title: Microspheres of biodegradable polymers as a drug-delivery system in the vitreous.
abstract: Microspheres of biodegradable polymers were evaluated as a potential controlled-release drug-delivery system in the vitreous. The microspheres were prepared with polymers of poly(lactic acid) or copolymers of glycolic acid and lactic acid. The release of 5-fluorouracil (5-FU) from the microspheres was studied in vitro. Poly(lactic acid) microspheres released 70-85% of total 5-FU over 7 days. Microspheres of polymers with a smaller molecular weight released the drug more rapidly. Copolymer microspheres released 98% of 5-FU over 2 days. The rate of drug release was controllable by changing the molecular weight of the polymers or using a matrix of copolymer. The intravitreal kinetics of the microspheres were studied in ten rabbits in vivo. A suspension of microspheres was injected into the vitreous cavity of five normal eyes and five vitrectomized eyes. By 48 +/- 5.2 days after injection, the microspheres disappeared from the vitreous cavity in the five normal eyes. Clearance from the vitreous cavity was accelerated in the five rabbits that underwent vitrectomy (14 +/- 2.4 days; P less than 0.001). No difference was found in the b waves of electroretinograms before and after injection of the microspheres. The histologic study showed no abnormal findings as a result of the injection. These results suggested that microspheres of biodegradable polymers may be a potential delivery system for the controlled release of drugs in the vitreous.
authors.affiliation: Department of Ophthalmology, Faculty of Medicine, Kyoto University, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Moritera
authors.forename: Y
authors.initials: Y
authors.lastname: Ogura
authors.forename: Y
authors.initials: Y
authors.lastname: Honda
authors.forename: R
authors.initials: R
authors.lastname: Wada
authors.forename: S H
authors.initials: SH
authors.lastname: Hyon
authors.forename: Y
authors.initials: Y
authors.lastname: Ikada
mesh_terms: D000818:Animals; D001673:Biodegradation, Environmental; D003692:Delayed-Action Preparations; D004337:Drug Carriers; D004596:Electroretinography; D005472:Fluorouracil / Q000008:administration & dosage* / Q000493:pharmacokinetics; D008863:Microspheres; D011108:Polymers; D011817:Rabbits; D014821:Vitrectomy; D014822:Vitreous Body / Q000378:metabolism*
chemical_list: D003692:Delayed-Action Preparations; D004337:Drug Carriers; D011108:Polymers; D005472:Fluorouracil