Relato de caso de intoxicación con superwarfarinas: un desafío terapéutico / Managing Superwarfarin Poisoning: A Challenging Case

La intoxicación humana por rodenticidas anticoagulantes de acción prolongada, conocidos como superwarfarinas, provoca coagulopatía de prolongado manejo. Presentamos el caso de un hombre de 42 años que ingirió una dosis tóxica de rodenticida en un intento suicida, evolucionando con epistaxis, INR de 11,6 y necesidad de hospitalización. Durante 7 días se realizaron controles seriados de pruebas de coagulación, con optimización de diferentes dosis de suplementación de Vitamina K. El caso destaca la potencia y vida media prolongada (aproximadamente 6 semanas) de este tipo de anticoagulantes, hecho que requiere un control clínico regular y una adherencia al tratamiento satisfactoria.

Human intoxication by long-acting anticoagulant rodenticides, known as superwarfarins, causes coagulopathy that is difficult to manage. We present the case of a 42-year-old man who ingested a toxic dose of rodenticide in a suicide attempt, evolving with epistaxis, INR of 11.6, and needing hospitalization. For seven days, serial controls of coagulation tests were carried out, with optimization of different doses of Vitamin K supplementation. The case highlights this type of anticoagulant's potency and prolonged half-life (approximately six weeks), which requires regular clinical control and satisfactory treatment adherence.

[Managing Superwarfarin Poisoning: A Challenging Case]. / Relato de caso de intoxicación con superwarfarinas: un desafío terapéutico.

Human intoxication by long-acting anticoagulant rodenticides, known as superwarfarins, causes coagulopathy that is difficult to manage. We present the case of a 42-year-old man who ingested a toxic dose of rodenticide in a suicide attempt, evolving with epistaxis, INR of 11.6, and needing hospitalization. For seven days, serial controls of coagulation tests were carried out, with optimization of different doses of Vitamin K supplementation. The case highlights this type of anticoagulant's potency and prolonged half-life (approximately six weeks), which requires regular clinical control and satisfactory treatment adherence.

Edoxaban versus Vitamin K Antagonist for Atrial Fibrillation after TAVR.

BACKGROUND: The role of direct oral anticoagulants as compared with vitamin K antagonists for atrial fibrillation after successful transcatheter aortic-valve replacement (TAVR) has not been well studied. METHODS: We conducted a multicenter, prospective, randomized, open-label, adjudicator-masked trial comparing edoxaban with vitamin K antagonists in patients with prevalent or incident atrial fibrillation as the indication for oral anticoagulation after successful TAVR. The primary efficacy outcome was a composite of adverse events consisting of death from any cause, myocardial infarction, ischemic stroke, systemic thromboembolism, valve thrombosis, or major bleeding. The primary safety outcome was major bleeding. On the basis of a hierarchical testing plan, the primary efficacy and safety outcomes were tested sequentially for noninferiority, with noninferiority of edoxaban established if the upper boundary of the 95% confidence interval for the hazard ratio did not exceed 1.38. Superiority testing of edoxaban for efficacy would follow if noninferiority and superiority were established for major bleeding. RESULTS: A total of 1426 patients were enrolled (713 in each group). The mean age of the patients was 82.1 years, and 47.5% of the patients were women. Almost all the patients had atrial fibrillation before TAVR. The rate of the composite primary efficacy outcome was 17.3 per 100 person-years in the edoxaban group and 16.5 per 100 person-years in the vitamin K antagonist group (hazard ratio, 1.05; 95% confidence interval [CI], 0.85 to 1.31; P = 0.01 for noninferiority). Rates of major bleeding were 9.7 per 100 person-years and 7.0 per 100 person-years, respectively (hazard ratio, 1.40; 95% CI, 1.03 to 1.91; P = 0.93 for noninferiority); the difference between groups was mainly due to more gastrointestinal bleeding with edoxaban. Rates of death from any cause or stroke were 10.0 per 100 person-years in the edoxaban group and 11.7 per 100 person-years in the vitamin K antagonist group (hazard ratio, 0.85; 95% CI, 0.66 to 1.11). CONCLUSIONS: In patients with mainly prevalent atrial fibrillation who underwent successful TAVR, edoxaban was noninferior to vitamin K antagonists as determined by a hazard ratio margin of 38% for a composite primary outcome of adverse clinical events. The incidence of major bleeding was higher with edoxaban than with vitamin K antagonists. (Funded by Daiichi Sankyo; ENVISAGE-TAVI AF ClinicalTrials.gov number, NCT02943785.).

In Silico Analysis to Identify Molecular Targets for Chemicals of Concern: The Case Study of Flocoumafen, an Anticoagulant Pesticide.

Rodenticides are pesticides used worldwide, with little information available regarding health consequences in wildlife and humans. The aim of the present study was to use virtual screening to identify potential targets for flocoumafen, a superwarfarin rodenticide. Blind docking of more than 841 human proteins was carried out employing AutoDock Vina. The strength of the ligand interaction with the proteins was quantified based on the binding affinity score (kcal/mol). Results indicate that flocoumafen could be a promiscuous ligand for diversity of cellular protein targets. The best complexes were obtained for prostaglandin F synthase (-14.2 kcal/mol) and serum albumin (-14.0 kcal/mol) followed by glucocorticoid receptor 2, matrix metalloproteinase-9, nuclear receptor ROR-alpha, and activin receptor type-1, all with values equal or better than -13.5 kcal/mol. Docking method validation based on the root-mean-square deviation showed that flocoumafen had good capability to predict corresponding co-crystallized poses; and molecular dynamics simulations suggested the complex with greater binding affinity was thermodynamically stable. Protein-protein interaction networks built with main protein targets revealed that protein kinase B (AKT1), ribosomal protein S6 kinase B1 (RPS6KB1), phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA), retinoid X receptor alpha (RXRA), and protein phosphatase 2 catalytic subunit alpha (PPP2CA) were major hub proteins, whereas the gene ontology analysis reported that cellular response to endogenous stimulus, protein binding, and the TOR complex were the biological processes, molecular function, and cell component enrichments, respectively. These results should motivate more ecotoxicity testing for flocoumafen and other superwarfarins, as well as precautionary legislation to minimize exposure to these highly toxic chemicals. Environ Toxicol Chem 2021;40:2034-2043. © 2021 SETAC.

Reverse Docking for the Identification of Molecular Targets of Anticancer Compounds.

Molecular docking is a useful and powerful computational method for the identification of potential interactions between small molecules and pharmacological targets. In reverse docking, the ability of one or a few compounds to bind a large dataset of proteins is evaluated in silico. This strategy is useful for identifying molecular targets of orphan bioactive compounds, proposing new molecular mechanisms, finding alternative indications of drugs, or predicting drug toxicity. Herein, we describe a detailed reverse docking protocol for the identification of potential targets for 4-hydroxycoumarin (4-HC). Our results showed that RAC1 is a target of 4-HC, which partially explains the biological activities of 4-HC on cancer cells. The strategy reported here can be easily applied to other compounds and protein datasets.

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.

Palatability and efficacy of bromadiolone rodenticide block bait previously exposed to environmental conditions.

BACKGROUND: In São Paulo city, rodent infestation is considered to be a serious public health problem and is the object of a municipal rodent control programme. One of the most important routine methods involves baiting in sewers, using bromadiolone block bait in a pulsed baiting strategy. It has been observed that, after each pulse, bait is not always consumed, and its appearance is altered, which has led to concerns about efficacy. We assessed whether exposure to sewer conditions influences the palatability and efficacy of rodenticide baits to Norway rats (Rattus norvegicus). Baits containing bromadiolone as active ingredient were placed in sewers, removed after 30 days and offered to rats in a two-choice food trial and a no-choice food trial. RESULTS: The appearance of the rodenticide baits changed after 30 days exposure to sewer conditions, but they continued to be palatable and effective against rats. The level of mortality was considered to be satisfactory, 75% in the two-choice food trial and 100% in the no-choice food trial. CONCLUSION: Results support the reuse of rodenticide block bait in rodent control. It seems to be justified to continue using/reuse baits even when their appearance has changed after 30 days exposure in sewer systems.

Structure-anti-leukemic activity relationship study of ortho-dihydroxycoumarins in U-937 cells: key role of the δ-lactone ring in determining differentiation-inducing potency and selective pro-apoptotic action.

Previous studies indicated the need of at least one phenolic hydroxyl group in the coumarin core for induction of cytotoxicity in different cell lines. Herein, we present an exhaustive structure-activity relationship study including ortho-dihydroxycoumarins (o-DHC) derivatives, cinnamic acid derivatives (as open-chain coumarin analogues) and 1,2-pyrones (representative of the δ-lactone ring of the coumarin core), carried out to further identify the structural features of o-DHC required to induce leukemic cell differentiation and apoptosis in U-937 cells. Our results show for the first time that the δ-lactone ring positively influences the aforementioned biological effects, by conferring greater potency to compounds with an intact coumarin nucleus. Most tellingly, we reveal herein the crucial role of this molecular portion in determining the selective toxicity that o-DHC show for leukemic cells over normal blood cells. From a pharmacological perspective, our findings point out that o-DHC may be useful prototypes for the development of novel chemotherapeutic agents.

Antitrypanosomal and antioxidant properties of 4-hydroxycoumarins derivatives.

In the present communication we prepared a series of six 4-hydroxycoumarin derivatives, isosters of quercetin, recognized as an antioxidant natural compound, with the aim of evaluating the antitrypanosomal activity against Trypanosoma cruzi, the parasite responsible for Chagas disease, and the antioxidant properties. We have used the 4-hydroxycoumarin moiety (compound 1) as the molecular template for the synthesis of compounds 2-7. These derivates have shown moderate trypanocidal activity. However they have been proved to be good antioxidants. In particular compound 7 is the most active antioxidant and it is, therefore, a potential candidate for a successful employment in conditions characterized by free radicals overproduction.

Effect of different C3-aryl substituents on the antioxidant activity of 4-hydroxycoumarin derivatives.

The antioxidant activity of 4-hydroxycoumarin synthetic derivatives and 4-methylumbelliferone were determined taking 4-hydroxycoumarin as the reference compound. Six 3-aryl-4-hydroxycoumarin derivatives were synthesized from 4-hydroxycoumarin as precursor in order to evaluate changes in their antioxidant properties due to C3-aryl substituent nature. Free radical scavenging capacities of these compounds against two different species DPPH(·) and ABTS(·+) and the protecting ability towards the ß-carotene-linoleic acid co-oxidation enzymatically induced by lipoxygenase were measured. In addition, the relationship between the activities of these molecules against DPPH radical and the bond dissociation energy of O-H (BDE) calculated using methods of computational chemistry was evaluated.

Bromadiolone susceptibility in wild and laboratory Mus musculus L.(house mice) in Buenos Aires, Argentina.

BACKGROUND: Rodents are major pests in many agricultural systems, where they can cause significant economic losses and involve a sanitary risk. The application of anticoagulant rodenticides for rodent control has showed a decrease in effectiveness through time because of the development of resistant populations and the development of aversion behaviour. The goal of the present study was to test the susceptibility to bromadiolone and the existence of anticoagulant resistance in Mus musculus L. (house mouse) in Argentina. We conducted a feeding test with wild animals captured in poultry farms and a laboratory strain that were fed with bromadiolone bait. RESULTS: Three animals of the field experimental group survived the 21 days study period, while for laboratory animals mortality was 100%. Control field animals which were fed without anticoagulant showed 100% survival. CONCLUSION: We found evidence of the presence of anticoagulant resistant M. musculus L. in the study area. Feeding behaviour may have contributed to increasing the time of survival, and may be a mechanism that allows metabolic clearance of the bromadiolone. Under field conditions control with anticoagulants would be less effective because animals have alternative food.

Intestinal anti-inflammatory activity of coumarin and 4-hydroxycoumarin in the trinitrobenzenesulphonic acid model of rat colitis.

Coumarins represent an important class of phenolic compounds with multiple biological activities, including inhibition of lipidic peroxidation and neutrophil-dependent anion superoxide generation, anti-inflammatory and immunosuppressor actions. All of these proprieties are essential for that a drug may be used in the treatment of inflammatory bowel disease. The present study examined intestinal anti-inflammatory activity of coumarin and its derivative, the 4-hydroxycoumarin on experimental ulcerative colitis in rats. This was performed in two different experimental settings, i.e. when the colonic mucosa is intact or when the mucosa is in process of recovery after an initial insult. The results obtained revealed that the coumarin and 4-hydroxycoumarin, at doses of 5 and 25 mg/kg, significantly attenuated the colonic damage induced by trinitrobenzenesulphonic acid (TNBS) in both situations, as evidenced macroscopically, microscopically and biochemically. This effect was related to an improvement in the colonic oxidative status, since coumarin and 4-hydroxycoumarin prevented the glutathione depletion that occurred as a consequence of the colonic inflammation.

Brodifacoum poisoning with toxicokinetic data.

The case of a 46-year-old woman who survived after a brodifacoum poisoning is presented. The patient was admitted due to a severe coagulopathy. Initial prothrombin time and activated partial thromboplastin time were both greater than 110 seconds and the patient suffered severe gastric and pulmonary hemorrhage requiring fresh frozen plasma transfusion and parenteral phytonadione administration (up to 100 mg per day). Serum brodifacoum levels were determined by HPLC during seven months. Five days after admission, serum brodifacoum level was 1302 ng/ml. Serum brodifacoum levels decreased till day 209 when became not detectable. Brodifacoum elimination showed a first order kinetic and a 56-day half-life. Investigation of superwarfarin should be considered in any patient with vitamin K dependent coagulation disorder. It would be also useful to obtain periodic brodifacoum levels and build the corresponding elimination curve to help direct phytonadione therapy in poisoned patients.

4-Hydroxycoumarin disorganizes the actin cytoskeleton in B16-F10 melanoma cells but not in B82 fibroblasts, decreasing their adhesion to extracellular matrix proteins and motility.

This study determined the in vitro effects of 4-hydroxycoumarin (4-HC) employing the melanoma cell line B16-F10 and the non-malignant fibroblastic cell line B82. 4-HC disorganized the actin cytoskeleton in B16-F10 cells, but not in B82 fibroblasts. Cytoskeletal disorganization correlated with reductions in cell adhesion to four extracellular matrix proteins and inhibition of random motility. 4-HC did not modify cell viability or actin expression, but decreased tyrosine phosphorylation of several proteins in melanoma cells. Because adhesion of tumor cells to extracellular matrix is required during the metastatic process, 4-HC might be useful as an adjuvant therapy for melanoma.

[Hemorrhagic syndrome caused by exposure to a rodenticide. Report of a case]. / Síndrome hemorragíparo por exposición a raticida. Comunicación de un caso.

We report a 22 years old male, admitted to the emergency room due to a life threatening coagulation disorder, with prothrombin times fluctuation between 5 and 37% and very low activity of factors II, VII, IX and X. In the month prior to the admission, the patient had used the rodenticide difethialone, without any precaution to avoid accidental exposure. The patient was maintained with fresh frozen plasma until oral vitamin K1 was obtained. This medication corrected the coagulation disorder.

Spontaneous hemorrhage associated with accidental brodifacoum poisoning in a child.

A 36-month-old child had spontaneous hemorrhage from her nose, mouth, and urinary tract, and a fall in hemoglobin of 20 gm/L (2 gm/dl). The prothrombin time and partial thromboplastin time were markedly prolonged with a decrease in the vitamin K-dependent factors. The child had ingested brodifacoum, a long-acting rodenticide. Prolonged follow-up and treatment with vitamin K were necessary.