title: [Long-acting injectable microspheres of glucagon-like peptide-1].
abstract: OBJECTIVE
  To prepare glucagon-like peptide-1 (GLP-1) loaded long-acting injectable microspheres and to evaluate their in vitro release behavior as well as its pharmacodynamics.
  
  
  METHODS
  GLP-1 loaded microspheres were prepared with poly (lactic-co-glycolic acid) (PLGA) as carrier materials by dowble emulsion (W/O/W) method. Physical and chemical characteristics of microspheres, such as mean diameter, morphology and drug loading were evaluated. The in vitro release behavior and its influencing factors were determined by HPLC, also the bioactivity of GLP-1 in the course of encapsulation process and in vitro release were evaluated by in vivo animal experiments. The effect of reducing plasma glucose about GLP-1 microspheres were evaluated on the diabetes mice.
  
  
  RESULTS
  Microspheres with good shape and dispersive quality were prepared. The drug entrapment efficiency was more than 80%. The accumulated release in one month is up to 85% and the release equation is in accord with zero-class release model. The bioactivity of GLP-1 was conserved with glutin as inner water phase, but in the course of in vitro release, the specific activity of CLP-1 in the microspheres decreased a little. GLP-1 microspheres can decrease the plasma glucose significantly and the effect can go on for one month.
  
  
  CONCLUSIONS
  GLP-1 can be encapsulated in injectable microspheres to yield one-month continuous release when using biodegradable polymers PLGA as carrier material, and this technique will have a favorable perspective in the near future.
authors.affiliation: School of Pharmacy, Second Military Medical University, Shanghai 200433, China.
authors.forename: Dong-feng
authors.initials: DF
authors.lastname: Yin
authors.forename: Cheng
authors.initials: C
authors.lastname: Wu
authors.forename: Ying
authors.initials: Y
authors.lastname: Lu
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhu
authors.forename: Yan-qiang
authors.initials: YQ
authors.lastname: Zhong
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000378:metabolism*; D003692:Delayed-Action Preparations; D003921:Diabetes Mellitus, Experimental / Q000097:blood*; D052216:Glucagon-Like Peptide 1 / Q000008:administration & dosage* / Q000737:chemistry / Q000493:pharmacokinetics; D054795:Incretins / Q000008:administration & dosage / Q000737:chemistry / Q000493:pharmacokinetics; D007267:Injections; D019344:Lactic Acid / Q000737:chemistry*; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D008855:Microscopy, Electron, Scanning; D008863:Microspheres; D010316:Particle Size; D011100:Polyglycolic Acid / Q000737:chemistry*; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011108:Polymers / Q000737:chemistry*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D001786:Blood Glucose; D003692:Delayed-Action Preparations; D054795:Incretins; D011108:Polymers; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid; D052216:Glucagon-Like Peptide 1