“The ratio of donepezil to total radioactivity in brain was 86.9 to 93.0%, indicating low permeability of the metabolites through the blood-brain barrier”
“... and in brain, unchanged donepezil was mostly detected. No metabolites were found in brain”
I believe that statement is about the metabolites not penetrating the BBB not donepezil.
BBB penetration apparently not that great. So 70h half-life is not much use.
You specifically made the statement that DZP was metabolized more quickly. When the half-life suggested that was incorrect you shifted to the statement that the real issue is BBB penetration.
"the concentration in each part of the brain was 1.74 to 2.24 times the plasma concentration" One might even say DZP is concentrated in the brain...at least relative to plasma.
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