Preparation and properties of finasteride loaded poly(propylene carbonate maleate) sustained release microspheres

The novel polymer poly(propylene carbonate maleate) (PPCM) was used as drug carriers, PPCM microspheres loaded with drug finasteride were prepared by oil-in-water emulsion solvent evaporation method, and the effects of mass ratios of polymer to drug on the properties of PPCM microspheres were examined. The results show that PPCM microspheres have spherical surface, and the mean diameter of microspheres is approximately 2 μm. With the increase of finasteride proportion, the drug loading increases, while the encapsulation efficiency decreases obviously. Greater drug loading and encapsulation efficiency of microspheres are 14.78% and 66.17%, respectively when m(PPCM):m(finasteride) is 5:1. In vitro drug release of microspheres is performed in a pH 7.4 phosphate-buffered solution. The microspheres are proved to be successful in prolonging drug release up to 42 d, and cumulative drug release is (92.59±2.62)%. The properties of drug release from microspheres follow the Higuchi matrix model Qt = 3.11+15.07 t1/2. It is suggested that PPCM is suitable for long-term sustained release drug delivery system.