Preparation And Preliminary Anti-tumor Activity Of Triptolide PLGA Microspheres And Particles

Objective:To prepare uniform-sized Triptolide loaded poly (lactic-co-glycolic acid)(PLGA) sustained-release microspheres by premix membrane emulsification-solvent evaporation method and study its influencing factors. Comparision of the triptolide-PLGA microspheres, triptolide particles and triptolide-PLGA particles in physical and chemical properties, release characteristics and anti-tumor activity in vitro. To provide new ideas on the decreasing toxicity and increasing efficacy in triptolide preparation.Method:To establish a RP-HPLC method for the determination of triptolide. Triptolide as the model drug and PLGA as the carrier material, Triptolide-PLGA microspheres were prepared by premix membrane emulsification-solvent evaporation method, Triptolide-PLGA particles and Triptolide particles were prepared by solvent evaporation method. Using volume average particle size(D0.5), span, drug loading and encapsulation efficiency to evaluate the quality of microspheres comprehensively. Study the influencing factors by single-factor test, such as membrane pore size, transmembrane pressure, oil phase solvent, solidifying liquid category and so on. The surface morphology of microspheres was observed under scanning electron microscope, further dispersion was measured by optical microscope, the dispersion of triptolide was studied using DSC. Immediate release method was used to study the drug release rule of TP-PLGA microspheres and TP-PLGA particles. The apoptosis of CT26cells induced by microspheres, particles and TP was evaluated by Annexin V-FITC/PI flow cytometry method, in order to evaluate its anti-tumor activity.Result:The two optimized process conditions were as follows:membrane pore size5.2μm transmembrane pressure0.30Mpa, concentration of PLGA is10%, ratio of drug and carrier material1:16.7, volume ratio of oil phase to external water phase1:9and1:4, and no solidify liquid. Prepared microspheres were round and with a smooth surface, but there were free drug in microspheres system, had a uniform-sized, good dispersion. The mean diameter were2.243μm and3.059μm. The span were1.293and4.239. The average drug loading were0.84%and1.43%, and entrapment efficiency was9.4%and10.29%. In vitro release, after4h quick-release, they kept sustained release. The pharmacodynamics study showed that the PLGA had cytotoxic effect in low-dose group. Triptolide can induce apoptosis and microspheres groups which inducing apoptosis were less than model drug in high-dose group.Conclusion:From the study of physical and chemical properties, the microspheres prepared by premix membrane emulsification had a uniform-sized, controlled particle size. But low entrapment efficiency and the sudden release showed triptolide have a certain solubility in water. The cells experiment showed that triptolide had significantly anti-tumor effect, and in high-dose group, the microspheres showed obvious effect-enhancing and toxic-reducing action.