[Study on chitosan-modified tripterygium glycoside nanoparticles and its renal targeting property]

To prepare chitosan-modified tripterygium glycoside nanoparticles (LMWC-TG-PLA-NPs), and assess its renal targeting property in rats.

Chitosan-modified tripterygium glycoside nanoparticles (LMWC-TG-PLA-NPs) were prepared by modified spontaneous emulsification solvent evaporation method, and modified with 50% deacetylated low molecular weight chitosan (LMWC). The shape of nanoparticles was observed under a transmission electron microscope. The mean diameter of nanoparticles was measured by particle size analyzer. The drug encapsulation efficiency and drug loading were measured by centrifuge method. The in vitro release behavior was studied with dialysis bags. Renal microdialysis technique and renal artery administration technique were combined to study the renal targeting property of nanopartcles. LMWC-TG-PLA-NPs were administrated in rats by tail vein injection (TVI) and renal artery administration (RAA), respectively, with TG-PLA-NPs as the control group. Renal dialysis fluid was regularly collected to determine the drug concentration in the dialysis fluid, map drug concentration-time curves, and calculate AUC ratio in kidneys through the two injection approaches as the renal targeting parameter (RTP), in order to assess the renal targeting property of LMWC-TG-PLA-NPs.

The prepared LMWC-TG-PLA-NPs looked smooth and round. Their average diameter, polydispersity index, encapsulation efficiency and drug loading were (207.6 +/- 3.4) nm, (0.078 +/- 0.009)%, (61.83 +/- 2.43)%, and (10.70 +/- 0.37)%, respectively. The pH 7.4 PBS buffer solution containing 20% ethanol showed obvious sustained release behavior. LMWC-TG-PLA-NPs showed a RTP of 71.97%, which was 3.6 times of TG-PLA-NPs of the control group.

The prepared LMWC-TG-PLA-NPs showed high drug encapsulation efficiency and drug loading, with obvious sustained release characteristics and renal targeting property. LMWC-TG-PLA-NPs are expected to become a new type vector for reducing toxic and side effects of tripterygium glycoside. Meanwhile, a new method is established for assessing renal targeting property with AUC ratio in kidneys after administrated through caudal veins and renal arteries as the renal targeting parameter.