title: Development of a sustained-release system for perivascular delivery of dipyridamole.
abstract: Vascular access grafts implanted in dialysis patients are prone to failure in the long-term because of stenosis and occlusion caused by neointimal hyperplasia. Local delivery of antiproliferative drugs may be effective to prevent this consequence while minimizing the systemic side effects they cause. We developed a combination of poly(lactide-co-glycolide) (PLGA) microspheres with ReGel, an injectable copolymer, as a sustained-release system for perivascular delivery of an antiproliferative drug, dipyridamole. Dipyridamole-incorporated PLGA microspheres with various molecular weights (MWs) of PLGA were prepared by oil-in-water emulsion method. Encapsulation efficiency and surface morphology of microspheres were characterized. In vitro release kinetics of dipyridamole from ReGel or from microspheres/ReGel was experimentally determined. Without microspheres, 40% of the dipyridamole was released from ReGel as an initial burst in the first 3 days followed by continuous release in the subsequent 2 weeks. The use of PLGA microspheres decreased the initial burst and extended dipyridamole release from 23 to 35 days with increasing MW of PLGA. The highest MW PLGA showed a lag time of 17 days before consistent drug release occurred. Mixing microspheres and ReGel with two different MW PLGA achieved a continuous release for 35 days with little initial burst. In vivo release of dipyridamole from microspheres/ReGel exhibited a comparable release pattern to that seen in vitro. This injectable platform is a promising technique for sustained perivascular delivery of antiproliferative drugs.
authors.affiliation: Department of Pharmaceutics and Pharmaceutical Chemistry, University of Utah, Salt Lake City, 84108, USA.
authors.forename: Weiwei
authors.initials: W
authors.lastname: Zhu
authors.forename: Takahisa
authors.initials: T
authors.lastname: Masaki
authors.forename: You Han
authors.initials: YH
authors.lastname: Bae
authors.forename: Ramesh
authors.initials: R
authors.lastname: Rathi
authors.forename: Alfred K
authors.initials: AK
authors.lastname: Cheung
authors.forename: Steven E
authors.initials: SE
authors.lastname: Kern
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry / Q000378:metabolism*; D001808:Blood Vessels / Q000378:metabolism; D003692:Delayed-Action Preparations; D004176:Dipyridamole / Q000737:chemistry / Q000378:metabolism*; D004337:Drug Carriers / Q000737:chemistry / Q000378:metabolism*; D016503:Drug Delivery Systems; D006801:Humans; D019344:Lactic Acid / Q000737:chemistry / Q000378:metabolism*; D008422:Materials Testing; D008863:Microspheres; D008970:Molecular Weight; D010316:Particle Size; D010975:Platelet Aggregation Inhibitors / Q000737:chemistry / Q000378:metabolism; D011100:Polyglycolic Acid / Q000737:chemistry / Q000378:metabolism*; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011108:Polymers / Q000737:chemistry / Q000378:metabolism*; D051381:Rats; D013499:Surface Properties; D013552:Swine; D014783:Viscosity
chemical_list: D001672:Biocompatible Materials; D003692:Delayed-Action Preparations; D004337:Drug Carriers; D010975:Platelet Aggregation Inhibitors; D011108:Polymers; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid; D004176:Dipyridamole