1 / 28

Poly(lactic acid), Poly(glycolic acid), and their copolymer, PLGA

Poly(lactic acid), Poly(glycolic acid), and their copolymer, PLGA. April 21, 2008. Why PLA, PGA, and PLGA?. Biodegradable Derived from renewable resources Applications -Surgical sutures -Drug Delivery Systems -Internal Fixation Devices -Tissue Engineering Scaffolds.

robbin
Download Presentation

Poly(lactic acid), Poly(glycolic acid), and their copolymer, PLGA

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Poly(lactic acid), Poly(glycolic acid), and their copolymer, PLGA April 21, 2008

  2. Why PLA, PGA, and PLGA? • Biodegradable • Derived from renewable resources • Applications • -Surgical sutures • -Drug Delivery Systems • -Internal Fixation Devices • -Tissue Engineering Scaffolds

  3. Poly(lactic acid) (PLA) • Start with anhydride (lactide) • Ring-Opening Polymerization • tin (II) chloride or stannous octoate

  4. Poly(glycolic acid) (PGA) • Start with anhydride (glycolide) • Ring-Opening Polymerization K11

  5. Poly(lactic-co-glycolic acid) (PLGA) • Start with anhydrides (lactide and glycolide) • Ring-Opening Polymerization

  6. Processing and Cost • Similar processing for PLA, PGA, and PLGA • Melt spinning • PGA more difficult that PLA and PLGA • Tm PGA = 220° C • Cost • PLA - $1.30 / lb. • PGA > PGLA > PLA

  7. Properties • PLA • Tg≈ 65° C • Tm≈ 175° C • PGA • Tg≈ 37° C • Tm≈ 230° C • Higher strength and modulus • PLGA • Vary with % composition

  8. PLA and PGA Degradation • Hydrolysis + H2O Polylactic acid Lactic acid + H2O Glycolic acid Polyglycolic acid

  9. Surface Degradation Surface Degradation • Fluid is not absorbed by material • Only the surface is degraded Fluid Material

  10. Surface Degradation Surface Degradation • Fluid is not absorbed by material • Only the surface is degraded Fluid Material

  11. Surface Degradation Surface Degradation • Fluid is not absorbed by material • Only the surface is degraded Fluid Material

  12. Surface Degradation Surface Degradation • Fluid is not absorbed by material • Only the surface is degraded Fluid Material

  13. Bulk Degradation • Fluid is absorbed by material • Entirety of the material is degraded Fluid Material

  14. Bulk Degradation Bulk Degradation • Fluid is absorbed by material • Entirety of the material is degraded Fluid Material

  15. Bulk Degradation Bulk Degradation • Fluid is absorbed by material • Entirety of the material is degraded Fluid Material

  16. Bulk Degradation Bulk Degradation • Fluid is absorbed by material • Entirety of the material is degraded Fluid Material

  17. Bulk Degradation Bulk Degradation • Fluid is absorbed by material • Entirety of the material is degraded Fluid Material

  18. Molecular Weights Molecular Weights • Surface Degradation • Bulk Degradation

  19. Molecular Weights Molecular Weights • Surface Degradation • Bulk Degradation

  20. Molecular Weights Molecular Weights • Surface Degradation • Bulk Degradation

  21. Degradation Weights Degradation Rates • Dependent on crystallinity • PLA degrades faster due to lower crystallinity • Co-polymerization greatly increases rate

  22. Biological Factors Biological Factors • Implantations face immune response • Macrophages use acids, hydroxyls, peroxides, alcohols to degrade materials • More corrosive than water

  23. PLGA Applications PLGA Applications • PLGA degraded via hydrolysis at ester bonds • Degradation rate depends on co-polymer ratio of lactide and glycolide composition • Lactic acid is hydrophobic – degrades slower than glycolic acid PLGA chemical structure where X= lactide ratio, Y=glycolide ratio • Synthetic biodegradable polymers have higher mechanical, biocompatible, biodegradable properties than natural polymers (ie – collagen)

  24. PLGA Applications PLGA Applications • Faster hydrolytic and degradation processes if glycolide ratio greater than lactide (except 50:50) • Hydrolytic mechanism ideal for drug release • Manipulate co-polymer ratio to vary drug release rates • Environmentally friendly: PLGA enters carboxylic acid cycle; CO2& H2O by-products

  25. PLGA Applications: Vaccines PLGA Applications: Vaccines • PLGA microspheres more efficient than protein/peptide delivery methods • Daily intravenous injections of protein/peptide drugs have short half lives in vivo • Drug encapsulated in PLGA to control drug release by modifying hydrophilicity properties • Increases patient compliance and minimizes number of injections

  26. PLGA Applications: Tissue Engineering PLGA Applications: Tissue Engineering • Bone regeneration via porous PLGA scaffold • Pore size, shape, and interconnectivity in PLGA scaffold for cellular growth and tissue regeneration • Integrity of scaffold manipulated by co-polymer ratio • 85:15 PLGA ideal – minimal degradation within body to support bone growth

  27. Biological Factors PLGA Applications: Drug-Eluting Stent • Restenosis: re-occlusion of coronary vessel • Fully biodegradable stent provides higher drug loadings that reduce hyperplasia in artery • Drug simultaneously released into tissue as PLGA layer degrades • Layer thickness relates to MW – lower MW degrades faster than heavier polymer Fully biodegradable multilayer PLGA stent has more efficient drug release control Quick degradation rate Drug containing layer: glycolide easily degraded for efficient drug elution Support layer: slow hydrolytic processes

  28. Questions

More Related