Ultrasonic activated drug delivery from Pluronic P-105 micelles.

Pluronic copolymer P-105 at micellar concentration of 10 wt% was found to increase the activity of the anti-cancer drug, doxorubicin (DOX) against HL-60 cells. Despite the enhanced activity, drug uptake by the cells from P-105 micelles (measured by fluorescence) was found to be much lower than that from a molecular solution of DOX (without the surfactant). Ultrasound (US) was applied as a tool to release drug from the micelles. Based on the combination of ultrasound and micellar treatment, doxorubicin exhibited IC50 concentrations of 2.35, 0.9, 1.25, 0.19 microg/ml with respect to DOX, DOX/US, micellar DOX, and micellar DOX/US, respectively. The results suggest that by encapsulating the anti-cancer drug in micellar carriers and focussing ultrasound on the tumor site, a new approach to drug targetting can be developed.