What Is Amantadine Used For? (Cont.)

 
Why Is Amantadine Used for Parkinsonism?
Amantadine is approved to treat parkinsonism, which includes Parkinson's disease and several other Parkinson's-like conditions. Specifically, it is approved to treat the following:
 
  • Parkinson's disease
  • Postencephalic parkinsonism
  • Toxin-induced parkinsonism caused by carbon monoxide poisoning
  • Arteriosclerotic parkinsonism.
     
(Please see Parkinsonism for more information on these different types.)
 
Amantadine seems to be less effective than levodopa for the treatment of Parkinson's disease symptoms. It can be used alone or in combination with other medications for Parkinson's.
 
Why Is Amantadine Used for Extrapyramidal Symptoms?
Some medications cause a group of side effects known as "extrapyramidal symptoms" (also known as EPS). These side effects include a variety of movement disorders, muscle tension disorders, and a few other miscellaneous problems. They are often caused by antipsychotic medications (especially older antipsychotics), but can be caused by other medications as well.
 
Amantadine is approved to treat extrapyramidal symptoms caused by other medications.
 

How Does Amantadine Work?

Amantadine may work for the flu by inhibiting the uncoating of the flu virus, an important step in the replication (the "reproduction") of the virus. Specifically, it inhibits the activity of the influenza virus M2 protein, which forms a channel in the virus membrane. As a result, the virus cannot replicate (make copies of itself) after it enters a human cell.
 
Amantadine is effective only for some influenza A viruses and is not effective against influenza B viruses. Because the "bird flu" or "avian flu" virus (H5N1) is a type of influenza A, amantadine may work for some strains of this virus. However, many strains of H5N1 influenza are resistant to it.
 
For any given year, the predominant flu strain may or may not be susceptible to amantadine. If the predominant flu strain is not susceptible, this medication should not be used to prevent or treat the flu.
 
It is not known exactly how amantadine works for Parkinson's disease and other similar conditions or movement disorders. The drug is known to affect several different brain chemicals, including dopamine and NMDA (N-methyl D-aspartate).
 
(What Is Amantadine Used For? Continued: Page 3)

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Written by/reviewed by: Kristi Monson, PharmD; Arthur Schoenstadt, MD
Last reviewed by: Kristi Monson, PharmD;