Objective:To determine
pharmacokinetics profiles of dexamethasone (DEX) in perilymph of guinea pig with different intratympanic
administrations,and to provide experimental evidence for clinical choice about administration.Method:Two different topical
administrations placing a granule gelfoam soaked with DEX(10 g/L) in the niche of round window of guinea pig and infusing tympanic bulb with DEX solution(10 g/L) were conducted. Perilymph of the scala tympani was sampled 1-6 h after administration.DEX in the samples was assayed with high-performance liquid chromatograghy.Result:The concentrations of DEX in perilymph after placing a granule gelfoam soaked with DEX in the niche of round window were significantly higher than that after intratympanic infusing.The half-life time of DEX after placing a granule gelfoam was longer.Conclusion:DEX could effectively penetrate round window membrane into perilymph after different intratympanic administrations, and the method of placing a granule gelfoam soaked with DEX in the niche of round window is more effective than that of intratympanic infusing.