The emerging threat of superwarfarins: history, detection, mechanisms, and countermeasures

Deploying Validated Mass Spectrometry for Frontline Detection and Treatment of Human Poisoning by Long-Acting Anticoagulant Rodenticides

Derived from the same natural anticoagulant as warfarin (dicoumarol), long-acting anticoagulant rodenticides (LAARs) or superwarfarins have much longer half-lives in human blood than warfarin (weeks instead of hours) and are more potent inhibitors of the same enzyme, vitamin K epoxide reductase component 1. While used effectively worldwide as rodenticides, LAARs can elicit severe, protracted, life-threatening coagulopathy in humans at blood concentrations >10 ng/mL leading to numerous accidental and intentional poisonings annually. To facilitate timely identification and quantitative analysis of LAARs in patients presenting unexplained severe, protracted, life-threatening coagulopathy, several analytical methods have been developed, all of which are based on electrospray liquid chromatography-mass spectrometry (LC-MS). In this perspective, we evaluated and compared these LC-MS methods in terms of validation, simultaneous detection of multiple LAARs, measurement of individual stereoisomers, and clinical applications.

Short-term treatment with cholestyramine increases long-acting anticoagulant rodenticide clearance from rabbits without affecting plasma vitamin K1 levels or blood coagulation

Administration of high-dose vitamin K1 (VK1) overcomes coagulopathy and bleeding elicited by acute poisoning with long-acting anticoagulant rodenticides (LAARs). However, long-term (months) treatment is required due to long LAAR biological half-lives that may lead to poor compliance and recurrent coagulopathy. The half-lives of LAARs are extended by slow metabolism, and similar to warfarin, are thought to undergo enterohepatic recirculation. We now show that treatment with the bile acid sequestrant cholestyramine (CSA) administered concomitantly with VK1 decreases plasma LAAR levels and increases LAAR fecal excretion. Daily CSA treatment for 14 days did not reduce plasma VK1 levels, or increase prothrombin time. Collectively, these data show that CSA accelerates LAAR clearance from rabbits without adverse effects on VK1 anticoagulation, and could provide an additional therapeutic option for treatment of LAAR poisoning.

Active monitoring of long-eared owl (Asio otus) nestlings reveals widespread exposure to anticoagulant rodenticides across different agricultural landscapes

The widespread use of anticoagulant rodenticides (ARs) poses a worldwide threat to farmland wildlife. These compounds accumulate in tissues of both target and non-target species, potentially endangering both direct consumers and their predators. However, investigations on ARs in blood of free-ranging predatory birds are rare. Here, the long-eared owl (Asio otus) has been used as a model predator to assess AR exposure in different agricultural landscapes from a Mediterranean semiarid region. A total of 69 owlets from 38 nests were blood-sampled over 2021 and 2022, aiming to detect AR residues and explore factors that determine their exposure, such as land uses. In addition, prothrombin time (PT) test was conducted to assess potential effects of AR contamination. Overall, nearly all the samples (98.6 %) tested positive for at least one compound and multiple ARs were found in most of the individuals (82.6 %). Among the ARs detected, flocoumafen was the most common compound (88.4 % of the samples). AR total concentration (ΣARs) in blood ranged from 0.06 to 34.18 ng mL-1, detecting the highest levels in the most intensively cultivated area. The analysis of owl pellets from 19 breeding territories showed relevant among-site differences in the contribution of rodents and birds into the diet of long-eared owls, supporting its high dietary plasticity and indicating AR presence at multiple trophic levels. Moreover, a positive and significant correlation was found between ΣARs and PT (Rho = 0.547, p < 0.001), which demonstrates the direct effect of ARs on free-living nestlings. Our results provide a preliminary overview of AR exposure in a little-studied owl species inhabiting agricultural and rural landscapes. Despite the low detected levels, these findings indicate widespread exposure -often to multiple compounds- from early life stages, which raises concern and draws attention to an ongoing and unresolved contamination issue.

Exposure assessment of anticoagulant rodenticides in the liver of red foxes (Vulpes vulpes) in Slovenia

The study deals with the environmental residues of anticoagulant rodenticides (ARs) in Slovenia to evaluate the toxicological risk of secondary poisoning of red foxes (Vulpes vulpes) as representatives of non-target wildlife, and in relation to the investigated use patterns of ARs and specific local parameters in Slovenia. From 2019 to 2022, 148 liver tissue samples of adult red foxes were collected from almost all state geographical regions. The samples were extracted with methanol/water (2:1, v/v), cleaned-up using a solid supported liquid-liquid extraction, and measured by liquid chromatography-electrospray tandem mass spectrometry (LC-ESI-MS/MS) with reporting limits of 0.5 to 5.0 ng/g. Residues of at least one rodenticide were detected in 77.7 % of the samples. The second generation ARs of bromadiolone, brodifacoum and difenacoum were the most frequently found, appearing in 75.0, 51.4, and 18.9 % of the samples, respectively. Concentrations of pooled ARs ranged from 1.5 to 2866.5 ng/g with mean and median values of 601.4 and 350.2 ng/g, respectively. We determined bromadiolone and brodifacoum at concentrations of ≥800 ng/g in 10.8 and 10.1 % of the samples, and 1.4 and 0.7 % of the samples contained residues >2000 ng/g, respectively. These concentrations are much higher than those found in comparable studies in Europe and elsewhere in the world. Residues of ARs were detected in all monitored statistical regions of Slovenia, with higher concentrations in the eastern parts of the country. First generation ARs were found in only 9.5 % of samples, and residues were below 10 ng/g with one exception (coumatetralyl with 55 ng/g). The results of the study indicate a serious toxicological risk for red foxes in Slovenia as part of the Western Balkans, and will contribute to the growing body of knowledge about the protection of European ecosystems, as wildlife is not limited by national borders.

Persistent Coagulopathy After Synthetic Cannabinoid Use

Synthetic cannabinoids (SCs) are chemical compounds created and manufactured, without quality control standards or requirements, to mimic tetrahydrocannabinol (THC). They are widely available in the USA, and they are sold under various brand names, including "K2" and "spice." Many adverse effects have been attributed to SCs, but most recently, they have also been associated with bleeding. There have been reported cases around the globe of SCs contaminated with long-acting anticoagulant rodenticide (LAAR) or superwarfarins. They are developed from compounds such as bromethalin, brodifacoum (BDF), and dicoumarol. LAAR exhibits their mechanism as a vitamin K antagonist inhibiting vitamin K 2,3-epoxide reductase, preventing activation of vitamin K1 (phytonadione). Therefore, reducing the activation of clotting factors II, VII, IX, and X and proteins C and S. In contrast to warfarin, BDF has an extremely long-acting biological half-life of 90 days due to minimal metabolism and limited clearance. Here, we report a 45-year-old male who presented to the emergency room with a 12-day history of gross hematuria and mucosal bleeding without previous history of coagulopathy and recurrent SCs use.

Structural and cellular basis of vitamin K antagonism

Vitamin K antagonists (VKAs), such as warfarin, are oral anticoagulants widely used to treat and prevent thromboembolic diseases. Therapeutic use of these drugs requires frequent monitoring and dose adjustments, whereas overdose often causes severe bleeding. Addressing these drawbacks requires mechanistic understandings at cellular and structural levels. As the target of VKAs, vitamin K epoxide reductase (VKOR) generates the active, hydroquinone form of vitamin K, which in turn drives the γ-carboxylation of several coagulation factors required for their activity. Crystal structures revealed that VKAs inhibit VKOR via mimicking its catalytic process. At the active site, two strong hydrogen bonds that facilitate the catalysis also afford the binding specificity for VKAs. Binding of VKAs induces a global change from open to closed conformation. Similar conformational change is induced by substrate binding to promote an electron transfer process that reduces the VKOR active site. In the cellular environment, reducing partner proteins or small reducing molecules may afford electrons to maintain the VKOR activity. The catalysis and VKA inhibition require VKOR in different cellular redox states, explaining the complex kinetics behavior of VKAs. Recent studies also revealed the mechanisms underlying warfarin resistance, warfarin dose variation, and antidoting by vitamin K. These mechanistic understandings may lead to improved anticoagulation strategies targeting the vitamin K cycle.

Retrospective analysis of clinical characteristics of and treatment strategies for patients with long-acting anticoagulant rodenticide poisoning

OBJECTIVE

Long-acting anticoagulant rodenticide (LAAR) poisoning remains a serious public health problem. The aim of this study was to explore the clinical characteristics of different LAARs and a method of making a decision on the VK1 treatment course and the time to stop VK1 treatment safely.

METHOD

This retrospective study compared the clinical characteristics of two LAARs poisoning patients and used multivariate regression method to explore the relationship between blood LAAR concentration and vitamin K1 dose/treatment time.

RESULT

A total of 115 patients with LAAR poisoning were included in this study after screening. Of these, 50 patients attempted to commit suicide. The median LAAR concentration of the patients at admission was 409 (157-1174) ng/mL, and the VK1 treatment duration was 14 (8-34) days. The total VK1 treatment time in patients with LAAR poisoning was positively correlated with admission LAAR concentration. During the maintenance treatment period, the VK1 dosage was positively correlated with blood LAAR concentration.

CONCLUSION

Low dose of VK1 during the maintenance period is indicative of the blood LAAR concentration being relatively low. This provides a basis for judging the LAAR content in the body during the maintenance treatment period.

Methods in food defence: a simple and robust screening for 16 rodenticides by LC-DAD/FLD following QuEChERS-based extraction

Fortunately, the intentional contamination of food or water supplies out of criminal or terroristic motivation is a rather rare event. However, in the face of asymmetric warfare and as the consequences of such an event would be severe, food defence as a necessary supplement to food safety is gaining increased attention. While some progress has been made in developing non-target detection devices, the contamination of food or water supplies using readily available rodenticides may still be revealed only by complex analytical techniques. The presented study therefore aimed to develop a quick and easy screening method for the detection of sixteen globally common rodenticides in foodstuffs. Robust operation with limited personnel and analytical resources were one benchmark to be met by the method, which uses a slightly modified QuEChERS (quick, easy, cheap, effective, rugged, safe) protocol for dispersive solid-phase extraction and subsequent ion-pair chromatography with diode-array and fluorescence detection. Quantification limits were as low as 5 µg/kg with satisfying bias (recovery) and repeatability rates of 77 to 117% and 1.8 to 17.1%, respectively. The developed method provides reliable and robust detection of these deadly poisons at toxic concentrations, which was demonstrated impressively in an improvised assault scenario.

Superwarfarin poisoning: challenges still remain

Superwarfarin (long-acting anticoagulant rodenticide) poisoning should be suspected in unexplained bleeding with prolonged prothrombin time, especially in the absence of another explanation. Diagnosis and treatment of this intoxication remain a challenge as the direct analysis of superwarfarin in serum is not always possible. Therefore, toxin bioavailability remains unknown and close monitoring and treatment for long periods are required to avoid serious bleeding complications. Here, we discuss a case of suspected superwarfarin poisoning to highlight the challenges in early diagnosis and the challenges we encountered in treatment management and ensuring compliance for long periods.

Methanol Intoxication After Suicidal Ingestion of Liquid Rodenticides: A Report of Two Cases

Methanol is highly toxic to humans. Although methanol poisoning is not uncommon in developing countries, poisoning caused by ingestion of commercial products containing undeclared methanol has rarely been reported. Herein, we describe two patients who experienced methanol poisoning after ingestion of liquid rodenticides. A 39-year-old woman attempted suicide by ingesting liquid rodenticide which contained bromadiolone. She developed high anion gap metabolic acidosis and coagulopathy. Methanol poisoning was confirmed 20 hours later. She received oral ethanol therapy and hemodialysis. Vitamin K1 was also administered. She did not develop any hemorrhage or visual impairment and was discharged after 11 days. The rodenticide sample was tested and found to have a methanol concentration of 324 g/L. In another case, a 62-year-old man ingested the same brand of rodenticide. Laboratory data showed mild metabolic acidosis with an increased osmol gap, suggestive of methanol poisoning. He received hemodialysis and eventually recovered without sequelae. Liquid rodenticide may contain methanol as a solvent. Ingestion of a methanol-containing commercial product without a clear label can result in a considerable delay in diagnosis and management. Methanol poisoning should be considered for patients who present with unexplained metabolic acidosis following exposure to liquid rodenticides or other liquid commercial products.

The Public Health Response to a Large Poisoning Outbreak Involving an Illicit Substance: Synthetic Cannabinoids Contaminated With a Long-Acting Anticoagulant Rodenticide, Illinois, March-July, 2018

During March-July 2018, the Illinois Department of Public Health responded to an acute outbreak of severe coagulopathy among patients with recent synthetic cannabinoid use. Toxicological testing indicated that cases were exposed to brodifacoum, a long-acting anticoagulant rodenticide. A total of 174 confirmed and probable cases, including 5 deaths, were linked to this outbreak. On the basis of the experience of responding to this complex outbreak, we recommend several steps for consideration to improve health department preparation for acute outbreaks involving illicit substances including strengthening communication between public health and law enforcement agencies, reviewing legal authority to investigate noninfectious acute disease outbreaks, continuing strong partnerships with state poison control centers, partnering with substance abuse and mental health agencies to provide services to patients, and determining health department ability to rapidly enter into public-private partnership agreements.

Chiral liquid chromatography-tandem mass spectrometry analysis of superwarfarin rodenticide stereoisomers - Bromadiolone, difenacoum and brodifacoum - In human plasma

Superwarfarins are second-generation long-acting anticoagulant rodenticides that can cause unintended human and wildlife toxicity due, in part, to their prolonged half-lives. Commercially available superwarfarin rodenticides are synthesized as racemates with two asymmetric carbons, producing four stereoisomers. To support studies of human plasma half-lives of individual superwarfarin stereoisomers, a method was developed based on LC-MS/MS to separate and quantify stereoisomers of the commercially important superwarfarins bromadiolone, difenacoum and brodifacoum. Human plasma samples were prepared using protein precipitation and centrifugation. Chiral-phase HPLC separation was carried out on-line with tandem mass spectrometric quantitative analysis of the eluting stereoisomers using selected-reaction monitoring with positive ion electrospray on a triple quadrupole mass spectrometer. All four stereoisomers of each superwarfarin were resolved within 12.5 min with calibration curves spanning 2-3 orders of magnitude and lower limits of quantitation between 0.87 and 2.55 ng/mL. This method was used to determine the half-lives of superwarfarin stereoisomers in plasma from patients who had inhaled synthetic cannabinoid products contaminated with superwarfarins. These data may be used to guide the development of safer next generation anticoagulant rodenticides stereoisomers.

Acute toxic encephalopathy following bromadiolone intoxication: a case report

Background

Clinically, bromadiolone poisoning is characterized by severe bleeding complications in various organs and tissues. Bromadiolone-induced toxic encephalopathy is extremely rare. Here, we report a special case of bromadiolone-induced reversible toxic encephalopathy in a patient who had symmetrical lesions in the deep white matter.

Case presentation

A 23-year-old woman mainly presented with dizziness, fatigue, alalia and unsteady gait after the ingestion of bromadiolone. The laboratory examinations showed normal coagulation levels. Brain magnetic resonance imaging (MRI) showed apparent diffusion restriction in the bilateral deep white matter. The clinical manifestations and MRI alterations were reversible within one month of treatment with vitamin K. The neuropsychological assessment showed no neurodegenerative changes at the 2-year follow-up.

Conclusion

With the increased use of bromadiolone as a rodenticide, more cases of ingestion have been reported annually over the past several years. Bromadiolone-induced toxic encephalopathy has no special clinical manifestations and is potentially reversible with timely treatment. Because of the reversible restricted diffusion on diffusion-weighted images (DWI) and low apparent diffusion coefficient (ADC) values, transient intramyelinic cytotoxic oedema is thought to be the cause rather than persistent ischaemia. The underlying pathophysiological mechanism is still unknown and may be coagulant-independent. This clinical case extends the current knowledge about neurotoxicity in cases of bromadiolone poisoning and indicates that MRI is useful for the early detection of bromadiolone-induced toxic encephalopathy.

Biomarkers Potency to Monitor Non-target Fauna Poisoning by Anticoagulant Rodenticides

The widespread use of pesticides to control agricultural pests is a hot topic on the public scene of environmental health. Selective pest control for minimum environmental impact is a major goal of the environmental toxicology field, notably to avoid unintended poisoning in different organisms. Anticoagulant rodenticides cause abnormal blood coagulation process; they have been widely used to control rodents, allowing inadvertent primary and secondary exposure in domestic animals and non-target predatory wildlife species through direct ingestion of rodenticide-containing bait or by consumption of poisoned prey. To report toxic effect, the most common approach is the measurement of liver or plasma residues of anticoagulant rodenticides in dead or intoxicated animals showing clinical symptoms. However, one major challenge is that literature currently lacks a hepatic or plasma concentration threshold value for the differentiation of exposure from toxicity. Regarding the variation in pharmacology properties of anticoagulant rodenticides inter- and intra-species, the dose-response relationship must be defined for each species to prejudge the relative risk of poisoning. Beyond that, biomarkers are a key solution widely used for ecological risk assessment of contaminants. Since anticoagulant rodenticides (AR) have toxic effects at the biochemical level, biomarkers can serve as indicators of toxic exposure. In this sense, toxicological knowledge of anticoagulant rodenticides within organisms is an important tool for defining sensitive, specific, and suitable biomarkers. In this review, we provide an overview of the toxicodynamic and toxicokinetic parameters of anticoagulant rodenticides in different animal species. We examine different types of biomarkers used to characterize and differentiate the exposure and toxic effects of anticoagulant rodenticide, showing the strengths and weaknesses of the assays. Finally, we describe possible new biomarkers and highlight their capabilities.

Effects of vitamin K1 treatment on plasma concentrations of long-acting anticoagulant rodenticide enantiomers following inhalation of contaminated synthetic cannabinoids

Background: An outbreak of synthetic cannabinoid (SC)-associated coagulopathy and bleeding in Illinois, USA was determined to be due to inhalation of SC contaminated with brodifacoum (BDF), difenacoum (DiF), and bromadiolone (BDL), highly potent long-acting anticoagulant rodenticides (LAARs). Treatment with high-dose vitamin K1 (VK1) prevented mortality; however, plasma LAAR levels were not measured risking recurrence of coagulopathy and bleeding due to premature discontinuation. The goal of this study was to determine if plasma LAAR levels were reduced following standard of care treatment to normalize coagulopathy.Methods: Blood samples were collected from a cohort of 32 patients, and ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) analysis used to quantify plasma LAAR levels including enantiomers.Results: BDF was detected in 31 samples; 30 also contained DiF and 18 contained BDL. Initial plasma levels were 581 ± 87, 11.0 ± 1.9, and 14.9 ± 5.9 ng/mL for BDF, DiF, and BDL, respectively (mean ± SE). At discharge plasma, BDF levels remained elevated at 453 ± 68 ng/mL. Plasma half-lives for BDF, DiF, and BDL were 7.5 ± 1.3, 7.2 ± 1.9, and 1.8 ± 0.3 days, respectively. The half-life for trans-BDF enantiomers (5.7 ± 0.8 days) was shorter than for cis-enantiomers (7.6 ± 1.9 days). BDF half-lives were shorter, and coagulopathy normalized faster in patients receiving intravenous VK1 as compared to oral VK1. Patients prescribed VK1 at discharge had fewer re-admittances.Conclusions: These results demonstrate that plasma LAAR levels at discharge were elevated in poisoned patients despite normal coagulation, and that the route of VK1 administration affected LAAR pharmacokinetics and INR normalization. We propose plasma LAAR levels and coagulation be monitored concomitantly during follow-up of patients with LAAR poisoning. KEY POINTSIn patients treated with high-dose vitamin K1 for LAAR poisoning, plasma levels remained 40-fold above safe levels upon discharge from hospital.LAAR half-lives, normalization of coagulopathy, and readmittances were reduced by treatment with intravenous vitamin K1.

Separation and Quantification of Superwarfarin Rodenticide Diastereomers-Bromadiolone, Difenacoum, Flocoumafen, Brodifacoum, and Difethialone-in Human Plasma

BACKGROUND

Superwarfarins, second-generation long-acting anticoagulant rodenticides, are 4-hydroxycoumarin analogues of warfarin that contain a large hydrophobic side chain. These compounds contain two chiral centers and are synthesized for commercial use as two pairs of diastereomer.

OBJECTIVE

To support studies of superwarfarin pharmacokinetics and other efforts to improve clinical care for poisoning victims, a quantitative assay was developed for the measurement of diastereomer of bromadiolone, difenacoum, flocoumafen, brodifacoum, and difethialone in human plasma.

METHOD

Based on ultrahigh-pressure liquid chromatography-tandem mass-spectrometry (UHPLC-MS/MS), this method was validated according to U.S. Food and Drug Administration (FDA) guidelines. Sample preparation involved simple protein precipitation followed by reversed phase UHPLC, which resolved all five pairs of cis/trans diastereomer in less than 10 min. Superwarfarins were measured using negative ion electrospray followed by selected-reaction monitoring on a triple quadrupole mass spectrometer.

RESULTS

Calibration curves covered 3-4 orders of magnitude with linear regression coefficients of >0.999. The lower limits of quantitation were from 0.013 to 2.41 ng/mL, and intra-day and inter-day accuracy and precision coefficients of variation were <12%.

CONCLUSIONS

A 10-min UHPLC-MS/MS assay was developed and validated for the separation and quantitative analysis of the pairs of diastereomer of five superwarfarins in human plasma.

HIGHLIGHTS

This method was used to identify and measure superwarfarins and their cis/trans diastereomers in plasma obtained from patients treated for coagulopathy following consumption of contaminated synthetic cannabinoid products.

Disseminated Intravascular Coagulopathy Secondary to Unintentional Brodifacoum Poisoning via Synthetic Marijuana

Recent evidence demonstrates a rising epidemic of unintentional brodifacoum poisoning associated with synthetic cannabinoid use. Synthetic cannabinoid use is on the rise because of its inexpensiveness as well as difficulty to screen and regulate. We present a rare case of severe coagulopathy and cardiac arrest secondary to synthetic cannabinoid use complicated by brodifacoum toxicity.

In silico evaluation of pesticides as potential modulators of human DNA methyltransferases

DNA methylations are carried out by DNA methyltransferases (DNMTs) that are key enzymes during gene expression. Many chemicals, including pesticides, have shown modulation of epigenetic functions by inhibiting DNMTs. In this work, human DNMTs were evaluated as a potential target for pesticides through virtual screening of 1038 pesticides on DNMT1 (3SWR) and DNMT3A (2QRV). Molecular docking calculations for DNMTs-pesticide complexes were performed using AutoDock Vina. Binding-affinity values and contact patterns were employed as selection criteria of pesticides as virtual hits for DNMTs. The best three DNMT-pesticides complexes selected according to their high absolute affinity values (kcal/mol), for both DNMT1 and DNMT3A, were flocoumafen (-12.5; -9.9), brodifacoum (-12.4; -8.4) and difenacoum (-12.1; -8.7). These chemicals belong to second-generation rodenticides. The most frequent predicted interacting residues for DNMT1-pesticide complexes were Trp1170A, Phe1145A, Asn1578A, Arg1574A and Pro1225A; whereas for DNMT3A those were Arg271B, Lys740A, and Glu303B. These results suggest that rodenticides used for pest control are potential DNMT ligands and therefore, may modulate DNA methylations. This finding has important environmental and clinical implications, as epigenetic pathways are critical in many biochemical processes leading to diseases.

Superwarfarin (Long-Acting Anticoagulant Rodenticides) Poisoning: from Pathophysiology to Laboratory-Guided Clinical Management

Superwarfarins are long-acting anticoagulant rodenticides developed from warfarin. The mechanism of action is by inhibition of vitamin K epoxide reductase, resulting in the inability of the body to recycle vitamin K. Deficiency of vitamin K thereafter leads to inability for the body to synthesise vitamin K-dependent coagulation factors, factor II, VII, IX, and X, leading to prolonged prothrombin time. Due to the bulky aromatic sidechains, superwarfarins have a much longer half-life when compared to warfarin, and exposure to superwarfarins results in a prolonged period of anticoagulation which can result in clinical bleeding. Diagnosis is straightforward in patients with known history of superwarfarin exposure but has proved difficult for patients who did not report superwarfarin intake. Superwarfarin poisoning should therefore be suspected in all patients with unexplained prolongation of prothrombin time, and can be confirmed by their detection in serum. Treatment for superwarfarin poisoning includes rapid correction of factor deficiencies with either 4-factor prothrombin complex concentrate or fresh frozen plasma in patients with active bleeding, and high dose vitamin K therapy given multiple times per day for a prolonged period of weeks to months.

Potential Health Risk to Humans Related to Accumulation of Brodifacoum and Bromadiolone in the Wheat Grown on Rodenticide Contaminated Soil

The aim of this study was to determine in a model experiment the potential residues of bromadiolone and brodifacoum in the wheat grown on soil treated with these rodenticides and to compare them with the respective acceptable daily intake (ADI) in order to obtain information lacking in the scientific literature. The study focused on the level of residues of chronic rodenticides Broder G, with the active ingredient brodifacoum, and DERATION G, with the active ingredient bromadiolone, in wheat (Triticum spp.). The preparations were used in the form of granular bait. In the wheat grown on the soil treated with 100 g.m−2 of the preparation BRODER G, the brodifacoum residues ranged from 0.012 to 0.0218 mg.kg−1, while the treatment of soil with 500 g.m−2 resulted in residues ranging between 0.0344 and 0.0436 mg.kg−1. When using the preparation DE-RATION G, bromadiolone residues ranged between 0.012 and 0.018 mg.kg−1 after the treatment of soil with 100 g.m−2 and between 0.030 and 0.0428 mg.kg−1 after the treatment with 500 g.m−2. We observed that the acceptable daily intake was exceeded significantly in all of the cases and the residual levels depended on the rodenticide dose. In the case of brodifacoum, the ADI was exceeded more than 700-fold at a dose of 100 g.m−2 and more than 1400-fold at a dose of 500 g.m−2 of soil. With bromadio-lone, the ADI was exceeded 150-fold at a dose of 100 g.m−2 and more than 350-fold at a dose of 500 g.m−2. This indicates the risk to consumers from such crops.

Synthetic cannabinoid-associated coagulopathy secondary to long-acting anticoagulant rodenticides: Observational case series and management recommendations

Synthetic cannabinoids have become increasingly popular drugs of abuse due to low cost and inability to detect these substances on routine drug screenings. In the United States, incidence of synthetic cannabinoid contamination with long-acting anticoagulant rodenticides (LAARs) resulting in coagulopathy and bleeding complications has been described.We sought to describe the natural history, management approach, and outcomes of bleeding secondary to synthetic cannabinoid-associated LAAR toxicity in an observational case series of patients evaluated at an urban academic medical system.We conducted an observational study of patients with suspected exposure to LAAR-contaminated synthetic cannabinoids and associated bleeding treated within the Johns Hopkins Health System.In this 16 subject cohort, hematuria was the most common bleeding symptom at presentation. The majority of the cohort (75%) had international normalized ratio (INR) > 9.6 at presentation. Of the 13 patients with brodifacoum testing, 12/13 (92%) were positive. Twelve patients (75%) had at least 1 INR value below 2 within 24 hours of the first INR measurement. Of this cohort, 1/16 (6%) died in hospital. The median length of hospital stay was 4 days, (interquartile range = 3-6). The average cost of pharmacological treatment for coagulopathy during inpatient hospitalization was $5300 (range, $2241-$8086).In patients presenting with unexplained coagulopathy it is important for emergency department providers to consider LAAR intoxication and consider formal testing for brodifacoum to assist with treatment planning. Use of a standardized management algorithm including intravenous/oral vitamin K, judicious use of blood products and close laboratory monitoring is essential to optimizing outcomes.

Adherence to Long-Term Follow-Up of Patients with Life-Threatening, Inhaled Synthetic Cannabinoids-Associated Coagulopathy in Chicago

A large-scale outbreak of life-threatening, inhaled synthetic cannabinoids (Spice/K2)-associated coagulopathy with bleeding complications was recently reported in Illinois. The causative agents were brodifacoum, difenacoum, and bromadiolone, potent, long-acting, 4-hydroxycoumarin anticoagulant rodenticides (LAAR) that were mixed with Spice/K2 products procured and then inhaled by the victims. We report on 3 poisoned patients who reside in underserved, socioeconomically disadvantaged neighborhoods of Chicago that were admitted and treated successfully at two inner-city, tertiary care hospitals in Chicago. The patients were discharged from the hospitals on daily long-term high-dose oral vitamin K₁ (VK₁), provided free of charge. However, 2 patients were lost to follow-up prior to safe discontinuation of oral VK₁ therapy. The third patient was treated and followed successfully for 7 months when VK₁ was discontinued. We conclude that prolonged oral VK₁ therapy and follow-up of acute, life-threatening LAAR poisoning are variable and present challenges to healthcare providers. Appropriate practice guidelines to improve patient access and adherence to daily high-dose oral VK₁ therapy and follow-up should be developed and implemented.

An Outbreak of Synthetic Cannabinoid-Associated Coagulopathy in Illinois

BACKGROUND

In March and April 2018, more than 150 patients presented to hospitals in Illinois with coagulopathy and bleeding diathesis. Area physicians and public health organizations identified an association between coagulopathy and synthetic cannabinoid use. Preliminary tests of patient serum samples and drug samples revealed that brodifacoum, an anticoagulant, was the likely adulterant.

METHODS

We reviewed physician-reported data from patients admitted to Saint Francis Medical Center in Peoria, Illinois, between March 28 and April 21, 2018, and included in a case series adult patients who met the criteria used to diagnose synthetic cannabinoid-associated coagulopathy. A confirmatory anticoagulant poisoning panel was ordered at the discretion of the treating physician.

RESULTS

A total of 34 patients were identified as having synthetic cannabinoid-associated coagulopathy during 45 hospitalizations. Confirmatory anticoagulant testing was performed in 15 of the 34 patients, and superwarfarin poisoning was confirmed in the 15 patients tested. Anticoagulant tests were positive for brodifacoum in 15 patients (100%), difenacoum in 5 (33%), bromadiolone in 2 (13%), and warfarin in 1 (7%). Common symptoms at presentation included gross hematuria in 19 patients (56%) and abdominal pain in 16 (47%). Computed tomography was performed to evaluate abdominal pain and revealed renal abnormalities in 12 patients. Vitamin K₁ (phytonadione) was administered orally in all 34 patients and was also administered intravenously in 23 (68%). Red-cell transfusion was performed in 5 patients (15%), and fresh-frozen plasma infusion in 19 (56%). Four-factor prothrombin complex concentrate was used in 1 patient. One patient died from complications of spontaneous intracranial hemorrhage.

CONCLUSIONS

Our data indicate that superwarfarin adulterants of synthetic cannabinoids can lead to clinically significant coagulopathy. In our series, in most of the cases in which the patient presented with bleeding diathesis, symptoms were controlled with the use of vitamin K₁ replacement therapy. The specific synthetic cannabinoid compounds are not known.

VKORC1L1, An Enzyme Mediating the Effect of Vitamin K in Liver and Extrahepatic Tissues

Vitamin K is an essential nutrient involved in the regulation of blood clotting and tissue mineralization. Vitamin K oxidoreductase (VKORC1) converts vitamin K epoxide into reduced vitamin K, which acts as the co-factor for the γ-carboxylation of several proteins, including coagulation factors produced by the liver. VKORC1 is also the pharmacological target of warfarin, a widely used anticoagulant. Vertebrates possess a VKORC1 paralog, VKORC1-like 1 (VKORC1L1), but until very recently, the importance of VKORC1L1 for protein γ-carboxylation and hemostasis in vivo was not clear. Here, we first review the current knowledge on the structure, function and expression pattern of VKORC1L1, including recent data establishing that, in the absence of VKORC1, VKORC1L1 can support vitamin K-dependent carboxylation in the liver during the pre- and perinatal periods in vivo. We then provide original data showing that the partial redundancy between VKORC1 and VKORC1L1 also exists in bone around birth. Recent studies indicate that, in vitro and in cell culture models, VKORC1L1 is less sensitive to warfarin than VKORC1. Genetic evidence is presented here, which supports the notion that VKORC1L1 is not the warfarin-resistant vitamin K quinone reductase present in the liver. In summary, although the exact physiological function of VKORC1L1 remains elusive, the latest findings clearly established that this enzyme is a vitamin K oxidoreductase, which can support γ-carboxylation in vivo.

The Long-Lasting Rodenticide Brodifacoum Induces Neuropathology in Adult Male Rats

Superwarfarins are very long-lasting rodenticides effective in warfarin-resistant rodents at extremely low doses. The consequences of chronic superwarfarin levels in tissues, due to biological half-lives on the order of 20 days, have not been examined. We now characterized the neurological effects of brodifacoum (BDF), one of the most widely used superwarfarins, in adult male Sprague Dawley rats. Dosing curves established the acute oral lethal dose for BDF as 221 ± 14 μg/kg. Measurement of tissue BDF levels showed accumulation throughout the body, including the central nervous system, with levels diminishing over several days. Immunocytochemical staining showed that both astrocyte and microglial activation was increased 4 days after BDF administration, as were levels of carbonylated proteins, and neuronal damage assessed by fluorojade B staining. Direct toxic effects of BDF on neurons and glia were observed using enriched cultures of cerebellar neurons and cortical astrocytes. Proteomic analysis of cerebellar lysates revealed that BDF altered expression of 667 proteins in adult rats. Gene ontology and pathway analysis identified changes in several functional pathways including cell metabolism, mitochondria function, and RNA handling with ribosomal proteins comprising the largest group. In vitro studies using primary astrocytes showed that BDF suppressed de novo protein synthesis. These findings demonstrate that superwarfarin accumulation increases indices of neuroinflammation and neuropathology in adult rodents, suggesting that methods which minimize BDF toxicity may not address delayed neurological sequelae.

Retrospective Study of the Characteristics of Anticoagulant-Type Rodenticide Poisoning in Hong Kong

INTRODUCTION

Warfarin- and superwarfarin-type anticoagulants are commonly used as rodenticides. Exposure to these agents, especially superwarfarins with long-acting anticoagulant effect, can cause life-threatening coagulopathy in humans. Most superwarfarin poisoning cases had an obvious history of exposure, though occult cases without exposure history have also been reported. The current study aims to examine anticoagulant-type rodenticide poisoning in Hong Kong and to identify the similarities and differences between patients with known exposure history and those whose exposure is recognized only through laboratory testing.

METHODS

The present study was conducted in a tertiary referral clinical toxicology laboratory in Hong Kong. This was a retrospective cohort study of all patients with biochemically confirmed anticoagulant-type rodenticide exposure, from 2010 to 2014.

RESULTS

Superwarfarin was the most common group of anticoagulant-type rodenticides identified (87.8%), in which bromadiolone and brodifacoum were the most frequently encountered. Among the 41 cases identified, 31 had an obvious exposure history, and 10 were occult poisoning in which the context of exposure remained unidentified. All occult poisoning patients without exposure history presented with bleeding events. These occult poisoning cases often went unrecognized by frontline clinicians, leading to delayed investigation and initiation of treatment. This group of patients was associated with a longer time to diagnose coagulopathy (p < 0.001) and confirm rodenticide poisoning (p < 0.05), a higher rate of international normalized ratio (INR) rebound after initiation of antidote (p < 0.001), and a longer time needed for normalizing INR (p < 0.05).

CONCLUSION

Occult superwarfarin poisoning is an important yet under-recognized differential cause of unexplained coagulopathy. A high index of clinical suspicion and availability of specialized toxicological test for superwarfarins play a vital role in diagnosis and early initiation of appropriate management. The underlying cause of such poisoning remains obscure and warrants further study.

Quantitative method for analysis of six anticoagulant rodenticides in faeces, applied in a case with repeated samples from a dog

Background

Accidental poisoning with anticoagulant rodenticides is not uncommon in dogs, but few reports of the elimination kinetics and half-lives in this species have been published. Our objectives were to develop and validate a new method for the quantification of anticoagulant rodenticides in canine blood and faeces using reversed phase ultra-high performance liquid chromatography–tandem mass spectrometry (UHPLC–MS/MS) and apply the method on a case of anticoagulant rodenticide intoxication.

Results

Sample preparation was liquid–liquid extraction. Six anticoagulant rodenticides were separated using a UPLC^® BEH C₁₈-column with a mobile phase consisting of 5 mM ammonium formate buffer pH 10.2 and methanol. MS/MS detection was performed with positive electrospray ionization and two multiple reaction monitoring transitions. The limits of quantification were set at the levels of the lowest calibrator (1.5–2.7 ng/mL or ng/g). The method was successfully applied to a case from a dog accidentally poisoned with anticoagulant rodenticide. Coumatetralyl and brodifacoum concentrations were determined from serial blood and faecal samples. A terminal half-life of at least 81 days for coumatetralyl in blood was estimated, which is longer than previous reported in other species. A slow elimination of brodifacoum from the faeces was found, with traces still detectable in the faeces at day 513.

Conclusions

This study offers a new method of detection and quantification of six frequently used anticoagulant rodenticides in canine faeces. Such drugs might cause serious health effects and it is important to be able to detect these drugs, to initiate proper treatment. The very long elimination half-lives detected in our study is important to be aware of in assessment of anticoagulant rodenticide burden to the environment.

A guide to acquired vitamin K coagulophathy diagnosis and treatment: the Russian perspective

Abstract

Physicians often come across with cases of vitamin K antagonists–dependent coagulopathy for reasons such as accidental use of the vitamin K antagonists (VKA), excessive administration of prescribed anticoagulants of indirect action or not reported administration of vitamin K antagonists due to memory impairment and/or other mental disorders, even deliberate use thereof (attempt to murder or suicide). Rodenticide-poisoning (coumarins, warfarins) via food or occupational accidents are difficult to diagnose. This article discusses different types of acquired vitamin K-dependent coagulopathy. Differential diagnosis is primarily based on patient statements before additional causes of vitamin K deficiency are explored. Even when pathological vitamin K deficiency is not determined, appropriate and urgent medical treatment is necessary: administration of fresh frozen plasma or concentrated factors of the prothrombin complex, administration of vitamin K remedies along with symptomatic therapy. With early diagnosis and prescription of appropriate therapy, prognosis is favorable.

Graphical abstract

Reasons for vitamin K antagonists–dependent coagulopathy cases

Chemical toxicity prediction for major classes of industrial chemicals: Is it possible to develop universal models covering cosmetics, drugs, and pesticides?

Computational models have earned broad acceptance for assessing chemical toxicity during early stages of drug discovery or environmental safety assessment. The majority of publicly available QSAR toxicity models have been developed for datasets including mostly drugs or drug-like compounds. We have evaluated and compared chemical spaces occupied by cosmetics, drugs, and pesticides, and explored whether current computational models of toxicity endpoints can be universally applied to all these chemicals. Our analysis of the chemical space overlap and applicability domain (AD) of models built previously for twenty different toxicity endpoints showed that most of these models afforded high coverage (>90%) for all three classes of compounds analyzed herein. Only T. pyriformis models demonstrated lower coverage for drugs and pesticides (38% and 54%, respectively). These results show that, for the most part, historical QSAR models built with data available for different toxicity endpoints can be used for toxicity assessment of novel chemicals irrespective of the intended commercial use; however, the AD restriction is necessary to assure the expected prediction accuracy. Local models may need to be developed to capture chemicals that appear as outliers with respect to global models.

Effects of bromadiolone poisoning on the central nervous system

Cases of rodenticide poisoning (second-generation long-acting dicoumarin rodenticide, superwarfarin) have occasionally been reported. The main symptoms of bromadiolone poisoning are skin mucosa hemorrhage, digestive tract hemorrhage, and hematuresis. However, the symptoms of central nervous system toxicity have rarely been reported. Our case reports on a 41-year-old male who had no contact with bromadiolone. His main symptoms were dizziness, unsteady gait, and abnormal behavior. Laboratory test results revealed the presence of bromadiolone in his blood and urine, a longer prothrombin time, activated partial thromboplastin time, and a high international normalized ratio. Magnetic resonance imaging of the brain showed that the bilateral posterior limb of the internal capsule, splenium of corporis callosum, and bilateral centrum semiovale formed symmetrical patch distribution. The patient gradually recovered after treated with vitamin K1 and plasma transfusion. Our clinical study could pave the way to improve the detection of bromadiolone poisoning and avoid misdiagnosis.