Understanding Symmetrel Effects and Specific Indications
Symmetrel Uses for Parkinsonism
Symmetrel 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.)
Symmetrel 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.
Symmetrel Uses 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.
Symmetrel is approved to treat extrapyramidal symptoms caused by other medications.
How Does Symmetrel Work?Symmetrel likely works for the flu by inhibiting the uncoating of the flu virus, an important step in the replication (the "reproduction") of the virus. Specifically, amantadine (the active ingredient in Symmetrel) 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.
Symmetrel 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, it is possible that Symmetrel 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 Symmetrel. If the predominant flu strain is not susceptible to it, this medication should not be used to prevent or treat the flu.
It is not known exactly how Symmetrel works for Parkinson's disease and other similar conditions or movement disorders. It is known that the drug affects several different brain chemicals, including dopamine and NMDA (N-methyl D-aspartate).