In vitro and in vivo evaluation of oridonin-loaded long circulating nanostructured lipid carriers.

The purpose of this study was to develop poly(ethylene glycol)-coated nanostructured lipid carriers (PEG-NLC) for parenteral delivery of oridonin (ORI) to prolong drug circulation time in blood. Oridonin-loaded PEG-NLC (ORI-PEG-NLC) consisting of PEG(2000)-stearate, glycerol monostearate and medium chain triglycerides were prepared by emulsion-evaporation and low temperature-solidification technique. Oridonin-loaded NLC (ORI-NLC) were also prepared as control. ORI-PEG-NLC were observed by transmission election microscope and the morphology was in rotiform shape. The mean particle size of ORI-PEG-NLC was 329.2 nm and entrapment efficacy was 71.18%. The results of differential scanning calorimetry and X-ray diffraction revealed a low-crystalline structure of ORI and verified the incorporation of ORI into the nanoparticles. In vitro drug release of ORI-PEG-NLC exhibited biphasic drug release patterns with burst release initially and prolonged release afterwards. Pharmacokinetic analysis showed that the mean residence time of ORI-PEG-NLC was prolonged and AUC (area under tissue concentration-time curve) value was also improved compared with ORI-NLC and ORI solution. In conclusion, ORI-PEG-NLC could be a potential carrier to get prolonged retention time of oridonin in blood.