Evaluation of Porous Polycaprolactone Microspheres for Extended-Release Drug Delivery

This study evaluated the suitability of porous polycaprolactone (PCL) microspheres to act as a 7-14 day extended-release drug delivery system for a hydrophobic compound, modeled using rhodamine‑123 (Rh123), to the retina. At this time, the targeted application of the actual drug has not been published and is not permitted for discussion. Porous PCL microspheres were formed via a combination ink-jetting and thermally-induced phase separation methods. Microspheres were characterized with scanning electron and light microscopies which displayed a rough surface morphology and a mean diameter of 117.0 ± 38.6 micrometers. Degradation testing of the microspheres utilizing gel permeation chromatography showed no change in microsphere molecular weight over the course of 23 days. Rh123 was loaded in two different ways, one pre-formation and one post-formation of the microspheres. Fluorescence spectroscopy measured drug release of each loading method from the microspheres, revealing low drug release and/or loading efficacy. Further research recommended to determine the suitability of the proposed drug delivery system include polymer blending to increase speed of degradation and use of a dialysis bag for drug release studies to increase accuracy and precision.