The level of inhibition will depend pretty well on the serum level, which will drive the cytosolic level in cells. That will vary depending upon how close cells are to the blood stream.
This says Rapamycin (Sirolimus) is a specific mTOR inhibitor with IC50 of ~0.1 nM HEK293 cells.
https://www.selleckchem.com/products/Rapamycin.html
The molar mass of Rapamyc is is 914 grams. Hence 0.1nM is 0.0914 ng/ml. (1nM=914ng/L =0.914ng/ml)
IC50 means when half of the kinases are inhibited. (in those particular cells). However, it would imply a good threshold for activity is 1ng/ml (actually it is going to be active below that level).
The serum level will be higher than that in the cell as well.
I think the surface area of human skin is something like 1.6-1.8 metres.
Hence the doses above are roughly 50% higher than the values.
Say 0.45, 1.5, 4.5, 7.5, 12.
That, however, is not with accelerators.
That gives a rough number of hours for which 50% of the kinases are inhibited as being
3?, 24, 72, 144, 192.
In days
1/8, 1, 3, 6, 8
On the chart above it clearly has a long half life. Rapamcyin is, however, effective at just under nanomolar levels of concentration.
The body has got lots of ways of getting around different parts not working which means inhibition of 50% of the mTOR complexes will not bring things to a total halt. However, it does seem pretty clear that Rapamycin’s immediate negative effects of inhibition last for quite a while for higher doses.
The interesting questions are what the minimum measurement threshold and what the minimum activity level area.
