Previously, we have demonstrated that 2,2-bis(2-oxazoline) linked
poly-epsilon-caprolactone (PCL-O) is degraded in vitro enzymatically by surface erosion which could enable the novel use of this material for
drug delivery and other biomedical applications. In this study, degradation, erosion (
weight loss) and toxicity of PCL-O poly(
ester-
amide)s were evaluated in vivo. PCL and three PCL-O
polymers with different PCL block lengths (M(n): 1500, 3900, 7500 g/mol) were melt-pressed in the form of discs and implanted subcutaneously in Wistar rats (dose approximately 340 mg/kg) for 1, 4 and 12 weeks. With implantation for 12 weeks, up to 16.5%
weight loss of
polymer discs was measured for the most extensively linked
PCL-O polymer (block length 1500 g/mol) whereas practically no
weight loss was observed with the other
polymers. NMR, DSC and SEC studies as well as SEM micrographs before and after implantation and in vitro hydrolysis studies indicate that
enzyme based surface erosion of PCL-O
polymers occurred in vivo. The in vivo evaluation based on results from hematology, clinical chemistry and histology of the implantation area and main organs (i.e. heart, lung, liver, kidney, spleen and brain) demonstrated that PCL-O
polymers are biocompatible and safe,
enzyme sensitive
biomaterials.