Paeonol Phenol Poly (lactic Acid) Sustained-release Preparation And Pharmaceutical Properties Of The Microspheres

Paeonolum is the effective component of Cynanchum Paniculatum and Paeonia Suff ruticosa Andr., which is widely used in traditional Chinese medicines. In this research, paeonolum was extracted form the root of Cynanchum Paniculatum by steam distillation and the paeonolum microspheres (Pae-MS) were prepared using biodegradable polylactic acid (PLA) as carrier material and evaluated in vitro.The Pae-MS were prepared using O/W emulsion solvent evaporation method. The effects of types of emulsifier, ratio of oil/water, PLA concentration, stirring speed, gelatin concentration, emulsifying time and ratio of paeonolum/PLA on the preparation of microspheres were studied. The embedding ratio of microspheres was taken as an experiment index. L₉(3⁴) orthogonal test design was used to optimize the technology of preparation. The evaluation result of the optimal preparation showed that paeonolum was successfully entrapped in the microparticles. The volume average size of microspheres is 23.25±0.15um, drug loading is 11.4±0.5% and embedding ratio is 63.8±1.6%. The repeatability of the experiments was good.The results of differential scanning calorimetry showed that paeonolum was molecularly dispersed in the carrier material. The in vitro release kinetics of paeonolum from PLA microspheres showed that the sustained-release effect of paeonolum microspheres was good. Studies on stability at 37℃ showed that the microspheres fused and aggregated. While the surface morphology, drug loading and in vitro release of microspheres did not alter when stored at 4℃ or room temperature in dry condition for six months.In conclusion, Pae-MS prepared using biodegradable PLA exhibited good sustained-release capacity.