Thomasy Sara M, Pypendop Bruno H, Ilkiw Jan E, Stanley Scott D
K. L. Maddy Equine Analytical Chemistry Laboratory, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
Am J Vet Res. 2005 Jul;66(7):1162-6. doi: 10.2460/ajvr.2005.66.1162.
To describe the pharmacokinetics of lidocaine and its active metabolite, monoethylglycinexylidide (MEGX), after i.v. administration of a single bolus of lidocaine in cats that were awake in phase 1 and anesthetized with isoflurane in phase 2 of the study.
8 healthy adult cats.
During phase 1, cats were administered lidocaine (2 mg/kg, i.v.) as a bolus injection (time 0). During phase 2, cats were anesthetized with isoflurane and maintained at 0.75 times the minimum alveolar concentration of isoflurane for each specific cat. After a 15-minute equilibration period, lidocaine (2 mg/kg, i.v.) was administered as a bolus injection to each cat (time 0). In both phases, plasma concentrations of lidocaine and MEGX were measured at various time points by use of liquid chromatography-mass spectrometry.
Anesthesia with isoflurane significantly decreased the volume of the central compartment, clearance, and elimination half-life of lidocaine and significantly increased the extrapolated plasma drug concentration at time 0, compared with values for awake cats. Pharmacokinetics of MEGX were also changed by isoflurane-induced anesthesia because the maximum observed plasma concentration (C(max)), area under the concentration-time curve extrapolated to infinity, and time to C(max) were significantly higher in anesthetized cats, compared with values for awake cats.
Pharmacokinetics of lidocaine and MEGX were substantially altered in cats anesthetized by use of isoflurane. When pharmacokinetic variables are used to determine loading and infusion doses in awake or anesthetized cats, they should be measured in cats that are awake or anesthetized, respectively.
描述在研究的第1阶段清醒和第2阶段用异氟烷麻醉的猫静脉注射单次推注利多卡因后，利多卡因及其活性代谢物单乙基甘氨酰二甲苯胺（MEGX）的药代动力学。
8只健康成年猫。
在第1阶段，给猫静脉推注利多卡因（2mg/kg）（时间0）。在第2阶段，用异氟烷麻醉猫，并将每只猫维持在异氟烷最低肺泡浓度的0.75倍。经过15分钟的平衡期后，给每只猫静脉推注利多卡因（2mg/kg）（时间0）。在两个阶段，均使用液相色谱-质谱法在不同时间点测量利多卡因和MEGX的血浆浓度。
与清醒猫的值相比，异氟烷麻醉显著降低了利多卡因的中央室容积、清除率和消除半衰期，并显著增加了时间0时的外推血浆药物浓度。异氟烷诱导的麻醉也改变了MEGX的药代动力学，因为与清醒猫的值相比，麻醉猫的最大观察到的血浆浓度（C(max)）、浓度-时间曲线外推至无穷大的面积以及达到C(max)的时间显著更高。
使用异氟烷麻醉的猫中，利多卡因和MEGX的药代动力学发生了显著改变。当使用药代动力学变量来确定清醒或麻醉猫的负荷剂量和输注剂量时，应分别在清醒或麻醉的猫中进行测量。
