Active exposures of rapamycin are achievable in vivo at low doses.
A) Immunoblot for phospho- and total p70S6K in K7M2 (murine) and MG63.3 (human) highly metastatic osteosarcoma cells treated with vehicle, 0.1μM rapamycin, or 1μM rapamycin for 4 hours. Images cropped to show relevant bands.
B) Whole blood rapamycin levels on day 14 in mice receiving 5mg/kg IP rapamycin three times per week. Blood was drawn on day 14 prior to treatment (trough) as well as 2 and 6 hours following IP administration of 5mg/kg rapamycin. N=3 mice.
C) Whole blood rapamycin levels in naïve mice treated with a single dose of 5mg/kg rapamycin IP. Whole blood was collected immediately following rapamycin administration (0 hours) and at 2, 6, 24, and 48 hour time points. N=3 mice.