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Kassa J, Fusek J. The Influence of Oxime Selection on the Efficacy of Antidotal Treatment of Soman-Poisoned Rats. ACTA MEDICA (HRADEC KRÁLOVÉ) 2019. [DOI: 10.14712/18059694.2019.52] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
1. The influence of some acetylcholinesterase reactivators (HI-6, obidoxime, pralidoxime) on the efficacy of antidotal treatment to eliminate soman-induced disturbance of respiration and circulation and to protect experimental animals poisoned with supralethal dose of soman (1.5 × LD50) was investigated in a rat model with on-line monitoring of respiratory and circulatory parameters. 2. Obidoxime or pralidoxime in combination with atropine were insufficient to enable soman-poisoned rats to survive for 2 hours when given 1 minute after the administration of soman. 3. On the other hand, the ability of the oxime HI-6 in combination with atropine to prevent soman-induced alteration of respiration and circulation was significantly higher. Some rats treated with HI-6 in combination with atropine were fully protected against the lethal toxic effects of soman within 2 hours following soman administration. 4. Our findings confirm that the oxime HI-6 seems to be a much more suitable and efficacious acetylcholinesterase reactivator for the antidotal treatment of severe acute soman-induced poisoning than currently used obidoxime or pralidoxime.
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2
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Neuroprotective effects of a catalytic antioxidant in a rat nerve agent model. Redox Biol 2018; 20:275-284. [PMID: 30384261 PMCID: PMC6215030 DOI: 10.1016/j.redox.2018.10.010] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Revised: 10/10/2018] [Accepted: 10/13/2018] [Indexed: 12/19/2022] Open
Abstract
Persistent inhibition of acetylcholinesterase resulting from exposure to nerve agents such as soman, is associated with prolonged seizure activity known as status epilepticus (SE). Without medical countermeasures, exposure to soman and resultant SE leads to high morbidity and mortality. Currently available therapeutics are effective in limiting mortality, however effects on morbidity are highly time-dependent and rely on the ability to suppress SE. We have previously demonstrated significant protection from secondary neuronal injury in surrogate nerve agent models by targeting oxidative stress. However, whether oxidative stress represents a relevant therapeutic target in genuine nerve agent toxicity is unknown. Here, we demonstrate that soman exposure results in robust region- and time-dependent oxidative stress. Targeting this oxidative stress in a post-exposure paradigm using a small molecular weight, broad spectrum catalytic antioxidant, was sufficient to attenuate brain and plasma oxidative stress, neuroinflammation and neurodegeneration. Thus, targeting of oxidative stress in a post-exposure paradigm can mitigate secondary neuronal injury following soman exposure. Soman exposure results in time- and region- dependent oxidative stress in brain. A catalytic antioxidant inhibited oxidative stress, neuroinflammation and degeneration. Post-exposure treatment with the antioxidant attenuates secondary neuronal injury.
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Voicu VA, Medvedovici AV, Sakurada K, Ohta H, Rădulescu FȘ, Miron DS. The forgotten or underestimated relevance of biopharmaceutical-based assessments for the oral absorption studies of oxime reactivators. Expert Opin Drug Metab Toxicol 2016; 12:743-52. [DOI: 10.1080/17425255.2016.1179282] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Victor A. Voicu
- Department of Pharmacology, Toxicology and Clinical Psychopharmacology, University of Medicine and Pharmacy ‘Carol Davilla’, Bucharest, Romania
- Medical Science Section, Romanian Academy, Bucharest, Romania
| | | | - Koichi Sakurada
- Department of Forensic Dentistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
| | - Hikoto Ohta
- Department of Forensic Chemistry, Toxicology Section, National Research Institute of Police Science, National Police Agency, Kashiwa City, Chiba, Japan
| | | | - Dalia Simona Miron
- Faculty of Pharmacy, University of Medicine and Pharmacy Carol Davila, Bucharest, Romania
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Perkins MW, Wong B, Rodriguez A, Devorak JL, Dao TT, Leuschner JA, Kan RK, Sciuto AM. Vapor inhalation exposure to soman in conscious untreated rats: preliminary assessment of neurotoxicity. Inhal Toxicol 2015; 28:14-21. [PMID: 26711353 DOI: 10.3109/08958378.2015.1125973] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Neurological toxicity and brain injury following vapor inhalation exposure to the chemical warfare nerve agent (CWNA) soman (GD) were examined in untreated non-anesthetized rats. In this study, male Sprague-Dawley rats (300-350 g) were exposed to 600 mg × min/m(3) of soman or vehicle in a customized head-out inhalation system for 7 min. Convulsant animals were observed for clinical signs and various regions of the brain (dorsolateral thalamus, basolateral amygdala, piriform cortex, and lateral cortex) were collected for pathological observations 24 h post-exposure. Signs of CWNA-induced cholinergic crises including salivation, lacrimation, increased urination and defecation, and tremors were observed in all soman-exposed animals. Soman-exposed animals at 24 h post-exposure lost 11% of their body weight in comparison to 2% in vehicle-exposed animals. Whole blood acetylcholinesterase (AChE) activity was significantly inhibited in all soman-exposed groups in comparison to controls. Brain injury was confirmed by the neurological assessment of hematoxylin-eosin (H&E) staining and microscopy in the piriform cortex, dorsolateral thalamus, basolateral amygdala, and lateral cortex. Severe damage including prominent lesions, edematous, congested, and/or hemorrhagic tissues was observed in the piriform cortex, dorsolateral thalamus, and lateral cortex in soman-exposed animals 24 h post-exposure, while only minimal damage was observed in the basolateral amygdala. These results indicate that inhalation exposure to soman vapor causes neurological toxicity and brain injury in untreated unanesthetized rats. This study demonstrates the ability of the described soman vapor inhalation exposure model to cause neurological damage 24 h post-exposure in rats.
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Affiliation(s)
- Michael W Perkins
- a Analytical Toxicology Branch, United States Army Medical Research Institute of Chemical Defense , Aberdeen Proving Ground , MD , USA
| | - Benjamin Wong
- a Analytical Toxicology Branch, United States Army Medical Research Institute of Chemical Defense , Aberdeen Proving Ground , MD , USA
| | - Ashley Rodriguez
- a Analytical Toxicology Branch, United States Army Medical Research Institute of Chemical Defense , Aberdeen Proving Ground , MD , USA
| | - Jennifer L Devorak
- a Analytical Toxicology Branch, United States Army Medical Research Institute of Chemical Defense , Aberdeen Proving Ground , MD , USA
| | - Thuy T Dao
- a Analytical Toxicology Branch, United States Army Medical Research Institute of Chemical Defense , Aberdeen Proving Ground , MD , USA
| | - Jessica A Leuschner
- a Analytical Toxicology Branch, United States Army Medical Research Institute of Chemical Defense , Aberdeen Proving Ground , MD , USA
| | - Robert K Kan
- a Analytical Toxicology Branch, United States Army Medical Research Institute of Chemical Defense , Aberdeen Proving Ground , MD , USA
| | - Alfred M Sciuto
- a Analytical Toxicology Branch, United States Army Medical Research Institute of Chemical Defense , Aberdeen Proving Ground , MD , USA
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5
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Perkins MW, Wong B, Rodriguez A, Devorak J, Sciuto AM. Measurement of various respiratory dynamics parameters following acute inhalational exposure to soman vapor in conscious rats. Inhal Toxicol 2015. [DOI: 10.3109/08958378.2015.1068890] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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6
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Conti ML, Che MM, Boylan M, Sciuto AM, Gordon RK, Nambiar MP. Acute microinstillation inhalation exposure to sarin induces changes in respiratory dynamics and functions in guinea pigs. Int J Toxicol 2010; 28:436-47. [PMID: 19815847 DOI: 10.1177/1091581809344879] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
This study investigates the toxic effects of sarin on respiratory dynamics following microinstillation inhalation exposure in guinea pigs. Animals are exposed to sarin for 4 minutes, and respiratory functions are monitored at 4 hours and 24 hours by whole-body barometric plethysmography. Data show significant changes in respiratory dynamics and function following sarin exposure. An increase in respiratory frequency is observed at 4 hours post exposure compared with saline controls. Tidal volume and minute volume are also increased in sarin-exposed animals 4 hours after exposure. Peak inspiratory flow increases, whereas peak expiratory flow increases at 4 hours and is erratic following sarin exposure. Animals exposed to sarin show a significant decrease in expiratory time and inspiratory time. End-inspiratory pause is unchanged whereas end-expiratory pause is slightly decreased 24 hours after sarin exposure. These results indicate that inhalation exposure to sarin alters respiratory dynamics and function at 4 hours, with return to normal levels at 24 hours post exposure.
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Affiliation(s)
- Michele L Conti
- United States Army Medical Research Institute of Chemical Defense, Edgewood, MD, USA
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Katos AM, Conti M, Moran TS, Chon TW, Gordon RK, Sciuto AM, Doctor BP, Nambiar MP. Acute microinstillation inhalation exposure to soman induces changes in respiratory dynamics and functions in guinea pigs. Inhal Toxicol 2009; 21:1-10. [DOI: 10.1080/08958370802331217] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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8
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Joosen MJ, Jousma E, van den Boom TM, Kuijpers WC, Smit AB, Lucassen PJ, van Helden HP. Long-term cognitive deficits accompanied by reduced neurogenesis after soman poisoning. Neurotoxicology 2009; 30:72-80. [DOI: 10.1016/j.neuro.2008.11.010] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2008] [Revised: 11/12/2008] [Accepted: 11/24/2008] [Indexed: 01/13/2023]
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9
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Lundy PM, Raveh L, Amitai G. Development of the Bisquaternary Oxime HI-6 Toward Clinical Use in the Treatment of Organophosphate Nerve Agent Poisoning. ACTA ACUST UNITED AC 2006; 25:231-43. [PMID: 17288495 DOI: 10.2165/00139709-200625040-00004] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The traditional therapeutic treatment of organophosphate cholinesterase inhibitor (nerve agents) poisoning consists of co-treatment with an antimuscarinic (atropine) and a reactivator of inhibited acetylcholinesterase (AChE), which contains a nucleophilic oxime function. Two oximes are presently widely available for clinical use, pralidoxime and obidoxime (toxogonin), but both offer little protection against important nerve agent threats. This has highlighted the real need for the development and availability of more effective oximes for human use, a search that has been going on for up to 30 years. However, despite the demonstration of more effective and safe oximes in animal experiments, no additional oximes have been licensed for human use. HI-6, (1-[[[4(aminocarbonyl)-pyridinio]methoxy]methyl]-2(hydroxyimino)pyridinium dichloride; CAS 34433-31-3) has been studied intensively and has been proved effective in a variety of species including non-human primates and appears from clinical experience to be safe in humans. These studies have led to the fielding of HI-6 for use against nerve agents by the militaries of the Czech republic, Sweden, Canada and under certain circumstances the Organisation for the Prohibition of Chemical Weapons. Nevertheless HI-6 has not been granted a license for clinical use, must be used only under restricted guidelines and is not available for civilian use as far as is known. This article will highlight those factors relating to HI-6 that pertain to the licensing of new compounds of this type, including the mechanism of action, the clinical and pre-clinical demonstration of safety and its efficacy against a variety of nerve agents particularly in non-human primates, since no relevant human population exists. This article also contains important data on the use of HI-6 in baboons, which has not been available previously. The article also discusses the possibility of successful therapy with HI-6 against poisoning in humans relative to doses used in non-human primates and relative to its ability to reactivate inhibited human AChE.
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Affiliation(s)
- Paul M Lundy
- Therapeutic Response, Medicine Hat, Alberta, Canada
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Kuca K, Pícha J, Jun D. Reactivation potency of new group of acetylcholinesterase reactivators and their comparison with currently available oximes. ACTA MEDICA (HRADEC KRALOVE) 2006; 49:233-5. [PMID: 17438836 DOI: 10.14712/18059694.2017.138] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
In this work, in vitro potency of novel serie of monoquaternary pyridinium oximes to reactivate cyclosarin-inhibited acetylcholinesterase (AChE) was tested. Currently available oximes (pralidoxime, obidoxime, trimedoxime, HI-6 and BI-6) were used as oximes for comparison. As resulted, none of tested new reactivators was able to reactivate AChE inhibited by cyclosarin. Also pralidoxime, obidoxime and trimedoxime did not reach good reactivation results. Only oximes HI-6 and BI-6 achieved sufficient reactivation potency. From obtained results, it can be deduced, that only reactivators with oxime group in position two are able to reactivate cyclosarin-inhibited AChE.
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Affiliation(s)
- Kamil Kuca
- University of Defence in Brno, Faculty of Military Health Sciences in Hradec Králové, Czech Republic.
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Marrs TC, Rice P, Vale JA. The Role of Oximes in the Treatment of Nerve Agent Poisoning in Civilian Casualties. ACTA ACUST UNITED AC 2006; 25:297-323. [PMID: 17288500 DOI: 10.2165/00139709-200625040-00009] [Citation(s) in RCA: 136] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
There are important differences between on-target military attacks against relatively well protected Armed Forces and nerve agent attacks initiated by terrorists against a civilian population. In contrast to military personnel, civilians are unlikely to be pre-treated with pyridostigmine and protected by personal protective equipment. Furthermore, the time after exposure when specific therapy can first be administered to civilians is likely to be delayed. Even conservative estimates suggest a delay between exposure and the first administration of atropine/oxime of at least 30 minutes. The organophosphorus nerve agents are related chemically to organophosphorus insecticides and have a similar mechanism of toxicity, but a much higher mammalian acute toxicity, particularly via the dermal route. Nerve agents phosphonylate a serine hydroxyl group in the active site of the enzyme, acetylcholinesterase (AChE), which results in accumulation of acetylcholine and, in turn, causes enhancement and prolongation of cholinergic effects and depolarisation blockade. The rate of spontaneous reactivation of AChE is variable, which partly accounts for differences in acute toxicity between the nerve agents. With soman in particular, an additional reaction occurs known as 'aging'. This consists of monodealkylation of the dialkylphosphonyl enzyme, which is then resistant to spontaneous hydrolysis and reactivation by oximes. Monodealkylation occurs to some extent with all dialkylphosphonylated AChE complexes; however, in general, is only of clinical importance in relation to the treatment of soman poisoning, where it is a very serious problem. With soman, aging occurs so fast that no clinically relevant spontaneous reactivation of AChE occurs before aging has taken place. Hence, recovery of function depends on resynthesis of AChE. As a result, it is important that an oxime is administered as soon after soman exposure as possible so that some reactivation of AChE occurs before all the enzyme becomes aged. Even though aging occurs more slowly and reactivation occurs relatively rapidly in the case of nerve agents other than soman, early oxime administration is still clinically important in patients poisoned with these agents. Experimental studies on the treatment of nerve agent poisoning have to be interpreted with caution. Some studies have used prophylactic protocols, whereas the drugs concerned (atropine, oxime, diazepam) would only be given to a civilian population after exposure. The experimental use of pyridostigmine before nerve agent exposure, although rational, is not of relevance in the civilian context. With the possible exception of the treatment of cyclosarin (GF) and soman poisoning, when HI-6 might be preferred, a review of available experimental evidence suggests that there are no clinically important differences between pralidoxime, obidoxime and HI-6 in the treatment of nerve agent poisoning, if studies employing pre-treatment with pyridostigmine are excluded.
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Affiliation(s)
- Timothy C Marrs
- National Poisons Information Service (Birmingham Unit), City Hospital, Birmingham, UK
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12
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Kuca K, Cabal J, Kassa J, Jun D, Hrabinová M. Comparison ofin vitro potency of oximes (pralidoxime, obidoxime, HI-6) to reactivate sarin-inhibited acetylcholinesterase in various parts of pig brain. J Appl Toxicol 2005; 25:271-6. [PMID: 16021679 DOI: 10.1002/jat.1053] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The potency of currently used oximes to reactivate sarin-inhibited acetylcholinesterase (AChE) in various parts of pig brain and whole pig brain was evaluated using in vitro methods. Significant differences in reactivation potency among all tested oximes were observed. At concentrations (10(-4) M) corresponding to recommended doses in vivo, the oxime HI-6 seems to be a more efficacious reactivator of sarin-inhibited AChE in whole pig brain as well as in cerebral hemispheres and cerebellum compared with the other oximes studied. Nevertheless, there are not any differences in the potency of oximes tested to reactivate sarin-inhibited AChE in medulla oblongata. Thus, the oxime HI-6 appears to be the most promising oxime among currently available oximes for the antidotal treatment of acute sarin poisoning, although it is not more efficacious than other currently used oximes in medulla oblongata, whose function is necessary for the vital functions of respiration and circulation.
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Affiliation(s)
- Kamil Kuca
- Department of Toxicology, Faculty of Military Health Sciences, PO Box 35/T, 500 01, Hradec Králové, Czech Republic
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Taysse L, Calvet JH, Buée J, Christin D, Delamanche S, Breton P. Comparative efficacy of diazepam and avizafone against sarin-induced neuropathology and respiratory failure in guinea pigs: influence of atropine dose. Toxicology 2003; 188:197-209. [PMID: 12767691 DOI: 10.1016/s0300-483x(03)00086-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
This investigation compared the efficacy of diazepam and the water-soluble prodiazepam-avizafone-in sarin poisoning therapy. Guinea pigs, pretreated with pyridostigmine 0.1 mg/kg, were intoxicated with 4LD(50) of sarin (s.c. route) and 1 min after intoxication treated by intramuscular injection of atropine (3 or 33.8 mg/kg), pralidoxime (32 mg/kg) and either diazepam (2 mg/kg) or avizafone (3.5 mg/kg). EEG and pneumo-physiological parameters were simultaneously recorded. When atropine was administered at a dose of 3 mg/kg, seizures were observed in 87.5% of the cases; if an anticonvulsant was added (diazepam (2 mg/kg) or avizafone (3.5 mg/kg)), seizure was prevented but respiratory disorders were observed. At 33.8 mg/kg, atropine markedly increased the seizure threshold and prevented early respiratory distress induced by sarin. When diazepam was administered together with atropine, seizures were not observed but 62.5% of the animals displayed respiratory difficulties. These symptoms were not observed when using avizafone. The pharmacokinetic data showed marked variation of the plasma levels of atropine and diazepam in different antidote combination groups, where groups receiving diazepam exhibited the lowest concentration of atropine in plasma. Taken together, the results indicate that avizafone is suitable in therapy against sarin when an anticonvulsant is judged necessary.
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Affiliation(s)
- L Taysse
- Centre d'Etudes du Bouchet, Defense Research Centre, BP No. 3, Vert-Le-Petit 91710, France.
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