Engineering polymer blend microparticles: an investigation into the influence of polymer blend distribution and interaction.
The aim of this work was to understand the influence of polymer interaction and distribution on drug release from microparticles fabricated from blends of polymers. Blends of pH dependent polymer (Eudragit S, soluble above pH 7) and pH independent polymer (Eudragit RL, Eudragit RS or ethylcellulose) were incorporated into prednisolone loaded microparticles using a novel emulsion solvent evaporation method. Microparticles fabricated from blends of Eudragit S and Eudragit RL or RS did not modify drug release compared to microparticles fabricated from Eudragit S alone. This can be attributed to the high degree of miscibility of Eudragit S with Eudragit RS or Eudragit RL within the microparticles as confirmed by glass transition temperature measurements and confocal laser scanning microscopy. In contrast, microparticles prepared from blends of Eudragit S (75%) and ethylcellulose (25%) extended the release of prednisolone at pH 7.4 (compared to Eudragit S microparticles). This change in release profile was related to the immiscibility of Eudragit S and ethylcellulose as assessed by thermal analysis, and confirmed by microscopy which showed pores within the microparticle structures following dissolution of the Eudragit S domains. The ability of water insoluble polymers to extend drug release from enteric polymer microparticles is dependent on the miscibility and interaction of the polymers. This knowledge is important in the design of pH responsive microparticles capable of extending drug release in the gastrointestinal tract.
Department of Pharmaceutics, The School of Pharmacy, University of London, 29/39 Brunswick Square, London, United Kingdom.
Mohamed A
MA
Alhnan
Abdul W
AW
Basit
D000180:Acrylic Resins / Q000737:chemistry; D002152:Calorimetry, Differential Scanning; D002482:Cellulose / Q000031:analogs & derivatives / Q000737:chemistry; D004337:Drug Carriers / Q000737:chemistry*; D004339:Drug Compounding; D041981:Gastrointestinal Tract / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D018613:Microscopy, Confocal; D008855:Microscopy, Electron, Scanning; D008863:Microspheres; D010316:Particle Size; D004364:Pharmaceutical Preparations / Q000008:administration & dosage* / Q000737:chemistry; D044367:Phase Transition; D011108:Polymers / Q000737:chemistry*; D011109:Polymethacrylic Acids / Q000737:chemistry; D011239:Prednisolone / Q000008:administration & dosage / Q000737:chemistry; D012995:Solubility; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties; D013678:Technology, Pharmaceutical / Q000379:methods*
D000180:Acrylic Resins; D004337:Drug Carriers; D004364:Pharmaceutical Preparations; D011108:Polymers; D011109:Polymethacrylic Acids; C038300:methylmethacrylate-methacrylic acid copolymer; C050528:Eudragit RS; C058665:Eudragit RL; C013517:ethyl cellulose; D002482:Cellulose; D011239:Prednisolone