Intralipid: A novel frontline countermeasure for brodifacoum poisoning

描述（由申请人提供）：超级华法林是华法林（香豆素）的改良形式，具有更大的毒性和更长的作用时间。它们通过抑制维生素K的再循环，导致维生素K依赖性蛋白质（包括凝血酶原）的活性丧失，从而有效地降低整个身体的维生素K水平。凝血酶原的丧失导致全身抗凝，因此是广泛使用超华法林作为杀鼠剂和减少中风患者栓塞的基础。超级华法林是在华法林耐药性啮齿动物菌株的报告之后开发的，现在在世界各地普遍使用。在美国，报告的超级华法林中毒的临床发生率已达到每年超过16，000例，其中>90%发生在6岁以下的儿童中。虽然超级华法林中毒可以治疗，但需要长期补充维生素K，治疗的任何中断都可能导致症状复发。其他VKDP在大脑发育中发挥重要作用;这些蛋白质的减少与炎症增加、神经元损伤、髓鞘丢失和认知缺陷有关。此外，子宫内暴露于华法林对胚胎发育有不良影响，表明子宫内暴露于超级华法林可能会产生灾难性的后果。今天最常用的超级杀鼠灵是溴鼠灵（BDF）。估计的人类致命口服剂量非常低（15毫克），由于它具有高度亲脂性，它在组织中蓄积，生物半衰期超过20天。因此，即使有一个现有的治疗BDF中毒（慢性维生素K治疗），它的毒性，特别长的半衰期，相对容易获得它，以及潜在的方法阵列 由于其有害的分布（通过气溶胶扩散或直接应用于植物溶胶或食物而造成污染），使BDF成为一种严重的潜在化学威胁。在本提案中，我们将测试已获FDA批准的脂肪乳剂（LE）作为BDF中毒对策的治疗潜力。LE的输注已经用于治疗某些有毒药物过量，并且被认为部分通过清除毒素并转移到肝脏进行代谢来发挥作用。急性LE输注应能快速清除体内BDF，从而防止危及生命的凝血减少，防止中毒的长期衰弱性CNS后遗症;并防止子宫内暴露。此外，由于静脉内施用对抗措施在涉及大规模伤亡的情况下可能是不切实际的，我们已经开发了一种替代施用方法，即骨内（IO），其将LE注入骨中，使其能够快速进入血流。在本项目中，我们将优化IO LE从成年大鼠组织中消除BDF的能力。如果单次IO推注不能显著降低水平，我们将增加LE的后续IV输注。我们将描述子宫内暴露于BDF的后果，并优化LE妊娠大鼠的治疗，以最大限度地减少后期后果。本项目的主要目标是提交使用LE治疗BDF中毒的IND;由于在人体中进行测试不可行，因此在本项目的第4年，我们 将在兔子身上进行类似的研究，以符合FDA对新药动物规则的要求。我们预计LE将被证明是BDF中毒的有效治疗方法，从而提供一种机制来解决由于有意或意外原因导致的BDF大规模释放而造成的潜在损害。

DESCRIPTION (provided by applicant): Superwarfarins are modified forms of warfarin (Coumadin) with greater toxicity and longer duration of action. They potently reduce vitamin K levels throughout the body by inhibiting its recycling leading to loss of activity of Vitamin K dependent proteins including prothrombin. Loss of prothrombin leads to systemic anticoagulation, hence the basis for the widespread use of superwarfarins as rodenticides and to reduced embolisms in stroke patients. Superwarfarins were developed following reports of warfarin resistant rodent strains and are now commonly used throughout the world. Reported clinical occurrences of superwarfarin poisoning have reached over 16,000 per year in the USA, with >90% in children under age 6. Although superwarfarin poisoning can be treated it requires long term supplementation with Vitamin K, and any interruption in treatment can lead to recurrence of symptoms. Other VKDPs play important roles in brain development; and reductions in those proteins is associated with increased inflammation, neuronal damage, loss of myelin, and cognitive deficits. In addition, in utero exposure to warfarin has adverse effects on embryonic development, suggesting the in utero exposure to superwarfarins could have disastrous outcomes. The superwarfarin most commonly used today as a rodenticide is brodifacoum (BDF). The estimated fatal oral dose for humans is very low (15 mg), and because it is highly lipophilic, it accumulates in tissues with a biological half-life of over 20 days. Thu, even though there is an existing cure BDF poisoning (chronic Vitamin K treatment), its toxicity, exceptionally long half-life, the relative ease of obtaining it, and the array of potential methods for its harmful distribution (contamination by aerosol dispersal or direct application on plants sol, or food), make BDF a serious potential chemical threat. In this proposal, we will test the therapeutic potential of an already approved FDA treatment, Lipid Emulsion (LE), as a countermeasure against BDF poisoning. The infusion of LE is already used to treat certain toxic drug overdoses, and is thought to act in part by scavenging toxins and movement to the liver where they are metabolized. Acute LE infusion should offer rapid removal of BDF from the body, thereby preventing life threatening reductions in clotting, protect against long-term debilitating CNS sequelae of poisoning; and prevention of in utero exposure. In addition, since intravenous administration of a counter measure may be impractical in a scenario involving mass casualties, we have developed an alternative method of administration, namely intraosseous (IO) which infuses LE into bone where it can rapidly enter the blood stream. In this program, we will optimize the ability of IO LE to eliminate BDF from adult rat tissues. If levels are not sufficienty reduced by a single IO bolus, we will add follow up IV infusions of LE. We will characterize the consequences of in utero exposure to BDF, and optimize treatment of pregnant rats with LE to minimize those later consequences. A major goal of this project is to submit an IND for the use of LE to treat BDF poisoning; since testing in humans is not feasible, in year 4 of this project we will carry out similar studies in rabbits to match the FDA requirements under the animal rule for a new drug. We anticipate that LE will be proven to be an effective treatment for BDF poisoning, thereby providing a mechanism to address the potential damage due to a large scale release of BDF by either intentional or accidental causes.