brodifacoum

Brodifacoum is a highly potent anticoagulant rodenticide in the 4-hydroxycoumarin family. It is used for rodent control because of its long-acting effects and the potential for single-dose lethality, allowing lower application frequencies than some earlier formulations. The compound acts as a vitamin K antagonist.

Mechanism of action: Brodifacoum inhibits hepatic vitamin K epoxide reductase (VKORC1), blocking the regeneration of reduced vitamin K. This disrupts the gamma-carboxylation of vitamin K–dependent clotting factors II, VII, IX, and X, as well as anticoagulant proteins C and S, leading to a coagulopathy and a tendency toward spontaneous bleeding.

Pharmacology and risk: Brodifacoum is highly lipophilic with a long biological half-life in mammals, causing effects that can persist for weeks to months after exposure. Non-target species, including pets and wildlife, are at risk, and there is potential for secondary poisoning if predators or scavengers consume poisoned rodents.

Exposure, diagnosis, and treatment: In humans and animals, signs of poisoning may include bleeding, bruising, pale mucous membranes, lethargy, or hemorrhagic manifestations, with onset potentially delayed after ingestion. Diagnosis is suggested by a markedly prolonged prothrombin time (INR) and can be confirmed by detection of brodifacoum in blood or tissues. Treatment emphasizes removal of exposure and replenishment of vitamin K1 (phytonadione) for an extended period, often weeks to months, with monitoring of coagulation parameters. Severe bleeding often requires supportive care, including transfusion.

Regulation and environmental considerations: Brodifacoum-containing products are subject to regulatory controls in many countries due to risks to non-target species and secondary poisoning. Usage guidelines aim to minimize environmental impact while controlling rodent populations.