Abstract:

Objective  To prepare tetramethylpyrazine (TMP) loaded PLGA microspheres. Methods  TMP loaded PLGA microspheres were prepared by an O/W emulsion-solvent evaporation method. The formulation and the preparation conditions were optimized by orthogonal experiments using entrapment efficiency and drug loading as the composite evaluation index. The morphology was evaluated by an optical microscope. The particle size distribution was evaluated by Mastersizer 3000 (Malvern).The entrapment efficiency and the drug loading were assessed. Results  The results showed that TMP loaded PLGA microspheres were concinnous and spherical in shape. The mean diameter was (10±2.2)μm. The average entrapment efficiency was (81.36±1.15)% and drug loading was (8.2±0.43)%. In vitro release of the TMP loaded PLGA microspheres sustained for 768 h and the release profile was depicted by Weibull kinetics. The formation of a new material phase was testified by analysis of differential scanning calorimetry (DSC). Conclusion  TMP loaded PLGA microspheres with a highly encapsulation efficiency, drug loading, uniform size distribution and sustained release profile were prepared by an O/W emulsion-solvent evaporation method.

Key words: Tetramethylpyrazine； Microspheres； PLGA； Emulsion solvent evaporation method； Orthogonal experiments