Dear Beth, I have taken Symmtrel since the day I was diagnosed. Symmetrel is just the brand name for Amantadine. If you don't know already, amantadine is an anti-viral drug that has been found to reduce rigidity and bradykinesia in Parkinson's patients. It sure seems to me that it works; whenever I miss a dose, I can feel the effects. Hope that brief explanation helps. Jacob Drollinger