Background In recent years the interest of sustained drug delivery into inner ear is promising,at the same time a great deal of novel oral drugs using biodegradable vehicles have been produced to achieve sustained drug release.The aim of this study was to use biodegradable vehicles to release dexamethasone in the round window membrane application.Methods Dexamethasone gels composed of alginate and chitin were prepared and the release-permeating profiles were studied using a reproducible in vitro apparatus.A longer-period time course was simulated using the parameters acquired in this study.The data obtained in this study was compared with those of other studies in intratympanic drug delivery,and an appropriate initial dosage was extrapolated.Results The combination of alginate and chitin could efficiently restrict dexamethasone diffusion and the time course suggested a sustained drug concentration within 24 hours.A higher initial dosage was estimated to achieve a stable therapeutic concentration in vivo.Conclusion The combination of alginate and chitin could be used as vehicle for sustained release of dexamethasone in intratympanic application.