Progress report on new antiepileptic drugs: A summary of the Thirteenth Eilat Conference on New Antiepileptic Drugs and Devices (EILAT XIII)

A profile of azetukalner for the treatment of epilepsy: from pharmacology to potential for therapy

INTRODUCTION

Epilepsies are a group of heterogeneous brain disorder, and antiseizure medications (ASMs) are the mainstay of treatment. Despite the availability of more than 30 drugs, at least one third of individuals with epilepsy are drug-resistant. This emphasizes the need for novel compounds that combine efficacy with improved tolerability.

AREAS COVERED

A literature review on the pharmacology, efficacy, tolerability, and safety of azetukalner (XEN1101), a second-generation opener of neuronal potassium channels currently in Phase 3 development as ASM.

EXPERT OPINION

Results from the phase 2b clinical trial strongly support the ongoing clinical development of azetukalner as a new ASM. Its pharmacokinetic properties support convenient once-daily dosing, eliminating the need for titration at initiation or tapering at the conclusion of treatment. CYP3A4 is the main enzyme involved in its metabolism and drug-drug interactions can affect the drug exposure. Preliminary analysis of an ongoing open-label study reveals no reported pigmentary abnormalities. The upcoming Phase 3 clinical trials are expected to provide further insight into the efficacy, tolerability, and safety of azetukalner in treating focal-onset and primary generalized tonic-clonic seizures. Structurally distinct from currently marketed ASMs, azetukalner has the potential to be the only-in-class Kv7.2/7.3 opener on the market upon regulatory approval.

Modulators of GABAA receptor-mediated inhibition in the treatment of neuropsychiatric disorders: past, present, and future

The predominant inhibitory neurotransmitter in the brain, γ-aminobutyric acid (GABA), acts at ionotropic GABAA receptors to counterbalance excitation and regulate neuronal firing. GABAA receptors are heteropentameric channels comprised from subunits derived from 19 different genes. GABAA receptors have one of the richest and well-developed pharmacologies of any therapeutic drug target, including agonists, antagonists, and positive and negative allosteric modulators (PAMs, NAMs). Currently used PAMs include benzodiazepine sedatives and anxiolytics, barbiturates, endogenous and synthetic neurosteroids, and general anesthetics. In this article, I will review evidence that these drugs act at several distinct binding sites and how they can be used to alter the balance between excitation and inhibition. I will also summarize existing literature regarding (1) evidence that changes in GABAergic inhibition play a causative role in major depression, anxiety, postpartum depression, premenstrual dysphoric disorder, and schizophrenia and (2) whether and how GABAergic drugs exert beneficial effects in these conditions, focusing on human studies where possible. Where these classical therapeutics have failed to exert benefits, I will describe recent advances in clinical and preclinical drug development. I will also highlight opportunities to advance a generation of GABAergic therapeutics, such as development of subunit-selective PAMs and NAMs, that are engendering hope for novel tools to treat these devastating conditions.

Current pharmacotherapy approaches and novel GABAergic antidepressant development in postpartum depression

Postpartum depression has deleterious effects on childbearing persons globally. Existing treatments have been largely extrapolated from those for other forms of depression and have included pharmacotherapy, psychotherapy, and neuromodulation. Hormonal treatments with oestrogen and progestogens, thought to be a rational approach to treatment in response to an emerging literature on the pathophysiology of postpartum depression, have only limited evidence for efficacy to date. Novel antidepressant development with allopregnanolone analogues, in contrast, has proven a promising avenue for the development of rationally designed and efficacious treatments. This state-of-the-art review presents the evidence for the current standard-of-care pharmacotherapy, hormonal treatment, and emerging allopregnanolone analogues for the treatment of postpartum depression along with a discussion of the current understanding of its neuroactive steroid-driven pathophysiology.

Treating Epilepsy with Natural Products: Nonsense or Possibility?

Epilepsy is a neurological disease characterized by recurrent seizures that can lead to uncontrollable muscle twitching, changes in sensitivity to sensory perceptions, and disorders of consciousness. Although modern medicine has effective antiepileptic drugs, the need for accessible and cost-effective medication is urgent, and products derived from plants could offer a solution. For this review, we have focused on natural compounds that have shown anticonvulsant activity in in vivo models of epilepsy at relevant doses. In some cases, the effects have been confirmed by clinical data. The results of our search are summarized in tables according to their molecular targets. We have critically evaluated the data we present, identified the most promising therapeutic candidates, and discussed these in the text. Their perspectives are supported by both pharmacokinetic properties and potential interactions. This review is intended to serve as a basis for future research into epilepsy and related disorders.

Cannabis Pharmacogenomics: A Path to Personalized Medicine

Cannabis and related compounds have created significant research interest as a promising therapy in many disorders. However, the individual therapeutic effects of cannabinoids and the incidence of side effects are still difficult to determine. Pharmacogenomics may provide the answers to many questions and concerns regarding the cannabis/cannabinoid treatment and help us to understand the variability in individual responses and associated risks. Pharmacogenomics research has made meaningful progress in identifying genetic variations that play a critical role in interpatient variability in response to cannabis. This review classifies the current knowledge of pharmacogenomics associated with medical marijuana and related compounds and can assist in improving the outcomes of cannabinoid therapy and to minimize the adverse effects of cannabis use. Specific examples of pharmacogenomics informing pharmacotherapy as a path to personalized medicine are discussed.

The efficacy and safety of ganaxolone for the treatment of refractory epilepsy: A meta-analysis from randomized controlled trials

OBJECTIVE

Epilepsy is one of the most common and refractory neurological disorders globally. Ganaxolone, a neuroactive steroid that enhances GABAergic inhibition, has been tested in many trials for the resolution of refractory epilepsy. Based on these, our study implemented a meta-analysis to evaluate the general benefit of ganaxolone for refractory epilepsy.

METHODS

EMBASE, Medline, Scopus, Cochrane Library, and Clinicaltrials.gov were searched for relevant randomized controlled trials (RCTs) up to June 20, 2022. The risk ratio (RR) and standard mean difference (SMD) were analyzed using dichotomous and continuous outcomes, respectively with a random effect model. Trial sequential analysis (TSA) was also performed to judge the reliability of results.

RESULTS

We totally collected 659 patients from four RCTs to evaluate the efficacy and safety of ganaxolone. As results showed, ≥50% reduction in mean seizure frequency has improved significantly compared with placebo (RR = 1.60, 95%CI: 1.02-2.49, p = 0.04, I²  = 30%), which is supported by TSA. However, the percentage of seizure-free days shows no statistical significance (p = 0.36). For safety outcomes, adverse events (AEs), serious adverse events, and AE leading to study drug discontinuation all revealed no obvious difference between ganaxolone and placebo (p > 0.05).

SIGNIFICANCE

Based on our research, we have observed that ganaxolone is safe and has potential efficacy in the treatment of refractory epilepsy, waiting for further studies.

Novel neurosteroid pregnanolone pyroglutamate suppresses neurotoxicity syndrome induced by tetramethylenedisulfotetramine but is ineffective in a rodent model of infantile spasms

BACKGROUND

Neurosteroids are investigated as effective antidotes for the poisoning induced by tetramethylenedisulfotetramine (TMDT) as well as treatments for epileptic spasms during infancy. Both these conditions are quite resistant to pharmacotherapy; thus, a search for new treatments is warranted.

METHODS

In this study, we determined the efficacy of two novel neurosteroids, pregnanolone glutamate (PAG) and pregnanolone pyroglutamate (PPG), and tested these drugs in doses of 1-10 mg/kg (ip) against the TMDT syndrome and in our rodent model of infantile spasms.

RESULTS

Only PPG in doses 5 and 10 mg/kg suppressed the severity of the TMDT syndrome and TMDT-induced lethality, while the 1 mg/kg dose was without an effect. Interestingly, the 1 mg/kg dose of PPG in combination with 1 mg/kg of diazepam was also effective against TMDT poisoning. Neither PAG nor PPG were effective against experimental spasms in the N-methyl-D-aspartate (NMDA)-triggered model of infantile spasms.

CONCLUSIONS

While evidence suggests that PAG can act through multiple actions which include allosteric inhibition of NMDA-induced and glycine receptor-evoked currents as well as augmentation of ɣ-aminobutyric acid subtype A (GABAA) receptor-induced currents, the agent appears to neither have the appropriate mechanistic signature for activity in the infantile spasm model, nor the adequate potency, relative to PPG, for ameliorating the TMDT syndrome. The full mechanisms of action of PPG, which may become a potent TMDT antidote either alone or in combination with diazepam are yet unknown and thus require further investigation.

Synergistic effects of the galanin analog 810-2 with the antiseizure medication levetiracetam in rodent seizure models

OBJECTIVE

The use of many antiseizure medications (ASMs) is limited due to pharmacoresistance and dose-limiting side effects, suggesting an unmet need for novel therapeutic approaches. The neuropeptide galanin reduces seizures in several preclinical seizure and epilepsy models, but its clinical utility is limited due to rapid metabolism and poor blood-brain barrier penetration. The lead galanin analog 810-2 is systemically bioavailable and reduces seizures when administered alone. Further development of this analog, with the potential for use as an add-on therapy in patients with epilepsy, requires a better understanding of the use of this analog in combination with approved ASMs. We sought to evaluate 810-2 in combination with commonly used ASMs in rodent models of seizures.

METHODS

The mouse 6-Hz seizure assay was used to test efficacy of 810-2 in combination with levetiracetam (LEV), valproic acid (VPA), or lacosamide (LCM) using a 1:1 dose ratio in isobolographic studies. Further characterization was performed for the combination of 810-2 and LEV in the mouse corneal kindling and rat 6-Hz assays.

RESULTS

Whereas the combination of 810-2 with VPA and LCM yielded additive interactions, the combination of 810-2 with LEV demonstrated a synergistic interaction in the mouse 6-Hz assay. Supra-additive effects were also observed in the mouse corneal kindling and rat 6-Hz assays for this combination.

SIGNIFICANCE

The combination of 810-2 with LEV suggests the potential for this galanin analog to be further developed as an add-on therapy for patients with epilepsy, particularly when coadministered with LEV.

Timing of referral to evaluate for epilepsy surgery: Expert Consensus Recommendations from the Surgical Therapies Commission of the International League Against Epilepsy

Epilepsy surgery is the treatment of choice for patients with drug-resistant seizures. A timely evaluation for surgical candidacy can be life-saving for patients who are identified as appropriate surgical candidates, and may also enhance the care of nonsurgical candidates through improvement in diagnosis, optimization of therapy, and treatment of comorbidities. Yet, referral for surgical evaluations is often delayed while palliative options are pursued, with significant adverse consequences due to increased morbidity and mortality associated with intractable epilepsy. The Surgical Therapies Commission of the International League Against Epilepsy (ILAE) sought to address these clinical gaps and clarify when to initiate a surgical evaluation. We conducted a Delphi consensus process with 61 epileptologists, epilepsy neurosurgeons, neurologists, neuropsychiatrists, and neuropsychologists with a median of 22 years in practice, from 28 countries in all six ILAE world regions. After three rounds of Delphi surveys, evaluating 51 unique scenarios, we reached the following Expert Consensus Recommendations: (1) Referral for a surgical evaluation should be offered to every patient with drug-resistant epilepsy (up to 70 years of age), as soon as drug resistance is ascertained, regardless of epilepsy duration, sex, socioeconomic status, seizure type, epilepsy type (including epileptic encephalopathies), localization, and comorbidities (including severe psychiatric comorbidity like psychogenic nonepileptic seizures [PNES] or substance abuse) if patients are cooperative with management; (2) A surgical referral should be considered for older patients with drug-resistant epilepsy who have no surgical contraindication, and for patients (adults and children) who are seizure-free on 1-2 antiseizure medications (ASMs) but have a brain lesion in noneloquent cortex; and (3) referral for surgery should not be offered to patients with active substance abuse who are noncooperative with management. We present the Delphi consensus results leading up to these Expert Consensus Recommendations and discuss the data supporting our conclusions. High level evidence will be required to permit creation of clinical practice guidelines.

Review: Cannabinoids as Medicinals

Purpose of review

There have been many debates, discussions, and published writings about the therapeutic value of cannabis plant and the hundreds of cannabinoids it contains. Many states and countries have attempted, are attempting, or have already passed bills to allow legal use of cannabinoids, especially cannabidiol (CBD), as medicines to treat a wide range of clinical conditions without having been approved by a regulatory body. Therefore, by using PubMed and Google Scholar databases, we have reviewed published papers during the past 30 years on cannabinoids as medicines and comment on whether there is sufficient clinical evidence from well-designed clinical studies and trials to support the use of CBD or any other cannabinoids as medicines.

Recent findings

Current research shows that CBD and other cannabinoids currently are not ready for formal indications as medicines to treat a wide range of clinical conditions as promoted except for several exceptions including limited use of CBD for treating two rare forms of epilepsy in young children and CBD in combination with THC for treating multiple-sclerosis-associated spasticity.

Summary

Research indicates that CBD and several other cannabinoids have potential to treat multiple clinical conditions, but more preclinical, and clinical studies and clinical trials, which follow regulatory guidelines, are needed to formally recommend CBD and other cannabinoids as medicines.

Galanin analogs prevent mortality from seizure-induced respiratory arrest in mice

Objective

Sudden Unexpected Death in Epilepsy (SUDEP) accounts for 20% of mortality in those with recurrent seizures. While risk factors, monitoring systems, and standard practices are in place, the pathophysiology of SUDEP is still not well understood. Better knowledge of SUDEP and its potential mechanisms of action is crucial to reducing risk in this patient population and developing potential treatment options. Clinical studies and animal models of SUDEP suggest that diminished post-ictal respiratory control may be the dominant mechanism contributing to mortality. Recently, it was demonstrated that the depletion of the neuropeptide galanin in the amygdala occurs in human SUDEP. The amygdala plays a key role in the central integration of respiratory signaling; the depletion of galanin may represent a critical change that predisposes individuals to SUDEP.

Materials and methods

To evaluate the impact of enhancing galaninergic signaling to potentially protect against SUDEP, we studied seizure-induced respiratory arrest (S-IRA) following central (intracerebroventricular, intra-amygdala) and systemic (intraperitoneal, subcutaneous) administration of galanin analogs. Seizure naïve and seizure experienced (fully kindled) mice were tested.

Results

Central and systemically administered galanin analogs protect against S-IRA in naïve C57Bl/6J mice. Differential efficacy between receptor subtype-selective analogs varied based on the route of administration. Sub-chronic systemic administration at doses that reduced 6 Hz seizures also protected against S-IRA. Acute treatment benefits also extended to fully kindled mice experiencing tonic extension.

Significance

These data demonstrate that galanin analogs may be protective against post-ictal respiratory collapse.

Seizure-induced strengthening of a recurrent excitatory circuit in the dentate gyrus is proconvulsant

Epilepsy is a devastating brain disorder for which effective treatments are very limited. There is growing interest in early intervention, which requires a better mechanistic understanding of the early stages of this disorder. While diverse brain insults can lead to epileptic activity, a common cellular mechanism relies on uncontrolled recurrent excitatory activity. In the dentate gyrus, excitatory mossy cells (MCs) project extensively onto granule cells (GCs) throughout the hippocampus, thus establishing a recurrent MC-GC-MC excitatory loop. MCs are implicated in temporal lobe epilepsy, a common form of epilepsy, but their role during initial seizures (i.e., before the characteristic MC loss that occurs in late stages) is unclear. Here, we show that initial seizures acutely induced with an intraperitoneal kainic acid (KA) injection in adult mice, a well-established model that leads to experimental epilepsy, not only increased MC and GC activity in vivo but also triggered a brain-derived neurotrophic factor (BDNF)-dependent long-term potentiation (LTP) at MC-GC excitatory synapses. Moreover, in vivo induction of MC-GC LTP using MC-selective optogenetic stimulation worsened KA-induced seizures. Conversely, Bdnf genetic removal from GCs, which abolishes LTP, and selective MC silencing were both anticonvulsant. Thus, initial seizures are associated with MC-GC synaptic strengthening, which may promote later epileptic activity. Our findings reveal a potential mechanism of epileptogenesis that may help in developing therapeutic strategies for early intervention.

Genetic pathogenesis of the epileptogenic lesions in Tuberous Sclerosis Complex: Therapeutic targeting of the mTOR pathway

Tuberous sclerosis complex (TSC) is a genetic multisystem disease due to the mutation in one of the two genes TSC1 and TSC2, affecting several organs and systems and carrying a significant risk of early onset and refractory seizures. The pathogenesis of this complex disorder is now well known, with most of TSC-related manifestations being a consequence of the overactivation of the mammalian Target of Rapamycin (mTOR) complex. The discovery of this underlying mechanism paved the way for the use of a class of drugs called mTOR inhibitors including rapamycin and everolimus and specifically targeting this pathway. Rapamycin has been widely used in different animal models of TSC-related epilepsy and proved to be able not only to suppress seizures but also to prevent the development of epilepsy, thus demonstrating an antiepileptogenic potential. In some models, it also showed some benefit on neuropsychiatric manifestations associated with TSC. Everolimus has recently been approved by the US Food and Drug Administration and the European Medical Agency for the treatment of refractory seizures associated with TSC starting from the age of 2 years. It demonstrated a clear benefit when compared to placebo on reducing the frequency of different seizure types and exerting a higher effect in younger children. In conclusion, mTOR cascade can be a potentially major cause of TSC-associated epilepsy and neurodevelopmental disability, and additional research should investigate if early suppression of abnormal mTOR signal with mTOR inhibitors before seizure onset can be a more efficient approach and an effective antiepileptogenic and disease-modifying strategy in infants with TSC.

A Synopsis of Multitarget Potential Therapeutic Effects of Huperzine A in Diverse Pathologies-Emphasis on Alzheimer's Disease Pathogenesis

Numerous challenges are confronted when it comes to the recognition of therapeutic agents for treating complex neurodegenerative diseases like Alzheimer's disease (AD). The perplexing pathogenicity of AD embodies cholinergic dysfunction, amyloid beta (Aβ) aggregation, neurofibrillary tangle formation, neuroinflammation, mitochondrial disruption along with vicious production of reactive oxygen species (ROS) generating oxidative stress. In this frame of reference, drugs with multi target components could prove more advantageous to counter complex pathological mechanisms that are responsible for AD progression. For as much as, medicinal plant based pharmaco-therapies are emerging as potential candidates for AD treatment keeping the efficacy and safety parameters in terms of toxicity and side effects into consideration. Huperzine A (Hup A) is a purified alkaloid compound extracted from a club moss called Huperzia serrata. Several studies have reported both cholinergic and non-cholinergic effects of this compound on AD with significant neuroprotective properties. The present review convenes cumulative demonstrations of neuroprotection provided by Hup A in in vitro, in vivo, and human studies in various pathologies. The underlying molecular mechanisms of its actions have also been discussed. However, more profound evidence would certainly promote the therapeutic implementation of this drug thus furnishing decisive insights into AD therapeutics and various other pathologies along with preventive and curative management.

Reconnoitering the transformative journey of minocycline from an antibiotic to an antiepileptic drug

Minocycline, a second-generation tetracycline antibiotic is being widely tested in animals as well as clinical settings for the management of multiple neurological disorders. The drug has shown to exert protective action in a multitude of neurological disorders including spinal-cord injury, stroke, multiple sclerosis, amyotrophic lateral sclerosis, Huntington's disease, and Parkinson's disease. Being highly lipophilic, minocycline easily penetrates the blood brain barrier and is claimed to have excellent oral absorption (~100% bioavailability). Minocycline possesses anti-inflammatory, immunomodulatory, and anti-apoptotic properties, thereby supporting its use in treating neurological disorders. The article henceforth reviews all the recent advances in the transformation of this antibiotic into a potential antiepileptic/antiepileptogenic agent. The article also gives an account of all the clinical trials undertaken till now validating the antiepileptic potential of minocycline. Based on the reported studies, minocycline seems to be an important molecule for treating epilepsy. However, the practical therapeutic implementations of this molecule require extensive mechanism-based in-vitro (cell culture) and in-vivo (animal models) studies followed by its testing in randomized, placebo controlled and double-blind clinical trials in large population as well as in different form of epilepsies.

Advances in pharmacotherapy for postpartum depression: a structured review of standard-of-care antidepressants and novel neuroactive steroid antidepressants

Postpartum depression is one of the most common morbidities of childbearing, yet it is underdiagnosed and undertreated with negative consequences for mother and offspring. Despite the widespread use of standard-of-care antidepressants as the mainstay of treatment for postpartum depression, there is limited evidence on their safety and efficacy due to their slow onset of action and suboptimal outcomes. The emergence of gamma-aminobutyric acidergic neuroactive steroids may offer faster response and remission times and improved patient outcomes. This article reviews the evidence base for the efficacy of standard-of-care antidepressants, hormonal therapeutics including progestins and estradiol, and gamma-aminobutyric acidergic neuroactive steroids in the treatment of postpartum depression, as well as the safety of infant exposure to these agents during lactation.

Differences in aggression as psychiatric side effect of levetiracetam and perampanel in patients with epilepsy

PURPOSE

Aggression is the most commonly encountered antiepileptic-drug (AED)-induced psychiatric adverse effects. Levetiracetam (LEV) is well known to be associated with increased rates of aggression, while perampanel (PER) is also recognized as a potentially aggression-promoting agent, though opinions vary. However, few studies have addressed questions regarding whether the nature of irritability-aggression differs between those drugs. The present study used a standardized rating scale to examine aggression among patient with epilepsy who received LEV or PER using specific measures to confirm the effects of the drugs.

METHODS

We enrolled 144 consecutive outpatients receiving treatment for epilepsy with LEV (n = 103) or PER (n = 41), and determined their effects regarding aggression using the Buss-Perry Aggression Questionnaire (BAQ). For analysis, total BAQ scores for the LEV and PER subjects were compared to determine whether the aggression-promoting effects of the agents differed, and which BAQ subdomains (physical aggression, verbal aggression, anger, hostility) were related to production of aggression in patients taking either LEV or PER. As a subsidiary analysis, clinical variables inclusive of administered AED type that showed a significant impact on BAQ scores were determined.

RESULTS

The LEV group had a significantly higher hostility score (19.4 ± 5.8) as compared to the PER group (17.2 ± 6.3) in subscale analysis (p < 0.05). In multiple regression analysis, LEV had a significant association with higher hostility score (P = 0.006).

CONCLUSION

Our results indicate that while easily visible outward-directed aggression tends to be dominant in patients given PER, aggression provoked by LEV may be felt more subjectively or in an inward-directed manner, which can lead to more diverse expression and misrecognition.

Combined effects of levetiracetam and sodium valproate on paediatric patients with epilepsy: a systematic review and meta-analysis

OBJECTIVE

To estimate the safety and efficacy of sodium valproate combined with levetiracetam in paediatric patients with epilepsy based on randomized controlled trials (RCTs).

METHODS

The Cochrane Library, PubMed, Web of Science, Chinese Journal Full-Text Database (CNKI), WANGFANG DATA and Sino Med were searched between January 1946 and May 2021. The included literature was randomized controlled clinical trials focusing on sodium valproate combined with levetiracetam in paediatric patients with epilepsy. Two evaluators separately collected the data based on the retrieval strategy, filtered the literature in accordance with the inclusion and exclusion criteria, and summarized the literature that satisfied the criteria. The statistical programme used for the meta-analysis was Stata V14.0.

RESULTS

Of 577 original titles screened, data were extracted from 7 studies (617 participants). Compared with sodium valproate alone or sodium valproate combined with topiramate, the application of sodium valproate combined with levetiracetam in the treatment of paediatric epilepsy significantly improved the overall therapeutic effect (RR=1.24, 95% CI: 1.16 to 1.33, p=0.927). The observation group significantly reduced the occurrence of adverse drug reactions (ADRs) (RR=0.54, 95% CI: 0.37 to 0.79, p=0.602). Egger's regression test of the overall therapeutic effect showed no potential publication bias (p=0.122).

CONCLUSION

Based on this meta-analysis, compared with sodium valproate alone or sodium valproate with topiramate, the application of sodium valproate combined with levetiracetam in the treatment of paediatric epilepsy can significantly improve the overall therapeutic effect and simultaneously reduce the occurrence of ADR. Therefore, we recommend sodium valproate combined with levetiracetam for the therapy of paediatric patients with epilepsy.

What value can TSPO PET bring for epilepsy treatment?

Epilepsy is one of the most common neurological disorders and affects both the young and adult populations. The question we asked for this review was how positron emission tomography (PET) imaging with translocator protein (TSPO) radioligands can help inform the epilepsy clinic and the development of future treatments targeting neuroinflammatory processes.Even though the first TSPO PET scans in epilepsy patients were performed over 20 years ago, this imaging modality has not seen wide adoption in the clinic. There is vast scientific evidence from preclinical studies in rodent models of temporal lobe epilepsy which have shown increased levels of TSPO corresponding to neuroinflammatory processes in the brain. These increases peaked sub-acutely (1-2 weeks) after the epileptogenic insult (e.g. status epilepticus) and remained chronically increased, albeit at lower levels. In addition, these studies have shown a correlation between TSPO levels and seizure outcome, pharmacoresistance and behavioural morbidities. Histological assessment points to a complex interplay between different cellular components such as microglial activation, astrogliosis and cell death changing dynamically over time.In epilepsy patients, a highly sensitive biomarker of neuroinflammation would provide value for the optimization of surgical assessment (particularly for extratemporal lobe epilepsy) and support the clinical development path of anti-inflammatory treatments. Clinical studies have shown a systematic increase in asymmetry indices of TSPO PET binding. However, region-based analysis typically does not yield statistical differences and changes are often not restricted to the epileptogenic zone, limiting the ability of this imaging modality to localise pathology for surgery. In this manuscript, we discuss the biological underpinnings of these findings and review for which applications in epilepsy TSPO PET could bring added value.

Synthesis, antiepileptic effects, and structure-activity relationships of α-asarone derivatives: In vitro and in vivo neuroprotective effect of selected derivatives

In the present study, we compared the antiepileptic effects of α-asarone derivatives to explore their structure-activity relationships using the PTZ-induced seizure model. Our research revealed that electron-donating methoxy groups in the 3,4,5-position on phenyl ring increased antiepileptic potency but the placement of other groups at different positions decreased activity. Besides, in allyl moiety, the optimal activity was reached with either an allyl or a 1-butenyl group in conjugation with the benzene ring. The compounds 5 and 19 exerted better neuroprotective effects against epilepsy in vitro (cell) and in vivo (mouse) models. This study provides valuable data for further exploration and application of these compounds as potential anti-seizure medicines.

Pharmacotherapy for Seizures in Tuberous Sclerosis Complex

Epilepsy is one of the main symptoms affecting the lives of individuals with tuberous sclerosis complex (TSC), causing a high rate of morbidity. Individuals with TSC can present with various types of seizures, epilepsies, and epilepsy syndromes that can coexist or appear in relation to age. Focal epilepsy is the most frequent epilepsy type with two developmental and epileptic encephalopathies: infantile spasms syndrome and Lennox-Gastaut syndrome. Active screening and early management of epilepsy is recommended in individuals with TSC to limit its consequences and its impact on quality of life, cognitive outcome and the economic burden of the disease. The progress in the knowledge of the mechanisms underlying epilepsy in TSC has paved the way for new concepts in the management of epilepsy related to TSC. In addition, we are moving from traditional "reactive" and therapeutic choices with current antiseizure medications used after the onset of seizures, to a proactive approach, aimed at predicting and preventing epileptogenesis and the onset of epilepsy with vigabatrin, and to personalized treatments with mechanistic therapies, namely mechanistic/mammalian target of rapamycin inhibitors. Indeed, epilepsy linked to TSC is one of the only epilepsies for which a predictive and preventive approach can delay seizure onset and improve seizure response. However, the efficacy of such interventions on long-term cognitive and psychiatric outcomes is still under investigation.

Neuroinflammation: A Signature or a Cause of Epilepsy?

Epilepsy can be both a primary pathology and a secondary effect of many neurological conditions. Many papers show that neuroinflammation is a product of epilepsy, and that in pathological conditions characterized by neuroinflammation, there is a higher probability to develop epilepsy. However, the bidirectional mechanism of the reciprocal interaction between epilepsy and neuroinflammation remains to be fully understood. Here, we attempt to explore and discuss the relationship between epilepsy and inflammation in some paradigmatic neurological and systemic disorders associated with epilepsy. In particular, we have chosen one representative form of epilepsy for each one of its actual known etiologies. A better understanding of the mechanistic link between neuroinflammation and epilepsy would be important to improve subject-based therapies, both for prophylaxis and for the treatment of epilepsy.

Therapeutic potential of cannabidivarin for epilepsy and autism spectrum disorder

Recent years have seen a renewed interest on the possible therapeutic exploitations of specific cannabinoids derived from the Cannabis sativa plant. Thus far, the most studied non-psychotomimetic cannabinoid is cannabidiol (CBD), which has shown promising therapeutic potential for relieving a variety of neurological diseases. However, also its propyl analogue, cannabidivarin (CBDV), has recently gained much attention as a potential therapeutic agent for the management of disabling neurological conditions. This review aims at providing a comprehensive and updated overview of the available animal and human data, which have investigated the possible therapeutic potential of CBDV for the management of epilepsy and autism spectrum disorder.

Efficacy of Phytocannabinoids in Epilepsy Treatment: Novel Approaches and Recent Advances

Epilepsy is a neurological disorder mainly characterised by recurrent seizures that affect the entire population diagnosed with the condition. Currently, there is no cure for the disease and a significant proportion of patients have been deemed to have treatment-resistant epilepsy (TRE). A patient is deemed to have TRE if two or more antiepileptic drugs (AEDs) fail to bring about seizure remission. This inefficacy of traditional AEDs, coupled with their undesirable side effect profile, has led to researchers considering alternative forms of treatment. Phytocannabinoids have long served as therapeutics with delta-9-THC (Δ⁹-THC) receiving extensive focus to determine its therapeutic potential. This focus on Δ⁹-THC has been to the detriment of analysing the plethora of other phytocannabinoids found in the cannabis plant. The overall aim of this review is to explore other novel phytocannabinoids and their place in epilepsy treatment. The current review intends to achieve this aim via an exploration of the molecular targets underlying the anticonvulsant capabilities of cannabidiol (CBD), cannabidavarin (CBDV), delta-9-tetrahydrocannabivarin (Δ⁹-THCV) and cannabigerol (CBG). Further, this review will provide an exploration of current pre-clinical and clinical data as it relates to the aforementioned phytocannabinoids and the treatment of epilepsy symptoms. With specific reference to epilepsy in young adult and adolescent populations, the exploration of CBD, CBDV, Δ⁹-THCV and CBG in both preclinical and clinical environments can guide future research and aid in the further understanding of the role of phytocannabinoids in epilepsy treatment. Currently, much more research is warranted in this area to be conclusive.

Guardians of the Frequency: Neuronal Regulation by Microglia

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Ganaxolone treatment for epilepsy patients: from pharmacology to place in therapy

Introduction: Nonsulfated neurosteroids can provide phasic and tonic inhibition through activation of synaptic and extra-synaptic γ-aminobutyric acid (GABA)_A receptors, exhibiting a greater potency for the latter. These actions occur by interacting with modulatory sites that are distinct from those bound by benzodiazepines and barbiturates. Ganaxolone (GNX) is a synthetic analog of the endogenous neurosteroid allopregnanolone and a member of a novel class of neuroactive steroids called epalons.Areas covered: The authors review the pharmacology of GNX, summarize the main clinical evidence about its antiseizure efficacy and tolerability, and suggest implications for clinical practice and future research.Expert opinion: The clinical development of GNX is mainly oriented to target unmet needs and focused on status epilepticus and rare genetic epilepsies that have few or no treatment options.The availability of oral and intravenous formulations allows reaching adult and pediatric patients in acute and chronic care settings. Further evidence will complement the understanding of the potentialities of GNX and possibly lead to indications for use in clinical practice.

Comparison of the Therapeutic Effects of Sodium Valproate and Levetiracetam on Pediatric Epilepsy and the Effects of Nerve Growth Factor and γ-Aminobutyric Acid

Background:

We aimed to investigate the therapeutic effect of sodium valproate combined with levetiracetam on pediatric epilepsy and the effects of nerve growth factor and γ-aminobutyric acid.

Methods:

Eighty-three epileptic children admitted to Xuzhou Municipal Hospital of Xuzhou Medical University (Xuzhou, China) from Jan 2018 to Nov 2019 were collected and divided into a control group (40 cases, treated with sodium valproate alone) and an observation group (43 cases, treated with sodium valproate combined with levetiracetam). The therapeutic effect and incidence of adverse reactions were observed. The levels of nerve growth factor (NGF), γ-aminobutyric acid (GABA) and serum neuron-specific enolase (NSE) of children were compared. Changes of cognitive function and the total effective rate were evaluated. Logistic regression analysis was used to analyze the risk factors affecting the therapeutic effect.

Results:

After treatment, NGF, GABA and NSE in the observation group were significantly improved compared with those before treatment. The cognitive function of the observation group was significantly improved after treatment when compared with the control group. The total effective rate in the observation group was higher than that in the control group. Adverse reactions in the observation group were less than those in the control group. Seizure type, NGF, GABA, NSE and treatment methods were independent risk factors affecting the therapeutic effect of pediatric epilepsy.

Conclusion:

The application of sodium valproate combined with levetiracetam in the treatment of pediatric epilepsy is helpful to improve the overall therapeutic effect, significantly improve the cognitive function of children, and improve the levels of NGF, GABA and NSE.

Differences in levetiracetam and perampanel treatment-related irritability in patients with epilepsy

PURPOSE

The present study evaluated whether patients with epilepsy who received both levetiracetam (LEV) and perampanel (PER) therapy showed side effects of irritability. The study also examined the relationship between patient characteristics and irritability when it occurred as a side effect.

METHODS

We retrospectively examined medical records of 98 patients with epilepsy who were treated with both LEV and PER at the Department of Psychiatry in the Epilepsy Center of Nishiniigata Chuo National Hospital in Japan. We performed multiple regression analyses with the presence/absence of irritability due to LEV or PER as the dependent variables and clinical characteristics of the patients as independent variables.

RESULTS

LEV and PER caused irritability in 7 and 17 of 98 patients, respectively. LEV- and PER-related irritability did not occur in the same patients. A logistic multiple regression analysis revealed that EEG findings of temporal focal epileptic discharge were significantly associated with increased incidence of irritability due to LEV. LEV-related irritability decreased significantly with higher dosages of LEV. Another logistic multiple regression analysis revealed that a psychiatric comorbidity of irritability and EEG findings of nontemporal focal epileptic discharge were significantly associated with increased incidence of irritability due to PER.

CONCLUSIONS

LEV and PER cause irritability in different patient groups. Additionally, irritability as a side effect was present only at low dosages of LEV, but PER tended to cause irritability even at high dosages.

Modelling epilepsy in the mouse: challenges and solutions

In most mouse models of disease, the outward manifestation of a disorder can be measured easily, can be assessed with a trivial test such as hind limb clasping, or can even be observed simply by comparing the gross morphological characteristics of mutant and wild-type littermates. But what if we are trying to model a disorder with a phenotype that appears only sporadically and briefly, like epileptic seizures? The purpose of this Review is to highlight the challenges of modelling epilepsy, in which the most obvious manifestation of the disorder, seizures, occurs only intermittently, possibly very rarely and often at times when the mice are not under direct observation. Over time, researchers have developed a number of ways in which to overcome these challenges, each with their own advantages and disadvantages. In this Review, we describe the genetics of epilepsy and the ways in which genetically altered mouse models have been used. We also discuss the use of induced models in which seizures are brought about by artificial stimulation to the brain of wild-type animals, and conclude with the ways these different approaches could be used to develop a wider range of anti-seizure medications that could benefit larger patient populations.

Summary: This Review discusses the challenges of modelling epilepsy in mice, a condition in which the outward manifestation of the disorder appears only sporadically, and reviews possible solutions encompassing both genetic and induced models.

In Vivo Screening of Xanthones from Garcinia oligantha Identified Oliganthin H as a Novel Natural Inhibitor of Convulsions

Epilepsy is a chronic neurological disorder, characterized by recurrent, spontaneous, and transient seizures, and affects more than 70 million people worldwide. Although two dozen antiepileptic drugs (AEDs) are approved and available in the market, seizures remain poorly controlled in one-third of epileptic patients who are suffering from drug resistance or various adverse effects. Recently, the xanthone skeleton has been regarded as an attractive scaffold for the discovery and development of emerging anticonvulsants. We had isolated several dihydroxanthone derivatives previously, including oliganthin H, oliganthin I, and oliganthin N, whose structures were similar and delicately elucidated by spectrum analysis or X-ray crystallographic data, from extracts of leaves of Garcinia oligantha. These xanthone analogues were evaluated for anticonvulsant activity, and a novel xanthone, oliganthin H, has been identified as a sound and effective natural inhibitor of convulsions in zebrafish in vivo. A preliminary structure-activity relationship analysis on the relationship between structures of the xanthone analogues and their activities was also conducted. Oliganthin H significantly suppressed convulsant behavior and reduced to about 25% and 50% of PTZ-induced activity, in 12.5 and 25 μM treatment groups (P < 0.01 and 0.001), respectively. Meanwhile, it reduced seizure activity, velocity, seizure duration, and number of bursts in zebrafish larvae (P < 0.05). Pretreatment of oliganthin H significantly restored aberrant induction of gene expressions including npas4a, c-fos, pyya, and bdnf, as well as gabra1, gad1, glsa, and glula, upon PTZ treatment. In addition, in silico analysis revealed the stability of the oliganthin H-GABAA receptor complex and their detailed binding pattern. Therefore, direct interactions with the GABAA receptor and involvement of downstream GABA-glutamate pathways were possible mechanisms of the anticonvulsant action of oliganthin H. Our findings present the anticonvulsant activity of oliganthin H, provide a novel scaffold for further modifications, and highlight the xanthone skeleton as an attractive and reliable resource for the development of emerging AEDs.

Valproic Acid and Its Amidic Derivatives as New Antivirals against Alphaherpesviruses

Herpes simplex viruses (HSVs) are neurotropic viruses with broad host range whose infections cause considerable health problems in both animals and humans. In fact, 67% of the global population under the age of 50 are infected with HSV-1 and 13% have clinically recurrent HSV-2 infections. The most prescribed antiherpetics are nucleoside analogues such as acyclovir, but the emergence of mutants resistant to these drugs and the lack of available vaccines against human HSVs has led to an imminent need for new antivirals. Valproic acid (VPA) is a branched short-chain fatty acid clinically used as a broad-spectrum antiepileptic drug in the treatment of neurological disorders, which has shown promising antiviral activity against some herpesviruses. Moreover, its amidic derivatives valpromide and valnoctamide also share this antiherpetic activity. This review summarizes the current research on the use of VPA and its amidic derivatives as alternatives to traditional antiherpetics in the fight against HSV infections.

Progress report on new antiepileptic drugs: A summary of the Fifteenth Eilat Conference on New Antiepileptic Drugs and Devices (EILAT XV). II. Drugs in more advanced clinical development

The Fifteenth Eilat Conference on New Antiepileptic Drugs and Devices (EILAT XV) was held as a fully virtual conference from July 27 to July 30, 2020 for the sessions on drugs, and on August 3, 2020 for the sessions on devices. A total of 534 delegates from 63 countries attended lectures and interactive discussions, representing a broad range of disciplines from basic science, clinical research, and clinical care. This progress report provides summaries of recent findings on investigational compounds for which preclinical data as well as data from patient studies were presented. The report includes the following five compounds: anakinra, cenobamate, CVL-865, fenfluramine, and ganaxolone, all with novel modes of action compared to more established antiepileptic drugs. Some of these compounds demonstrated promising results in placebo-controlled phase 3 trials, and two have recently received approval from the US Food and Drug Administration (FDA). These include cenobamate, which was approved by the FDA on November 21, 2019 for the treatment of partial onset (focal) seizures in adults, and fenfluramine oral solution, which was approved by the FDA on June 25, 2020 for the treatment of seizures associated with Dravet syndrome in patients 2 years and older.

Cannabidivarin for HIV-Associated Neuropathic Pain: A Randomized, Blinded, Controlled Clinical Trial

HIV remains a major burden to the health care system and neuropathic pain is the most common neurological complication of HIV infection. Because current treatment strategies often lack satisfying pain relief, cannabinoids (CBs) are discussed as a new option. We investigated cannabidivarin (CBDV) as treatment for HIV-associated neuropathic pain. We conducted a randomized, double-blind, placebo-controlled crossover study. Patients underwent two successive treatment phases (4 weeks each) and were treated with CBDV (400 mg/day) or placebo in a randomized order. A 3-week washout phase was designed to eliminate potential carry-over effects. Patients were followed up for 3 weeks after the end of the second treatment phase. The primary end point was pain intensity on an 11-point numeric rating scale, recorded in a diary. Secondary end points were additional pain medication, pain characteristics, and quality of life. We included 32 patients. The mean pain intensity under CBDV was 0.62 points higher compared with placebo (P = 0.16, 95% confidence interval -0.27 to 1.51). CBDV did not influence the amount of additional pain medication, pain characteristics, or quality of life. The incidence of adverse events was similar during both treatments. No suspected unexpected adverse reactions occurred during either treatment. CBDV was safe but failed to reduce neuropathic pain in patients with HIV. This may be explained by a lack of CB receptor activation, as indicated by preclinical experiments. Although a larger patient number might be desirable, we would not expect a change in the conclusions because the present differences are far from statistical significance. Therefore, we would currently not consider CBDV as a clinically meaningful treatment option for neuropathic pain.

In vitro and in vivo characterization of Lu AA41178: A novel, brain penetrant, pan-selective Kv7 potassium channel opener with efficacy in preclinical models of epileptic seizures and psychiatric disorders

Activation of the voltage-gated Kv7 channels holds therapeutic promise in several neurological and psychiatric disorders, including epilepsy, schizophrenia, and depression. Here, we present a pharmacological characterization of Lu AA41178, a novel, pan-selective Kv7.2-7.5 opener, using both in vitro assays and a broad range of in vivo assays with relevance to epilepsy, schizophrenia, and depression. Electrophysiological characterization in Xenopus oocytes expressing human Kv7.2-Kv7.5 confirmed Lu AA41178 as a pan-selective opener of Kv7 channels by significantly left-shifting the activation threshold. Additionally, Lu AA41178 was tested in vitro for off-target effects, demonstrating a clean Kv7-selective profile, with no impact on common cardiac ion channels, and no potentiating activity on GABAA channels. Lu AA41178 was evaluated across preclinical in vivo assays with relevance to neurological and psychiatric disorders. In the maximum electroshock seizure threshold test and PTZ seizure threshold test, Lu AA41178 significantly increased the seizure thresholds in mice, demonstrating anticonvulsant efficacy. Lu AA41178 demonstrated antipsychotic-like activity by reducing amphetamine-induced hyperlocomotion in mice as well as lowering conditioned avoidance responses in rats. In the mouse forced swim test, a model with antidepressant predictivity, Lu AA41178 significantly reduced immobility. Additionally, behavioral effects typically observed with Kv7 openers was also characterized. In vivo assays were accompanied by plasma and brain exposures, revealing minimum effective plasma levels <1000 ng/ml. Lu AA41178, a potent opener of neuronal Kv7 channels demonstrate efficacy in assays of epilepsy, schizophrenia and depression and might serve as a valuable tool for exploring the role of Kv7 channels in both neurological and psychiatric disorders.

TSPO PET Identifies Different Anti-inflammatory Minocycline Treatment Response in Two Rodent Models of Epileptogenesis

Epileptogenesis-associated brain inflammation might be a promising target to prevent or attenuate epileptogenesis. Positron emission tomography (PET) imaging targeting the translocator protein (TSPO) was applied here to quantify effects of different dosing regimens of the anti-inflammatory drug minocycline during the latent phase in two rodent models of epileptogenesis. After induction of epileptogenesis by status epilepticus (SE), rats were treated with minocycline for 7 days (25 or 50 mg/kg) and mice for 5 or 10 days (50 or 100 mg/kg). All animals were subjected to scans at 1 and 2 weeks post-SE. Radiotracer distribution was analyzed and statistical parametric mapping (SPM) was performed, as well as histological analysis of astroglial activation and neuronal cell loss. Atlas-based analysis of [18F]GE180 PET in rats revealed a dose-dependent regional decrease of TSPO expression at 2 weeks post-SE. Results of SPM analysis depicted a treatment effect already at 1 week post-SE in rats treated with the higher minocycline dose. In mice, TSPO PET imaging did not reveal any treatment effects whereas histology identified only a treatment-related reduction in dispersion of dentate gyrus neurons. TSPO PET served as an auspicious tool for temporal monitoring and quantification of anti-inflammatory effects during epileptogenesis. Importantly, the findings underline the need to applying more than one animal model to avoid missing treatment effects. For future studies, the setup is ready to be applied in combination with seizure monitoring to investigate the relationship between individual early treatment response and disease outcome.

Cannabis sativa: Much more beyond Δ9-tetrahydrocannabinol

Cannabis is the most used illicit drug worldwide and its medicinal use is under discussion, being regulated in several countries. However, the psychotropic effects of Δ⁹-tetrahydrocannabinol (THC), the main psychoactive compound of Cannabis sativa, are of concern. Thus, the interest in the isolated constituents without psychotropic activity, such as cannabidiol (CBD) and cannabidivarin (CBDV) is growing. CBD and CBDV are lipophilic molecules with poor oral bioavailability and are mainly metabolized by cytochrome P450 (CYP450) enzymes. The pharmacodynamics of CBD is the best explored, being able to interact with diverse molecular targets, like cannabinoid receptors, G protein-coupled receptor-55, transient receptor potential vanilloid 1 channel and peroxisome proliferator-activated receptor-γ. Considering the therapeutic potential, several clinical trials are underway to study the efficacy of CBD and CBDV in different pathologies, such as neurodegenerative diseases, epilepsy, autism spectrum disorders and pain conditions. The anti-cancer properties of CBD have also been demonstrated by several pre-clinical studies in different types of tumour cells. Although less studied, CBDV, a structural analogue of CBD, is receiving attention in the last years. CBDV exhibits anticonvulsant properties and, currently, clinical trials are underway for the treatment of autism spectrum disorders. Despite the benefits of these phytocannabinoids, it is important to highlight their potential interference with relevant physiologic mechanisms. In fact, CBD interactions with CYP450 enzymes and with drug efflux transporters may have serious consequences when co-administered with other drugs. This review summarizes the therapeutic advances of CBD and CBDV and explores some aspects of their pharmacokinetics, pharmacodynamics and possible interactions. Moreover, it also highlights the therapeutic potential of CBD and CBDV in several medical conditions and clinical applications.

Cannabinoids in the Treatment of Epilepsy: Current Status and Future Prospects

Cannabidiol (CBD) is one of the prominent phytocannabinoids found in Cannabis sativa, differentiating from Δ9-tetrahydrocannabinol (THC) for its non-intoxicating profile and its antianxiety/antipsychotic effects. CBD is a multi-target drug whose anti-convulsant properties are supposed to be independent of endocannabinoid receptor CB1 and might be related to several underlying mechanisms, such as antagonism on the orphan GPR55 receptor, regulation of adenosine tone, activation of 5HT1A receptors and modulation of calcium intracellular levels. CBD is a lipophilic compound with low oral bioavailability (6%) due to poor intestinal absorption and high first-pass metabolism. Its exposure parameters are greatly influenced by feeding status (ie, high fat-containing meals). It is mainly metabolized by cytochrome P 450 (CYP) 3A4 and 2C19, which it strongly inhibits. A proprietary formulation of highly purified, plant-derived CBD has been recently licensed as an adjunctive treatment for Dravet syndrome (DS) and Lennox-Gastaut syndrome (LGS), while it is being currently investigated in tuberous sclerosis complex. The regulatory agencies' approval was granted based on four pivotal double-blind, placebo-controlled, randomized clinical trials (RCTs) on overall 154 DS patients and 396 LGS ones, receiving CBD 10 or 20 mg/kg/day BID as active treatment. The primary endpoint (reduction in monthly seizure frequency) was met by both CBD doses. Most patients reported adverse events (AEs), generally from mild to moderate and transient, which mainly consisted of somnolence, sedation, decreased appetite, diarrhea and elevation in aminotransferase levels, the last being documented only in subjects on concomitant valproate therapy. The interaction between CBD and clobazam, likely due to CYP2C19 inhibition, might contribute to some AEs, especially somnolence, but also to CBD clinical effectiveness. Cannabidivarin (CBDV), the propyl analogue of CBD, showed anti-convulsant properties in pre-clinical studies, but a plant-derived, purified proprietary formulation of CBDV recently failed the Phase II RCT in patients with uncontrolled focal seizures.

Anticonvulsant and neurotoxic effects of a novel 1,2,4-triazole-3-thione derivative (TPF-34) and its isobolographic interaction profile with classical antiepileptic drugs in mice

BACKGROUND

Anticonvulsant and acute toxic effects of 5-[(3-fluorophenyl)ethyl]-4-(n-hexyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione (TPF-34)-a candidate for novel antiepileptic drug-were examined in the maximal electroshock-induced seizure (MES) model and rotarod test in mice. The interaction profile of TPF-34 with four classical antiepileptic drugs (carbamazepine, phenobarbital, phenytoin and valproate) was also studied in the mouse MES model.

METHODS

Both ED₅₀ and TD₅₀ values for TPF-34 were determined at four treatment times (15, 30, 60 and 120 min after i.p. administration) in the MES model and rotarod test in adult male albino Swiss mice, respectively. The influence of TPF-34 on the protective anticonvulsant action of carbamazepine, phenobarbital, phenytoin and valproate in the mouse MES model was assessed with isobolographic analysis of interaction. Total brain antiepileptic drug concentrations were measured with fluorescence polarization immunoassay.

RESULTS

TPF-34, when administered alone at four pretreatment times (15, 30, 60 and 120 min before experiments), possessed a favorable preclinical profile with the protective index (a ratio of TD₅₀ and ED₅₀ values) ranging from 2.89 to 3.53. Moreover, TPF-34, when combined with carbamazepine, phenobarbital, phenytoin and valproate, exerted an additive interaction in the MES model in mice. TPF-34 had no impact on total brain antiepileptic drug concentrations in mice.

CONCLUSIONS

A protective index value higher than 3 allows recommending TPF-34 as a promising antiepileptic drug candidate for further preclinical testing using other experimental seizure models. The additive interaction of TPF-34 with carbamazepine, phenobarbital, phenytoin and valproate in the mouse MES model is worthy of recommendation to further clinical studies.

Novel treatment approaches and pediatric research networks in status epilepticus

This paper contains five contributions which were presented as part of the novel therapies section of the 7th London-Innsbruck Colloquium on Status Epilepticus and Acute Seizures. These illustrate recent advances being made in the management and therapy of status epilepticus. The five contributions concern: genetic variations in Na + channel genes and their importance in status epilepticus; the European Reference Network for rare and complex epilepsies EpiCARE; the North American Pediatric Status Epilepticus Research Group (pSERG); Fenfluramine as a potential therapy for status epilepticus' and the valproate derivatives, valnoctamide and sec-butylpropylacetamide (SPD), as potential therapies for status epilepticus. This article is part of the Special Issue "Proceedings of the 7th London-Innsbruck Colloquium on Status Epilepticus and Acute Seizures".

A systems-level framework for anti-epilepsy drug discovery

Modern anti-seizure drug development yielded benefits in terms of improved pharmacokinetics, safety and tolerability profiles, but offered no advances in efficacy compared to previous older generations of anti-seizure drugs. Despite significant advances in our understanding of the genetic bases to epilepsy, and a welcome renewed interest on the severe monogenic epilepsies, modern genetics has yet to directly inform more effective or disease-modifying anti-seizure drugs. Here, we describe a new approach to the identification of novel disease modifying anti-epilepsy drugs. The systems genetics approach aims to first identify pathophysiological mechanisms by integrating polygenic risk with cellular gene expression profiles and then to relate these molecular mechanisms to druggable targets using a gene regulatory (regulome) framework. The approach offers an exciting and flexible framework for future drug discovery in epilepsy, and is applicable to any disease for which appropriate cell-type and disease-context specific data exist. This article is part of the special issue entitled 'New Epilepsy Therapies for the 21st Century - From Antiseizure Drugs to Prevention, Modification and Cure of Epilepsy'.

Chirality as an Important Factor for the Development of New Antiepileptic Drugs

In recent years, chiral molecules (especially enantiomers) have occupied a significant place in pharmaceutical industry and have played a prominent role in the development of new drugs. Individual stereoisomers exhibit marked differences in pharmacodynamic, pharmacokinetic, and toxicological properties. Therefore, there is currently considerable interest in fully characterizing and examining both enantiomers in the early stages of new drug development. Despite the fact that epilepsy is a complex disease and that a given drug's mechanism of action may be multidirectional and not always fully understood, significant differences have been observed in the anticonvulsant activity of individual stereoisomers. Therefore, between 1996 and 2018, among 14 new antiepileptic drugs (AEDs) approved for the treatment of epilepsy, as many as seven are chiral and introduced to the market in the single-enantiomer (or diastereomer) form. This review provides an overview of the impact of chirality on the development and discovery of new AEDs that have entered into clinical trials or preclinical studies. These new AEDs were developed by applying the single-enantiomer approval strategy. Herein we focus our attention on the main synthetic pathways of stereoisomers, as well as on the influence of chirality on pharmacodynamic, pharmacokinetic, and/or toxicological properties.

The role of adenosine in epilepsy

Adenosine is a well-characterized endogenous anticonvulsant and seizure terminator of the brain. Through a combination of adenosine receptor-dependent and -independent mechanisms, adenosine affects seizure generation (ictogenesis), as well as the development of epilepsy and its progression (epileptogenesis). Maladaptive changes in adenosine metabolism, in particular increased expression of the astroglial enzyme adenosine kinase (ADK), play a major role in epileptogenesis. Increased expression of ADK has dual roles in both reducing the inhibitory tone of adenosine in the brain, which consequently reduces the threshold for seizure generation, and also driving an increased flux of methyl-groups through the transmethylation pathway, thereby increasing global DNA methylation. Through these mechanisms, adenosine is uniquely positioned to link metabolism with epigenetic outcome. Therapeutic adenosine augmentation therefore not only holds promise for the suppression of seizures in epilepsy, but moreover the prevention of epilepsy and its progression overall. This review will focus on adenosine-related mechanisms implicated in ictogenesis and epileptogenesis and will discuss therapeutic opportunities and challenges.