Egger Christine M, Souza Marcy J, Greenacre Cheryl B, Cox Sherry K, Rohrbach Barton W
Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN 37996, USA.
Am J Vet Res. 2009 Aug;70(8):945-9. doi: 10.2460/ajvr.70.8.945.
To evaluate the effect of IV administration of tramadol hydrochloride on the minimum alveolar concentration of isoflurane (ISOMAC) that prevented purposeful movement of rabbits in response to a noxious stimulus.
Six 6- to 12-month-old female New Zealand White rabbits.
Anesthesia was induced and maintained with isoflurane in oxygen. A baseline ISOMAC was determined by clamping a pedal digit with sponge forceps until gross purposeful movement was detected or a period of 60 seconds elapsed. Subsequently, tramadol (4.4 mg/kg) was administered IV and the posttreatment ISOMAC (ISOMAC(T)) was measured.
Mean +/- SD ISOMAC and ISOMAC(T) values were 2.33 +/- 0.13% and 2.12 +/- 0.17%, respectively. The ISOMAC value decreased by 9 +/- 4% after tramadol was administered. Plasma tramadol and its major metabolite (M1) concentrations at the time of ISOMAC(T) determination varied widely (ranges, 181 to 636 ng/mL and 32 to 61 ng/mL, respectively). Intervals to determination of ISOMAC(T) and plasma tramadol and M1 concentrations were not correlated with percentage change in the ISOMAC. Heart rate decreased significantly immediately after tramadol administration but by 10 minutes afterward was not different from the pretreatment value. Systolic arterial blood pressure decreased to approximately 60 mm Hg for approximately 5 minutes in 3 rabbits after tramadol administration. No adverse effects were detected.
As administered, tramadol had a significant but clinically unimportant effect on the ISOMAC in rabbits. Higher doses of tramadol may provide clinically important reductions but may result in a greater degree of cardiovascular depression.
评估静脉注射盐酸曲马多对异氟烷最低肺泡浓度（ISOMAC）的影响，该浓度可防止家兔因有害刺激而出现有目的的运动。
6只6至12月龄的雌性新西兰白兔。
采用异氟烷在氧气中诱导并维持麻醉。通过用海绵钳夹压足趾直至检测到明显的有目的运动或经过60秒来确定基线ISOMAC。随后，静脉注射曲马多（4.4mg/kg）并测量治疗后的ISOMAC（ISOMAC(T)）。
平均±标准差的ISOMAC和ISOMAC(T)值分别为2.33±0.13%和2.12±0.17%。注射曲马多后，ISOMAC值降低了9±4%。在测定ISOMAC(T)时，血浆曲马多及其主要代谢物（M1）的浓度差异很大（范围分别为181至636ng/mL和32至61ng/mL）。测定ISOMAC(T)的间隔时间以及血浆曲马多和M1的浓度与ISOMAC的百分比变化无关。注射曲马多后，心率立即显著下降，但10分钟后与治疗前值无差异。3只家兔在注射曲马多后，收缩动脉血压在约5分钟内降至约60mmHg。未检测到不良反应。
按所给剂量给药时，曲马多对家兔的ISOMAC有显著但临床意义不大的影响。更高剂量的曲马多可能会在临床上产生重要的降低作用，但可能会导致更大程度的心血管抑制。
