title: [Methylprednisolone pharmacokinetics in perilymph and plasma of guinea pig after topical administration and intracardial injection].
abstract: OBJECTIVE
  To determine pharmacokinetics profiles of methylprednisolone (MTH) in perilymph and plasma of guinea pig after topical and systemic administration.
  
  
  METHODS
  A granule gelfoam soaked with MTH (40 mg/ml) was placed in the niche of round window of guinea pig; otocyst was infused with MTH (40 mg/ml); 4 mg/kg of MTH was injected intracardially. Samples of blood and perilymph of the scala tympani were obtained 1-6 h after administration of two routes, respectively. High-performance liquid chromatography was used to assay MTH in the samples.
  
  
  RESULTS
  After intracardial injection of MTH, concentrations of drug in plasma were obviously higher than those of in perilymph in every hour while drug in perilymph could not be obtained in 4-6 h, and the results were significantly different. After niche was placed with granule gelfoam with drug or otocyst was infused with MTH,drug could not be obtained in plasma, concentrations of drug in perilymph were obviously higher than those of in plasma after intracardial injection,and the highest concentrations in perilymph were manifested in 1 h 20 min. The concentrations of drug in perilymph after otocyst was infused with MTH were higher than those of after niche was placed with granule gelfoam soaked with MTH in every hour, and there were significant differences in between except those in 4 and 6 h. The half-life time of MTH in perilymph after otocyst was infused was 1.51 h, and the one after niche was placed with granule gelfoam soaked with MTH was 1.55 h.
  
  
  CONCLUSIONS
  MTH could penetrate effectively through membrane of round window into the cochlear fluid and reach a much higher concentration following topical administration as compared with systemic application. The concentrations of drug in perilymph after otocyst was infused with MTH were higher.
authors.affiliation: Department of Otorhinolaryngology and Head-neck Surgery, Xinhua Hospital, Shanghai Second Medical University, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Zhang
authors.forename: Hao
authors.initials: H
authors.lastname: Wu
authors.forename: Jun
authors.initials: J
authors.lastname: Yang
authors.forename: Dongming
authors.initials: D
authors.lastname: Hou
authors.forename: Shunguo
authors.initials: S
authors.lastname: Zhang
authors.forename: Jie
authors.initials: J
authors.lastname: Chen
mesh_terms: D000287:Administration, Topical; D000818:Animals; D004432:Ear, Middle; D006168:Guinea Pigs; D008775:Methylprednisolone / Q000008:administration & dosage* / Q000493:pharmacokinetics*; D010498:Perilymph; D010949:Plasma
chemical_list: D008775:Methylprednisolone