The elucidation of poly(DL-lactic-co-glycolic acid) [PLGA] degradation mechanism in the NEVO� stent formulation is essential to understand and predict its performance in vivo. It has been shown that the ratio of lactide to glycolide in the co-polymer is a major factor regulating degradation rate and consequently, drug release. Incorporation of glycolide monomer units into the lactide chain enhances hydrophilicity of the material. Hydrolysis of the ester bonds in the PLGA polymer chain generates non-toxic monomers glycolic and lactic acids which are by-products of various metabolic pathways in the body. We have developed methods using NMR and Raman spectroscopies to determine the ratio of lactide to glycolide during PLGA degradation on NEVO� placebo stents in vitro. The results indicate that the lactide/glycolide ratio increases over time due to the higher susceptibility of the glycolic ester bond to hydrolysis. Furthermore, sterile samples degrade faster than non-sterile samples, presumably due to the effect of irradiation during sterilization. The excellent agreement in the results obtained by NMR and Raman techniques demonstrate the efficacy of the method to study PLGA degradation.

Development of NMR and Raman methods to analyze PLGA degradation in NEVO™ sirolimus-eluting stent

244th National Meeting (2012)

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