Methylprednisolone Pharmacokinetics In Perilymph Of Guinea Pig After Different Topical Administrations

Objective:To determine pharmacokinetics profiles of methylprednisolone (MTH) inperilymph of guinea pig with different intratympanic administrations，and to provideexperimental evidence for clinical choice about administrationMethod: Two different topical administrations infusing otocyst with MTHsolution(62.5mg/ml) and placing a granule gelfoam soaked with MTH(62.5mg/ml)inthe round window niche of guinea pig were conducted． Samples of perilymph ofthe scala tympani were obtained1～12h after administration of two routes,respectively. Highperformance liquid chromatography was used to assay MTH in thesamples.Result: After niche was placed with granule gelfoam with drug or otocyst was inffusedwith MTH, the highest concent rations in perilymph were manifested in1h30min.The concent rations of drug in perilimph after otocyst was infused with MTH werehigher than those of after niche was placed with granule gelfoam soaked with MTH inevery hour, and there were significant differences in between except those from5to12h. The halflife time of MTH in perilymph after otocyst was infused was1.84h,and the one after niche was placed with granule gelfoam soaked with MTH was1.87h. There were not differences in the thresholds of wave Ⅲof ABR before and l2hafter local MTH administration among two groups(P>0．05)．Conclusion:MTH could penetrate effectively through membrane of round window into thecochlear fluid.The concent rations of drug in perilimph after otocyst was infused withMTH were higher.