Received my memantine and took 150mg in 5 separate doses 30 minutes apart starting at 10pm. Other substances involved were kratom, alprazolam, clonazepam, dextroamphetamine, and olanzapine.
I can say at this dose that memantine is a true dissociative beyond my 600mg DXM experiences. Heavy body load, distorted vision, classic dissociative effects with music appreciation and serious 2D and 3D geometry CEVs. OEVs included altered perceived texture of flat surfaces.
This went on in its heaviest form for about 12 hours. I had a flight at 2pm the next day so I had hoped effects would wear off — they had not. During the cab ride I would close my eyes and see familiar multicolored dots spinning, morphing, going into alien script.
On the plane I fell asleep to patterns that ended with the sensation of snowflakes falling in a void. On the second plane ride I challenged my brain to do its worst and the friendly dots turned dark with unsettling symbols. Took 1mg xanax and things calmed.
This substance has an absurdly long duration. Do not take recreational doses if you have any obligations within 48 hours. This was irresponsible planning on my part.