Solidification of Nanostructured Lipid Carriers Loaded Testosterone Undecanoate: In Vivo and In Vitro Study

To enhance the bioavailability of testosterone undecanoate (TU) and overcome the current problem of soft capsules (Andriol Testocaps^®), Nano-structured lipid carriers (NLC) for TU was developed. First, suspension of TU-loaded NLC (TU-NLC) was prepared by high pressure homogenization; then adsorbent or a protective agent β-cyclodextrin was used to solidify the suspension through a vacuum system; finally, the solid powder of TU-loaded NLC (solid TU-NLC) was filled into hard capsules. The characteristics of solid TU-NLC, were investigated in vitro and vivo. The particle size of TU-NLC was about 273.3 nm, the potential was 0.156±0.04. Transmission electron microscope (TEM) revealed that the NLC was spherical and uniform. Differential scanning calorimetry (DSC) suggested the drug had been encapsulated into NLC lipid matrix. The drug release proved that solid TU-NLC showed a higher dissolution in vitro. The CaCO-2 cell permeability showed that solid TU-NLC could enhance trans-membrane absorption of the TU. Moreover, the AUC of solid TU-NLC formulations (4304±550.50 μg/L*min) was higher than commercial product Andriol Testocaps® (3075±372.50 μg/L*min). In conclusion, solid TU-NLC could enhance the rate of dissolution, and had a relatively higher bioavailability than Andriol Testocaps® in vivo GRAPHICAL ABSTRACT: .