title: In vitro permeability of round window membrane to transforming dexamethasone with delivery vehicles--a dosage estimation.
abstract: 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.
  
  
  CONCLUSIONS
  The combination of alginate and chitin could be used as vehicle for sustained release of dexamethasone in intratympanic application.
authors.affiliation: Center of Otolaryngology of PLA, Naval General Hospital, Beijing 100037, China. jjsun85@sina.com.cn
authors.forename: Jian-jun
authors.initials: JJ
authors.lastname: Sun
authors.forename: Ya
authors.initials: Y
authors.lastname: Liu
authors.forename: Wei-jia
authors.initials: WJ
authors.lastname: Kong
authors.forename: Ping
authors.initials: P
authors.lastname: Jiang
authors.forename: Wei
authors.initials: W
authors.lastname: Jiang
mesh_terms: D000464:Alginates / Q000008:administration & dosage; D000818:Animals; D048271:Chitosan / Q000008:administration & dosage; D002851:Chromatography, High Pressure Liquid; D003692:Delayed-Action Preparations; D003907:Dexamethasone / Q000008:administration & dosage* / Q000493:pharmacokinetics*; D005260:Female; D020723:Glucuronic Acid / Q000008:administration & dosage; D006168:Guinea Pigs; D006603:Hexuronic Acids / Q000008:administration & dosage; D008297:Male; D010539:Permeability; D014677:Pharmaceutical Vehicles; D012405:Round Window, Ear / Q000378:metabolism*
chemical_list: D000464:Alginates; D003692:Delayed-Action Preparations; D006603:Hexuronic Acids; D014677:Pharmaceutical Vehicles; D003907:Dexamethasone; D020723:Glucuronic Acid; D048271:Chitosan