The half-life definition is confusing but from what you're saying it how long the body takes to eliminate the drug from the body even though the drug effects continue on right?
On the question of Avodart, I found it to cause weight gain and bloating as well as mood changes.
I have always been an optimistic person and after taking Avodart for a few months experienced these side affects.
Furthermore, I experienced a large amount of hair shedding (as the drug does mention will happen) but never the growth afterwards.
So for me, its back on Propeica.
Cheers,
Greg