Department of Pharmacy, Michigan Medicine, Ann Arbor, MI, USA.
Michigan Poison & Drug Information Center, Detroit, MI, USA.
Clin Toxicol (Phila). 2022 Oct;60(10):1159-1162. doi: 10.1080/15563650.2022.2116337. Epub 2022 Sep 7.
Warfarin is a widely used oral anticoagulant with established reversal guidelines in the setting of a supratherapeutic international normalized ratio (INR). Limited literature exists on managing acute warfarin overdoses in patients who are not chronically anticoagulated.
A 15-year-old male, with no indication for anticoagulation, presented to a pediatric emergency department after an acute 1,000 mg warfarin ingestion. He had no significant complaints upon presentation aside from a mild intermittent headache. His past medical history was significant for anxiety, depression, Tourette syndrome, attention deficit hyperactivity disorder, and polysubstance misuse. Computed tomography of his head was unremarkable and serum acetaminophen, salicylate, and ethanol concentrations were negative. Approximately 16 h post-ingestion, his INR was 1.9 with an increase to 3.3 by 26 h. The regional poison center was consulted and recommended, consistent with the CHEST guidelines, holding treatment with vitamin K until INR was >10 or if signs or symptoms of bleeding occurred. The patient was admitted for monitoring and by hospital day (HD) #4, his INR had risen to >11.8 at which point oral vitamin K 10 mg was administered. On HD #7, the patient was deemed stable for transfer to inpatient psychiatry after repeat INRs of 2.9 and 3.4.
Case reports have demonstrated early administration of vitamin K can temporarily lower INR and prevent detection of rebound. The CHEST warfarin reversal guidelines describe the risks and benefits with respect to bleeding and thrombosis in the non-intentional overdose patient. Application and extrapolation of these guidelines to acute overdose in patients who lack an indication for anticoagulation may or may not be warranted.
While established clinical guidance exists on reversing a supratherapeutic INR in patients chronically anticoagulated with warfarin, the risks and benefits of extrapolating this approach are unclear in those who lack an indication for anticoagulation.
华法林是一种广泛使用的口服抗凝剂，在国际标准化比值（INR）高于治疗范围的情况下有明确的逆转指南。在没有长期抗凝治疗的情况下，管理急性华法林过量的文献有限。
一名 15 岁男性，无抗凝指征，在摄入 1000mg 华法林后，到儿科急诊就诊。他在就诊时除了间歇性轻度头痛外，没有其他明显的不适。他的既往病史包括焦虑症、抑郁症、妥瑞氏综合征、注意力缺陷多动障碍和多种物质滥用。头部 CT 无明显异常，血清对乙酰氨基酚、水杨酸盐和乙醇浓度均为阴性。摄入后约 16 小时，INR 为 1.9，26 小时时升至 3.3。区域中毒中心建议根据 CHEST 指南，在 INR 大于 10 或出现出血迹象或症状时，暂不使用维生素 K 治疗。患者入院监测，入院第 4 天（HD），INR 上升至>11.8，此时给予口服维生素 K10mg。入院第 7 天，患者 INR 分别为 2.9 和 3.4，再次复查后，患者病情稳定，转至住院精神科。
病例报告表明，早期给予维生素 K 可暂时降低 INR 并防止检测到反弹。CHEST 华法林逆转指南描述了非意图性过量患者在出血和血栓形成方面的风险和益处。将这些指南应用于缺乏抗凝指征的急性过量患者，是否有必要权衡利弊。
虽然有关于逆转慢性华法林抗凝患者超高 INR 的既定临床指南，但在缺乏抗凝指征的患者中，推断这种方法的风险和益处尚不清楚。
