Document Detail

Gamma irradiation effects on molecular weight and in vitro degradation of poly(D,L-lactide-CO-glycolide) microparticles.
MedLine Citation:
PMID:  7667189     Owner:  NLM     Status:  MEDLINE    
PURPOSE: The objective of the reported work was to quantitatively establish gamma-irradiation dose effects on initial molecular weight distributions and in vitro degradation rates of a candidate erodible biopolymeric delivery system. METHODS: Poly(D,L-lactide-coglycolide) (PLGA) porous microparticles were prepared by a phase-separation technique using a 50:50 copolymer with 30,000 nominal molecular weight. The microparticles were subjected to 0, 1.5, 2.5, 3.5, 4.5, and 5.5 Mrad doses of gamma-irradiation and examined by size exclusion chromatography (SEC) to determine molecular weight distributions. The samples were subsequently incubated in vitro at 37 degrees C in pH 7.4 PBS and removed at timed intervals for gravimetric determinations of mass loss and SEC determinations of molecular weight reduction. RESULTS: Irradiation reduced initial molecular weight distributions as follows (Mn values shown parenthetically for irradiation doses): 0 Mrad (Mn = 25200 Da), 1.5 Mrad (18700 Da), 2.5 Mrad (17800 Da), 3.5 Mrad (13800 Da), 4.5 Mrad (12900 Da), 5.5 Mrad (11300 Da). In vitro degradation showed a lag period prior to zero-order loss of polymer mass. Onset times for mass loss decreased with increasing irradiation dose: 0 Mrad (onset = 3.4 weeks), 1.5 Mrad (2.0 w), 2.5 Mrad (1.5 w), 3.5 Mrad (1.3 w), 4.5 Mrad (1.0 w), 5.5 Mrad (0.8 w). The zero-order mass loss rate was 12%/week, independent of irradiation dose. Onset of erosion corresponded to Mn = 5200 Da, the point where the copolymer becomes appreciably soluble. CONCLUSIONS: The data demonstrated a substantial effect of gamma-irradiation on initial molecular weight distribution and onset of mass loss for PLGA, but no effect on rate of mass loss.
A G Hausberger; R A Kenley; P P DeLuca
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Publication Detail:
Type:  In Vitro; Journal Article    
Journal Detail:
Title:  Pharmaceutical research     Volume:  12     ISSN:  0724-8741     ISO Abbreviation:  Pharm. Res.     Publication Date:  1995 Jun 
Date Detail:
Created Date:  1995-10-06     Completed Date:  1995-10-06     Revised Date:  2010-03-24    
Medline Journal Info:
Nlm Unique ID:  8406521     Medline TA:  Pharm Res     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  851-6     Citation Subset:  IM    
Pfizer, Inc., Groton, Connecticut, USA.
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MeSH Terms
Biocompatible Materials / chemistry,  radiation effects*
Dose-Response Relationship, Radiation
Lactic Acid*
Molecular Weight
Polyglycolic Acid*
Polymers / chemistry,  radiation effects*
Radiation Effects
Time Factors
Reg. No./Substance:
0/Biocompatible Materials; 0/Polymers; 0/polylactic acid-polyglycolic acid copolymer; 26009-03-0/Polyglycolic Acid; 50-21-5/Lactic Acid

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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