Full factorial design optimization of anti-inflammatory drug release by PCL-PEG-PCL microspheres

A biodegradable triblock poly(epsilon-caprolactone) poly(ethylene glycol)-poly(epsilon-caprolactone) copolymer was successfully synthesized by ring-opening polymerization of E-caprolactone, and was characterized by intrinsic viscosimetry, H-1 nuclear magnetic resonance, infrared spectroscopy and X-ray diffraction. Copolymer microparticles loaded with ibuprofen were prepared by an oil-in-water (o/w) emulsion solvent evaporation process. They were carefully weighted and characterized through their zeta potential. In this work, 4 selected process parameters (shaking speed X-1, time of contact X-2, poly(vinyl alcohol) concentration X-3, and ibuprofen concentration X-4) were adjusted at 2 different values. For each of the 16 experimental conditions, repeated twice, the drug encapsulation efficiency of the microspheres was determined, according to the following definition: EE (X-1, X-2, X-3, X-4) = mass of encapsulated ibuprofen / total weight of ibuprofen. A full factorial design method was applied to analyze the results statistically according to a polynomial fit and to determine the optimal conditions for the microencapsulation of the ibuprofen through an accurate statistical protocol. The microparticles obtained exhibit a spherical shape as shown by electron microscopy. (C) 2015 Published by Elsevier B.V.