1
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Voros C, Dias J, Timperley CM, Nachon F, Brown RCD, Baati R. The risk associated with organophosphorus nerve agents: from their discovery to their unavoidable threat, current medical countermeasures and perspectives. Chem Biol Interact 2024; 395:110973. [PMID: 38574837 DOI: 10.1016/j.cbi.2024.110973] [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: 01/18/2024] [Revised: 03/13/2024] [Accepted: 03/21/2024] [Indexed: 04/06/2024]
Abstract
The first organophosphorus nerve agent was discovered accidently during the development of pesticides, shortly after the first use of chemical weapons (chlorine, phosgene) on the battlefield during World War I. Despite the Chemical Weapons Convention banning these substances, they have still been employed in wars, terrorist attacks or political assassinations. Characterised by their high lethality, they target the nervous system by inhibiting the acetylcholinesterase (AChE) enzyme, preventing neurotransmission, which, if not treated rapidly, inevitably leads to serious injury or the death of the person intoxicated. The limited efficacy of current antidotes, known as AChE reactivators, pushes research towards new treatments. Numerous paths have been explored, from modifying the original pyridinium oximes to developing hybrid reactivators seeking a better affinity for the inhibited AChE. Another crucial approach resides in molecules more prone to cross the blood-brain barrier: uncharged compounds, bio-conjugated reactivators or innovative formulations. Our aim is to raise awareness on the threat and toxicity of organophosphorus nerve agents and to present the main synthetic efforts deployed since the first AChE reactivator, to tackle the task of efficiently treating victims of these chemical warfare agents.
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Affiliation(s)
- Camille Voros
- Ecole de Chimie Polymère et Matériaux ECPM, Université de Strasbourg, ICPEES UMR CNRS 7515, 25 rue Becquerel, F-67087, Strasbourg, France.
| | - José Dias
- Département de Toxicologie et Risques Chimiques, Institut de Recherche Biomédicale des Armées, F-91220 Brétigny-sur-Orge, France
| | - Christopher M Timperley
- Chemical, Biological and Radiological (CBR) Division, Dstl, Porton Down, Salisbury, Wiltshire, SP4 0JQ, UK.
| | - Florian Nachon
- Département de Toxicologie et Risques Chimiques, Institut de Recherche Biomédicale des Armées, F-91220 Brétigny-sur-Orge, France
| | - Richard C D Brown
- Department of Chemistry, University of Southampton, Highfield, Southampton, SO17 1BJ, UK.
| | - Rachid Baati
- Ecole de Chimie Polymère et Matériaux ECPM, Université de Strasbourg, ICPEES UMR CNRS 7515, 25 rue Becquerel, F-67087, Strasbourg, France; OPGS Pharmaceuticals, Paris BioTech Santé, 24 rue du Faubourg Saint-Jacques, F-75014, Paris, France.
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2
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Wigenstam E, Artursson E, Bucht A, Thors L. Pharmacological prophylaxis with pyridostigmine bromide against nerve agents adversely impact on airway function in an ex vivo rat precision-cut lung slice model. Toxicol Mech Methods 2023; 33:732-740. [PMID: 37537757 DOI: 10.1080/15376516.2023.2238060] [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: 05/26/2023] [Accepted: 07/13/2023] [Indexed: 08/05/2023]
Abstract
The carbamate pyridostigmine bromide (PB) is the only fielded pharmacological prophylaxis for military use against nerve agents. Previous studies have shown differences in the PB-pretreatment efficacy for various nerve agents and in the influence of post-exposure treatment with common antidotes. In the present study, the aim was to evaluate the possibility of using an ex vivo rat precision-cut lung slice model to determine the impact of PB pretreatment on VX-induced bronchoconstriction. In addition, the efficacy of post-exposure treatment with atropine sulfate following PB-prophylaxis was investigated.Bronchoconstriction was induced by electric-field stimulation and was significantly aggravated by 10 µM PB. Airway recovery was decreased by both 1 and 10 µM PB. Evaluation of acetylcholineesterese inhibition by PB showed that the lower concentration met the clinical criteria of residual enzyme activity while the higher concentration completely inhibited the activity. Exposure to VX with or without pretreatment demonstrated similar contractions. However, VX-incubation following pretreatment caused decreased airway relaxation compared to pretreatment alone. Atropine treatment following PB- and VX-exposure significantly decreased the maximum airway contraction and increased the relaxation.In conclusion, no beneficial effect of PB-prophylaxis on VX-induced contractions was observed. The atropine efficacy to relax airways was significant demonstrating the importance of efficient post-exposure therapeutics to protect against the life-threatening respiratory contractions.
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Affiliation(s)
- E Wigenstam
- Swedish Defence Research Agency, CBRN Defence and Security, Umeå, Sweden
| | - E Artursson
- Swedish Defence Research Agency, CBRN Defence and Security, Umeå, Sweden
| | - A Bucht
- Swedish Defence Research Agency, CBRN Defence and Security, Umeå, Sweden
| | - L Thors
- Swedish Defence Research Agency, CBRN Defence and Security, Umeå, Sweden
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3
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Nam JH, Kim MS, Song YJ, Kim CH, Kim WS, Yu CH, Joe HE, Hur GH, Seo MR, Kim Y, Park KE, Choi JY, Chung SJ, Shin YK. Pretreatment of rhesus monkeys with transdermal patches containing physostigmine and procyclidine: implications of the delivery system for the potential application against VX nerve agent intoxication in humans. Arch Toxicol 2023; 97:697-710. [PMID: 36633609 DOI: 10.1007/s00204-022-03438-4] [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: 10/21/2022] [Accepted: 12/21/2022] [Indexed: 01/13/2023]
Abstract
Physostigmine (Phs) is a reversible inhibitor of acetylcholinesterase (AChE) that penetrates the blood-brain barrier (BBB) and could be used to protect the central nervous system (CNS) against the effects of nerve agents. For prophylactic effectiveness, long, steady, and adequate inhibition of AChE activity by Phs is needed to broadly protect against the CNS effects of nerve agents. Here, we evaluated the efficacy of transdermal patches containing Phs and procyclidine (PC) as prophylactic agents. Patches (25 cm2) containing 4.4 mg Phs and 17.8 mg PC had a protective ratio of approximately 78.6-fold in rhesus monkeys challenged with VX nerve agent and given an antidote. Physiologically based pharmacokinetic model in conjunction with an indirect pharmacodynamic (PBPK/PD) was developed for Phs and scaled to rhesus monkeys. The model was able to reproduce the concentration profile and inhibitory effect on AChE of Phs in monkeys, as evidenced by correlation coefficients of 0.994 and 0.992 for 25 cm2 and 49 cm2 patches, respectively (i.e., kinetic data), and 0.989 and 0.968 for 25 cm2 and 49 cm2 patches, respectively (i.e., dynamic data). By extending the monkey PBPK/ PD model to humans, the effective human dose was predicted to be five applications of a 25 cm2 patch (i.e., 22 mg Phs), and two applications of a 49 cm2 patch (i.e., 17.4 mg Phs). Therefore, given that patch application of Phs in rhesus monkeys has a prolonged effect (namely, AChE inhibition of 19.6% for the 25 cm2 patch and 23.0% for the 49 cm2 patch) for up to 216 h, patch formulation of Phs may provide similar protection against nerve agent intoxication in humans.
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Affiliation(s)
- Ji-Hye Nam
- Laboratory of Molecular Pathology and Cancer Genomics, Department of Molecular Medicine and Biopharmaceutical Sciences, Graduate School of Convergence Science and Technology, Seoul National University, Seoul, 08826, Republic of Korea
- Logone Bio-Convergence Research Foundation, Seoul, 08394, Republic of Korea
| | - Min-Soo Kim
- College of Pharmacy, Seoul National University, Seoul, 08826, Republic of Korea
| | - Young-Jo Song
- Agency for Defense Development, Yuseong, Daejeon, 34186, Republic of Korea
| | - Chang-Hwan Kim
- Agency for Defense Development, Yuseong, Daejeon, 34186, Republic of Korea
| | - Wang Soo Kim
- Agency for Defense Development, Yuseong, Daejeon, 34186, Republic of Korea
| | - Chi Ho Yu
- Agency for Defense Development, Yuseong, Daejeon, 34186, Republic of Korea
| | - Hae Eun Joe
- Laboratory of Molecular Pathology and Cancer Genomics, College of Pharmacy and Research Institute of Pharmaceutical Science, Seoul National University, Seoul, 08826, Republic of Korea
- Agency for Defense Development, Yuseong, Daejeon, 34186, Republic of Korea
| | - Gyeung Haeng Hur
- Agency for Defense Development, Yuseong, Daejeon, 34186, Republic of Korea
| | - Myeung-Ryun Seo
- Laboratory of Molecular Pathology and Cancer Genomics, Department of Molecular Medicine and Biopharmaceutical Sciences, Graduate School of Convergence Science and Technology, Seoul National University, Seoul, 08826, Republic of Korea
| | - Yeongmun Kim
- Laboratory of Molecular Pathology and Cancer Genomics, Department of Molecular Medicine and Biopharmaceutical Sciences, Graduate School of Convergence Science and Technology, Seoul National University, Seoul, 08826, Republic of Korea
- Abion Inc, Seoul, 08394, Republic of Korea
| | | | | | - Suk-Jae Chung
- College of Pharmacy, Seoul National University, Seoul, 08826, Republic of Korea.
- Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul, 08826, Republic of Korea.
| | - Young Kee Shin
- Laboratory of Molecular Pathology and Cancer Genomics, Department of Molecular Medicine and Biopharmaceutical Sciences, Graduate School of Convergence Science and Technology, Seoul National University, Seoul, 08826, Republic of Korea.
- Laboratory of Molecular Pathology and Cancer Genomics, College of Pharmacy and Research Institute of Pharmaceutical Science, Seoul National University, Seoul, 08826, Republic of Korea.
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4
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Gage M, Rao NS, Samidurai M, Putra M, Vasanthi SS, Meyer C, Wang C, Thippeswamy T. Soman (GD) Rat Model to Mimic Civilian Exposure to Nerve Agent: Mortality, Video-EEG Based Status Epilepticus Severity, Sex Differences, Spontaneously Recurring Seizures, and Brain Pathology. Front Cell Neurosci 2022; 15:798247. [PMID: 35197823 PMCID: PMC8859837 DOI: 10.3389/fncel.2021.798247] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Accepted: 12/27/2021] [Indexed: 12/14/2022] Open
Abstract
Modeling a real-world scenario of organophosphate nerve agent (OPNA) exposure is challenging. Military personnel are premedicated with pyridostigmine, which led to the development of OPNA models with pyridostigmine/oxime pretreatment to investigate novel therapeutics for acute and chronic effects. However, civilians are not premedicated with pyridostigmine/oxime. Therefore, experimental models without pyridostigmine were developed by other laboratories though often only in males. Following OPNA exposure, prolonged convulsive seizures (CS) or status epilepticus (SE) are concerning. The duration and severity of CS/SE determine the extent of brain injury in survivors even after treating with medical countermeasures (MCM)/antidotes such as atropine, an oxime, and an anticonvulsant such as diazepam/midazolam. In this study, using a large mixed sex cohort of adult male and female rats, without pretreatment, we demonstrate severe SE lasting for >20 min in 82% of the animals in response to soman (GD,132 μg/kg, s.c.). Atropine sulfate (2 mg/kg, i.m.) and HI-6 (125 mg/kg, i.m.) were administered immediately following soman, and midazolam (3 mg/kg, i.m.) 1 h post-exposure. Immediate MCM treatment is impractical in civilian exposure to civilians, but this approach reduces mortality in experimental models. Interestingly, female rats, irrespective of estrous stages, had an average of 44 min CS (stage ≥ 3), while males had an average of 32 min CS during SE, starting from soman exposure to midazolam treatment. However, in telemetry device implanted groups, there were no significant sex differences in SE severity; males had 40 min and females 43 min of continuous CS until midazolam was administered. No animals died prior to midazolam administration and less than 5% died in the first week after soman intoxication. In telemetered animals, there was a direct correlation between EEG changes and behavioral seizures in real-time. In the long-term, convulsive spontaneously recurring seizures (SRS) were observed in 85% of randomly chosen animals. At 4-months post-soman, the brain histology confirmed reactive gliosis and neurodegeneration. The novel findings of this study are that, in non-telemetered animals, the SE severity following soman intoxication was significantly greater in females compared to males and that the estrous cycle did not influence the response.
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Affiliation(s)
- Meghan Gage
- Neuroscience Interdepartmental Program, Iowa State University, Ames, IA, United States.,Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, United States
| | - Nikhil S Rao
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, United States
| | - Manikandan Samidurai
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, United States
| | - Marson Putra
- Neuroscience Interdepartmental Program, Iowa State University, Ames, IA, United States.,Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, United States
| | - Suraj S Vasanthi
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, United States
| | - Christina Meyer
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, United States
| | - Chong Wang
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, United States
| | - Thimmasettappa Thippeswamy
- Neuroscience Interdepartmental Program, Iowa State University, Ames, IA, United States.,Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, United States
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5
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Batool S, Furqan T, Hasan Mahmood MS, Tweedie D, Kamal MA, Greig NH. In Silico and Ex Vivo Analyses of the Inhibitory Action of the Alzheimer Drug Posiphen and Primary Metabolites with Human Acetyl- and Butyrylcholinesterase Enzymes. ACS Pharmacol Transl Sci 2022; 5:70-79. [PMID: 35178511 PMCID: PMC8845043 DOI: 10.1021/acsptsci.1c00200] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Indexed: 02/08/2023]
Abstract
![]()
Alzheimer’s
disease (AD) is the most common neurodegenerative
disorder worldwide. Ongoing research to develop AD treatments has
characterized multiple drug targets including the cholinergic system,
amyloid-β peptide, phosphorylated tau, and neuroinflammation.
These systems have the potential to interact to either drive or slow
AD progression. Promising agents that simultaneously impact many of
these drug targets are the AD experimental drug Posiphen and its enantiomer
phenserine that, currently, are separately being evaluated in clinical
trials. To define the cholinergic component of these agents, the anticholinesterase
activities of a ligand dataset comprising Posiphen and primary metabolites
((+)-N1-norPosiphen, (+)-N8-norPosiphen, and (+)-N1,N8-bisnorPosiphen)
were characterized and compared to those of the enantiomer phenserine.
The “target” dataset involved the human cholinesterase
enzymes acetylcholinesterase (AChE) and butyrylcholinesterase (BChE).
Binding interactions between the ligands and targets were analyzed
using Autodock 4.2. The computationally determined inhibitory action
of these ligands was then compared to ex vivo laboratory-measured
values versus human AChE and BChE. While Posiphen lacked AChE inhibitory
action, its major and minor metabolites (+)-N1-norPosiphen and (+)-N1,N8-bisnorPosiphen,
respectively, possessed modest AChE inhibitory activity, and Posiphen
and all metabolites lacked BChE action. Phenserine, as a positive
control, demonstrated AChE-selective inhibitory action. In light of
AChE inhibitory action deriving from a major and minor Posiphen metabolite,
current Posiphen clinical trials in AD and related disorders should
additionally evaluate AChE inhibition; particularly if Posiphen should
be combined with a known anticholinesterase, since this drug class
is clinically approved and the standard of care for AD subjects, and
excessive AChE inhibition may impact drug tolerability.
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Affiliation(s)
- Sidra Batool
- Research School of Chemistry, Australian National University, Canberra, ACT 2601, Australia
| | - Tiyyaba Furqan
- Department of Biosciences, COMSATS University, Park Road, Chak Shahzad, Islamabad 45550, Pakistan
| | | | - David Tweedie
- Drug Design & Development Section, Translational Gerontology Branch, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland 21224, United States
| | - Mohammad A. Kamal
- West China School of Nursing / Institutes for Systems Genetics, Frontiers Science Center for Disease-related Molecular Network, West China Hospital, Sichuan University, Chengdu 610041 Sichuan, China
- King Fahd Medical Research Center, King Abdulaziz University, P.O. Box 80216, Jeddah 21589, Saudi Arabia
- Department of Pharmacy, Faculty of Allied Health Sciences, Daffodil International University, Khagan, Dhaka 1340, Bangladesh
- Enzymoics, Novel Global Community Educational Foundation, Hebersham, NSW 2770, Australia
| | - Nigel H. Greig
- Drug Design & Development Section, Translational Gerontology Branch, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland 21224, United States
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6
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Finnegan TJ, Gunawardana VWL, Badjić JD. Molecular Recognition of Nerve Agents and Their Organophosphorus Surrogates: Toward Supramolecular Scavengers and Catalysts. Chemistry 2021; 27:13280-13305. [PMID: 34185362 PMCID: PMC8453132 DOI: 10.1002/chem.202101532] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Indexed: 12/19/2022]
Abstract
Nerve agents are tetrahedral organophosphorus compounds (OPs) that were developed in the last century to irreversibly inhibit acetylcholinesterase (AChE) and therefore impede neurological signaling in living organisms. Exposure to OPs leads to a rapid development of symptoms from excessive salivation, nasal congestion and chest pain to convulsion and asphyxiation which if left untreated may lead to death. These potent toxins are prepared on a large scale from inexpensive staring materials, making it feasible for terrorist groups or states to use them against military and civilians. The existing antidotes provide limited protection and are difficult to apply to a large number of affected individuals. While new prophylactics are currently being developed, there is still need for therapeutics capable of both preventing and reversing the effects of OP poisoning. In this review, we describe how the science of molecular recognition can expand the pallet of tools for rapid and safe sequestration of nerve agents.
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Affiliation(s)
- Tyler J Finnegan
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, OH, USA
| | | | - Jovica D Badjić
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, OH, USA
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7
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Bajgar J, Kassa J, Kucera T, Musilek K, Jun D, Kuca K. Some Possibilities to Study New Prophylactics against Nerve Agents. Mini Rev Med Chem 2019; 19:970-979. [PMID: 30827238 DOI: 10.2174/1389557519666190301112530] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2017] [Revised: 04/10/2017] [Accepted: 04/26/2017] [Indexed: 11/22/2022]
Abstract
Nerve agents belong to the most dangerous chemical warfare agents and can be/were misused by terrorists. Effective prophylaxis and treatment is necessary to diminish their effect. General principles of prophylaxis are summarized (protection against acetylcholinesterase inhibition, detoxification, treatment "in advance" and use of different drugs). They are based on the knowledge of mechanism of action of nerve agents. Among different examinations, it is necessary to test prophylactic effectivity in vivo and compare the results with protection in vitro. Chemical and biological approaches to the development of new prophylactics would be applied simultaneously during this research. Though the number of possible prophylactics is relatively high, the only four drugs were introduced into military medical practice. At present, pyridostigmine seems to be common prophylactic antidote; prophylactics panpal (tablets with pyridostigmine, trihexyphenidyl and benactyzine), transant (transdermal patch containing HI-6) are other means introduced into different armies as prophylactics. Scavenger commercionally available is Protexia®. Future development will be focused on scavengers, and on other drugs either reversible cholinesterase inhibitors (e.g., huperzine A, gallantamine, physostigmine, acridine derivatives) or other compounds.
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Affiliation(s)
- J Bajgar
- Department of Chemistry, Faculty of Science, University of Hradec Kralove, Hradec Kralove, Czech Republic.,Biomedical Research Centre, University Hospital Hradec Kralove, Hradec Kralove, Czech Republic.,Department of Toxicology and Military Pharmacy, Faculty of Military Health Sciences, University of Defence, Hradec Kralove, Czech Republic
| | - J Kassa
- Department of Toxicology and Military Pharmacy, Faculty of Military Health Sciences, University of Defence, Hradec Kralove, Czech Republic
| | - T Kucera
- Department of Toxicology and Military Pharmacy, Faculty of Military Health Sciences, University of Defence, Hradec Kralove, Czech Republic
| | - K Musilek
- Department of Chemistry, Faculty of Science, University of Hradec Kralove, Hradec Kralove, Czech Republic.,Biomedical Research Centre, University Hospital Hradec Kralove, Hradec Kralove, Czech Republic
| | - D Jun
- Biomedical Research Centre, University Hospital Hradec Kralove, Hradec Kralove, Czech Republic.,Department of Toxicology and Military Pharmacy, Faculty of Military Health Sciences, University of Defence, Hradec Kralove, Czech Republic
| | - K Kuca
- Department of Chemistry, Faculty of Science, University of Hradec Kralove, Hradec Kralove, Czech Republic.,Biomedical Research Centre, University Hospital Hradec Kralove, Hradec Kralove, Czech Republic
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8
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Costanzi S, Machado JH, Mitchell M. Nerve Agents: What They Are, How They Work, How to Counter Them. ACS Chem Neurosci 2018; 9:873-885. [PMID: 29664277 DOI: 10.1021/acschemneuro.8b00148] [Citation(s) in RCA: 99] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Nerve agents are organophosphorus chemical warfare agents that exert their action through the irreversible inhibition of acetylcholinesterase, with a consequent overstimulation of cholinergic transmission followed by its shutdown. Beyond warfare, they have notoriously been employed in acts of terrorism as well as high profile assassinations. After a brief historical introduction on the development and deployment of nerve agents, this review provides a survey of their chemistry, the way they affect cholinergic transmission, the available treatment options, and the current directions for their improvement. As the review illustrates, despite their merits, the currently available treatment options present several shortcomings. Current research directions involve the search for improved antidotes, antagonists of the nicotinic receptors, small-molecule pretreatment options, as well as bioscavengers as macromolecular pretreatment options. These efforts are making good progress in many different directions and, hopefully, will lead to a lower target susceptibility, thus reducing the appeal of nerve agents as chemical weapons.
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Affiliation(s)
| | - John-Hanson Machado
- Department of Chemistry, The George Washington University, 800 22nd Street NW, Washington, DC 20052, United States
- Computational Biology Institute, The George Washington University, 45085 University Drive Suite 305, Ashburn, Virginia 20147, United States
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9
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Langston JL, Myers TM. VX toxicity in the Göttingen minipig. Toxicol Lett 2016; 264:12-19. [PMID: 27773723 DOI: 10.1016/j.toxlet.2016.10.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Revised: 09/20/2016] [Accepted: 10/19/2016] [Indexed: 11/18/2022]
Abstract
The present experiments determined the intramuscular LD50 of VX in male Göttingen minipigs at two stages of development. In pubertal animals (115 days old), the LD50 of VX was indeterminate, but approximated 33.3μg/kg. However, in sexually mature animals (152 days old), the LD50 was estimated to be only 17.4μg/kg. Signs of nerve agent toxicity in the Göttingen minipig were similar to those described for other species, with some notable exceptions (such as urticaria and ejaculation). Latencies to the onset of sustained convulsions were inversely related to the administered dose of VX in both ages of minipigs. Additionally, actigraphy was used to quantify the presence of tremor and convulsions and, in some cases, was useful for precisely estimating time of death. The main finding indicates that in minipigs, as in other species, even relatively small differences in age can substantially alter the toxicity of nerve agents. Additionally, actigraphy can serve as a non-invasive method of characterizing the tremors and convulsions that often accompany nerve agent intoxication.
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Affiliation(s)
- Jeffrey L Langston
- Analytical Toxicology Division, United States Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA
| | - Todd M Myers
- Analytical Toxicology Division, United States Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA.
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10
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Kaur S, Singh S, Chahal KS, Prakash A. Potential pharmacological strategies for the improved treatment of organophosphate-induced neurotoxicity. Can J Physiol Pharmacol 2014; 92:893-911. [DOI: 10.1139/cjpp-2014-0113] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Organophosphates (OP) are highly toxic compounds that cause cholinergic neuronal excitotoxicity and dysfunction by irreversible inhibition of acetylcholinesterase, resulting in delayed brain damage. This delayed secondary neuronal destruction, which arises primarily in the cholinergic areas of the brain that contain dense accumulations of cholinergic neurons and the majority of cholinergic projection, could be largely responsible for persistent profound neuropsychiatric and neurological impairments such as memory, cognitive, mental, emotional, motor, and sensory deficits in the victims of OP poisoning. The therapeutic strategies for reducing neuronal brain damage must adopt a multifunctional approach to the various steps of brain deterioration: (i) standard treatment with atropine and related anticholinergic compounds; (ii) anti-excitotoxic therapies to prevent cerebral edema, blockage of calcium influx, inhibition of apoptosis, and allow for the control of seizure; (iii) neuroprotection by aid of antioxidants and N-methyl-d-aspartate (NMDA) antagonists (multifunctional drug therapy), to inhibit/limit the secondary neuronal damage; and (iv) therapies targeting chronic neuropsychiatric and neurological symptoms. These neuroprotective strategies may prevent secondary neuronal damage in both early and late stages of OP poisoning, and thus may be a beneficial approach to treating the neuropsychological and neuronal impairments resulting from OP toxicity.
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Affiliation(s)
- Shamsherjit Kaur
- Department of Pharmacology, ISF College of Pharmacy, Moga 142001, Punjab, India
- Punjab Technical University, Kapurthala 144601, Punjab, India
| | - Satinderpal Singh
- Department of Pharmacology, ISF College of Pharmacy, Moga 142001, Punjab, India
| | - Karan Singh Chahal
- Department of Pharmacology, ISF College of Pharmacy, Moga 142001, Punjab, India
| | - Atish Prakash
- Department of Pharmacology, ISF College of Pharmacy, Moga 142001, Punjab, India
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11
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Galantamine prevents long-lasting suppression of excitatory synaptic transmission in CA1 pyramidal neurons of soman-challenged guinea pigs. Neurotoxicology 2014; 44:270-8. [PMID: 25064080 DOI: 10.1016/j.neuro.2014.07.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 07/08/2014] [Accepted: 07/15/2014] [Indexed: 12/27/2022]
Abstract
Galantamine, a drug currently approved for the treatment of Alzheimer's disease, has recently emerged as an effective pretreatment against the acute toxicity and delayed cognitive deficits induced by organophosphorus (OP) nerve agents, including soman. Since cognitive deficits can result from impaired glutamatergic transmission in the hippocampus, the present study was designed to test the hypothesis that hippocampal glutamatergic transmission declines following an acute exposure to soman and that this effect can be prevented by galantamine. To test this hypothesis, spontaneous excitatory postsynaptic currents (EPSCs) were recorded from CA1 pyramidal neurons in hippocampal slices obtained at 1h, 24h, or 6-9 days after guinea pigs were injected with: (i) 1×LD50 soman (26.3μg/kg, s.c.); (ii) galantamine (8mg/kg, i.m.) followed 30min later by 1×LD50 soman, (iii) galantamine (8mg/kg, i.m.), or (iv) saline (0.5ml/kg, i.m.). In soman-injected guinea pigs that were not pretreated with galantamine, the frequency of EPSCs was significantly lower than that recorded from saline-injected animals. There was no correlation between the severity of soman-induced acute toxicity and the magnitude of soman-induced reduction of EPSC frequency. Pretreatment with galantamine prevented the reduction of EPSC frequency observed at 6-9 days after the soman challenge. Prevention of soman-induced long-lasting reduction of hippocampal glutamatergic synaptic transmission may be an important determinant of the ability of galantamine to counter cognitive deficits that develop long after an acute exposure to the nerve agent.
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Prolonged administration of pyridostigmine impairs neuromuscular function with and without down-regulation of acetylcholine receptors. Anesthesiology 2013; 119:412-21. [PMID: 23563362 DOI: 10.1097/aln.0b013e318291c02e] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND The acetylcholinesterase inhibitor, pyridostigmine, is prophylactically administered to mitigate the toxic effects of nerve gas poisoning. The authors tested the hypothesis that prolonged pyridostigmine administration can lead to neuromuscular dysfunction and even down-regulation of acetylcholine receptors. METHODS Pyridostigmine (5 or 25 mg·kg·day) or saline was continuously administered via osmotic pumps to rats, and infused for either 14 or 28 days until the day of neuromuscular assessment (at day 14 or 28), or discontinued 24 h before neuromuscular assessment. Neurotransmission and muscle function were examined by single-twitch, train-of-four stimulation and 100-Hz tetanic stimulation. Sensitivity to atracurium and acetylcholine receptor number (quantitated by I-α-bungarotoxin) provided additional measures of neuromuscular integrity. RESULTS Specific tetanic tensions (Newton [N]/muscle weight [g]) were significantly (P < 0.05) decreased at 14 (10.3 N/g) and 28 (11.1 N/g) days of 25 mg·kg·day pyridostigmine compared with controls (13.1-13.6 N/g). Decreased effective dose (0.81-1.05 vs. 0.16-0.45 mg/kg; P < 0.05) and decreased plasma concentration (3.02-3.27 vs. 0.45-1.37 μg/ml; P < 0.05) of atracurium for 50% paralysis (controls vs. 25 mg·kg·day pyridostigmine, respectively), irrespective of discontinuation of pyridostigmine, confirmed the pyridostigmine-induced altered neurotransmission. Pyridostigmine (25 mg·kg·day) down-regulated acetylcholine receptors at 28 days. CONCLUSIONS Prolonged administration of pyridostigmine (25 mg·kg·day) leads to neuromuscular impairment, which can persist even when pyridostigmine is discontinued 24 h before assessment of neuromuscular function. Pyridostigmine has the potential to down-regulate acetylcholine receptors, but induces neuromuscular dysfunction even in the absence of receptor changes.
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Čolović MB, Krstić DZ, Lazarević-Pašti TD, Bondžić AM, Vasić VM. Acetylcholinesterase inhibitors: pharmacology and toxicology. Curr Neuropharmacol 2013; 11:315-35. [PMID: 24179466 PMCID: PMC3648782 DOI: 10.2174/1570159x11311030006] [Citation(s) in RCA: 1395] [Impact Index Per Article: 126.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Revised: 01/04/2013] [Accepted: 02/02/2013] [Indexed: 12/12/2022] Open
Abstract
Acetylcholinesterase is involved in the termination of impulse transmission by rapid hydrolysis of the neurotransmitter acetylcholine in numerous cholinergic pathways in the central and peripheral nervous systems. The enzyme inactivation, induced by various inhibitors, leads to acetylcholine accumulation, hyperstimulation of nicotinic and muscarinic receptors, and disrupted neurotransmission. Hence, acetylcholinesterase inhibitors, interacting with the enzyme as their primary target, are applied as relevant drugs and toxins. This review presents an overview of toxicology and pharmacology of reversible and irreversible acetylcholinesterase inactivating compounds. In the case of reversible inhibitors being commonly applied in neurodegenerative disorders treatment, special attention is paid to currently approved drugs (donepezil, rivastigmine and galantamine) in the pharmacotherapy of Alzheimer's disease, and toxic carbamates used as pesticides. Subsequently, mechanism of irreversible acetylcholinesterase inhibition induced by organophosphorus compounds (insecticides and nerve agents), and their specific and nonspecific toxic effects are described, as well as irreversible inhibitors having pharmacological implementation. In addition, the pharmacological treatment of intoxication caused by organophosphates is presented, with emphasis on oxime reactivators of the inhibited enzyme activity administering as causal drugs after the poisoning. Besides, organophosphorus and carbamate insecticides can be detoxified in mammals through enzymatic hydrolysis before they reach targets in the nervous system. Carboxylesterases most effectively decompose carbamates, whereas the most successful route of organophosphates detoxification is their degradation by corresponding phosphotriesterases.
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Affiliation(s)
- Mirjana B Čolović
- Department of Physical Chemistry, Vinča Institute of Nuclear Sciences, University of Belgrade, Belgrade, Serbia
| | - Danijela Z Krstić
- University School of Medicine, Institute of Medical Chemistry, University of Belgrade, Belgrade, Serbia
| | - Tamara D Lazarević-Pašti
- Department of Physical Chemistry, Vinča Institute of Nuclear Sciences, University of Belgrade, Belgrade, Serbia
| | - Aleksandra M Bondžić
- Department of Physical Chemistry, Vinča Institute of Nuclear Sciences, University of Belgrade, Belgrade, Serbia
| | - Vesna M Vasić
- Department of Physical Chemistry, Vinča Institute of Nuclear Sciences, University of Belgrade, Belgrade, Serbia
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Pohanka M, Sobotka J, Svobodova H, Stetina R. Investigation of oxidative stress in blood, brain, kidney, and liver after oxime antidote HI-6 application in a mouse experimental model. Drug Chem Toxicol 2011; 34:255-60. [PMID: 21649479 DOI: 10.3109/01480545.2010.542753] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Oxime reactivator HI-6 (asoxime, in some sources) is a potent antidote suitable for treatment of intoxication by nerve agents. Despite the fact that HI-6 is considered for practical application in emergency situations, the impact of HI-6 on patients' bodies has not been established yet. The present experiment was carried out in order to estimate whether HI-6 would be able to trigger or protect from oxidative stress in a BALB/c mice model. HI-6 was applied in doses ranging from 0.2 to 20% of LD₅₀. Ferric-reducing antioxidant power (FRAP), thiobarbituric acid reactive substances (TBARS), reduced glutathione (GSH), and glutathione reductase (GR) were assayed in the blood, liver, kidney, and brain of treated animals. It was found that HI-6 does not increase GR or TBARS. On the contrary, TBARS levels in the brain and liver were found to be significantly decreased in HI-6-treated animals. Pertinent antioxidant properties of HI-6 were excluded by the FRAP method. Endogenous antioxidants were unchanged, with the exception of the kidney. Low-molecular-weight antioxidants assayed by the FRAP method were significantly decreased in kidneys of animals treated with HI-6. However, GSH partially recovered the loss of the other low-molecular-weight antioxidants and was significantly increased in the kidney of HI-6-exposed mice. HI-6 potential to produce nephropathy is hypothesized. The achieved conclusions were quite surprising and showed a complex impact of HI-6 on the body.
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Affiliation(s)
- Miroslav Pohanka
- Faculty of Military Health Sciences, University of Defense, Hradec Kralove, Czech Republic.
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Pohanka M, Novotny L, Zdarova-Karasova J, Bandouchova H, Zemek F, Hrabinova M, Misik J, Kuca K, Bajgar J, Zitka O, Cernei N, Kizek R, Pikula J. Asoxime (HI-6) impact on dogs after one and tenfold therapeutic doses: assessment of adverse effects, distribution, and oxidative stress. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2011; 32:75-81. [PMID: 21787733 DOI: 10.1016/j.etap.2011.03.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2010] [Revised: 03/15/2011] [Accepted: 03/25/2011] [Indexed: 05/31/2023]
Abstract
Asoxime (HI-6) is a well known oxime reactivator used for counteracting intoxication by nerve agents. It is able to reactivate acetylcholinesterase (AChE) inhibited even by sarin or soman. The present experiment was aimed to determine markers of oxidative stress represented by thiobarbituric acid reactive substances and antioxidants represented by ferric reducing antioxidant power, reduced and oxidized glutathione in a Beagle dog model. Two groups of dogs were intramuscularly exposed to single (11.4 mg/kg.b.wt.) or tenfold (114 mg/kg.b.wt.) human therapeutically doses of HI-6. HI-6 affinity for AChE in vitro was evaluated in a separate experiment. Complete serum biochemistry and pharmacokinetics were also performed with significant alteration in blood urea nitrogen, creatine phosphokinase, glucose and triglycerides. Blood samples were collected before HI-6 application and after 30, 60, and 120 min. The overall HI-6 impact on organism is discussed.
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Affiliation(s)
- Miroslav Pohanka
- Faculty of Military Health Sciences, University of Defence, Trebesska 1575, 500 01 Hradec Kralove, Czech Republic.
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Maselli RA, Henderson JD, Ng J, Follette D, Graves G, Wilson BW. Protection of human muscle acetylcholinesterase from soman by pyridostigmine bromide. Muscle Nerve 2011; 43:591-5. [PMID: 21404290 DOI: 10.1002/mus.21922] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
INTRODUCTION Pretreatment with pyridostigmine bromide (PB) of human intercostal muscle fibers exposed to the irreversible acetylcholinesterase (AChE) inhibitor soman was investigated. METHODS Muscles were pretreated with 3 × 10(-6) M PB or saline for 20 minutes, then exposed to 10(-7) M soman for 10 minutes. RESULTS AChE of muscles treated with soman alone was inhibited >95%. In contrast, PB pretreatment of soman-exposed bundles protected 20% of AChE activity. AChE of bundles exposed to PB alone recovered after 4 hours, but bundles exposed to both PB and soman did not. Soman-induced reduction of resting membrane potentials and increment of amplitudes and decay times of miniature endplate potentials (MEPPs) were partially corrected by PB pretreatment. CONCLUSIONS In vitro pretreatment of human muscles with PB protected up to 20% of muscle AChE and ameliorated some deleterious effects on endplate physiology induced by soman.
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Affiliation(s)
- Ricardo A Maselli
- Department of Neurology, University of California Davis, Davis, California, USA
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Herkert N, Schulz S, Wille T, Thiermann H, Hatz R, Worek F. Pre- and post-treatment effect of physostigmine on soman-inhibited human erythrocyte and muscle acetylcholinesterase in vitro. Toxicol Appl Pharmacol 2011; 253:7-13. [DOI: 10.1016/j.taap.2011.03.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2011] [Revised: 03/04/2011] [Accepted: 03/06/2011] [Indexed: 11/16/2022]
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Herkert NM, Thiermann H, Worek F. In vitro kinetic interactions of pyridostigmine, physostigmine and soman with erythrocyte and muscle acetylcholinesterase from different species. Toxicol Lett 2011; 206:41-6. [PMID: 21414391 DOI: 10.1016/j.toxlet.2011.03.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2011] [Accepted: 03/02/2011] [Indexed: 10/18/2022]
Abstract
The low effectiveness of atropine and oxime treatment in soman poisoning may be enhanced by carbamates pre-treatment. For ethical reasons medical countermeasures can only be tested in animal models despite the fact of substantial species differences. With this kinetic in vitro study the interactions between pyridostigmine, physostigmine and soman with human, Rhesus monkey, swine and guinea pig erythrocyte AChE were investigated. In addition, the effect of the carbamates on the residual activity and enzyme recovery after soman inhibition was examined with erythrocyte and intercostal muscle AChE from these species with a dynamic in vitro model with real-time determination of AChE activity. Only small to moderate species differences of the inhibition and decarbamylation kinetics were recorded. It was possible to show that with erythrocyte and muscle AChE a similar level of protection by carbamates and reactivation after discontinuation of the carbamates and soman could be observed. Thus, these data indicate that carbamate pre-treatment is expected to protect a critical level of muscle AChE and confirm the presumption that erythrocyte AChE may serve as a surrogate for synaptic AChE. Hence, these and previous data fortify the notion that erythrocyte AChE is a proper tool for in vitro kinetic studies as well as for therapeutic monitoring in experimental and clinical studies.
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Affiliation(s)
- N M Herkert
- Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstrasse 11, 80937 Munich, Germany
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