title: Lysozyme release and polymer erosion behavior of injectable implants prepared from PLGA-PEG block copolymers and PLGA/PLGA-PEG blends.
abstract: OBJECTIVE
  We evaluated the controlled release of lysozyme from various poly(D,L-lactic-co-glycolic acid) (PLGA) 50/50-polyethylene glycol (PEG) block copolymers relative to PLGA 50/50.
  
  
  METHODS
  Lysozyme was encapsulated in cylindrical implants (0.8 mm diameter) by a solvent extrusion method. Release studies were conducted in phosphate buffered saline +0.02% Tween 80 (PBST) at 37°C. Lysozyme activity was measured by a fluorescence-based assay. Implant erosion was evaluated by kinetics of polymer molecular weight decline, water uptake, and mass loss.
  
  
  RESULTS
  Lysozyme release from an AB15 di-block copolymer (15% 5 kDa PEG, PLGA 28 kDa) was very fast, whereas an AB10 di-block copolymer (with 10% 5 kDa PEG, PLGA 45 kDa) and ABA10 tri-block copolymer (with 10% 6 kDa PEG, PLGA 27 kDa) showed release profiles similar to PLGA. We achieved continuous lysozyme release for up to 4 weeks from AB10 and ABA10 by lysozyme co-encapsulation with the pore-forming and acid-neutralizing MgCO3, and from AB15 by co-encapsulation of MgCO3 and blending AB15 with PLGA. Lysozyme activity was mostly recovered during 4 weeks.
  
  
  CONCLUSIONS
  These block co-polymers may have utility either alone or as PLGA blends for the controlled release of proteins.
authors: Vesna Milacic
authors: VM
authors: Vesna Milacic
authors: Steven P
authors: SP
authors: Schwendeman
mesh_terms: D003692:Delayed-Action Preparations / Q000737:chemistry; D005079:Excipients / Q000737:chemistry; D007267:Injections; D007700:Kinetics; D019344:Lactic Acid / Q000737:chemistry*; D008970:Molecular Weight; D009113:Muramidase / Q000737:chemistry*; D010316:Particle Size; D011092:Polyethylene Glycols / Q000737:chemistry*; D011100:Polyglycolic Acid / Q000737:chemistry*; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011108:Polymers / Q000737:chemistry*; D019736:Prostheses and Implants; D012997:Solvents / Q000737:chemistry; D014867:Water / Q000737:chemistry
chemical_list: D003692:Delayed-Action Preparations; D005079:Excipients; D011108:Polymers; D012997:Solvents; D014867:Water; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid; D011092:Polyethylene Glycols; D009113:Muramidase
references: Nat Biotechnol. 1998 Feb;16(2):153-7
references: 9487521
references: Vaccine. 1999 Feb 12;17(6):512-29
references: 10075157
references: J Control Release. 1999 Aug 5;60(2-3):297-309
references: 10425335
references: Adv Drug Deliv Rev. 2005 Jan 10;57(3):391-410
references: 15560948
references: Mol Pharm. 2008 Sep-Oct;5(5):808-17
references: 18710256
references: J Control Release. 2002 Aug 21;82(2-3):289-307
references: 12175744
references: Biotechnol Bioeng. 1991 Jan 20;37(2):177-84
references: 18597353
references: J Am Chem Soc. 2006 Apr 26;128(16):5384-90
references: 16620110
references: Mol Pharm. 2007 Jan-Feb;4(1):104-18
references: 17274668
references: Eur J Pharm Biopharm. 2008 Sep;70(1):187-98
references: 18472254
references: Biotechnology (N Y). 1990 Apr;8(4):308-17
references: 1369261
references: Crit Rev Ther Drug Carrier Syst. 2002;19(1):73-98
references: 12046892
references: J Control Release. 2007 Oct 8;122(3):331-7
references: 17706831
references: Adv Drug Deliv Rev. 2002 Jan 17;54(1):99-134
references: 11755708
references: Eur J Pharm Biopharm. 2006 Jun;63(2):205-14
references: 16621485
references: Int J Pharm. 2008 Dec 8;364(2):298-327
references: 18621492
references: Colloids Surf B Biointerfaces. 2000 Oct 1;18(3-4):371-379
references: 10915958
references: Biomaterials. 2002 Jan;23(1):239-45
references: 11762843
references: Pharm Res. 2000 Mar;17(3):351-7
references: 10801225
references: Nat Biotechnol. 2000 Jan;18(1):52-7
references: 10625391
references: Eur J Pharm Biopharm. 2001 May;51(3):171-81
references: 11343880
references: Biomaterials. 1997 Jan;18(1):27-30
references: 9003893
references: Vaccine. 2007 Jan 5;25(3):500-9
references: 16996662
references: Pharm Res. 2001 Jun;18(6):878-85
references: 11474795