[Dexamethasone pharmacokinetics in perilymph of guinea pig after different topical administrations].

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 chromatography. RESULT: The concentrations of DEX in perilymph after placing a granule gel-foam 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.