Carroll G L, Boothe D M, Hartsfield S M, Martinez E A, Spann A C, Hernandez A
Department of Small Animal Medicine, College of Veterinary Medicine, Texas A&M University, College Station 77843-4474, USA.
J Am Vet Med Assoc. 2001 Nov 1;219(9):1263-7. doi: 10.2460/javma.2001.219.1263.
To evaluate disposition of butorphanol after i.v. and i.m. administration, effects on physiologic variables, and analgesic efficacy after i.m. administration in llamas.
Nonrandomized crossover study.
6 healthy adult male llamas.
Butorphanol (0.1 mg/kg [0.045 mg/lb] of body weight) was administered i.m. first and i.v. 1 month later. Blood samples were collected intermittently for 24 hours after administration. Plasma butorphanol versus time curves were subjected to pharmacokinetic analysis. Two months later, butorphanol (0.1 mg/kg) was administered i.m., and physiologic variables and analgesia were assessed.
Extrapolated peak plasma concentrations after i.v. and i.m. administration were 94.8 +/- 53.1 and 34.3 +/- 11.6 ng/ml, respectively. Volume of distribution at steady state after i.v. administration was 0.822 +/- 0.329 L/kg per minute and systemic clearance was 0.050 +/- 0.014 L/kg per minute. Slope of the elimination phase was significantly different, and elimination half-life was significantly shorter after i.v. (15.9 +/- 9.1 minutes) versus i.m. (66.8 +/- 13.5 minutes) administration. Bioavailability was 110 +/- 49% after i.m. administration. Heart rate decreased and rectal temperature increased. Somatic analgesia was increased for various periods. Two llamas became transiently sedated, and 2 became transiently excited after butorphanol administration.
Although i.v. administration of butorphanol results in a short half-life that may limit its analgesic usefulness, the elimination half-life of butorphanol administered i.m. is likely to be clinically useful. The relationship among plasma butorphanol concentration, time, and analgesia differed with the somatic analgesia model; clinically useful analgesia may occur at lower plasma concentrations than those reported here.
评估布托啡诺静脉注射和肌肉注射后的处置情况、对生理变量的影响以及肌肉注射后在美洲驼中的镇痛效果。
非随机交叉研究。
6只健康成年雄性美洲驼。
首先给美洲驼肌肉注射布托啡诺（0.1毫克/千克[0.045毫克/磅]体重），1个月后进行静脉注射。给药后24小时内间歇性采集血样。对血浆布托啡诺浓度随时间变化的曲线进行药代动力学分析。两个月后，肌肉注射布托啡诺（0.1毫克/千克），并评估生理变量和镇痛情况。
静脉注射和肌肉注射后的外推血浆峰值浓度分别为94.8±53.1纳克/毫升和34.3±11.6纳克/毫升。静脉注射后稳态分布容积为0.822±0.329升/千克每分钟，全身清除率为0.050±0.014升/千克每分钟。消除相斜率有显著差异，静脉注射后的消除半衰期（15.9±9.1分钟）明显短于肌肉注射后的（66.8±13.5分钟）。肌肉注射后的生物利用度为110±49%。心率下降，直肠温度升高。在不同时间段躯体镇痛作用增强。两只美洲驼在注射布托啡诺后出现短暂镇静，两只出现短暂兴奋。
虽然静脉注射布托啡诺的半衰期较短，可能会限制其镇痛效果，但肌肉注射布托啡诺的消除半衰期在临床上可能有用。血浆布托啡诺浓度、时间和镇痛之间的关系因躯体镇痛模型而异；临床上有效的镇痛可能在低于本文报道的血浆浓度时出现。
