Are the current commercially available oximes capable of reactivating acetylcholinesterase inhibited by the nerve agents of the A-series?

Current Perspectives on the Management of Patients Poisoned With Novichok: A Scoping Review

INTRODUCTION

Nerve agents have emerged as a global threat since their discovery in the 1930s, posing severe risks due to their inhibition of acetylcholinesterase and the subsequent accumulation of acetylcholine in nerve synapses. Despite the enforcement of the Chemical Weapon Convention to control chemical weapons, including nerve agents, recent events, such as the Novichok attacks on Sergei Skripal and Alexei Navalny, have highlighted the persistent threat. Novichok, a distinct class of nerve agents, raises specific concerns regarding its management due to limited understanding. This article aims to comprehensively analyze existing literature.

MATERIALS AND METHODS

A scoping review was employed to comprehensively assess the current state of knowledge on managing patients poisoned with Novichok. Following the PRISMA-ScR guidelines, relevant literature was identified in peer-reviewed journals covering symptoms, diagnosis, treatment, decontamination, and long-term effects. Searches were conducted on February 1, 2023, across four electronic databases (PubMed, EMBASE, MEDLINE, and Web of Science) using "Novichok" as a keyword. No restrictions were applied, and additional studies were sought from the references of identified papers. Eligible papers included discussions on Novichok or its specific properties impacting management, regardless of study type, language, or publication date, while those unrelated to the study's conceptual framework were excluded.

RESULTS

A total of 170 records were identified from the initial database search, with 86 studies screened after removing duplicates. Among these, 28 publications met the eligibility criteria and were included in the analysis. An additional relevant study was identified from the citation lists of included studies, bringing the total to 29. The review encompasses studies published from 2018 onwards, indicating the growing interest in this topic. While most studies are reviews on Novichok or nerve agents in general, several theoretical and experimental investigations were also found.

CONCLUSION

This review highlights the significant uncertainties and knowledge gaps surrounding the management of patients poisoned with Novichok. While some aspects align with other nerve agents, limited research likely due to safety and ethical challenges leads to assumptions and uncertainties in patient care. The review identifies areas with ongoing research, such as decontamination and biomarker recognition, while other aspects remain understudied. The possible inefficacy of current treatment options and the need for further research on oximes, bioscavengers, and long-term effects emphasize the necessity for increased research to optimize patient outcomes. More studies are essential to clarify the actual threat and toxicity of Novichok. Moreover, raising awareness among medical staff is crucial for early diagnosis, prompt treatment, and safety. This review offers valuable insights into managing Novichok-poisoned patients and calls for increased research and awareness in this critical area.

Underestimations in the In Silico-Predicted Toxicities of V-Agents

V-agents are exceedingly toxic nerve agents. Recently, it was highlighted that V-agents constitute a diverse subclass of compounds with most of them not extensively studied. Although chemical weapons have been banned under the Chemical Weapons Convention (CWC), there is an increased concern for chemical terrorism. Thus, it is important to understand their properties and toxicities, especially since some of these agents are not included in the CWC list. Nonetheless, to achieve this goal, the testing of a huge number of compounds is needed. Alternatively, in silico toxicology offers a great advantage for the rapid assessment of toxic compounds. Here, various in silico tools (TEST, VEGA, pkCSM ProTox-II) were used to estimate the acute oral toxicity (LD50) of different V-agents and compare them with experimental values. These programs underestimated the toxicity of V-agents, and certain V-agents were estimated to be relatively non-toxic. TEST was also used to estimate the physical properties and found to provide good approximations for densities, surface tensions and vapor pressures but not for viscosities. Thus, attention should be paid when interpreting and estimating the toxicities of V-agents in silico, and it is necessary to conduct future detailed experiments to understand their properties and develop effective countermeasures.

A-agents, misleadingly known as "Novichoks": a narrative review

"Novichok" refers to a new group of nerve agents called the A-series agents. Their existence came to light in 2018 after incidents in the UK and again in 2020 in Russia. They are unique organophosphorus-based compounds developed during the Cold War in a program called Foliant in the USSR. This review is based on original chemical entities from Mirzayanov's memoirs published in 2008. Due to classified research, a considerable debate arose about their structures, and hence, various structural moieties were speculated. For this reason, the scientific literature is highly incomplete and, in some cases, contradictory. This review critically assesses the information published to date on this class of compounds. The scope of this work is to summarize all the available and relevant information, including the physicochemical properties, chemical synthesis, mechanism of action, toxicity, pharmacokinetics, and medical countermeasures used to date. The environmental stability of A-series agents, the lack of environmentally safe decontamination, their high toxicity, and the scarcity of information on post-contamination treatment pose a challenge for managing possible incidents.

Advances in Derivatization Techniques Enabled by DABCO for Novichok Agent Analysis in Biofluids Using LC-MS

The characterization of Novichoks (NVs), a new group of nerve agents that have been implicated in two recent poisonings, has not been extensively conducted. Here, we present a novel method for analyzing NV hydrolysates using liquid chromatography-tandem mass spectrometry (LC-MS/MS) enabled by pentafluorobenzyl (PFB) derivatization followed by reaction with 1,4-diazabicyclo[2.2.2]octane (DABCO). This approach enabled efficient, simultaneous screening of six NV hydrolysates, with 1-2 orders improvement in the limit of detection in relation to that achieved through previous methods. A straightforward pretreatment using DABCO and filtration was employed for biological samples, mitigating instrument damage and allowing LC-MS/MS after a reaction with highly hydrophobic PFB bromide (PFBBr). In addition, the use of pralidoxime (PAM) significantly enhanced the detection of NV hydrolysates from NV-surrogate-spiked serum. While PAM is not a proven NV antidote, its effectiveness as an analytical reagent to aid in the detection of NV hydrolysates was demonstrated for the first time. Understanding the proposed mechanism of DABCO-mediated derivatization reagent removal in this research could broaden the range of compounds amenable to derivatization LC, thereby enhancing the capabilities of conventional derivatization techniques.

Review of Possible Therapies in Treatment of Novichoks Poisoning and HAZMAT/CBRNE Approaches: State of the Art

Novichoks-organophosphorus compounds belong to the nerve agents group, constituting the fourth generation of chemical warfare agents. The tremendous toxicity of Novichoks is assumed to be several times greater than that of VX, whereas no published experimental research supports this. They were surreptitiously created during the Cold War by the Soviet Union. Novichok’s toxic action mechanism consists of the inhibition of acetylcholinesterase activity. The review includes data on treating poisoning caused by OPs which could be used as guidelines for the therapy in case of Novichok exposure and HAZMAT/CBRNE approaches. Novichoks pose a severe threat due to their toxicity; however, there is insufficient information about the identity of A-series nerve agents. Filling in the missing data gaps will accelerate progress in improving protection against Novichoks and developing optimal therapy for treating poisoning casualties. Furthermore, introducing solutions to protect medical personnel in contact with a hazardous substance increases the chances of saving casualties of HAZMAT/CBRNE incidents.

A complete, evidence-based review on novichok poisoning based on epidemiological aspects and clinical management

Background: The whole world has learned about the existence of a highly toxic neuro-paralytic substance called Novichok. A wide range of neuro-paralytic toxins were used during the wars of decades ago, which also had harmful and irreversible effects. Fortunately, the establishment of conventions prohibiting the use of these weapons prevented the adverse clinical consequences of these compounds. What we did in the present study was to evaluate the clinical features of Novichok, how to manage exposure to it, and to evaluate the prognostic aspects associated with this poisoning agent. Methods: The manuscript especial databases including Medline, Web of knowledge, Google scholar, and Scopus were deeply searched by the two blinded investigators for all eligible studies based on the considered keywords. Initially 98 articles were initially collected by database searching that considering eligibility criteria, 83 articles were finally eligible for the final assessment. There is a lack of clinical trials and case-cohort studies on general population about treatment and side effects when it comes to human nerve agents and most of the data in our search is based on animal studies. Results: In evaluating various clinical, auto physiological and prognostic aspects of exposure to these substances, special attention was necessary to the following points. First, Novichok agents are considered more potent than other toxic agents. Pathophysiologically, these agents irreversibly bind acetylcholinesterase and produce a rapid cholinergic toxidrome which is responsible for the clinical manifestations as well as the potential dangerous and life threatening side effects caused by these agents. Uniquely, these agents are thought to also target every neuron in the central and peripheral nervous system. As a managerial and therapeutic approach, early and timely treatment of its related complication along with prevents massive exposure and decontamination in addition to rapid resuscitation can prohibit debilitating neuropathy and death due to facing it. Conclusion: The present review highlights the importance of recognizing the potential acute toxic effects of Novichok agents, diagnostic and therapeutic approaches (life-saving antidotal therapy) to complications and ultimately the application of guidelines to improve the prognosis of exposure to these agents for both victims and medical community.

Multiple neurological effects associated with exposure to organophosphorus pesticides in man

This article reviews available data regarding the possible association of organophosphorus (OP) pesticides with neurological disorders such as dementia, attention deficit hyperactivity disorder, neurodevelopment, autism, cognitive development, Parkinson's disease and chronic organophosphate-induced neuropsychiatric disorder. These effects mainly develop after repeated (chronic) human exposure to low doses of OP. In addition, three well defined neurotoxic effects in humans caused by single doses of OP compounds are discussed. Those effects are the cholinergic syndrome, the intermediate syndrome and organophosphate-induced delayed polyneuropathy. Usually, the poisoning can be avoided by an improved administrative control, limited access to OP pesticides, efficient measures of personal protection and education of OP pesticide applicators and medical staff.