title: [Study on preparation and pharmacodynamics of insulin-loaded polyester microparticles].
abstract: OBJECTIVE
  To investigate the possibility of using poly (epsilon-caprolactone-block-D, L-lactide) (PLCA) as a kind of materials to prepare the microparticles drug carrier.
  
  
  METHODS
  PCLA-MP (microparticle, MP) was prepared by double-emulsification solvent evaporation method. Its morphology was examined by scanning electron microscope. Its size diameter was examined by particle analyser. Insulin (INS), as a model drug, was then encapsulated into PCLA-MP (INS-PCLA-MP). HPLC method was established for determining INS in INS-PCLA-MP. An "antibody-capture" procedure was devised for investigating encapsulation mechanism. The in vitro release behaviour of INS-PCLA-MP was determined in phosphatic buffer solution (pH 7.4). The diabetic rat model was established and blood glucose levels were measured using glucose oxidase (GOD-PAP) method to evaluate the hypoglycaemic effects after subcutaneous administration of INS-PCLA-MP. The pharmacological bioavailability (PBA) of INS-PCLA-MP was calculated from the area above the curve (AAC) in contrast with INS-solution.
  
  
  RESULTS
  The mean diameter of INS-PCLA-MP was 1.9 microns, while the encapsulation ratio of INS reached to 76.46%. Only 18.25% encapsulated INS was on the surface of the microparticles, it could be measured by "antibody-capture" experiment. The in vitro release curve of INS-PCLA-MP consists of initial rapid release stage followed by slower exponential stage. In pharmacodynamic studies, after subcutaneous administration of INS-PCLA-MP 12 u.kg-1, the hypoglycaemic effect was significant. The PBA of INS-PCLA-MP was 123.08%.
  
  
  CONCLUSIONS
  PCLA might become a new drug carrier material in the future.
authors.affiliation: Department of Pharmacy, People's Hospital of Beijing Medical University, Beijing 100044, China.
authors.forename: L M
authors.initials: LM
authors.lastname: Ma
authors.forename: Q
authors.initials: Q
authors.lastname: Zhang
authors.forename: Y Z
authors.initials: YZ
authors.lastname: Li
authors.forename: Z W
authors.initials: ZW
authors.lastname: Gu
mesh_terms: D000818:Animals; D001789:Blood Group Antigens / Q000378:metabolism; D003921:Diabetes Mellitus, Experimental / Q000097:blood / Q000188:drug therapy*; D004337:Drug Carriers / Q000008:administration & dosage; D007004:Hypoglycemic Agents / Q000008:administration & dosage / Q000494:pharmacology*; D007328:Insulin / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D008863:Microspheres; D010316:Particle Size; D011108:Polymers; D051381:Rats; D017208:Rats, Wistar
chemical_list: D001789:Blood Group Antigens; D004337:Drug Carriers; D007004:Hypoglycemic Agents; D007328:Insulin; D011108:Polymers