Long-acting anticoagulant overdose: Brodifacoum kinetics and optimal vitamin K dosing

Ingestion of long-acting anticoagulant rodenticides such as brodifacoum can lead to prolonged and life-threatening coagulopathy. A paucity of conflict ing information is available on brodifacoum's half-life and elimination pha rmacokinetics. In addition, the optimal dose, duration, and route of admini stration of vitamin K-1 therapy are unknown. We report the case of a 52-yea r-old man who ingested eight 43-g boxes of a rodenticide (d-Con Mouse-Prufe II; 0.005% brodifacoum; Reckitt & Colman, Wayne, NJ). This case demonstrat es that after stabilization with fresh frozen plasma, high-dose oral vitami n K-1 therapy (congruent to 7 mg/kg per 24 hours divided every 6 hours) was effective in treating brodifacoum-induced coagulopathy. The concentration of vitamin K-1 required for normal coagulation in this case was less than t he accepted value of 1 mu g/mL, which is derived from a rabbit model. In th is case, brodifacoum appears to follow zero-order elimination pharmacokinet ics. In future cases of patients with ingestions of long-acting anticoagula nts who present with coagulopathy, it may be useful to obtain serial brodif acoum concentrations to determine elimination curves to help predict the du ration of oral vitamin K-1 therapy.