METHOXY POLY(ETHYLENE GLYCOL) AND EPSILON-CAPROLACTONE AMPHIPHILIC BLOCK COPOLYMERIC MICELLE CONTAINING INDOMETHACIN - II - MICELLE FORMATION AND DRUG-RELEASE BEHAVIORS

Amphiphilic diblock copolymer composed of methoxy poly(ethylene glycol ) (MePEG) and epsilon-caprolactone (epsilon-CL) was prepared by polyme rization of epsilon-CL initiated with MePEG. MePEG/epsilon-CL block co polymeric micelles containing indomethacin (IMC) were prepared by a di alysis method and evaluated as a novel drug carrier. The size of micel le formed was less than 200 nm, and the size distribution of the micel le showed a narrow and monodisperse unimodal pattern. Also, the micell es formed by a dialysis method exhibited spherical structures. The ind omethacin content in nanospheres was about 42.2%, for those prepared u sing copolymer, having molecular weight of about 12000 and polymer/IMC weight ratio of 1/1. A release rate of indomethacin from nanospheres was slow, and thus the release continued over 15 days. As the molecula r weights of the copolymer and the amount of drug entrapped increased, the release rate decreased. These results indicated that the drug-loa ded nanospheres could be useful as a novel drug carrier in injectable delivery systems for hydrophobic drugs. (C) 1998 Elsevier Science B.V.