Dyck J B, Maze M, Haack C, Vuorilehto L, Shafer S L
Department of Anesthesia, VA Medical Center, San Diego, California 92161-9125.
Anesthesiology. 1993 May;78(5):813-20. doi: 10.1097/00000542-199305000-00002.
Dexmedetomidine is an alpha 2 agonist with potential utility in clinical anesthesia for both its sedative and sympatholytic properties.
The pharmacokinetics and hemodynamic changes that occurred in ten healthy male volunteers were determined after administration of dexmedetomidine 2 micrograms/kg by intravenous or intramuscular route in separate study sessions.
The intramuscular absorption profile of dexmedetomidine, as determined by deconvolution of the observed concentrations against the unit disposition function derived from the intravenous data, was biphasic. The percentage bioavailability of dexmedetomidine administered intramuscularly compared with the same dose administered intravenously was 73 +/- 11% (mean +/- SD). After intramuscular administration, the mean time to peak concentration was 12 min (range 2-60 min) and the mean peak concentration was 0.81 +/- 0.27 ng/ml. After intravenous administration of dexmedetomidine, there were biphasic changes in blood pressure. During the 5-min intravenous infusion of 2 micrograms/kg dexmedetomidine, the mean arterial pressure (MAP) increased by 22% and heart rate (HR) declined by 27% from baseline values. Over the 4 h after the infusion, MAP declined by 20% from baseline and HR rose to 5% below baseline values. The hemodynamic profile did not show acute alterations after intramuscular administration. During the 4 h after intramuscular administration, MAP declined by 20% and HR declined by 10%.
The intramuscular administration of dexmedetomidine avoids the acute hemodynamic changes seen with intravenous administration, but results in similar hemodynamic alterations within 4 h.
右美托咪定是一种α2激动剂，因其镇静和抗交感神经特性在临床麻醉中具有潜在应用价值。
在单独的研究阶段，通过静脉或肌肉途径给10名健康男性志愿者注射2微克/千克右美托咪定后，测定其药代动力学和血流动力学变化。
通过将观察到的浓度与从静脉数据得出的单位处置函数进行反卷积确定，右美托咪定的肌肉吸收曲线呈双相。与静脉注射相同剂量相比，肌肉注射右美托咪定的生物利用度百分比为73±11%（平均值±标准差）。肌肉注射后，平均达峰时间为12分钟（范围2 - 60分钟），平均峰浓度为0.81±0.27纳克/毫升。静脉注射右美托咪定后，血压出现双相变化。在静脉输注2微克/千克右美托咪定的5分钟内，平均动脉压（MAP）较基线值升高22%，心率（HR）下降27%。在输注后的4小时内，MAP较基线值下降20%，HR升至比基线值低5%。肌肉注射后血流动力学曲线未显示急性改变。在肌肉注射后的4小时内，MAP下降20%，HR下降10%。
肌肉注射右美托咪定可避免静脉注射时出现的急性血流动力学变化，但在4小时内会导致类似的血流动力学改变。
