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Polet SS, de Koning TJ, Lambrechts RA, Tijssen MAJ, Sibon OCM, Gorter JA. Conventional and novel anti-seizure medications reveal a particular role for GABA A in a North Sea progressive myoclonus Epilepsy Drosophila model. Epilepsy Res 2024; 203:107380. [PMID: 38781737 DOI: 10.1016/j.eplepsyres.2024.107380] [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: 12/18/2023] [Revised: 04/01/2024] [Accepted: 05/06/2024] [Indexed: 05/25/2024]
Abstract
OBJECTIVE North Sea Progressive Myoclonus Epilepsy (NS-PME) is a rare genetic disorder characterized by ataxia, myoclonus and seizures with a progressive course. Although the cause of NS-PME is known, namely a homozygous mutation in the GOSR2 gene (c.430 G>T; p. Gly144Trp), sufficient treatment is lacking. Despite combinations of on average 3-5 anti-seizure medications (ASMs), debilitating myoclonus and seizures persist. Here we aimed to gain insight into the most effective anti-convulsive target in NS-PME by evaluating the individual effects of ASMs in a NS-PME Drosophila model. METHOD A previously generated Drosophila model for NS-PME was used displaying progressive heat-sensitive seizures. We used this model to test 1. a first-generation ASM (sodium barbital), 2. common ASMs used in NS-PME (clonazepam, valproic acid, levetiracetam, ethosuximide) and 3. a novel third-generation ASM (ganaxolone) with similar mode of action to sodium barbital. Compounds were administered by adding them to the food in a range of concentrations. After 7 days of treatment, the percentage of heat-induced seizures was determined and compared to non-treated but affected controls. RESULTS As previously reported in the NS-PME Drosophila model, sodium barbital resulted in significant seizure suppression, with increasing effect at higher dosages. Of the commonly prescribed ASMs, clonazepam and ethosuximide resulted in significant seizure suppression, whereas both valproic acid and levetiracetam did not show any changes in seizures. Interestingly, ganaxolone did result in seizure suppression as well. CONCLUSION Of the six drugs tested, three of the four that resulted in seizure suppression (sodium barbital, clonazepam, ganaxolone) are primary known for their direct effect on GABAA receptors. This suggests that GABAA could be a potentially important target in the treatment of NS-PME. Consequently, these findings add rationale to the exploration of the clinical effect of ganaxolone in NS-PME and other progressive myoclonus epilepsies.
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Affiliation(s)
- Sjoukje S Polet
- Department of Neurology, University Medical Center Groningen, University of Groningen, 30.001 AB51, Groningen 9700 RB, the Netherlands; Expertise Center Movement Disorders Groningen, University Medical Center Groningen, University of Groningen, 30.001 AB51, Groningen 9700 RB, the Netherlands.
| | - Tom J de Koning
- Expertise Center Movement Disorders Groningen, University Medical Center Groningen, University of Groningen, 30.001 AB51, Groningen 9700 RB, the Netherlands; Department of Neurology and Medical Genetics, University Medical Center Groningen, University of Groningen, 30.001 AB51, Groningen 9700 RB, the Netherlands; Department of Clinical Sciences, Pediatrics, Lund University, Lund BMC I12, 221 84, Sweden
| | - Roald A Lambrechts
- Expertise Center Movement Disorders Groningen, University Medical Center Groningen, University of Groningen, 30.001 AB51, Groningen 9700 RB, the Netherlands; Department of Neurology, University Medical Center Groningen, University of Groningen, 30.001 AB51, Groningen 9700 RB, the Netherlands
| | - Marina A J Tijssen
- Expertise Center Movement Disorders Groningen, University Medical Center Groningen, University of Groningen, 30.001 AB51, Groningen 9700 RB, the Netherlands; Department of Neurology, University Medical Center Groningen, University of Groningen, 30.001 AB51, Groningen 9700 RB, the Netherlands
| | - Ody C M Sibon
- Expertise Center Movement Disorders Groningen, University Medical Center Groningen, University of Groningen, 30.001 AB51, Groningen 9700 RB, the Netherlands; Department of Biomedical Sciences (BMS), University Medical Center Groningen, University of Groningen, 30.001 FB32, Groningen 9700 AD, the Netherlands
| | - Jenke A Gorter
- Expertise Center Movement Disorders Groningen, University Medical Center Groningen, University of Groningen, 30.001 AB51, Groningen 9700 RB, the Netherlands; Department of Biomedical Sciences (BMS), University Medical Center Groningen, University of Groningen, 30.001 FB32, Groningen 9700 AD, the Netherlands
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Reddy DS. Neurosteroids as Novel Anticonvulsants for Refractory Status Epilepticus and Medical Countermeasures for Nerve Agents: A 15-Year Journey to Bring Ganaxolone from Bench to Clinic. J Pharmacol Exp Ther 2024; 388:273-300. [PMID: 37977814 PMCID: PMC10801762 DOI: 10.1124/jpet.123.001816] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 10/05/2023] [Accepted: 10/23/2023] [Indexed: 11/19/2023] Open
Abstract
This article describes recent advances in the use of neurosteroids as novel anticonvulsants for refractory status epilepticus (RSE) and as medical countermeasures (MCs) for organophosphates and chemical nerve agents (OPNAs). We highlight a comprehensive 15-year journey to bring the synthetic neurosteroid ganaxolone (GX) from bench to clinic. RSE, including when caused by nerve agents, is associated with devastating morbidity and permanent long-term neurologic dysfunction. Although recent approval of benzodiazepines such as intranasal midazolam and intranasal midazolam offers improved control of acute seizures, novel anticonvulsants are needed to suppress RSE and improve neurologic function outcomes. Currently, few anticonvulsant MCs exist for victims of OPNA exposure and RSE. Standard-of-care MCs for postexposure treatment include benzodiazepines, which do not effectively prevent or mitigate seizures resulting from nerve agent intoxication, leaving an urgent unmet medical need for new anticonvulsants for RSE. Recently, we pioneered neurosteroids as next-generation anticonvulsants that are superior to benzodiazepines for treatment of OPNA intoxication and RSE. Because GX and related neurosteroids that activate extrasynaptic GABA-A receptors rapidly control seizures and offer robust neuroprotection by reducing neuronal damage and neuroinflammation, they effectively improve neurologic outcomes after acute OPNA exposure and RSE. GX has been selected for advanced, Biomedical Advanced Research and Development Authority-supported phase 3 trials of RSE and nerve agent seizures. In addition, in mechanistic studies of neurosteroids at extrasynaptic receptors, we identified novel synthetic analogs with features that are superior to GX for current medical needs. Development of new MCs for RSE is complex, tedious, and uncertain due to scientific and regulatory challenges. Thus, further research will be critical to fill key gaps in evaluating RSE and anticonvulsants in vulnerable (pediatric and geriatric) populations and military persons. SIGNIFICANCE STATEMENT: Following organophosphate and nerve agent intoxication, refractory status epilepticus (RSE) occurs despite benzodiazepine treatment. RSE occurs in 40% of status epilepticus patients, with a 35% mortality rate and significant neurological morbidity in survivors. To treat RSE, neurosteroids are better anticonvulsants than benzodiazepines. Our pioneering use of neurosteroids for RSE and nerve agents led us to develop ganaxolone as a novel anticonvulsant and neuroprotectant with significantly improved neurological outcomes. This article describes the bench-to-bedside journey of bringing neurosteroid therapy to patients, with ganaxolone leading the way.
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Affiliation(s)
- Doodipala Samba Reddy
- Department of Neuroscience and Experimental Therapeutics, Texas A&M University School of Medicine, Bryan, Texas and Institute of Pharmacology and Neurotherapeutics, Texas A&M University Health Science Center, Bryan, Texas
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Yuan S, Shen DD, Jia R, Sun JS, Song J, Liu HM. New drug approvals for 2022: Synthesis and clinical applications. Med Res Rev 2023; 43:2352-2391. [PMID: 37211904 DOI: 10.1002/med.21976] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 04/13/2023] [Accepted: 05/08/2023] [Indexed: 05/23/2023]
Abstract
The U.S. Food and Drug Administration has approved a total of 37 new drugs in 2022, which are composed of 20 chemical entities and 17 biologics. In particular, 20 chemical entities, including 17 small molecule drugs, 1 radiotherapy, and 2 diagnostic agents, provide privileged scaffolds, breakthrough clinical benefits, and a new mechanism of action for the discovery of more potent clinical candidates. The structure-based drug development with clear targets and fragment-based drug development with privileged scaffolds have always been the important modules in the field of drug discovery, which could easily bypass the patent protection and bring about improved biological activity. Therefore, we summarized the relevant valuable information about clinical application, mechanism of action, and chemical synthesis of 17 newly approved small molecule drugs in 2022. We hope this timely and comprehensive review could bring about creative and elegant inspiration on the synthetic methodologies and mechanism of action for the discovery of new drugs with novel chemical scaffolds and extended clinical indications.
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Affiliation(s)
- Shuo Yuan
- Children's Hospital Affiliated to Zhengzhou University, Henan Children's Hospital, Zhengzhou Children's Hospital, Zhengzhou, China
- School of Pharmaceutical Sciences & Key Laboratory of Advanced Drug Preparation Technologies, Zhengzhou University, Zhengzhou, China
- Department of Pharmacology, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, China
| | - Dan-Dan Shen
- Department of Obstetrics and Gynecology, Zhengzhou Key Laboratory of Endometrial Disease Prevention and Treatment Zhengzhou China, The Third Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Rui Jia
- Children's Hospital Affiliated to Zhengzhou University, Henan Children's Hospital, Zhengzhou Children's Hospital, Zhengzhou, China
| | - Ju-Shan Sun
- Children's Hospital Affiliated to Zhengzhou University, Henan Children's Hospital, Zhengzhou Children's Hospital, Zhengzhou, China
| | - Jian Song
- School of Pharmaceutical Sciences & Key Laboratory of Advanced Drug Preparation Technologies, Zhengzhou University, Zhengzhou, China
- Department of Pharmacology, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, China
| | - Hong-Min Liu
- School of Pharmaceutical Sciences & Key Laboratory of Advanced Drug Preparation Technologies, Zhengzhou University, Zhengzhou, China
- Department of Pharmacology, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, China
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Perucca E, Bialer M, White HS. New GABA-Targeting Therapies for the Treatment of Seizures and Epilepsy: I. Role of GABA as a Modulator of Seizure Activity and Recently Approved Medications Acting on the GABA System. CNS Drugs 2023; 37:755-779. [PMID: 37603262 PMCID: PMC10501955 DOI: 10.1007/s40263-023-01027-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 07/06/2023] [Indexed: 08/22/2023]
Abstract
γ-Aminobutyric acid (GABA) is the most prevalent inhibitory neurotransmitter in the mammalian brain and has been found to play an important role in the pathogenesis or the expression of many neurological diseases, including epilepsy. Although GABA can act on different receptor subtypes, the component of the GABA system that is most critical to modulation of seizure activity is the GABAA-receptor-chloride (Cl-) channel complex, which controls the movement of Cl- ions across the neuronal membrane. In the mature brain, binding of GABA to GABAA receptors evokes a hyperpolarising (anticonvulsant) response, which is mediated by influx of Cl- into the cell driven by its concentration gradient between extracellular and intracellular fluid. However, in the immature brain and under certain pathological conditions, GABA can exert a paradoxical depolarising (proconvulsant) effect as a result of an efflux of chloride from high intracellular to lower extracellular Cl- levels. Extensive preclinical and clinical evidence indicates that alterations in GABAergic inhibition caused by drugs, toxins, gene defects or other disease states (including seizures themselves) play a causative or contributing role in facilitating or maintaning seizure activity. Conversely, enhancement of GABAergic transmission through pharmacological modulation of the GABA system is a major mechanism by which different antiseizure medications exert their therapeutic effect. In this article, we review the pharmacology and function of the GABA system and its perturbation in seizure disorders, and highlight how improved understanding of this system offers opportunities to develop more efficacious and better tolerated antiseizure medications. We also review the available data for the two most recently approved antiseizure medications that act, at least in part, through GABAergic mechanisms, namely cenobamate and ganaxolone. Differences in the mode of drug discovery, pharmacological profile, pharmacokinetic properties, drug-drug interaction potential, and clinical efficacy and tolerability of these agents are discussed.
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Affiliation(s)
- Emilio Perucca
- Department of Medicine (Austin Health), The University of Melbourne, Melbourne, VIC, Australia.
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC, Australia.
- Melbourne Brain Centre, 245 Burgundy Street, Heidelberg, VIC, 3084, Australia.
| | - Meir Bialer
- Institute of Drug Research, School of Pharmacy, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
- David R. Bloom Center for Pharmacy, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - H Steve White
- Department of Pharmacy, School of Pharmacy, University of Washington, Seattle, WA, USA
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