Anavex Life Sciences Corp (AVXL)

[falconer66a]

Serum Half-life Probably Not The Activity Period

The half life of A2-73 is 8.56 hours - so by end of 24 hours - there is practically no amount left in blood.

This is surely a clear fact.

But the determination of Anavex 2-73 freely circulating in the blood (serum) is probably not a perfect index to its therapeutic activity.

First, the molecule is known to easily cross the blood/brain barrier. It therefore probably also easily penetrates the plasma membranes (enclosing outer membranes) of neurons. Anavex 2-73 in the serum has little or no activity. Its mechanism of action occurs within the neuron, where it chemically binds to sigma-1 receptors, causing neuron organelles to re-connect and function properly.

Yes, the serum half-life of the molecule may be less than 9 hrs. But ample concentrations may remain undetected, internally bound to neuron organelles for lengthy periods. The molecule may not merely diffuse out of neurons along a conventional concentration gradient. Instead of being freely dissolved in the cytosol (intracellular fluid), it chemically attaches to organelles, unable to float off and away. Once in the neuron, it is very likely Anavex 2-73 stays there for some time.