*3.3. Drug Release*

Profiles of released DMS were detected for Sil, Sil-PLLA and Sil-DCF/PLLA. As DMS release decreases after PLLA-coating, the coating acts as diffusion barrier. Surprisingly, the incorporation of DCF in the PLLA coating led to a significant increase in the release of DMS from 7 to 10% after 13 weeks in vitro DMS release. This is likely due to the incorporation of DCF, which in turn leads to an altered spacing of the polymer chains of PLLA from each other, favoring the formation of enlarged pores compared to PLLA without DCF. To our knowledge, this is the first time that DCF sodium was incorporated in PLLA. Therefore, the behavior has also not been observed before, especially not in a dual drug-release system. The large increase in burst DCF release with 20% DCF in the layer compared to the 10% supports the hypothesis of enlarged pores by DCF in general and by the increased concentration in particular.
