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

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.

A facile fluorescence microplate immunoassay based on an in situ fluorogenic reaction for the detection of two highly toxic anticoagulant rodenticides in food and biological matrix

Bromadiolone and brodifacoum, the most frequently used anticoagulant rodenticides, are highly toxic and pose a threat to public health by causing food poisoning incidents. Here, we developed a fluorescence microplate immunoassay for facile and sensitive detection of bromadiolone and brodifacoum by introducing three commercial chemicals (p-phenylenediamine, polyethyleneimine, H2O2) as a new substrate of horseradish peroxidase and then generating fluorescence signals based on an in situ fluorogenic reaction (detection time within 75 min). This assay exhibited higher efficiency in generating fluorescence signals, thereby exhibiting a 6-fold improvement in sensitivity compared with colorimetric ELISA. The limit of detection was 0.23-0.28 ng/mL (ng/g) for bromadiolone and 0.34-0.61 ng/mL (ng/g) for brodifacoum in corn and human serum, with recovery ratios higher than 82.3 %. These satisfactory results illustrated our proposed assay was a potential tool for food analysis and poisoning diagnosis caused by bromadiolone and brodifacoum.

Fast and sensitive method for the diagnosis and follow-up of anticoagulant rodenticides poisoning in animal whole blood

Rodent control strategies are primarily based on the use of anticoagulant rodenticides (ARs), making them widely used worldwide. However, due to their high toxicity and availability, ARs are among the leading causes of animal poisoning in Europe. They are the primary agents involved in intoxication in cats and the second in dogs. Additionally, their long persistence in the body can lead to secondary exposure, particularly in wild predators. The laboratory findings and clinical signs of intoxication can range from increased clotting time (prolonged prothrombin time and activated partial thromboplastin time) to severe bleeding and death. Despite the prevalence and severity of this intoxication, only a few methods are available for the identification and quantification of ARs in animals, and most of them are suitable only for post-mortem diagnosis. In this study, we present the validation of a rapid and sensitive method for the identification and quantification of ARs in animal whole blood, using a small sample volume. The developed LC-MS/MS method demonstrated high accuracy and precision at the limit of quantification (LOQ), as well as at low, medium, and high concentrations. It exhibited higher sensitivity (LOQ 0.1 - 0.3 ng/mL) compared to previously published methods. After validation, the method was successfully applied to real cases of suspected poisoning events, resulting in the identification of several positive samples. The examples presented in this study highlight the utility of this method for diagnosis and follow-up, emphasizing the importance of method sensitivity in order to avoid misclassifying truly positive samples as negative.

Developmental toxicity induced by brodifacoum in zebrafish (Danio rerio) early life stages

OBJECTIVES

The present study mainly focused on the assessment of developmental toxicity induced by exposure to brodifacoum (BDF) in zebrafish at early life stages.

MATERIAL AND METHODS

Zebrafish embryos were exposed to 0.2, 0.4, and 0.8 mg/L of BDF from 6 to 96 hr post-fertilization (hpf), and the toxic effects of BDF on early embryonic development were investigated in terms of morphological changes, oxidative stress, and alterations in heart development-related genes.

RESULTS

The experimental results showed that BDF significantly decreased the heart rate, survival rate, body length, and spontaneous movements of zebrafish embryos at 0.8 mg/L, and the morphological developmental abnormalities were also observed at 96 hpf. In addition, exposure to BDF significantly increased oxidative stress levels in zebrafish embryos by increasing the enzymatic activities of catalase (CAT), superoxide dismutase (SOD), and malondialdehyde (MDA) levels, and decreased glutathione (GSH) levels. Furthermore, BDF treatment-induced alterations in the expression levels of the heart development-related genes (gata4, sox9b, tbx2b, and nppa).

CONCLUSION

Results from this study indicated that exposure to BDF could lead to marked growth inhibition and significantly alter the activities of antioxidant enzymes in zebrafish embryos. Moreover, BDF exposure exhibited severe cardiotoxicity and significantly disrupted heart development-related genes. The results indicated that BDF could induce developmental and cardiac toxicity in zebrafish embryos.

Unmet clinical laboratory need in patients hospitalized for acute poisoning from long-acting anticoagulant rodenticides

The importance of real-time, quantitative toxicology data available for physicians treating poisoned patients was illustrated during the 2018 outbreak in Illinois of severe coagulopathy caused by inhaling illicit synthetic cannabinoids products contaminated with commercially-available brodifacoum, difenacoum, and bromadiolone, three potent, long-acting anticoagulant rodenticides (LAARs). Identification and quantification of these life-threatening toxins in blood samples of hospitalized patients required toxicology testing with liquid chromatography-tandem mass spectrometry (LC-MS/MS) that was not available in clinical laboratories of hospitals at the time of the outbreak. This highly-sensitive, quantitative assay can provide critical information to guide patient care during and after hospitalization, including identification of offending LAARs, estimates of the ingested dose, and dosage and discontinuation of oral vitamin K1 therapy after hospital discharge once plasma LAARs concentrations decreased to a safe level (<10 ng/mL). Accordingly, we propose an action plan to enable treating physicians to quantify plasma concentrations of several LAARs simultaneously in poisoned patients. It involves rapid (<15 min), sensitive, and validated LC-MS/MS methods developed, tested and validated in our laboratory. This will allow treating physicians to request quantitative plasma LAARs testing, report test results in the patient's hospital discharge summary, and recommend regular monitoring of plasma LAARs concentrations in the outpatient setting.