A nanoparticulate drug-delivery system for 20(S)-protopanaxadiol: formulation, characterization, increased oral bioavailability and anti-tumor efficacy.

As with many other hydrophobic anticancer agents, 20(S)-protopanaxadiol (PPD) has a very low oral bioavailability. In this study, a precipitation-combined ultrasonication technique was used to prepare PPD nanosuspensions. The mean particle size of the nanosuspensions was approximately 222 +/- 12nm, the drug payload achieved 50% after lyophilization and the maximum PPD concentration can reach 100mg/ml, which is over 30000 times the solubility of PPD in aqueous solution (3g/ml). After oral administration, the C-max and AUC(last) values of PPD nanosuspensions were approximately 3.66-fold and 3.48-fold as those of PPD coarse suspensions, respectively. In contrast to the free drug solution, PPD nanosuspensions showed higher in vitro anti-tumor activity against HepG-2 cells (an IC50 value of 1.40 versus 5.83g/ml at 24h, p<0.01). The in vivo study in H22-tumor-bearing mice demonstrated that PPD nanosuspensions showed good anti-tumor efficacy with an inhibition rate of 79.47% at 100mg/kg, while 50mg/kg of cyclophosphamide was displayed as positive control, and the inhibition rate was 87.81%. Considering the highest drug payload, oral bioavailability reported so far, significant anti-tumor efficacy and excellent safety of encapsulated drugs, PPD nanosuspensions could be used in potential effective strategies for anticancer therapy; further investigation is ongoing.