It is amazing to me that it has not dawned on the doctors yet, that starting out with so much of a new medicine is a really bad idea. Of course that is only my own, homegrown and entirely unprofessional opinion as a patient.
Amantadine is wonderful, I love Amantadine.
I was prescribed 200 mg per day, but I began to see patterns on white surfaces, and to feel as if my head had been wrapped in wool and put in a bucket - i.e. not quite myself, and not quite there. I can only imagine how I would feel on 300 mg per day. I think I would be 'out of it', I think it would make me feel completely unreal.
I cut it down to 100mg per day, and it is helping my symptoms just as much as it did on 100 mg. For me at least, taking more than 100 mg Amantadine per day is unnecessary and counter productive.
If you start at 200 mg and never try just 100 mg, you will never know if 100 mg is enough.
If you start at 200 mg and add another 100 mg so soon after, you have not given the 200 mg time enough to see if it is too little or too much.
So I would not take that third pill.

All the best,
birte