Cullen L K, Reynoldson J A
J Vet Pharmacol Ther. 1987 Jun;10(2):134-43. doi: 10.1111/j.1365-2885.1987.tb00090.x.
Amitraz is a formamidine compound used as a topical acaricide mainly in dogs and cattle. In an initial attempt to explain some of its side-effects, the actions of amitraz were studied on the cardiovascular and respiratory systems in thiopentone/methoxyflurane-anaesthetized dogs. In separate experiments, amitraz, at doses of 1, 2 and 5 mg/kg i.v., dissolved in DMSO, increased blood pressure for 1 hour. Heart rate decreased initially then showed a dose-related return towards control values. Tidal volume, respiratory rate and respiratory minute volume all showed initial transient depression. Hyperventilation was a feature after high doses of amitraz. Cumulative doses of amitraz of 0.5, 1, 2, 5 and 10 mg/kg i.v., at intervals of 5 min, increased blood pressure. Heart rate decreased at lower doses but increased slightly after higher doses. Five minutes after injection, cardiac index had returned to control values while total peripheral resistance showed a dose-related increase. The mechanism of action of amitraz in dogs cannot be determined from these results; however, other reports have described an alpha 2-adrenoceptor agonist action of this formamidine compound.
双甲脒是一种脒类化合物，主要用作犬类和牛类的局部杀螨剂。为初步解释其一些副作用，研究了双甲脒对硫喷妥钠/甲氧氟烷麻醉犬的心血管和呼吸系统的作用。在单独的实验中，溶解于二甲基亚砜的双甲脒以1、2和5毫克/千克的静脉注射剂量，使血压升高1小时。心率最初下降，然后呈剂量相关地恢复至对照值。潮气量、呼吸频率和每分通气量均最初出现短暂抑制。高剂量双甲脒后出现过度通气。以5分钟的间隔静脉注射累积剂量为0.5、1、2、5和10毫克/千克的双甲脒，可使血压升高。较低剂量时心率下降，但较高剂量后略有升高。注射后5分钟，心脏指数恢复至对照值，而总外周阻力呈剂量相关增加。从这些结果无法确定双甲脒在犬类中的作用机制；然而，其他报告描述了这种脒类化合物的α2-肾上腺素能受体激动剂作用。
