Drug-release controlling system

摘要

A system of controlling drug-release which makes it possible to appropriately control the release speed and prolongation time of a drug and can be applied to retina or the vitreous body without any restriction in drug type. By using this drug-release controlling system which comprises nanospheres composed of fine particles made of a nano-sized synthetic biodegradable polymer and a drug uniformly contained therein, the drug can be efficiently delivered to the retina or the vitreous body, i.e., the target site. It is preferable that the above-described synthetic biodegradable polymer is polylactic acid or a lactic acid/glycolic acid copolymer. It is preferable that the drug is contained in the fine particles as a matrix. The average particle size of the nanospheres preferably ranges from 50 to 200 nm.