CHARACTERIZATION OF POLYESTERURETHANE DEGRADATION PRODUCTS

Microthane foam, a poly(ester)urethane, used as a covering of some bre ast implants (Meme or Replicon by Surgitek) degrades readily in phosph ate buffer pH 7.4 producing multiple unknown products in addition to 2 ,4 and 2,6 toluenediamine (TDA). The cumulative weight loss of the foa m in buffer was 1.5% at 1 week and 2% at 2 weeks. Multiple peak molecu lar weights from 105 to 665000 were found in the aqueous foam extracts following 2 weeks of incubation at 37 degrees C using size exclusion chromatography (SEC). TDA was measured in the foam buffer extracts by high pressure liquid chromatography (HPLC) and confirmed by gas chroma tography/mass spectroscopy (GC/MS). The total cumulative levels of 2,4 TDA and 2,6 TDA measured were 3 +/- 0.65 mu g/g of foam and 1.13 +/- 0.19 mu g/g of foam following 36 days of incubation at 37 degrees C. H igher amounts, 8.96 mu g/g of 2,4 TDA and 3.3 mu g/g of 2,6 TDA, were obtained at 50 degrees C. The cumulative release of TDA in aqueous ext racts was found to correlate linearly with time suggesting a slow but continuous production of TDA under neutral conditions. However, less t han 0.2 mu g/g of TDA was detected as residual TDA in the methylene ch loride extracts following up to 60 days at 37 degrees C. PU foam extra cted with methylene chloride under similar conditions showed higher fo am weight loss, 4.4 and 5% at 1 and 2 weeks, respectively. The results presented in this study provide further evidence that Microthane unde rgoes hydrolysis under neutral conditions in aqueous solutions produci ng TDA and other unknown low molecular weight components and oligomers . (C) 1994 John Wiley and Sons, Inc.