Management of Rat Kill Poisoning (Rodenticide) with Hepamerz (Vitamin K1)
For a 21-year-old with rodenticide poisoning, the recommended initial dose of Hepamerz (Vitamin K1) is 10-25 mg intravenously, followed by high-dose oral vitamin K1 maintenance therapy (100 mg daily) for several months. 1, 2
Initial Management
- For acute rodenticide poisoning with active bleeding or severely prolonged coagulation parameters, administer 10-25 mg of Vitamin K1 intravenously by slow infusion (over 30 minutes) to rapidly correct coagulopathy 3, 1
- If the patient presents with life-threatening bleeding, consider adding prothrombin complex concentrate (PCC) or fresh frozen plasma along with the intravenous Vitamin K1 4, 1
- Monitor coagulation parameters (PT/INR) within 4-6 hours after initial treatment to assess response 5, 1
- Once stabilized, transition to high-dose oral Vitamin K1 maintenance therapy 1, 2
Maintenance Therapy
- Long-acting anticoagulant rodenticides (LAARs) require prolonged treatment with high-dose Vitamin K1 due to their extremely long half-lives 1, 2
- Administer oral Vitamin K1 at 100 mg daily, which is the most frequently used maintenance dose to suppress coagulopathy 1, 2
- Treatment duration averages 168 days (approximately 3-6 months) and should be guided by monitoring both coagulation parameters and serum LAAR concentrations 6, 1
- The maintenance dose may be gradually decreased over time but is not directly related to the toxicant concentration 7
Monitoring During Treatment
- Regular monitoring of PT/INR is essential throughout treatment 5, 6
- Normalization of INR alone is not sufficient to discontinue Vitamin K1 treatment 6
- Serum LAAR concentrations should be measured periodically, with treatment continuing until levels fall below 10 μg/L 6, 2
- After initial stabilization, monthly monitoring of brodifacoum (or other LAAR) levels can help determine the elimination half-life and guide treatment duration 2
Special Considerations
- Rebound coagulopathy is common with LAARs due to their high affinity for vitamin K epoxide reductase and long half-lives 1
- The half-life of brodifacoum (a common LAAR) ranges from 15-33 days, necessitating prolonged treatment 2
- Avoid premature discontinuation of Vitamin K1 therapy, as residual serum and tissue LAAR can cause symptom recurrence and rehospitalization 6
- Consider adjunctive therapy with cholestyramine to increase LAAR clearance in cases requiring very prolonged treatment 8
Potential Complications
- Most common bleeding sites are mucocutaneous, with hematuria being the most frequent presentation 1
- Intracranial hemorrhage is associated with the highest mortality 1
- Paradoxical thrombosis has been reported in some cases of LAAR poisoning 1
- Anaphylactic reactions can occur with intravenous administration of Vitamin K1, so administer by slow infusion over 30 minutes 5, 9