08 wt% for L-lactide monomer and below detection limit (< 0.02 wt%) for ��-caprolactone monomer. The L-lactide and ��-caprolactone monomer contents of the processed samples Bicalutamide ICI-176334 were analyzed from two points in the processing batch and there were two parallel samples in both. The L-lactide monomer content decreased slightly during processing. It was 0.04�C0.07 mol% and the caprolactone monomer content was below 0.02 mol% for all tested samples. Because there were no significant differences in the monomer contents of the manufactured materials, it can be assumed that the monomers did not cause differences in the hydrolytic degradation behavior of the studied composites.24 UV measurements utilizing the isosbestic point The UV-measurements of rifampicin proved challenging due to the oxidation of rifampicin to rifampicin quinone in aqueous solutions and in the presence of atmospheric oxygen.

This can be seen as a change in the UV-spectrum of a rifampicin solution as well as a change in the color of the solution.25 Rifampicin quinone has a UV-spectrum partly similar to rifampicin and also has antibacterial properties.25 The fact that rifampicin quinone degrades further to other compounds that do not have absorbance in the UV/V is area naturally affects the accuracy of this method. Part of the rifampicin is undetected if it has already degraded. The accuracy is highest when the measurements are made at short intervals, not letting the dissolution medium stay unchanged for long periods.

However, as the release test period in this study was long, part of the rifampicin that had oxidized to rifampicin quinone, had time to degrade to other compounds that do not have absorptivity in the UV/V is area, even if the measurements were performed in short intervals. It has also been reported that rifampicin degrades more in solutions with low rifampicin concentration.26 On the other hand, Le Guellec et al. suggest possible in vivo stabilization of the molecule.27 In the later stages of the release test period, it was noticed that the degradation products of the polymer matrix induce a broad UV-peak at the beginning of the scanned area (200�C220 nm). This broad peak, however, did not significantly interfere with the use of the isosbestic point at 226 nm. Rifampicin release from the materials The measured initial rifampicin contents were 6.5 wt% for PLCL + R, 7.

9 wt% for PLCL + TCP50 + R and 7.8 wt% for PLCL + TCP60 + R. The cumulative release of rifampicin from the studied materials is presented Carfilzomib in Figure 1A. It can be seen that the release occurred in four phases and that the ��-TCP content of the composites had a significant effect on the rifampicin release. Rifampicin release from the PLCL + TCP60 + R was faster than from the PLCL + TCP50 + R and reached 80% in 130 d. Rifampicin release from the PLCL + TCP50 + R was slower but closer to zero order release that is the desirable release profile in this case. After 150 d, the release slowed down.