title: The preparation of sustained release erythropoietin microparticle.
abstract: OBJECTIVE
  Protein microencapsulation in biodegradable polymers is a promising route to provide for sustained release. The erythropoietin (EPO) microparticles are using human serum albumin (HSA) and poly-L-lysine (PK) as the protection complex to increased EPO integrity, entrapped efficiency and active EPO release by w/o/w solvent evaporation techniques. The optimum formulation development process was also reported by using FITC-OVA as a model protein.
  
  
  METHODS
  The model protein FITC-ovalbumin and EPO are protected by human serum albumin and poly-L-lysine complex and encapsulated in 50:50 poly(DL-lactide-co-glycolide) by a w/o/w solvent evaporation method. Protein active integrity and degradation compound is measured by size-exclusion chromatography. Protein-loaded microparticle physical properties and in vitro active and degradation compounds release profile are characterized.
  
  
  RESULTS
  High active integrity protein loading efficiency and particle yield of EPO or OVA-HSA/PK-loaded PLG microparticles are successfully produced by a w/o/w solvent evaporation method. Varied protection protein complex formulations and encapsulation processes are investigated. The high OVA model protein loading efficiency (80.2%), FITC-OVA content (0.24 microg mg(-1)) and yield (72.4%) are obtained by adding 100 microg mL(-1) FITC-OVA complex with 10% HSA/0.05% PK (Mw 1.5-3 kD) in the initial solution to protect the model protein. In vitro release profiles show more active OVA release from HSA/PK OVA-loaded than OVA-loaded only microparticles and also the amount of degraded protein that comes out after 3 weeks incubated in the PBS medium for OVA-loaded only microparticles is observed. The same formulation and preparation process resulted in EPO loading efficiency (68.4%), EPO content (0.23 microg mg(-1)) and yield (76.1%) for HSA/PK EPO-loaded microparticles. In vitro release profiles show active EPO sustained release over 7 days. Using HSA/PK as carried in the primary emulsion of EPO-loaded microparticles resulted in less burst release% than EPO-loaded only microparticles.
authors: Department of Clinical Pharmacy, Tri-service General Hospital, National Defense Medical Center, Taipei, Taiwan. mkyeh@mail.ndmctsgh.edu.tw
authors: Ming-Kung
authors: MK
authors: Yeh
authors: Jiin-Long
authors: JL
authors: Chen
authors: Chiao-Hsi
authors: CH
authors: Chiang
authors: Zhi-Yang
authors: ZY
authors: Chang
mesh_terms: D002214:Capsules; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003692:Delayed-Action Preparations / Q000302:isolation & purification*; D004339:Drug Compounding / Q000379:methods*; D004921:Erythropoietin / Q000008:administration & dosage*; D016650:Fluorescein-5-isothiocyanate / Q000008:administration & dosage; D006801:Humans; D010047:Ovalbumin / Q000008:administration & dosage; D011107:Polylysine; D011994:Recombinant Proteins; D012709:Serum Albumin
chemical_list: D002214:Capsules; D003692:Delayed-Action Preparations; D011994:Recombinant Proteins; D012709:Serum Albumin; D004921:Erythropoietin; D011107:Polylysine; D010047:Ovalbumin; D016650:Fluorescein-5-isothiocyanate