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Isbister GK, Jenkins S, Downes MA, Fakes K, Buckley NA. A randomized controlled trial and prospective cohort investigating antivenom for red-bellied black snake envenomation. Clin Toxicol (Phila) 2024; 62:343-351. [PMID: 38913734 DOI: 10.1080/15563650.2024.2367677] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2024] [Accepted: 06/07/2024] [Indexed: 06/26/2024]
Abstract
INTRODUCTION Antivenom is first line treatment for snake envenomation worldwide, despite few placebo controlled clinical trials demonstrating effectiveness. We aimed to investigate whether early antivenom in red-bellied black snake (Pseudechis porphyriacus) bites would prevent systemic myotoxicity. METHODS We undertook a multicentre randomized placebo-controlled trial of antivenom for red-bellied black snake bites with patients recruited from the Australian Snakebite Project (July 2014 to June 2020). In addition, we report all patients with red-bellied black snake bites during the same period, comparing the same outcomes. Patients over 2 years of age with definite red-bellied black snake bites and early systemic effects were randomized to receive 50 per cent glucose (placebo) or tiger snake antivenom within 6 hours post-bite, or in the cohort group received antivenom determined by the treating clinician. The primary outcome was the proportion of patients with myotoxicity (peak creatine kinase activity >1,000 U/L). Secondary outcomes were: area under the curve of total creatine kinase elevation over 48 hours, presence of venom post-antivenom, and adverse reactions. We analyzed both the randomized control trial patients and the combination of randomized control trial and cohort patients. RESULTS Fifteen patients were recruited to the randomized controlled trial, and a cohort of 68 patients who were not randomized were included in the analysis. After treatment, two of seven patients given placebo had a peak creatine kinase activity >1,000 U/L versus none of the eight given antivenom (difference in favour of antivenom; 29 per cent; 95 per cent confidence interval:-18 per cent to +70 per cent; P = 0.2). The median area under the curve of total creatine kinase elevation over 48 hours in patients given placebo was 0 U/L*h (interquartile range: 0-124 U/L*h), which was not significantly different to those given antivenom: 197 U/L*h (interquartile range: 0-66,353 U/L*h; P = 0.26). Venom was not detected post-antivenom in six patients with measured venom concentrations given antivenom. Two patients given antivenom had immediate hypersensitivity reactions, one severe anaphylaxis, and another had serum sickness. Combining randomized and not randomized patients, three of 36 (8 per cent) administered antivenom less than 6 hours post-bite had a peak creatine kinase activity >1,000 U/L versus 17/47 (36 per cent) patients not receiving antivenom less than 6 hours post-bite (difference in favour of antivenom 29 per cent; 95 per cent confidence interval: 8 per cent to 44 per cent; P < 0.004). Overall, 13/36 (36 per cent) patients administered antivenom within 6 hours had hypersensitivity reactions, six severe anaphylaxis (17 per cent). DISCUSSION We found that early antivenom was effective in red-bellied black snake bites, and only three patients need to be given antivenom within 6 hours to prevent myotoxicity in one (number needed to treat = 3). However, one in three patients administered antivenom developed a hypersensitivity reaction, and one in six had severe anaphylaxis. The major limitation of this study was the small number of patients recruited to the randomized controlled trial. CONCLUSION Administration of antivenom in red-bellied black snake envenomation within 6 hours post-bite appeared to decrease the proportion of patients with myotoxicity, but a third of patients had adverse reactions.
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Affiliation(s)
- Geoffrey K Isbister
- Clinical Toxicology Research Group, University of Newcastle, Newcastle, Australia
- Department of Clinical Toxicology, Newcastle, Australia
- New South Wales Poison Information Centre, Childrens Hospital Westmead, Sydney, Australia
| | - Shane Jenkins
- Clinical Toxicology Research Group, University of Newcastle, Newcastle, Australia
| | - Michael A Downes
- Clinical Toxicology Research Group, University of Newcastle, Newcastle, Australia
- Department of Clinical Toxicology, Newcastle, Australia
- New South Wales Poison Information Centre, Childrens Hospital Westmead, Sydney, Australia
| | - Kellie Fakes
- Clinical Toxicology Research Group, University of Newcastle, Newcastle, Australia
| | - Nicholas A Buckley
- Department of Clinical Toxicology, Newcastle, Australia
- New South Wales Poison Information Centre, Childrens Hospital Westmead, Sydney, Australia
- Clinical Pharmacology & Toxicology Research Group, School of Medical Sciences, University of Sydney
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Bartlett KE, Hall SR, Rasmussen SA, Crittenden E, Dawson CA, Albulescu LO, Laprade W, Harrison RA, Saviola AJ, Modahl CM, Jenkins TP, Wilkinson MC, Gutiérrez JM, Casewell NR. Dermonecrosis caused by a spitting cobra snakebite results from toxin potentiation and is prevented by the repurposed drug varespladib. Proc Natl Acad Sci U S A 2024; 121:e2315597121. [PMID: 38687786 PMCID: PMC11087757 DOI: 10.1073/pnas.2315597121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Accepted: 02/26/2024] [Indexed: 05/02/2024] Open
Abstract
Snakebite envenoming is a neglected tropical disease that causes substantial mortality and morbidity globally. The venom of African spitting cobras often causes permanent injury via tissue-destructive dermonecrosis at the bite site, which is ineffectively treated by current antivenoms. To address this therapeutic gap, we identified the etiological venom toxins in Naja nigricollis venom responsible for causing local dermonecrosis. While cytotoxic three-finger toxins were primarily responsible for causing spitting cobra cytotoxicity in cultured keratinocytes, their potentiation by phospholipases A2 toxins was essential to cause dermonecrosis in vivo. This evidence of probable toxin synergism suggests that a single toxin-family inhibiting drug could prevent local envenoming. We show that local injection with the repurposed phospholipase A2-inhibiting drug varespladib significantly prevents local tissue damage caused by several spitting cobra venoms in murine models of envenoming. Our findings therefore provide a therapeutic strategy that may effectively prevent life-changing morbidity caused by snakebite in rural Africa.
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Affiliation(s)
- Keirah E. Bartlett
- Centre for Snakebite Research & Interventions, Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, LiverpoolL3 5QA, United Kingdom
| | - Steven R. Hall
- Centre for Snakebite Research & Interventions, Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, LiverpoolL3 5QA, United Kingdom
- Centre for Drugs & Diagnostics, Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, LiverpoolL3 5QA, United Kingdom
| | - Sean A. Rasmussen
- Department of Pathology and Laboratory Medicine, Queen Elizabeth II Health Sciences Centre and Dalhousie University, Halifax, NSB3H 1V8, Canada
| | - Edouard Crittenden
- Centre for Snakebite Research & Interventions, Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, LiverpoolL3 5QA, United Kingdom
| | - Charlotte A. Dawson
- Centre for Snakebite Research & Interventions, Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, LiverpoolL3 5QA, United Kingdom
| | - Laura-Oana Albulescu
- Centre for Snakebite Research & Interventions, Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, LiverpoolL3 5QA, United Kingdom
- Centre for Drugs & Diagnostics, Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, LiverpoolL3 5QA, United Kingdom
| | - William Laprade
- Department of Applied Mathematics and Computer Science, Technical University of Denmark, Kongens LyngbyDK-2800, Denmark
| | - Robert A. Harrison
- Centre for Snakebite Research & Interventions, Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, LiverpoolL3 5QA, United Kingdom
- Centre for Drugs & Diagnostics, Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, LiverpoolL3 5QA, United Kingdom
| | - Anthony J. Saviola
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver, Aurora, CO80045
| | - Cassandra M. Modahl
- Centre for Snakebite Research & Interventions, Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, LiverpoolL3 5QA, United Kingdom
| | - Timothy P. Jenkins
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Kongens LyngbyDK-2800, Denmark
| | - Mark C. Wilkinson
- Centre for Snakebite Research & Interventions, Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, LiverpoolL3 5QA, United Kingdom
| | - José María Gutiérrez
- Instituto Clodomiro Picado, Facultad de Microbiología, Universidad de Costa Rica, San José11501–2060, Costa Rica
| | - Nicholas R. Casewell
- Centre for Snakebite Research & Interventions, Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, LiverpoolL3 5QA, United Kingdom
- Centre for Drugs & Diagnostics, Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, LiverpoolL3 5QA, United Kingdom
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Johnston CI, Silva A, Hodgson W, Isbister GK. Investigating skeletal muscle biomarkers for the early detection of Australian myotoxic snake envenoming: an animal model pilot study. Clin Toxicol (Phila) 2024; 62:280-287. [PMID: 38804832 DOI: 10.1080/15563650.2024.2349690] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Accepted: 04/25/2024] [Indexed: 05/29/2024]
Abstract
INTRODUCTION Myotoxicity is an important toxidrome that can occur with envenoming from multiple Australian snake types. Early antivenom administration is an important strategy to reduce the incidence and severity of myotoxicity. The current gold standard biomarker, serum creatine kinase activity, does not rise early enough to facilitate early antivenom administration. Several other skeletal muscle biomarkers have shown promise in other animal models and scenarios. The aim of this study was to examine the predictive values of six skeletal muscle biomarkers in a rat model of Australian snake myotoxicity. METHODS Sprague-Dawley rats were anaesthetised and administered either Pseudechis porphyriacus (red-bellied black snake) or Notechis scutatus (tiger snake) venom, or normal saline via intramuscular injection. Blood samples were collected. Assays were performed for serum creatine kinase skeletal muscle troponin-I concentration, skeletal muscle troponin-C concentration, myoglobin activity, skeletal muscle myosin light chain-1 concentration, and creatine kinase-MM activity. Serum markers were plotted against time, with comparison of area under the concentration (or activity)-time curve. The predictive values of six skeletal muscle biomarkers were examined using receiver operating characteristic curves. RESULTS There was no difference in area under the serum creatine kinase activity-time curve between venom and control groups. Serum creatine kinase-MM activity rose early in the venom treated rats, which had a significantly greater area under the serum activity-time curve. No difference in area under the serum concentration-time curve was demonstrated for the other biomarkers. Creatine kinase-MM activity had a superior predictive values than creatine kinase activity at 0-4 hours and 0-10 hours after venom administration, as indicated by area under the receiver operating characteristic curves (95 per cent confidence intervals) of 0.91 (0.78-1.00) and 0.88 (0.73-1.00) versus 0.79 (0.63-0.95) and 0.66 (0.51-0.80). DISCUSSION The limitations of serum creatine kinase activity in early detection of myotoxicity were demonstrated in this rat model. CONCLUSION Serum creatine kinase-MM activity was superior for early detection of Australian myotoxic snake envenoming.
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Affiliation(s)
| | - Anjana Silva
- Department of Parasitology, Faculty of Medicine and Allied Sciences, Rajarata University of Sri Lanka, Anuradhapura, Sri Lanka
| | - Wayne Hodgson
- Monash Venom Group, Department of Pharmacology, Biomedical Discovery Institute, Monash University, Clayton, VIC, Australia
| | - Geoffrey K Isbister
- Clinical Toxicology Research Group, University of Newcastle, Newcastle, NSW, Australia
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M Morris N, A Blee J, Hauert S. Global parameter optimisation and sensitivity analysis of antivenom pharmacokinetics and pharmacodynamics. Toxicon 2023; 232:107206. [PMID: 37356552 DOI: 10.1016/j.toxicon.2023.107206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 06/05/2023] [Accepted: 06/22/2023] [Indexed: 06/27/2023]
Abstract
In recent years it has become possible to design snakebite antivenoms with diverse pharmacokinetic properties. Owing to the pharmacokinetic variability of venoms, the choice of antivenom scaffold may influence a treatment's neutralisation coverage. Computation offers a useful medium through which to assess the pharmacokinetics and pharmacodynamics of envenomation-treatment systems, as antivenoms with identical neutralising capacities can be simulated. In this study, we simulate envenomation and treatment with a variety of antivenoms, to define the properties of effective antivenoms. Systemic envenomation and treatment were described using a two-compartment pharmacokinetic model. Treatment of Naja sumatrana and Cryptelytrops purpureomaculatus envenomation was simulated with a set of 200,000 theoretical antivenoms across 10 treatment time delays. These two venoms are well-characterised and have differing pharmacokinetic properties. The theoretical antivenom set varied across molecular weight, dose, kon, koff, and valency. The best and worst treatments were identified using an area under the curve metric, and a global sensitivity analysis was performed to quantify the influence of the input parameters on treatment outcome. The simulations show that scaffolds of diverse molecular formats can be effective. Molecular weight and valency have a negligible direct impact on treatment outcome, however low molecular weight scaffolds offer more flexibility across the other design parameters, particularly when treatment is delayed. The simulations show kon to primarily mediate treatment efficacy, with rates above 105 M-1s-1 required for the most effective treatments. koff has the greatest impact on the performance of less effective scaffolds. While the same scaffold preferences for improved treatment are seen for both model snakes, the parameter bounds for C. purpureomaculatus envenomation are more constrained. This paper establishes a computational framework for the optimisation of antivenom design.
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Affiliation(s)
- Natalie M Morris
- Department of Engineering Mathematics, Ada Lovelace Building, University of Bristol, University Walk, Bristol, BS8 1TW, UK.
| | - Johanna A Blee
- Department of Engineering Mathematics, Ada Lovelace Building, University of Bristol, University Walk, Bristol, BS8 1TW, UK.
| | - Sabine Hauert
- Department of Engineering Mathematics, Ada Lovelace Building, University of Bristol, University Walk, Bristol, BS8 1TW, UK.
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Duffull S, Isbister G. Challenges faced when modeling clinical toxicology and toxinology events. CPT Pharmacometrics Syst Pharmacol 2022; 11:532-534. [PMID: 35397195 PMCID: PMC9124354 DOI: 10.1002/psp4.12792] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Accepted: 03/18/2022] [Indexed: 11/25/2022] Open
Affiliation(s)
- Stephen Duffull
- School of PharmacyUniversity of OtagoDunedinNew Zealand
- Certara USA, Inc.PrincetonNew JerseyUSA
| | - Geoff Isbister
- Clinical Toxicology Research GroupUniversity of NewcastleNewcastleNew South WalesAustralia
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Wun MK, Padula AM, Greer RM, Leister EM. A review of 91 canine and feline red-bellied black snake (Pseudechis porphyriacus) envenomation cases and lessons for improved management. Aust Vet J 2022; 100:318-328. [PMID: 35318641 PMCID: PMC9542610 DOI: 10.1111/avj.13159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2021] [Revised: 02/28/2022] [Accepted: 03/06/2022] [Indexed: 11/28/2022]
Abstract
Introduction Most cases of red‐bellied black snake (RBBS) envenomation in dogs respond favourably to treatment comprising of tiger‐brown snake antivenom (TBAV), intravenous fluid therapy, analgesia and, if indicated, mechanical ventilation and/or blood transfusion. However, there remains a subset of patients who develop fatal complications despite intensive treatment and risk factors for these occurring remain unknown. Here we present a retrospective cross‐sectional survey of 91 canine and feline RBBS envenomation cases. Methods Cases seen between June 2010 and June 2020 were retrieved from the databases of seven practices in South East and coastal Queensland. From the canine case population, logistic regression analysis was performed to assess the impact of potential risk factors at presentation on the likelihood of death. A final multivariable model was developed using a manual backwards elimination approach based on overall likelihood ratio tests and Wald chi‐square P‐values for each variable. Where model convergence failed due to quasi‐complete separation, Firth's penalised maximum likelihood method was implemented. Such separation may occur when an outcome is completely predicted by an explanatory variable in one group. Results Of the 88 canine cases, 7 died (8.0%), all after prognosis‐based euthanasia. Of the three feline cases, one died after unsuccessful resuscitation following cardiopulmonary arrest. Compared to survivors, dogs that died were older, exhibited pigmenturia, received antivenom later and had a higher total plasma protein (TPP), activated clotting time (ACT) and lower packed cell volume (PCV) at presentation.
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Affiliation(s)
- M K Wun
- Veterinary Specialist Services, 1-15 Lexington Rd, Underwood, Queensland, 4119, Australia.,William R. Pritchard Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of California, Davis, California, 95616, USA
| | - A M Padula
- Australian Venom Research Unit, Department of Pharmacology and Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Melbourne, Victoria, 3010, Australia.,Padula Serums, Bairnsdale, Victoria, 3875, Australia
| | - R M Greer
- Torus Research, Brisbane, Queensland, Australia.,Faculty of Medicine, The University of Queensland, St Lucia, Queensland, 4072, Australia
| | - E M Leister
- Pet Intensive Care Unit, 1-15 Lexington Rd, Underwood, Queensland, 4119, Australia
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