Preparation of PLGA Microsphere and Preliminary Study of Its Pulsatile Drug Delivery

OBJECTIVE:To prepare polylactic acid-glycolic acid copolymer(PLGA)microsphere,and to investigate its feasibility for pulsatile drug delivery systems.METHODS:Using bovine serum albumin(BSA) as model drug,S/O/W(Solid-in-oil-in-water)method and S/O/O(Solid-in-oil-in-oil)method were used to prepare PLGA(75:25)and PLGA(50:50)microspheres.The surface morphology of the microspheres,encapsulation efficiency and drug-loading amount were compared,and drug release behavior of two kinds of microspheres were investigated in vitro.RESULTS:The microspheres prepared by S/O/W and S/O/O method were rounded,with good shape and no adhension,but the surface of microspheres prepared by S/O/W method were relatively flat,and the surface of microspheres prepared by S/O/O method was evenly distributed in a large depression.The encapsulation efficiency of PLGA(75:25)and PLGA(50:50)microspheres prepared by S/O/W method were(60.15±5.95)% and(49.50± 3.69)%,drug-loading amount of them were(2.56±0.25)% and(2.10±0.16)%,about 10% of drug were released within 10 h,and then drug release suddenly increased with the degradation of the polymer.The encapsulation efficiency of PLGA microspheres prepared by S/O/O method were(84.36±1.11)% and(77.94±1.42)%,drug-loading amount of them were(3.58±0.05)% and(3.31±0.06)%,and about 50% of drug were released within 24 h,and then presented a stable release behavior.The encapsulation efficiency and drug-loading amount of microsphere prepared by S/O/O method were higher than S/O/W method.The drug release of PLGA microspheres prepared by S/O/W method presented certain pulse behavior,and release behavior of PLGA(75:25)microspheres in vitro was influenced by the particle size of microspheres.CONCLUSION:PLGA microspheres prepared by S/O/W method represent a certain pulse-release effect,and the particle size of microspheres is preferably controlled below 120 μm.