Intravenous (i.v.) bolus administration of xylazine (XYL) (0.5 mg/kg) immediately followed by a continuous rate infusion (CRI) of 1 mg kg⁻¹ hr⁻¹ for 2, 4, and 6 hr produced immediate sedation, which lasted throughout the duration of the CRI. Heart rate decreased and blood pressure increased significantly (p > .05) in all horses during the first 15 min of infusion, both returned to and then remained at baseline during the duration of the infusion. Compartmental models were used to investigate the pharmacokinetics of XYL administration. Plasma concentration–time curves following bolus and CRI were best described by a one‐compartment model. No differences were found between pharmacokinetic estimates of the CRIs for the fractional elimination rate constant (K_e), half‐life (t_1/2e), volume of distribution (V_d), and clearance (Cl). Median and range were 0.42 (0.15–0.97)/hr, 1.68 (0.87–4.52) hr, 5.85 (2.10–19.34) L/kg, and 28.7 (19.6–39.5) ml min⁻¹ kg⁻¹, respectively. Significant differences were seen for area under the curve ( ) (p < .0002) and maximum concentration (C_max) (p < .04). This indicates that with increasing duration of infusion, XYL may not accumulate in a clinically relevant way and hence no adjustments are required in a longer XYL CRI to maintain a constant level of sedation and a rapid recovery.

中文翻译：

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在马中连续速率输注2、4和6小时后，赛拉嗪的药代动力学。

立即静脉推注赛拉嗪（XYL）（0.5 mg / kg），然后以1 mg kg ^-1  hr ^-1的持续速率输注（CRI）2、4和6 hr进行立即镇静，持续镇静在整个CRI期间。 在输注的前15分钟内，所有马匹的心率均下降且血压显着升高（p > .05），在输注期间均恢复至基线，然后保持在基线水平。隔室模型用于研究XYL给药的药代动力学。推注和CRI后的血浆浓度-时间曲线最好用单室模型描述。在CRI的药代动力学估计之间，对于分数消除率常数（K _e），半衰期（t _{1 / 2e}），分布体积（V _d）和清除率（Cl）。中位数和范围分别为0.42（0.15-0.97）/hr、1.68（0.87-4.52）hr，5.85（2.10-19.34）L / kg和28.7（19.6-39.5）ml min ^-1  kg ^-1。曲线下面积（）（p  <.0002）和最大浓度（C _max）（p  <.04）有明显差异。这表明随着输注时间的延长，XYL可能不会以临床上相关的方式积聚，因此在更长的XYL CRI中无需进行任何调整即可保持稳定的镇静水平和快速恢复。