大鼠耳后和肌肉注射地塞米松后内耳组织药物浓度分析

Determination of the dexamethasone in the cochlear tissue after postaurical and intramuscular injection

目的探讨耳后注射和肌肉注射地塞米松磷酸钠两种不同给药方式内耳组织地塞米松浓度的差异。方法行双侧肾上腺切除术后将动物分三组:耳后注射组、肌肉注射组及生理盐水空白对照组。给药后0.25、0.5、2.5、5、1 2、24、72小时取材,内耳组织机械匀浆,利用酶联免疫吸附测定法检测地塞米松浓度。结果耳后注射组地塞米松浓度明显高于肌肉注射组,差异有统计学意义。耳后注射组在给药0.25小时后浓度达到高峰(175.2±36.0)ng/ml,然后逐渐下降,12小时后浓度明显下降,24小时几乎检测不到。肌肉注射组给药后2.5小时浓度达到高峰(141.1±8.9)ng/ml,5小时后明显下降,24小时几乎检测不到。结论与肌肉注射相比,给药后耳后注射组在内耳组织的局部药物浓度高,出现高峰早,持续时间长。

OBJECTIVE To measure the dexamethasone concentration in the cochlear tissue after postaurical and intramuscular administration.METHODS After bilateral adrenalectomy, animals were divided into three groups： postaurical injection group, intramuscular injection group, and physiological saline injected blank control group. At 0.25, 0.5, 2.5, 5, 12, 24, 72 h after injection （1mg/100g）, cochleae together with the intact endolymphatic sac were removed and homogenated. After that, the dexamethasone was detected by enzymelinked immunosorbent assay （ELISA） . RESULTS The dexamethasone levels in the cochlear tissue in postaurical injection group were significantly higher than that in the intramuscular injection group. In the postaurical administration group, a mean peak cochlear tissue concentration of （175.2±36.0） ng/ml was detected at 0.25 h after injection, then declined obviously 12 h and was below detection limits by 24h. While in the intramuscular administration group, a mean peak concentration was observed 2.5 h at the concentration of （141.1±8.9） ng/ml, then rapidly declined from 5h and beyond detection by 24 h. CONCLUSION Compared with intramuscular administration, the dexamethasone levels in the postaurical injection group were significantly higher, with peak concentration reached earlier, and last longer.