Corticosteroid-releasing cochlear implant: A novel hybrid of biomaterial and drug delivery system

In this study, drug-eluting cochlear implant (Cl) electrodes were prepared, and the amount of drug released was determined. Dexamethasone (DEX) (0.25-2% w/w, the weight percent of the final cured polymer) was used as a bioactive agent to suppress postsurgical inflammations upon mixing with a two-part nonrestricted pourable medical-grade silicone elastomer. Batch reproducibility analysis was performed on three consecutive batches. Drug release experiments were accomplished in normal saline medium, where DEX was analyzed via a validated HPLC method. The drug loading percentage and the device surface area were the most dominant parameters explored to monitor the drug release behavior from Cl coatings. Total cumulative amount of DEX released from various loaded samples was in the order of 2 > 1 > 0.5 > 0.35 > 0.25% w/w, but the cumulative percentage of drug released showed a reverse order. The DEX dosages between 0.1 and 1 mu g were released from samples of smallest to highest loadings during the initial 24 h, and dosages <1-5 mu g were released from similar samples of various loadings at the first patency 2 weeks. The extent of crosslinking was only effective on release profile at lower drug loadings of 0.25% w/w relative to 0.5%. It was also found that release profile was not affected by postcuring. (C) 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 94B: 388-398, 2010.