The poison center has been receiving reports across the state of people with a history of synthetic cannabinoid use presenting with severe acquired coagulopathy presumed to be secondary to long-acting coumarin rodenticides, otherwise known as superwarfarins. Her serum subsequently tests positive for brodifacoum, and her urine is positive for two popular synthetic cannabinoids. With the FFP and vitamin K1, her PT and INR rapidly correct, and her bleeding symptoms resolve over the course of the next couple of days. She is ultimately discharged on 50 mg oral vitamin K1 twice daily.

The poison center has been receiving reports across the state of people with a history of synthetic cannabinoid use presenting with severe acquired coagulopathy presumed to be secondary to long-acting coumarin rodenticides, otherwise known as superwarfarins.

Discussion

In March 2018, the Illinois Poison Center became aware of multiple patients presenting to emergency departments across the state with profoundly elevated INRs with various bleeding complaints. The aforementioned patient is actually a composite of multiple patients to illustrate the typical presentation according to our bedside experience.

Early on when working with the Illinois Department of Public Health, the common thread through these cases was synthetic cannabinoid use. This correlation was confirmed by performing a detailed interview, urine and serum testing for various popular synthetic cannabinoids, and serum testing for several long-acting anticoagulants. The case count grew rapidly to include multiple states with 165 cases and three fatalities, as was published in the May Morbidity and Mortality Weekly Report (MMWR).² Since that May report, many additional cases have presented to hospitals across multiple states.

Sporadic case reports exist of patients exposed to brodifacoum through smoking crack cocaine, marijuana, and tobacco.^3,4 There are lay press reports of police seizures of synthetic cannabinoids laced with rodenticides.⁵ However, experience with inhalational exposure to brodifacoum is limited because most previously reported cases of brodifacoum poisoning have been oral ingestions.

Coumarin rodenticides work by blocking quinone reductase and epoxide reductase to prevent the conversion of vitamin K epoxide to vitamin K hydroquinone (K1), which is required for the synthesis of activated factors II, VII, IX, and X and factors C, S, and Z. Brodifacoum is a derivative of 4-hydroxycoumarin that adds a halogenated side chain. Compared to warfarin, it features greater affinity for K1-2,3-epoxide reductase, disrupts the K1-epoxide cycle at multiple points, and causes hepatic accumulation and profoundly longer biological half-lives due to prolonged lipid solubility and enterohepatic circulation.¹