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Toxicology – Warfarin & Superwarfarin Toxicity
Source
Warfarin is a commonly prescribed anticoagulant that works by blocking vitamin K–dependent clotting pathways. “Superwarfarins” are long-acting anticoagulant rodenticides that include agents such as brodifacoum, bromadiolone, difenacoum, and chlorophacinone. These compounds are far more potent and longer lasting than standard warfarin.
Typical Presentation
Patients may present with unexplained bleeding after accidental, intentional, or occupational exposure. Children may ingest rodenticide pellets, while adults often present later once bleeding symptoms appear.
Clinical Features
Both warfarin and superwarfarins impair blood clotting, leading to elevated PT/INR levels and bleeding manifestations such as:
Mechanism of Action
These agents inhibit vitamin K epoxide reductase, preventing regeneration of active vitamin K. This decreases production of clotting factors II, VII, IX, and X, resulting in impaired coagulation.
Management
Treatment depends on severity and timing of exposure:
Source
Warfarin is a commonly prescribed anticoagulant that works by blocking vitamin K–dependent clotting pathways. “Superwarfarins” are long-acting anticoagulant rodenticides that include agents such as brodifacoum, bromadiolone, difenacoum, and chlorophacinone. These compounds are far more potent and longer lasting than standard warfarin.
Typical Presentation
Patients may present with unexplained bleeding after accidental, intentional, or occupational exposure. Children may ingest rodenticide pellets, while adults often present later once bleeding symptoms appear.
Clinical Features
Both warfarin and superwarfarins impair blood clotting, leading to elevated PT/INR levels and bleeding manifestations such as:
- Easy bruising and ecchymoses
- Nosebleeds and gum bleeding
- Bloody stools or vomit
- Blood in urine
- Heavy menstrual bleeding
- Pulmonary or internal hemorrhage
Mechanism of Action
These agents inhibit vitamin K epoxide reductase, preventing regeneration of active vitamin K. This decreases production of clotting factors II, VII, IX, and X, resulting in impaired coagulation.
Management
Treatment depends on severity and timing of exposure:
- Activated charcoal and whole bowel irrigation may be considered after large recent ingestions.
- Coagulation studies (especially PT/INR) should be closely monitored.
- Active bleeding is treated with vitamin K and fresh frozen plasma (FFP) or clotting factor concentrates.
- Superwarfarin poisoning may require high-dose oral vitamin K therapy for weeks to months to maintain a normal INR.
- Superwarfarins have much longer effects than prescription warfarin.
- Elevated PT/INR is a hallmark laboratory finding.
- Severe bleeding may occur spontaneously.
- Long-term vitamin K therapy is often required after rodenticide exposure.
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