Polycaprolactone-b-poly(ethylene oxide) copolymer micelles as a delivery vehicle for dihydrotestosterone

Block copolymer micelles formed from copolymers of poly(caprolactone)-b-pol y(ethylene oxide) (PCL-b-PEO) were investigated as a drug delivery vehicle for dihydrotestosterone (DHT). The physical parameters of the PCL-b-PEO mic elle-incorporated DHT were measured, including the loading capacity of the micelles for DHT, the apparent partition coefficient of DHT between the mic elles and the external medium and the kinetics of the release of DHT from t he micelle solution. The MTT survival assay was used to assess the in vitro biocompatibility of PCL-b-PEO micelles in HeLa cell cultures. The biologic al activity of the micelle-incorporated DHT was evaluated in HeLa cells whi ch had been co-transfected with the expression vectors for the androgen rec eptor and the MMTV-LUC reporter gene. The PCL-b-PEO micelles were found to have a high loading capacity for DHT and the release profile of the drug fr om the micelle solution was found to be a slow steady release which continu ed over a 1-month period. The biological activity of the micelle-incorporat ed DHT was found to be fully retained. (C) 2000 Elsevier Science B.V. All r ights reserved.