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Evaluation of fosphenytoin, levetiracetam, and propofol as treatments for nerve agent-induced seizures in pediatric and adult rats. Neurotoxicology 2020; 79:58-66. [PMID: 32220603 DOI: 10.1016/j.neuro.2020.03.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 02/21/2020] [Accepted: 03/14/2020] [Indexed: 10/24/2022]
Abstract
Multiple recent instances of nerve agent (NA) exposure in civilian populations have occurred, resulting in a variety of negative effects and lethality in both adult and pediatric populations. Seizures are a prominent effect of NAs that can result in neurological damage and contribute to their lethality. Current anticonvulsant treatments for NAs are approved for adults, but no approved pediatric treatments exist. Further, the vast majority of NA-related research in animals has been conducted in adult male subjects. There is a need for research that includes female and pediatric populations in testing. In this project, adult and pediatric male and female rats were challenged with sarin or VX and then treated with fosphenytoin, levetiracetam, or propofol. In this study, fosphenytoin and levetiracetam failed to terminate seizure activity when animals were treated 5 min after seizure onset. Propofol was effective, exhibiting high efficacy and potency for terminating seizure activity quickly in pediatric and adult animals, suggesting it may be an effective anticonvulsant for NA-induced seizures in pediatric populations.
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Dorandeu F, Dhote F, Barbier L, Baccus B, Testylier G. Treatment of status epilepticus with ketamine, are we there yet? CNS Neurosci Ther 2013; 19:411-27. [PMID: 23601960 PMCID: PMC6493567 DOI: 10.1111/cns.12096] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2012] [Revised: 02/23/2013] [Accepted: 02/23/2013] [Indexed: 12/24/2022] Open
Abstract
Status epilepticus (SE), a neurological emergency both in adults and in children, could lead to brain damage and even death if untreated. Generalized convulsive SE (GCSE) is the most common and severe form, an example of which is that induced by organophosphorus nerve agents. First- and second-line pharmacotherapies are relatively consensual, but if seizures are still not controlled, there is currently no definitive data to guide the optimal choice of therapy. The medical community seems largely reluctant to use ketamine, a noncompetitive antagonist of the N-methyl-d-aspartate glutamate receptor. However, a review of the literature clearly shows that ketamine possesses, in preclinical studies, antiepileptic properties and provides neuroprotection. Clinical evidences are scarcer and more difficult to analyze, owing to a use in situations of polytherapy. In absence of existing or planned randomized clinical trials, the medical community should make up its mind from well-conducted preclinical studies performed on appropriate models. Although potentially active, ketamine has no real place for the treatment of isolated seizures, better accepted drugs being used. Its best usage should be during GCSE, but not waiting for SE to become totally refractory. Concerns about possible developmental neurotoxicity might limit its pediatric use for refractory SE.
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Affiliation(s)
- Frederic Dorandeu
- Département de Toxicologie et risques chimiques, Institut de Recherche Biomédicale des Armées - Centre de Recherches du Service de Santé des Armées (IRBA-CRSSA), La Tronche Cedex, France.
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Pouliot W, Bialer M, Hen N, Shekh-Ahmad T, Kaufmann D, Yagen B, Ricks K, Roach B, Nelson C, Dudek FE. A comparative electrographic analysis of the effect of sec-butyl-propylacetamide on pharmacoresistant status epilepticus. Neuroscience 2012; 231:145-56. [PMID: 23159312 DOI: 10.1016/j.neuroscience.2012.11.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2012] [Accepted: 11/03/2012] [Indexed: 01/10/2023]
Abstract
Better treatment of status epilepticus (SE), which typically becomes refractory after about 30 min, will require new pharmacotherapies. The effect of sec-butyl-propylacetamide (SPD), an amide derivative of valproic acid (VPA), on electrographic status epilepticus (ESE) was compared quantitatively to other standard-of-care compounds. Cortical electroencephalograms (EEGs) were recorded from rats during ESE induced with lithium-pilocarpine. Using a previously-published algorithm, the effects of SPD on ESE were compared quantitatively to other relevant compounds. To confirm benzodiazepine resistance, diazepam (DZP) was shown to suppress ESE when administered 15 min after the first motor seizure, but not after 30 min (100mg/kg). VPA (300 mg/kg) also lacked efficacy at 30 min. SPD (130 mg/kg) strongly suppressed ESE at 30 min, less after 45 min, and not at 60 min. At a higher dose (180 mg/kg), SPD profoundly suppressed ESE at 60 min, similar to propofol (100mg/kg) and pentobarbital (30 mg/kg). After 4-6h of SPD-induced suppression, EEG activity often overshot control levels at 7-12h. Valnoctamide (VCD, 180 mg/kg), an SPD homolog, was also efficacious at 30 min. SPD blocks pilocarpine-induced electrographic seizures when administered at 1h after the first motor seizure. SPD has a faster onset and greater efficacy than DZP and VPA, and is similar to propofol and pentobarbital. SPD and structurally similar compounds may be useful for the treatment of refractory ESE. Further development and use of automated analyses of ESE may facilitate drug discovery for refractory SE.
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Affiliation(s)
- W Pouliot
- Department of Physiology, University of Utah School of Medicine, Salt Lake City, UT, USA
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Abstract
This review briefly synthesizes the molecular biology of troponin, which is currently the best biochemical marker for the detection of cardiac injury and, thus, acute myocardial infarction as well. Potential new uses for the marker based on these insights, with a specific interest in cardiac troponin fragments that potentially could be linked to distinct clinical conditions, are described. Some of the clinical problems clinicians are faced with including how to use the markers in renal failure and the difficulties associated with the heterogeneity of current troponin assays are also discussed. Finally, we present the possibility of specific cardiac troponin fragments resulting from modification or degradation, associated with distinct pathological processes, as new potential uses for this biomarker.
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Affiliation(s)
- Vlad C Vasile
- Mayo Clinic & Mayo Medical School, Department of Internal Medicine, Division of Cardiovascular Diseases & Department of Laboratory Medicine & Pathology, Rochester, Minnesota, USA
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Abstract
There is well-founded concern that a chemical or radioactive agent will at some point be used as a weapon of terror. There are several antidotes that, if used correctly in a timely fashion, can help lessen the harm caused by these agents. This article is meant to introduce the clinician to several such agents, along with the antidotes useful in the management of exposure to these. It covers the indications, administration, and precautions for using these antidotes.
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Affiliation(s)
- David T Lawrence
- Blue Ridge Poison Center, Division of Medical Toxicology, Department of Emergency Medicine, University of Virginia, Charlottesville, VA 22908-0774, USA.
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Abstract
BACKGROUND Nerve agents, the deadliest of the classic chemical warfare agents, primarily function as acetylcholinesterase inhibitors and cause a rapidly progressive cholinergic crisis. Originally developed for battlefield use, they have been used in terrorist attacks and are considered threats to the civilian population. REVIEW SUMMARY The pathophysiology and clinical presentation of acute nerve agent poisoning are summarized and acute treatment protocols reviewed. Timely support and antidotal treatment are crucial and may be lifesaving. Pyridostigmine bromide, recently approved by the Food and Drug Administration as a pretreatment for soman poisoning, forms part of battlefield doctrine but is unlikely to be used in the civilian sector. Aside from that, civilian recommendations for acute therapy derive, with only minor modifications, from military doctrine. CONCLUSION Neurologists should familiarize themselves with the pathophysiology and treatment principles for the syndromes caused by nerve agents, not only to assist with the hospital care of these patients but also to serve as resources to their local medical communities in preparation for chemical terrorism. Because nerve agents injure the nervous system, nonneurologists have a right to expect neurologists to have mastered these principles.
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Affiliation(s)
- Jonathan Newmark
- Deputy Joint Program Executive Officer for Medical Systems, Joint Program Executive Office for Chemical/Biological Defense, Falls Church, Virginia 22041-3203, USA.
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Abstract
The organic phosphorous compounds (OPC) include both the military grade nerve agents and the organic phosphorous pesticides. The major mechanism of OPC toxicity is through inhibition of acetylcholinesterase in neuronal synapses leading to excess acetylcholine and overstimulation of target organs. Signs and symptoms depend on the affinity of the OPC for muscarinic versus nicotinic receptors, and are likely to include both. Muscarinic symptoms may include diarrhea, urination, bronchospasm, bronchorrhea, emesis, and salivation. Nicotinic symptoms such as paralysis and fasciculations may also occur. Central nervous system toxicity may include seizures, altered mental status, and apnea, and require prompt intervention. Treatment includes early airway and ventilatory support as well as antidotal therapy with atropine, pralidoxime, and diazepam. Goals of therapy include prevention and rapid treatment of hypoxia and seizures, as these are linked to patient outcome.
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Affiliation(s)
- Claudia L Barthold
- Georgia Poison Center, Hughes Spalding Children's Hospital, Grady Health System, 80 Jesse Hill Jr. Drive SE, Atlanta, GA 30303-3801, USA.
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Harrison PK, Sheridan RD, Green AC, Tattersall JEH. Effects of anticonvulsants on soman-induced epileptiform activity in the guinea-pig in vitro hippocampus. Eur J Pharmacol 2005; 518:123-32. [PMID: 16054127 DOI: 10.1016/j.ejphar.2005.06.032] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2005] [Revised: 06/14/2005] [Accepted: 06/21/2005] [Indexed: 11/18/2022]
Abstract
Seizures arising from acetylcholinesterase inhibition are a feature of organophosphate anticholinesterase intoxication. Although benzodiazepines are effective against these seizures, alternative anticonvulsant drugs may possess greater efficacy and fewer side-effects. We have investigated in the guinea-pig hippocampal slice preparation the ability of a series of anticonvulsants to suppress epileptiform bursting induced by the irreversible organophosphate anticholinesterase, soman (100 nM). Carbamazepine (300 microM), phenytoin (100 microM), topiramate (100-300 microM) and retigabine (1-30 microM) reduced the frequency of bursting but only carbamazepine and phenytoin induced a concurrent reduction in burst duration. Felbamate (100-500 microM) and clomethiazole (100-300 microM) had no effect on burst frequency but decreased burst duration. Clozapine (3-30 microM) reduced the frequency but did not influence burst duration. Levetiracetam (100-300 microM) and gabapentin (100-300 microM) were without effect. These data suggest that several compounds, in particular clomethiazole, clozapine, felbamate, topiramate and retigabine, merit further evaluation as possible treatments for organophosphate poisoning.
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Affiliation(s)
- Patrick K Harrison
- Department of Biomedical Sciences, Dstl, Porton Down, Salisbury, Wiltshire SP4 0JQ, UK.
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Abstract
PURPOSE OF REVIEW Although conventional anticonvulsant agents can terminate status epilepticus in most cases, a substantial minority of patients develops medically refractory status and requires more aggressive care. This review explores the options available. RECENT FINDINGS Increasing numbers of previously unexpected etiologies for refractory status epilepticus continue to be reported. There are also some promising new therapies on the horizon, both for the short and the longer terms. SUMMARY Refractory status epilepticus, while a challenge to the intensivist, can be treated with drugs that are commonly used by intensivists. The cooperation of an interested electroencephalographer is vital.
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Affiliation(s)
- Thomas P Bleck
- The University of Virginia, Charlottesville, Virginia 22908-0394, USA.
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Abstract
The clinical syndrome of nerve agent toxicity varies widely, ranging from the classic cholinergic syndrome to flaccid paralysis and status epilepticus. All nerve agents are capable of producing marked neuropathology. Seizure control is strongly associated with protection against acute lethality and brain pathology. The mainstays of therapy of nerve agent poisoned patients are atropine, pralidoxime, and benzodiazepines. Fosphenytoin provides little therapeutic anticonvulsant effectiveness for nerve agent-induced status epilepticus. Tachycardia is not a contraindication to treatment with atropine in nerve agent toxicity. Atropine should be administered to alleviate respiratory distress, symptomatic bradycardia, and as an adjunct to benzodiazepines and pralidoxime to alleviate seizure activity. In significant nerve agent toxicity, a continuous pralidoxime infusion may be considered.
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Affiliation(s)
- Christopher P Holstege
- Division of Medical Toxicology, University of Virginia, P.O. Box 800774, Charlottesville, VA 22908, USA.
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