Development of an International Standard Set of Outcomes and Measurement Methods for Routine Practice for Adults with Epilepsy: The International Consortium for Health Outcomes Measurement Consensus Recommendations.

At present, there is no internationally accepted set of core outcomes or measurement methods for epilepsy clinical practice. Therefore, the International Consortium for Health Outcomes Measurement (ICHOM) convened an international working group of experts in epilepsy, people with epilepsy and their representatives to develop minimum sets of standardized outcomes and outcomes measurement methods for clinical practice that support patient-clinician decision-making and quality improvement. Consensus methods identified 20 core outcomes. Measurement tools were recommended based on their evidence of strong clinical measurement properties, feasibility, and cross-cultural applicability. The essential outcomes included many non-seizure outcomes: anxiety, depression, suicidality, memory and attention, sleep quality, functional status, and the social impact of epilepsy. The proposed set will facilitate the implementation of the use of patient-centered outcomes in daily practice, ensuring holistic care. They also encourage harmonization of outcome measurement, and if widely implemented should reduce the heterogeneity of outcome measurement, accelerate comparative research, and facilitate quality improvement efforts.

Development of an International Standard Set of Outcomes and Measurement Methods for Routine Practice for Infants, Children, and Adolescents with Epilepsy: The International Consortium for Health Outcomes Measurement Consensus Recommendations.

At present, there is no internationally accepted set of core outcomes or measurement methods for epilepsy clinical practice. The International Consortium for Health Outcomes Measurement (ICHOM) convened an international working group of experts in epilepsy, people with epilepsy, and their representatives to develop minimum sets of standardized outcomes and outcome measurement methods for clinical practice. Using modified Delphi consensus methods with consecutive rounds of online voting over 12 months, a core set of outcomes and corresponding measurement tool packages to capture the outcomes were identified for infants, children, and adolescents with epilepsy. Consensus methods identified 20 core outcomes. In addition to the outcomes identified for the ICHOM Epilepsy adult standard set, behavioral, motor, and cognitive/language development outcomes were voted as essential for all infants and children with epilepsy. The proposed set of outcomes and measurement methods will facilitate the implementation of the use of patient-centered outcomes in daily practice.

Safe delivery, perinatal outcomes and breastfeeding in women with epilepsy.

Safe delivery and optimal peripartum and postpartum care in women with epilepsy (WWE) is a major concern which has received limited attention in recent years. A diagnosis of epilepsy per se is not an indication for a planned cesarean section or induction of labor, even though epidemiological studies indicate that cesarean delivery is more common among WWE compared to the general population. Pregnancy in WWE is associated with an increased risk of obstetrical complications and increased perinatal morbidity and mortality, and these risks may be greater among WWE taking ASMs. Wherever feasible, pregnant WWE should be directed to specialist care. Risk minimization includes, when appropriate, dose adjustment to compensate for pregnancy-related changes in the pharmacokinetics of some ASMs. With respect to postpartum management, WWE should be advised that the benefits of breastfeeding outweigh the small risk of adverse drug reactions in the infant.

Risk of Major Congenital Malformations and Exposure to Antiseizure Medication Monotherapy.

Importance: Women with epilepsy (WWE) require treatment with antiseizure medications (ASMs) during pregnancy, which may be associated with an increased risk of major congenital malformations (MCMs) in their offspring. Objective: To investigate the prevalence of MCMs after prenatal exposure to 8 commonly used ASM monotherapies and changes in MCM prevalence over time. Design, Setting, and Participants: This was a prospective, observational, longitudinal cohort study conducted from June 1999 to October 2022. Since 1999, physicians from more than 40 countries enrolled ASM-treated WWE before pregnancy outcome was known and followed up their offspring until 1 year after birth. Participants aged 14 to 55 years who were exposed to 8 of the most frequently used ASMs during pregnancy were included in this study. Data were analyzed from April to September 2023. Exposure: Maternal use of ASMs at conception. Main Outcomes and Measures: MCMs were assessed 1 year after birth by a committee blinded to type of exposure. Teratogenic outcomes across exposures were compared by random-effects logistic regression adjusting for potential confounders and prognostic factors. Results: A total of 10 121 prospective pregnancies exposed to ASM monotherapy met eligibility criteria. Of those, 9840 were exposed to the 8 most frequently used ASMs. The 9840 pregnancies occurred in 8483 women (mean [range] age, 30.1 [14.1-55.2] years). MCMs occurred in 153 of 1549 pregnancies for valproate (9.9%; 95% CI, 8.5%-11.5%), 9 of 142 for phenytoin (6.3%; 95% CI, 3.4%-11.6%), 21 of 338 for phenobarbital (6.2%; 95% CI, 4.1%-9.3%), 121 of 2255 for carbamazepine (5.4%; 95% CI, 4.5%-6.4%), 10 of 204 for topiramate (4.9%; 95% CI, 2.7%-8.8%), 110 of 3584 for lamotrigine (3.1%; 95% CI, 2.5%-3.7%), 13 of 443 for oxcarbazepine (2.9%; 95% CI, 1.7%-5.0%), and 33 of 1325 for levetiracetam (2.5%; 95% CI, 1.8%-3.5%). For valproate, phenobarbital, and carbamazepine, there was a significant increase in the prevalence of MCMs associated with increasing dose of the ASM. Overall prevalence of MCMs decreased from 6.1% (153 of 2505) during the period 1998 to 2004 to 3.7% (76 of 2054) during the period 2015 to 2022. This decrease over time was significant in univariable logistic analysis but not after adjustment for changes in ASM exposure pattern. Conclusions and Relevance: Of all ASMs with meaningful data, the lowest prevalence of MCMs was observed in offspring exposed to levetiracetam, oxcarbazepine, and lamotrigine. Prevalence of MCMs was higher with phenytoin, valproate, carbamazepine, and phenobarbital, and dose dependent for the latter 3 ASMs. The shift in exposure pattern over time with a declining exposure to valproate and carbamazepine and greater use of lamotrigine and levetiracetam was associated with a 39% decline in prevalence of MCMs, a finding that has major public health implications.

Stereoselective Analysis of the Antiseizure Activity of Fenfluramine and Norfenfluramine in Mice: Is l-Norfenfluramine a Better Follow-Up Compound to Racemic-Fenfluramine?

The aim of this study was to investigate the comparative antiseizure activity of the l-enantiomers of d,l-fenfluramine and d,l-norfenfluramine and to evaluate the relationship between their concentration in plasma and brain and anticonvulsant activity. d,l-Fenfluramine, d,l-norfenfluramine and their individual enantiomers were evaluated in the mouse maximal electroshock seizure (MES) test. d,l-Fenfluramine, d,l-norfenfluramine and their individual l-enantiomers were also assessed in the DBA/2 mouse audiogenic seizure model. All compounds were administered intraperitoneally. Brain and plasma concentrations of the test compounds in DBA/2 mice were quantified and correlated with anticonvulsant activity. In the MES test, fenfluramine, norfenfluramine and their enantiomers showed comparable anticonvulsant activity, with ED50 values between 5.1 and 14.8 mg/kg. In the audiogenic seizure model, l-norfenfluramine was 9 times more potent than d,l-fenfluramine and 15 times more potent than l-fenfluramine based on ED50 (1.2 vs. 10.2 and 17.7 mg/kg, respectively). Brain concentrations of all compounds were about 20-fold higher than in plasma. Based on brain EC50 values, l-norfenfluramine was 7 times more potent than d,l-fenfluramine and 13 times more potent than l-fenfluramine (1940 vs. 13,200 and 25,400 ng/g, respectively). EC50 values for metabolically formed d,l-norfenfluramine and l-norfenfluramine were similar to brain EC50 values of the same compounds administered as such, suggesting that, in the audiogenic seizure model, the metabolites were responsible for the antiseizure activity of the parent compounds. Because of the evidence linking d-norfenfluramine to d,l-fenfluramine to cardiovascular and metabolic adverse effects, their l-enantiomers could potentially be safer follow-up compounds to d,l-fenfluramine. We found that, in the models tested, the activity of l-fenfluramine and l-norfenfluramine was comparable to that of the corresponding racemates. Based on the results in DBA/2 mice and other considerations, l-norfenfluramine appears to be a particularly attractive candidate for further evaluation as a novel, enantiomerically pure antiseizure medication.

Which terms should be used to describe medications used in the treatment of seizure disorders? An ILAE position paper.

A variety of terms, such as "antiepileptic," "anticonvulsant," and "antiseizure" have been historically applied to medications for the treatment of seizure disorders. Terminology is important because using terms that do not accurately reflect the action of specific treatments may result in a misunderstanding of their effects and inappropriate use. The present International League Against Epilepsy (ILAE) position paper used a Delphi approach to develop recommendations on English-language terminology applicable to pharmacological agents currently approved for treating seizure disorders. There was consensus that these medications should be collectively named "antiseizure medications". This term accurately reflects their primarily symptomatic effect against seizures and reduces the possibility of health care practitioners, patients, or caregivers having undue expectations or an incorrect understanding of the real action of these medications. The term "antiseizure" to describe these agents does not exclude the possibility of beneficial effects on the course of the disease and comorbidities that result from the downstream effects of seizures, whenever these beneficial effects can be explained solely by the suppression of seizure activity. It is acknowledged that other treatments, mostly under development, can exert direct favorable actions on the underlying disease or its progression, by having "antiepileptogenic" or "disease-modifying" effects. A more-refined terminology to describe precisely these actions needs to be developed.

Corticosteroids versus clobazam for treatment of children with epileptic encephalopathy with spike-wave activation in sleep (RESCUE ESES): a multicentre randomised controlled trial.

BACKGROUND: Epileptic encephalopathy with spike-wave activation in sleep (EE-SWAS) is a rare syndrome associated with cognitive and behavioural regression. On the basis of mostly small observational and retrospective studies, corticosteroids and clobazam are often considered the most effective treatments for this syndrome. We aimed to compare cognitive outcomes of children with EE-SWAS 6 months after starting treatment with either corticosteroids or clobazam. METHODS: We did a multicentre, randomised controlled trial at eight tertiary referral centres for rare epilepsies in seven European countries. Children were eligible to participate if they were aged 2-12 years, were diagnosed with EE-SWAS within 6 months before inclusion, and had not been treated with corticosteroids or clobazam previously. Participants were randomly assigned (1:1) to treatment with corticosteroids (either continuous treatment with 1-2 mg/kg per day of prednisolone orally or pulse treatment with 20 mg/kg per day of methylprednisolone intravenously for 3 days every 4 weeks) or clobazam (0·5-1·2 mg/kg per day orally). The primary outcome was cognitive functioning after 6 months of treatment, which was assessed by either the intelligence quotient (IQ) responder rate (defined as improvement of ≥11·25 IQ points) or the cognitive sum score responder rate (defined as improvement of ≥0·75 points). Safety was assessed by number of adverse events and serious adverse events. Data were analysed in the intention-to-treat population, which included all children as randomised who had primary outcome data available at 6 months. The trial is registered with the Dutch Trial Register, Toetsingonline, NL43510.041.13, and the ISRCTN registry, ISRCTN42686094. The trial was terminated prematurely because enrolment of the predefined number of 130 participants was deemed not feasible. FINDINGS: Between July 22, 2014, and Sept 3, 2022, 45 children were randomly assigned to either corticosteroids (n=22) or clobazam (n=23); two children assigned clobazam dropped out before 6 months and were excluded from the intention-to-treat analysis. At the 6-month assessment, an improvement of 11·25 IQ points or greater was reported for five (25%) of 20 children assigned corticosteroids versus zero (0%) of 18 assigned clobazam (risk ratio [RR] 10·0, 95% CI 1·2-1310·4; p=0·025). An improvement of 0·75 points or more in the cognitive sum score was recorded for one (5%) of 22 children assigned corticosteroids versus one (5%) of 21 children assigned clobazam (RR 1·0, 95% CI 0·1-11·7, p=0·97). Adverse events occurred in ten (45%) of 22 children who received corticosteroids, most frequently weight gain, and in 11 (52%) of 21 children who received clobazam, most often fatigue and behavioural disturbances. Occurrence of adverse events did not differ between groups (RR 0·8, 95% CI 0·4-1·4; p=0·65). Serious adverse events occurred in one child in the corticosteroid group (hospitalisation due to laryngitis) and in two children in the clobazam group (hospitalisation due to seizure aggravation, and respiratory tract infection). No deaths were reported. INTERPRETATION: The trial was terminated prematurely, and the target sample size was not met, so our findings must be interpreted with caution. Our data indicated an improvement in IQ outcomes with corticosteroids compared with clobazam treatment, but no difference was seen in cognitive sum score. Our findings strengthen those from previous uncontrolled studies that support the early use of corticosteroids for children with EE-SWAS. FUNDING: EpilepsieNL, WKZ fund, European Clinical Research Infrastructure Network, and Ming fund.

Effect of drug treatment changes and seizure outcomes on depression and suicidality in adults with drug-resistant focal epilepsy.

OBJECTIVE: To investigate changes in depressive and suicidality status and their relationship with seizure outcomes after the addition or substitution of another antiseizure medication (ASM) in adults with drug-resistant focal epilepsy. METHODS: Seven hundred seventy consecutively enrolled patients were assessed and followed prospectively for seizure outcome and depressive status over a 6-month period after starting treatment with a newly introduced ASM. The Neurological Disorders Depression Inventory for Epilepsy (NDDIE) was used to screen for depression and suicidality. Correlations of NDDIE results with clinical and treatment-related variables were assessed by using a stepwise logistic regression model. RESULTS: At baseline, 50% of patients had a positive screening test result for depression and 13% had a positive screening test result for suicidal ideation. A psychiatric comorbidity at baseline was associated with a 2.3 times increased risk of an initially negative NDDIE screening result becoming positive at re-assessment after 6 months. In addition, the number of ASMs taken at baseline correlated with an increased risk of a change in depression screening test results from negative to positive during follow-up, whereas no association was identified with sociodemographic and epilepsy-related variables, including seizure outcomes. Approximately 6% of patients who were initially negative at screening for suicidal ideation became positive at the 6-month re-assessment. The risk of switch from a negative to a positive screening test result for suicidal ideation was increased more than two-fold in individuals who screened positive for depression at baseline, and was unrelated to the type of ASM introduced, sociodemographic variables, or seizure outcomes. SIGNIFICANCE: Almost 1 in 5 adults with drug-resistant focal epilepsy who screen negative for depression become positive when re-assessed 6 months after a treatment change. At re-assessment 6 months later, 6.1% who screen initially negative for passive suicidal ideation become positive. These changes in screening status are independent of type of ASM introduced or seizure outcomes but correlate with psychiatric status at baseline.

Pharmacokinetics of d- and l-norfenfluramine following their administration as individual enantiomers in rats.

The effect of fenfluramine and norfenfluramine enantiomers in rodent seizure models and their correlation with the pharmacokinetics of d- and l-fenfluramine in rats have been reported recently. To complement these findings, we investigated the pharmacokinetics of d- and l- norfenfluramine in rat plasma and brain. Sprague-Dawley rats were injected intraperitoneally with 20 mg/kg and 1 mg/kg l- norfenfluramine. A 1 mg/kg dose of d-norfenfluramine was used because higher doses caused severe toxicity. The concentration of each enantiomer in plasma and brain was determined at different time points by liquid chromatography/mass spectrometry. Pharmacokinetic parameters were compared between norfenfluramine enantiomers, and with those reported previously for fenfluramine enantiomers after a 20 mg/kg, i.p., dose. All enantiomers were absorbed rapidly and eliminated, with half-lives ranging from 0.9 h (l-fenfluramine) to 6.1 h (l- norfenfluramine, 20 mg/kg) in plasma, and from 3.6 h (d-fenfluramine) to 8.0 h (l-fenfluramine) in brain. Brain-to-plasma concentration ratios ranged from 15.4 (d-fenfluramine) to 27.6 (d-norfenfluramine), indicating extensive brain penetration. The fraction of d- and l-fenfluramine metabolized to norfenfluramine was estimated to be close to unity. This work is part of ongoing investigations to determine the potential value of developing enantiomerically pure l-fenfluramine or l-norfenfluramine as follow-up compounds to the marketed racemic fenfluramine.

Call for the use of the ILAE terminology for seizures and epilepsies by health care professionals and regulatory agencies to benefit patients and caregivers.

The International League Against Epilepsy (ILAE) introduced a classification for seizure types in 2017 and updated the classification for epilepsy syndromes in 2022. These classifications aim to improve communication among healthcare professionals and help patients better describe their condition. So far, regulatory agencies have used different terminology. This paper stresses the crucial need for consistently adopting ILAE terminology in both regulatory processes and clinical practice. It highlights how language plays a significant role in healthcare communication and how standardized terminology can enhance patient comprehension. The ongoing review of guidelines by regulatory bodies offers a timely opportunity. Aligning regulatory terminologies holds the potential to facilitate discussions on future drug development and harmonize practices across diverse regions, ultimately fostering improved care and research outcomes in epilepsy treatment.

Efficacy and Safety of XEN1101, a Novel Potassium Channel Opener, in Adults With Focal Epilepsy: A Phase 2b Randomized Clinical Trial.

Importance: Many patients with focal epilepsy experience seizures despite treatment with currently available antiseizure medications (ASMs) and may benefit from novel therapeutics. Objective: To evaluate the efficacy and safety of XEN1101, a novel small-molecule selective Kv7.2/Kv7.3 potassium channel opener, in the treatment of focal-onset seizures (FOSs). Design, Setting, and Participants: This phase 2b, randomized, double-blind, placebo-controlled, parallel-group, dose-ranging adjunctive trial investigated XEN1101 over an 8-week treatment period from January 30, 2019, to September 2, 2021, and included a 6-week safety follow-up. Adults experiencing 4 or more monthly FOSs while receiving stable treatment (1-3 ASMs) were enrolled at 97 sites in North America and Europe. Interventions: Patients were randomized 2:1:1:2 to receive XEN1101, 25, 20, or 10 mg, or placebo with food once daily for 8 weeks. Dosage titration was not used. On completion of the double-blind phase, patients were offered the option of entering an open-label extension (OLE). Patients not participating in the OLE had follow-up safety visits (1 and 6 weeks after the final dose). Main Outcomes and Measures: The primary efficacy end point was the median percent change from baseline in monthly FOS frequency. Treatment-emergent adverse events (TEAEs) were recorded and comprehensive laboratory assessments were made. Modified intention-to-treat analysis was conducted. Results: A total of 325 patients who were randomized and treated were included in the safety analysis; 285 completed the 8-week double-blind phase. In the 325 patients included, mean (SD) age was 40.8 (13.3) years, 168 (51.7%) were female, and 298 (91.7%) identified their race as White. Treatment with XEN1101 was associated with seizure reduction in a robust dose-response manner. The median (IQR) percent reduction from baseline in monthly FOS frequency was 52.8% (P < .001 vs placebo; IQR, -80.4% to -16.9%) for 25 mg, 46.4% (P < .001 vs placebo; IQR, -76.7% to -14.0%) for 20 mg, and 33.2% (P = .04 vs placebo; IQR, -61.8% to 0.0%) for 10 mg, compared with 18.2% (IQR, -37.3% to 7.0%) for placebo. XEN1101 was generally well tolerated and TEAEs were similar to those of commonly prescribed ASMs, and no TEAEs leading to death were reported. Conclusions and Relevance: The efficacy and safety findings of this clinical trial support the further clinical development of XEN1101 for the treatment of FOSs. Trial Registration: ClinicalTrials.gov Identifier: NCT03796962.

New GABA-Targeting Therapies for the Treatment of Seizures and Epilepsy: II. Treatments in Clinical Development.

The inhibitory neurotransmitter γ-aminobutyric acid (GABA) plays an important role in the modulation of neuronal excitability, and a disruption of GABAergic transmission contributes to the pathogenesis of some seizure disorders. Although many currently available antiseizure medications do act at least in part by potentiating GABAergic transmission, there is an opportunity for further research aimed at developing more innovative GABA-targeting therapies. The present article summarises available evidence on a number of such treatments in clinical development. These can be broadly divided into three groups. The first group consists of positive allosteric modulators of GABAA receptors and includes Staccato® alprazolam (an already marketed benzodiazepine being repurposed in epilepsy as a potential rescue inhalation treatment for prolonged and repetitive seizures), the α2/3/5 subtype-selective agents darigabat and ENX-101, and the orally active neurosteroids ETX155 and LPCN 2101. A second group comprises two drugs already marketed for non-neurological indications, which could be repurposed as treatments for seizure disorders. These include bumetanide, a diuretic agent that has undergone clinical trials in phenobarbital-resistant neonatal seizures and for which the rationale for further development in this indication is under debate, and ivermectin, an antiparasitic drug currently investigated in a randomised double-blind trial in focal epilepsy. The last group comprises a series of highly innovative therapies, namely GABAergic interneurons (NRTX-001) delivered via stereotactic cerebral implantation as a treatment for mesial temporal lobe epilepsy, an antisense oligonucleotide (STK-001) aimed at upregulating NaV1.1 currents and restoring the function of GABAergic interneurons, currently tested in a trial in patients with Dravet syndrome, and an adenoviral vector-based gene therapy (ETX-101) scheduled for investigation in Dravet syndrome. Another agent, a subcutaneously administered neuroactive peptide (NRP2945) that reportedly upregulates the expression of GABAA receptor α and ß subunits is being investigated, with Lennox-Gastaut syndrome and other epilepsies as proposed indications. The diversity of the current pipeline underscores a strong interest in the GABA system as a target for new treatment development in epilepsy. To date, limited clinical data are available for these investigational treatments and further studies are required to assess their potential value in addressing unmet needs in epilepsy management.

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.

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.

Toward responsible clinical n-of-1 strategies for rare diseases.

N-of-1 strategies can provide high-quality evidence of treatment efficacy at the individual level and optimize evidence-based selection of off-label treatments for patients with rare diseases. Given their design characteristics, n-of-1 strategies are considered to lay at the intersection between medical research and clinical care. Therefore, whether n-of-1 strategies should be governed by research or care regulations remains a debated issue. Here, we delineate differences between medical research and optimized clinical care, and distinguish the regulations which apply to either. We also set standards for responsible optimized clinical n-of-1 strategies with (off-label) treatments for rare diseases. Implementing clinical n-of-1 strategies as defined here could aid in optimized treatment selection for such diseases.

Drug resistance in epilepsy.

Drug resistance is estimated to affect about a third of individuals with epilepsy, but its prevalence differs in relation to the epilepsy syndrome, the cause of epilepsy, and other factors such as age of seizure onset and presence of associated neurological deficits. Although drug-resistant epilepsy is not synonymous with unresponsiveness to any drug treatment, the probability of achieving seizure freedom on a newly tried medication decreases with increasing number of previously failed treatments. After two appropriately used antiseizure medications have failed to control seizures, individuals should be referred whenever possible to a comprehensive epilepsy centre for diagnostic re-evaluation and targeted management. The feasibility of epilepsy surgery and other treatments, including those targeting the cause of epilepsy, should be considered early after diagnosis. Substantial evidence indicates that a delay in identifying an effective treatment can adversely affect ultimate outcome and carry an increased risk of cognitive disability, other comorbidities, and premature mortality. Research on mechanisms of drug resistance and novel therapeutics is progressing rapidly, and potentially improved treatments, including those targeting disease modification, are on the horizon.

Should antiseizure medications be withdrawn after an extended period of seizure freedom in individuals with adult-onset epilepsy?

Unlike several epilepsies with onset in pediatric age, adult-onset epilepsies do not typically have a time course that is predictably self-remitting in the large majority of people. Still, about one-half of individuals with adult-onset epilepsy who have been seizure-free for an extended period (two years or longer) on antiseizure medications (ASMs) will remain in remission when their drug therapy is discontinued. Although a number of predictors of outcome have been identified (including specific adult-onset syndromes associated with a low probability of spontaneous remission), in most cases, the only way to establish whether the epilepsy has remitted in a given individual is to gradually withdraw ASMs. ASM withdrawal can be beneficial, particularly when the currently used treatment is not well tolerated, or could lead to adverse outcomes in the future (i.e., teratogenic effects should pregnancy occur in a female of childbearing potential). However, the risks associated with ASM withdrawal are significant. Relapse of seizures can have major adverse psychosocial consequences and also may carry a risk of morbidity and mortality. Most importantly, evidence suggests that in about 20% of individuals whose seizure relapsed following ASM withdrawal, re-institution of pharmacological therapy may not readily restore seizure control. Ultimately, management decisions should prioritize the preference of the well-informed person with epilepsy. Particularly, when adverse drug effects are a concern, options to be discussed should include not only withdrawal or continuation of the current treatment but also dose reduction or substitution with a different ASM.

Comparative activity of the enantiomers of fenfluramine and norfenfluramine in rodent seizure models, and relationship with their concentrations in plasma and brain.

OBJECTIVES: To investigate the comparative antiseizure activity of the individual enantiomers of fenfluramine and its major active primary metabolite norfenfluramine in rodent seizure models, and its relationship with the pharmacokinetics of these compounds in plasma and brain. METHODS: The antiseizure potency of d,l-fenfluramine (racemic fenfluramine) was compared with the respective potencies of its individual enantiomers and the individual enantiomers of norfenfluramine using the maximal electroshock (MES) test in rats and mice, and the 6-Hz 44 mA test in mice. Minimal motor impairment was assessed simultaneously. The time course of seizure protection in rats was compared with the concentration profiles of d-fenfluramine, l-fenfluramine, and their primary active metabolites in plasma and brain. RESULTS: All compounds tested were active against MES-induced seizures in rats and mice after acute (single-dose) administration, but no activity against 6-Hz seizures was found even at doses up to 30 mg/kg. Estimates of median effective doses (ED50 ) in the rat-MES test were obtained for all compounds except for d-norfenfluramine, which caused dose-limiting neurotoxicity. Racemic fenfluramine had approximately the same antiseizure potency as its individual enantiomers. Both d- and l-fenfluramine were absorbed and distributed rapidly to the brain, suggesting that seizure protection at early time points (≤2 h) was related mainly to the parent compound. Concentrations of all enantiomers in brain tissue were >15-fold higher than those in plasma. SIGNIFICANCE: Although there are differences in antiseizure activity and pharmacokinetics among the enantiomers of fenfluramine and norfenfluramine, all compounds tested are effective in protecting against MES-induced seizures in rodents. In light of the evidence linking the d-enantiomers to cardiovascular and metabolic adverse effects, these data suggest that l-fenfluramine and l-norfenfluramine are potentially attractive candidates for a chiral switch approach leading to development of a novel, enantiomerically-pure antiseizure medication.

Proposal for reference values for the developmental effects of valproate based on human data using a benchmark dose approach.

Following accidental release of valproate into ambient air during manufacture at a French production site in 2018, concerns were raised for inhabitants of the surrounding area. As no toxicological reference value (TRV) was available, the risks could not be properly assessed. The French Agency for Food, Environmental and Occupational Health and Safety (ANSES) was mandated to determine a TRV by inhalation to be used for risk assessment. Major congenital malformations (MCMs) in offsprings of mothers exposed to valproate during pregnancy have been reported in international scientific literature. As these adverse effects were the most sensitive effect identified, they were retained as the critical effect to be used for the TRV. The data from a robust registry on MCMs established by the International Registry of Antiepileptic Drugs and Pregnancy (EURAP) were modellized and support a strong DRR between the prevalence of MCMs in the fetus and in utero exposure. A benchmark dose (BMD) was then calculated as the dose that may trigger a 5% increase in this risk. A lower 95% confidence limit (BMD5%L95%) of 2.26 mg/kg/day, leading to an oral TRV of 0.08 mg/kg/day and a respiratory TRV of 0.26 mg.m-3 after applying an uncertainty factor of 30, was determined.

Cenobamate: A Review of its Pharmacological Properties, Clinical Efficacy and Tolerability Profile in the Treatment of Epilepsy.

Cenobamate is a novel antiseizure medication (ASM) commercially available in Europe and in the U.S. for the treatment of focal seizures in adults. The mechanisms responsible for its antiseizure activity include enhancement of the inactivated state of voltage-gated sodium channels with blockade of the persistent sodium current and positive allosteric modulation of GABAA receptors at a non-benzodiazepine binding site. Cenobamate has a high oral bioavailability that is not influenced by food intake. The terminal half-life is 50-60 hours, allowing for once-daily dosing. Cenobamate is a CYP2C19 inhibitor and an inducer of CYP3A4 and CYP2B6, and consequently, it can cause a number of drug-drug interactions. Efficacy and safety have been evaluated in two randomized, double-blind, placebo-controlled adjunctive therapy trials in adults with focal seizures. In both trials, cenobamate decreased significantly the frequency of focal seizures, with relatively high seizure freedom rates. Adverse events most commonly reported in double-blind trials included dizziness, somnolence, headache, fatigue, and diplopia. The occurrence of three cases of drug reaction with eosinophilia and systemic symptoms (DRESS) during early clinical development led to the conduction of a Phase 3 open-label long-term safety study in a total of 1339 patients. In this study, no serious idiosyncratic adverse reactions were observed using a start-low and go-slow approach. Further studies are required to determine whether the clinical activity profile of cenobamate extends to protection against other seizure types and to evaluate its efficacy and safety profile in special patient groups such as infants, children, the elderly, and patients with comorbid conditions.