2020 Nov 21. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan–.
ABSTRACT
Warfarin is a vitamin K antagonist used as an anticoagulant used for treatment and prevention of a variety of coagulopathic and thromboembolic disorders. While it was initially marketed as a rodenticide, it has been used as a medication for more than a half-century. Additionally, superwarfarins are now also used as pesticides and should be considered as agents that may cause potential “warfarin toxicity” and have been noted to be one hundred times as potent compared to warfarin.
Toxicity can be thought to occur in a variety of methods: 1) Intentional adult overdose; 2) Unintentional overdose/toxicity, and 3) pediatric ingestion. The intentional overdose may be the most obvious, though has been noted to be “relatively rare,” with one 25-year survey of two tertiary centers with toxicology services having a total of 22 non-pediatric intentional overdoses. Unintentional overdose or toxicity can occur through various mechanisms such as during the initial dosing phase, change in diet, interaction with other medications, and even secondary to metastatic liver disease. The initial dosing phase presents a specific timeframe of potential toxicity and risk not only due to potentially known aspects such as the patient’s specific comorbidities and diet, but also due to their genetic polymorphisms. Pediatric ingestion may result in warfarin toxicity and can occur due to exploratory ingestion of a child unknowingly taking a pill, as well as through potential Munchausen syndrome by proxy. In addition to the previously discussed methods of intoxication, there have also been reports of warfarin toxicity due to lacing superwarfarins with illicit drugs to prolong euphoric effects.