Physicochemical and biological characterization of sustained isopropyl unoprostone-release device made of poly(ethyleneglycol) dimethacrylates.

Transscleral drug delivery is becoming increasingly popular to manage posterior eye diseases. To evaluate the clinical application of a transscleral, sustained, unoprostone (UNO)-release device (URD) constructed of photopolymerized tri(ethyleneglycol) dimethacrylate and poly(ethyleneglycol) dimethacrylate, we evaluated physicochemical and biological properties of this device. The URD consists of a drug-impermeable reservoir and a semi-permeable cover. The in vitro release rate of UNO from the URD increased with increasing temperatures from 20 to 45 °C. Scanning electron microscopy and atomic-force microscopy showed that the border between the reservoir and drug formulation was sharply defined but that between the cover and drug was poorly determined, indicating that UNO could permeate only through the cover. For stability tests, the URDs were sterilized with ethylene oxide gas and stored at 40 °C/75% for 3 and 6 months and at 25 °C/60% for 3, 6, 9, 12, 18, and 24 months; UNO content and release rate at 37 °C were then evaluated. There was no significant decrease in either UNO content or release rate after the storage conditions. Cytotoxicity was evaluated by examining the colony formation of Chinese hamster fibroblast V79 cells in a media extract of the URD without UNO. This extract did not affect colony formation of V79 cells, indicating the cytocompatibility of the URD. In conclusion, the URD was physically stable for 24 months and is potentially useful for clinical application.