Amantadine is not as effective as levodopa, but the medicines may be used at the same time if you have advanced Parkinson's disease and need to control the motor fluctuations caused by levodopa.

Amantadine doesn't work for everyone. It may take up to 2 weeks to be fully effective. Benefits can continue for as long as 1 year but often wear off during that period of time.

Side Effects

Amantadine by itself has very few side effects. However, when it is taken in high doses or in combination with anticholinergic medicine, side effects may include:

• Swelling of the ankles.
• Skin rash.
• Dry mouth.
• Blurred vision.

When amantadine is taken in combination with anticholinergic medicine, particularly by people older than 60, side effects may include:

• Confusion.
• Hallucinations (seeing or hearing things that aren't really there).
• Insomnia (difficulty falling or staying asleep).
• Nightmares.

Sudden withdrawal of amantadine can make some symptoms of Parkinson's disease worse. If your doctor is changing your medicine, he or she will gradually reduce the dose of amantadine to avoid complications.

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

If tremor is the main symptom, anticholinergics are likely to be more effective than amantadine.

Caution is needed when amantadine is used in people who are older than 65 because the risk of impaired thinking and reasoning is greater in older people.

Because amantadine is processed through the kidneys, people who have kidney problems must take smaller doses.

Complete the new medication information form (PDF)(What is a PDF document?) to help you understand this medication.

References

Citations

1. Minagar A, et al. (2003). Parkinson's disease. In RW Evans, ed., Saunders Manual of Neurologic Practice, pp. 205–209. Philadelphia: Saunders.