Sustained local drug release and high local drug concentrations can be achieved by specially designed DDSs, which can be created for different applications. This results in therapeutic drug amounts at the site of action, simultaneously providing a very low drug amount in total. Bodily compartments that contain liquids may be used to transport the drugs from DDS into the tissue, such as the cochlea with the perilymph in the case of cochlea implants. However, predominantly dry environments, such as the middle ear, are lacking such a medium but may deliver enough moisture for the use of swellable DDS through the surrounding mucus membranes. Therefore, DDS with new functionalities are needed to ensure a sustained drug release. In this study, the release of dexamethasone out of a photopolymer system is presented. The system is built from UV-polymerized PEGDA followed by the incorporation of dexamethasone via swelling. The drug release is tested in vitro with isotonic NaCl solution for specified time periods, showing two phases: a swelling phase and a release phase. After the swelling phase the concentration of dexamethasone in the release medium was not controlled by diffusion, although sink conditions were ensured. In contrast, this system can be used to release the drug until equilibrium with a final medium concentration that is far below the solubility of dexamethasone. Hence, such DDS may be useful for dexamethasone delivery into the cochlea through the round window membrane by ensuring a constant concentration in the perilymph.
© 2020 by Walter de Gruyter Berlin/Boston
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