Amantadine is a synthetic antiviral agent that also has strong antiparkinsonian properties. It is sold in the United States under the brand name Symmetrel, and is also available under its generic name.
Amantadine is used to treat a group of side effects (called parkinsonian side effects) that include tremors, difficulty walking, and slack muscle tone. These side effects may occur in patients who are taking antipsychotic medications used to treat mental disorders such as schizophrenia. An unrelated use of amantadine is in the treatment of viral infections of some strains of influenza A.
Some medicines, called antipsychotic drugs, that are used to treat schizophrenia and other mental disorders can cause side effects similar to the symptoms of Parkinson's disease. The patient does not have Parkinson's disease, but he or she may experience shaking in muscles while at rest, difficulty with voluntary movements, and poor muscle tone. These symptoms are similar to the symptoms of Parkinson's disease.
One way to eliminate these undesirable side effects is to stop taking the antipsychotic medicine. Unfortunately, the symptoms of the original mental disorder usually come back, so in most cases simply stopping the antipsychotic medication is not a reasonable option. Some drugs such as amantadine that control the symptoms of Parkinson's disease also control the parkinsonian side effects of antipsychotic medicines.
Amantadine works by restoring the chemical balance between dopamine and acetylcholine, two neuro-transmitter chemicals in the brain. Taking amantadine along with the antipsychotic medicine helps to control symptoms of the mental disorder, while reducing parkinsonian side effects. Amantadine is in the same family of drugs (commonly known as anticholinergic drugs) as biperiden and trihexyphenidyl.
Jack Raber Pharm.D., The Gale Group Inc., Gale, Detroit,