Preparation and characterization of flurbiprofen-loaded poly(3-hydroxybutyrate-co-3-hydroxyvalerate) microspheres

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) microspheres containing flurbiprofen were prepared by an oil-in-water emulsion solvent evaporation method, in order to develop a particulate drug delivery system for localized administration. A response surface method (RSM) using a central composite design was employed to evaluate the effect of the poly(vinyl alcohol) (PVA) (%, w/v) concentration in the aqueous phase and the PHBV concentration in the organic phase (%, w/v) on some of the resulting microspheres properties. The response variables were the encapsulation efficiency (EE), the mean particle size, the width of particle size distribution (expressed by the SPAN value) and the required time for the in vitro release of 50% of the encapsulated drug (t(50%)). Second-order polynomial and linear equations were fitted to experimental data and were also used to interpret the results. Results indicated that the concentration of the stabilizer (PVA) showed a highly negative effect on the EE probably due to the increased drug solubility in the aqueous phase as a result of the higher PVA concentrations. Particle diameter mean size increased with the increased polymer concentration while the width of the particle size distribution was found to decrease with the increase of the stabilizer agent. Finally, results indicated that none of the investigated variables presented a significant effect on the t(50%) values.