Enhancement of felodipine dissolution rate through its incorporation into eudragit® E-PHB polymeric microparticles: In vitro characterization and investigation of absorption in rats

In this study, felodipine was incorporated into microparticles prepared with Eudragit (R) E and it blended with poly(3-hydroxybutyrate) (PHB) using the emulsionsolvent evaporation technique, with the aim of improving the dissolution rate of the drug. The formulation prepared with Eudragit (R) E showed irregular and fragmented microparticles, with a loading efficiency (LE) of 82.6%. When the microparticles were prepared with a blend of Eudragit (R) E and PHB, they had a spherical form with a LE of 103.9%. X-ray diffraction and differential thermal analysis indicated a reduction in the crystallinity of felodipine after its incorporation into the microparticles, which caused a significant increase in the felodipine dissolution rate. An investigation into the absorption in rats was carried out using high-performance liquid chromatography analysis of the blood collected 20 and 60 min after the animals were administered felodipine [30 mg/Kg, orally (p.o.)] or felodipine microparticles (30 mg/Kg, p.o.). Animals that were given felodipine showed mean plasmatic levels of 0.0125 (+/- 0.00156) and 0.0240 (+/- 0.0069) mu g mL-1 after 20 and 60 min, respectively, whereas animals that received microparticles containing felodipine showed respective mean plasmatic levels of 0.0651 (+/- 0.0120) and 0.0369 (+/- 0.0145) mu g mL-1. Our data suggest that the incorporation into microparticles significantly enhanced the release of felodipine, improving its absorption in rats. (c) 2012 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 101:15181523, 2012