Superwarfarin and Glass Ingestion with Prolonged Coagulopathy Requiring High‐Dose Vitamin K₁ Therapy

Abstract

A 23-year-old man was brought to the emergency department after eating four boxes of brodifacoum-containing rodenticide over a 4-day interval and pieces from approximately two bottles of glass over the previous 2 weeks. He was asymptomatic but his prothrombin time was markedly elevated with an international normalized ratio (INR) of 37.8. A plain abdominal film showed diffuse radiopaque foreign bodies, presumably glass, in the large and distal small intestines. Treatment for ingested glass consisted of stool softeners and bulk-forming laxatives. The patient developed mild gingival bleeding and received fresh frozen plasma (FFP) infusions and vitamin K1 orally. At a vitamin K1 dosage of 300 mg/day, the INR corrected to less than 2.0 and the patient was discharged taking that dosage. He returned 26 days later with hematuria and flank pain, and his INR was 189. He was administered FFP and packed red blood cells, and his vitamin K1 dosage was increased to 800 mg/day; his INR returned to baseline. Compliance with taking the vitamin K1, which required ingestion of 60-160 tablets/day, was a serious problem, requiring numerous follow-up calls and visits to the patient at home and work. At 5-month follow he was doing well. Compliance with large daily doses of vitamin K1 for treatment of "superwarfarin" ingestion may be poor because of the duration of treatment and large number of pills required. A more concentrated formulation may be advantageous for management of patients with brodifacoum poisoning.

A Case of Superwarfarin Intoxication without a Definitive History of Brodifacoum Exposure

“…Because superwarfarin is 100-times more potent and has a much longer half-life than warfarin, the duration of the coagulopathy is more extended and treatment is more protracted, and requires much higher doses of vitamin K. Treatment periods and vitamin K doses required vary, due to; the different amount of superwarfarin consumed, deliberate or unintentional noncompliance with vitamin K therapy, continued exposure to superwarfarin, and different superwarfarin metabolic rates. Vitamin K doses ranging between 15mg/day and 800mg/day have been reported, although in some reports showed continuous coagulopathy after being administration of 15∼50mg/day of vitamin K. 14,15) In our patient, the coagulopathy responded to 5mg/day of vitamin K for a month. Treatment is usually necessary for many months, and vitamin K dosages should target the maintenance of a normal PT.…”

Long-acting anticoagulant rodenticide poisoning: An evidence-based consensus guideline for out-of-hospital management

“…There were four case reports (levels 4 and 6) with quantifiable dose-effect information on chronic brodifacoum exposure in patients 6 years of age and older (Table 5) (18,27,62,63). The lowest dose associated with toxicity was an ingestion of 168 g of a 0.005% preparation (8.4 mg brodifacoum) over approximately 12 hours by a 25-year-old man, which resulted in severe toxicity (27).…”

Superwarfarins

“…Internal and external bleeding are the most frequent clinical signs, followed by tachycardia and hypotension, and then multiple organ failure due to substantial blood loss. The onset of the signs of poisoning may not be evident until a few days after absorption (Vogel et al, 1988;Nighoghossian et al, 1990;Swigar et al, 1990;Weitzel et al, 1990;Wilton, 1991;Ross et al, 1992;Corke, 1997;Casner, 1998;Chua and Friedenberg, 1998;Baker et al, 2002;Tsutaoka et al, 2003).…”