Goodwin Wendy A, Keates Helen L, Pasloske Kirby, Pearson Martin, Sauer Ben, Ranasinghe Millaganamada Gedara
School of Veterinary Science, University of Queensland, Brisbane, Qld, Australia.
Vet Anaesth Analg. 2011 Sep;38(5):431-8. doi: 10.1111/j.1467-2995.2011.00634.x.
To determine the pharmacokinetics and pharmacodynamics of the neurosteroidal anaesthetic, alfaxalone, in horses after a single intravenous (IV) injection of alfaxalone, following premedication with acepromazine, xylazine and guaiphenesin.
Prospective experimental study.
Ten (five male and five female), adult, healthy, Standardbred horses.
Horses were premedicated with acepromazine (0.03 mg kg(-1) IV). Twenty minutes later they received xylazine (1 mg kg(-1) IV), then after 5 minutes, guaiphenesin (35 mg kg(-1) IV) followed immediately by IV induction of anaesthesia with alfaxalone (1 mg kg(-1) ). Cardiorespiratory variables (pulse rate, respiratory rate, pulse oximetry) and clinical signs of anaesthetic depth were evaluated throughout anaesthesia. Venous blood samples were collected at strategic time points and plasma concentrations of alfaxalone were assayed using liquid chromatography-mass spectrometry (LC/MS) and analysed by noncompartmental pharmacokinetic analysis. The quality of anaesthetic induction and recovery was scored on a scale of 1-5 (1 very poor, 5 excellent).
The median (range) induction and recovery scores were 4 (3-5) (good: horse slowly and moderately gently attained recumbency with minimal or no rigidity or paddling) and 4 (1-5) (good: horse stood on first attempt with some knuckling and ataxia) respectively. The monitored cardiopulmonary variables were within the range expected for clinical equine anaesthesia. The mean ± SD durations of anaesthesia from induction to sternal recumbency and from induction to standing were 42.7 ± 8.4 and 47 ± 9.6 minutes, respectively. The mean ± SD plasma elimination half life (t(1/2) ), plasma clearance (Clp) and volume of distribution (V(d) ) for alfaxalone were 33.4 minutes, 37.1 ± 11.1 mL minute(-1) kg(-1) and 1.6 ± 0.4 L kg(-1) , respectively.
Alfaxalone, in a 2-hydroxypropyl-beta-cyclodextrin formulation, provides anaesthesia with a short duration of recumbency that is characterised by a smooth induction and satisfactory recovery in the horse. As in other species, alfaxalone is rapidly cleared from the plasma in the horse.
在马经乙酰丙嗪、赛拉嗪和愈创甘油醚预处理后，单次静脉注射阿法沙龙，以确定该神经甾体麻醉剂在马体内的药代动力学和药效学。
前瞻性实验研究。
10匹（5匹雄性和5匹雌性）成年健康标准赛马。
马经乙酰丙嗪（0.03 mg kg⁻¹静脉注射）预处理。20分钟后给予赛拉嗪（1 mg kg⁻¹静脉注射），然后5分钟后给予愈创甘油醚（35 mg kg⁻¹静脉注射），随后立即静脉注射阿法沙龙（1 mg kg⁻¹）诱导麻醉。在整个麻醉过程中评估心肺变量（心率、呼吸频率、脉搏血氧饱和度）和麻醉深度的临床体征。在关键时间点采集静脉血样，使用液相色谱 - 质谱联用（LC/MS）测定阿法沙龙的血浆浓度，并通过非房室药代动力学分析进行分析。麻醉诱导和恢复质量按1 - 5分进行评分（1分非常差，5分优秀）。
诱导和恢复评分的中位数（范围）分别为4（3 - 5）（良好：马缓慢且适度平稳地卧倒，极少或无强直或划水动作）和4（1 - 5）（良好：马首次尝试站立时出现一些指关节屈曲和共济失调）。监测的心肺变量在临床马麻醉预期范围内。从诱导到胸骨卧倒和从诱导到站立的平均±标准差麻醉持续时间分别为42.7±8.4分钟和47±9.6分钟。阿法沙龙的平均±标准差血浆消除半衰期（t₁/₂）、血浆清除率（Clp）和分布容积（Vd）分别为33.4分钟、37.1±11.1 mL minute⁻¹ kg⁻¹和1.6±0.4 L kg⁻¹。
2 - 羟丙基 - β - 环糊精制剂的阿法沙龙在马中可提供卧倒时间短的麻醉，其特点是诱导平稳且恢复满意。与其他物种一样，阿法沙龙在马体内可迅速从血浆中清除。
