Pass M A, Mogg T D
Department of Physiology and Pharmacology, University of Queensland, St. Lucia, Australia.
J Vet Pharmacol Ther. 1995 Jun;18(3):210-5. doi: 10.1111/j.1365-2885.1995.tb00580.x.
Amitraz and its active metabolite BTS27271 were given intravenously to ponies and sheep at equimolar doses of 1 mg/kg and 0.68 mg/kg, respectively, and the plasma concentrations of amitraz and BTS27271 estimated at various times thereafter. Amitraz was hydrolysed to BTS27271 in both species. Amitraz was undetectable in sheep plasma after approximately 5 min but persisted in the plasma of ponies for at least 90 min. The persistence of unmetabolized amitraz in ponies may have implications for the toxicity of amitraz in that species. The primary and secondary disposition half-lives of amitraz in ponies were 2 and 39 min, respectively. BTS27271 was distributed rapidly outside the plasma in both species with a primary disposition half-life of 4.4 min in sheep and 5.9 min in ponies. The secondary disposition half-lives were 51 and 55 min, respectively. The secondary phase of the disposition of BTS27271 was similar whether BTS27271 was given directly or derived by hydrolysis from amitraz. However, significant differences were evident in the primary phase of the disposition of BTS27271. Sheep demonstrated a larger apparent volume of distribution of BTS27271 than ponies and more rapid body clearance.
将双甲脒及其活性代谢物BTS27271分别以1 mg/kg和0.68 mg/kg的等摩尔剂量静脉注射给小马和绵羊，然后在不同时间点估算双甲脒和BTS27271的血浆浓度。在这两个物种中，双甲脒均被水解为BTS27271。大约5分钟后，绵羊血浆中检测不到双甲脒，但在小马血浆中至少持续存在90分钟。未代谢的双甲脒在小马体内的持续存在可能对该物种中双甲脒的毒性有影响。双甲脒在小马体内的一级和二级处置半衰期分别为2分钟和39分钟。在这两个物种中，BTS27271均迅速分布到血浆外，在绵羊体内的一级处置半衰期为4.4分钟，在小马体内为5.9分钟。二级处置半衰期分别为51分钟和55分钟。无论BTS27271是直接给药还是由双甲脒水解产生，BTS27271处置的第二阶段都是相似的。然而，在BTS27271处置的第一阶段存在明显差异。与小马相比，绵羊体内BTS27271的表观分布容积更大，机体清除更快。
