Cenobamate as an Early Adjunctive Treatment in Drug-Resistant Focal-Onset Seizures: An Observational Cohort Study.

BACKGROUND AND OBJECTIVES: Cenobamate (CNB) is a new antiseizure medication (ASM) to treat drug-resistant, focal-onset seizures. Data on its use in early therapy lines are not yet available, and clinicians frequently consider CNB to be a later ASM drug choice. We investigated the efficacy and safety of CNB as an early adjunctive treatment in drug-resistant, focal-onset seizures. METHODS: The study population were patients with drug-resistant, focal-onset seizures who were initiated with CNB after they did not respond to two or three lifetime ASMs, including all prior and concomitant ASMs. These patients were matched (1:2) by sex, age, and seizure frequency to controls who were initiated with any ASM other than CNB. All participants participated in the Mainz Epilepsy Registry. We evaluated the retention rate after 12 months of CNB and after each new adjunctive ASM in the control group. In addition, seizure freedom and the response rate (reduction of seizure frequency by ≥ 50% from baseline) after 12 months were estimated. RESULTS: We included 231 patients aged 44.4 ± 15.8 years. Of these, 33.3% (n = 77) were on CNB, 19.0% (n = 44) on valproate (VPA), 17.3% (n = 40) on lacosamide (LCS), 16.4% (n = 38) on levetiracetam (LEV), and 13.9% (n = 32) on topiramate (TPM). The highest retention rate after 12 months since the beginning of the early adjunctive therapy was observed on CNB (92.0%), compared with LCS (80.0%), LEV (73.3%), VPA (68.2%), or TPM (62.5%) (p < 0.05). Seizure freedom and response rate were also the best on CNB (19.5% and 71.4%, respectively) compared with other ASMs (8.3% and 52.5%, respectively; p < 0.05). No significant differences in adverse events between CNB and other ASMs were observed. CONCLUSIONS: Our study provides evidence that CNB is an effective ASM with a good safety profile in the early therapy lines of drug-resistant, focal-onset seizures. This data should support medical decision making in the management of patients with refractory epilepsy. CLINICAL TRIAL ID: NCT05267405.

Relative Bioavailability of Cenobamate Administered as a Crushed Tablet, Either Orally or via Nasogastric Tube, versus an Intact Whole Tablet.

Cenobamate is approved for the treatment of focal seizures in adults and is currently available as an oral tablet. Alternative methods of drug administration are needed for patients who are unable to swallow whole intact tablets. This phase 1, open-label, randomized, single-dose, three-way crossover (3-period, 3-treatment, 6-sequence) study (NCT05572255), conducted in healthy volunteers, assessed the relative bioavailability of a crushed 200-mg cenobamate tablet administered orally or via nasogastric (NG) tube compared with an intact 200-mg tablet. Each treatment was separated by a 13-day washout period. Plasma samples for cenobamate concentration analysis were collected pre-dose and at multiple time points up to 264 h post-dose. Standard bioequivalence study criteria were applied to the relative bioavailability assessments. All 90% confidence intervals of test-to-reference geometric mean ratios for cenobamate pharmacokinetic parameters (Cmax, AUClast, and AUCinf) were within 85-110% (predefined limit, 80-125%), suggesting no difference in cenobamate exposures following administration of an intact tablet orally or a crushed tablet orally or via NG tube. All treatment-emergent adverse events (TEAEs) were classified as mild and resolved. There were no deaths or other serious AEs (SAEs), and no TEAEs led to discontinuation. Our results indicate that the administration of cenobamate as a crushed tablet taken orally or via an NG tube can provide additional flexibility when patients cannot swallow intact tablets. Based on the results of this study, cenobamate is now approved by FDA to be taken whole or the tablets can be crushed. The crushed tablet can be mixed with water and either administered by mouth as an oral suspension or administered via a nasogastric tube.

Efficacy and safety of adjunctive cenobamate based on patient etiology: Post-hoc analysis of YKP3089C017 randomized clinical trial.

INTRODUCTION: Adjunctive cenobamate was effective and safe for the treatment of uncontrolled focal onset seizures in a randomized, double-blind, placebo-controlled, phase 2 study (YKP3089C017; NCT01866111). This post-hoc analysis assessed the efficacy of adjunctive cenobamate in the treatment of patients with different epileptic etiologies during the study. METHODS: Adult patients with uncontrolled focal seizures who previously received 1 to 3 antiseizure medications (ASMs) were randomly assigned in a ratio of 1:1:1:1 to receive placebo or cenobamate 100, 200 or 400 mg/day. Patients were further stratified based on their etiologic causes as genetic/presumed genetic, unknown cause, structural cause, and not reported (NR) groups. The frequency per 28 days for an 18-week double-blind treatment period, responder rates (≥50 %, ≥75 %, ≥90 %, and 100 %) during the maintenance phase (12 weeks), and safety were assessed. RESULTS: A total of 394 patients were categorized into the genetic/presumed genetic (n = 9; 2.28 %), unknown cause (n = 199; 50.51 %), structural cause (n = 177; 44.92 %), and NR (n = 13; 3.30 %) groups, with 4 patients were classified into either of the two etiological causes each. The baseline characteristics were comparable. The percentage of reduction in seizure frequency per 28 days was significantly higher in the cenobamate-treated structural (p = 0.01) and unknown cause (p = 0.0003) groups compared with the placebo group. Responder rates of ≥50 %, ≥75 %, ≥90 %, and 100 % were also higher with cenobamate therapy. Notably, no serious treatment-emergent adverse events (TEAEs) were observed in the genetic/presumed genetic group treated with cenobamate. The most common TEAEs (≥10 %) occurring in patients treated with cenobamate were nervous system disorders by system organ class, and somnolence was the most commonly reported TEAE. CONCLUSION: Cenobamate reduces seizures in adult patients previously treated with ASMs, with high responder rates and acceptable safety, regardless of underlying causes.

A comparison of cenobamate with other newer antiseizure medications for adjunctive treatment of focal-onset seizures: A systematic review and network meta-analysis.

PURPOSE: To compare the efficacy, safety, and tolerability of cenobamate with other newer anti-seizure medications (ASMs) including brivaracetam, eslicarbazepine, lacosamide, perampanel, and zonisamide, approved for adjunctive treatment of drug-resistant focal-onset seizures (FOS) in adults with epilepsy. METHODS: A systematic literature review (SLR) was conducted to obtain relevant efficacy, safety, and tolerability data for ASMs for the treatment of drug-resistant FOS. All studies were thoroughly assessed for potential sources of heterogeneity and analysed via Bayesian network meta-analyses (NMAs). Efficacy outcomes were ≥50 % responder rate and seizure freedom during the maintenance period, which were modelled simultaneously using a multinomial Bayesian NMA. Safety and tolerability outcomes were the proportion of patients who experienced at least one treatment-emergent adverse event (TEAE) and the proportion who experienced at least one TEAE leading to discontinuation. RESULTS: The SLR identified 76 studies, of which 23 were included in the Bayesian NMAs. Cenobamate was associated with statistically significant higher rates for the ≥50 % responder rate and seizure freedom outcomes compared with all ASMs analysed. The point estimates indicated that cenobamate was associated with higher rates of experiencing at least one TEAE and at least one TEAE leading to discontinuation compared with brivaracetam, lacosamide, and zonisamide; however, no results were statistically significant. CONCLUSION: Cenobamate was associated with increased efficacy compared with all ASMs analysed. There were no statistically significant differences in the safety and tolerability outcomes. The results presented corroborate the conclusions drawn from previous published NMAs, which also highlight the notable efficacy of cenobamate in comparison with other ASMs.

Spanish consensus on the management of concomitant antiseizure medications when using cenobamate in adults with drug-resistant focal seizures.

OBJECTIVE: Cenobamate is an antiseizure medication (ASM) associated with high rates of seizure freedom and acceptable tolerability in patients with focal seizures. To achieve the optimal cenobamate dose for maximal potential effectiveness while avoiding or minimizing drug-related adverse events (AEs), the administration of cenobamate with other ASMs must be managed through concomitant ASM load reduction. A panel of Spanish epilepsy experts aimed to provide a Spanish consensus on how to adjust the dose of concomitant ASMs in patients with drug-resistant epilepsy (DRE) in order to improve the effectiveness and tolerability of adjunctive cenobamate. METHODS: A three-stage modified Delphi consensus process was undertaken, including six Spanish epileptologists with extensive experience using cenobamate. Based on current literature and their own expert opinion, the expert panel reached a consensus on when and how to adjust the dosage of concomitant ASMs during cenobamate titration. RESULTS: The expert panel agreed that tailored titration and close follow-up are required to achieve the best efficacy and tolerability when initiating cenobamate in patients receiving concomitant ASMs. When concomitant clobazam, phenytoin, phenobarbital, and sodium channel blockers are taken at high dosages, or when the patient is receiving two or more sodium channel blockers, dosages should be proactively lowered during the cenobamate titration period. Other concomitant ASMs should be reduced only if the patient reports a moderate/severe AE at any stage of the titration period. SIGNIFICANCE: Cenobamate is an effective ASM with a dose-dependent effect. To maximize effectiveness while maintaining the best tolerability profile, co-medication management is needed. The recommendations included herein provide practical guidance for proactive and reactive management of co-medication in cenobamate-treated patients with DRE and a high drug load. PLAIN LANGUAGE SUMMARY: Patients with epilepsy may continue to have seizures even after treatment with several different antiseizure medications (ASMs). Cenobamate is an ASM that can reduce seizures in these patients. In this study, six Spanish experts in epilepsy discussed the best way to use cenobamate in drug-resistant epilepsy. They provide practical guidance on when and how the dose of other ASMs might be adjusted to reduce side effects and optimize the use of cenobamate.

The Pharmacology and Clinical Efficacy of Antiseizure Medications: From Bromide Salts to Cenobamate and Beyond.

Epilepsy is one of the most common and disabling chronic neurological disorders. Antiseizure medications (ASMs), previously referred to as anticonvulsant or antiepileptic drugs, are the mainstay of symptomatic epilepsy treatment. Epilepsy is a multifaceted complex disease and so is its treatment. Currently, about 30 ASMs are available for epilepsy therapy. Furthermore, several ASMs are approved therapies in nonepileptic conditions, including neuropathic pain, migraine, bipolar disorder, and generalized anxiety disorder. Because of this wide spectrum of therapeutic activity, ASMs are among the most often prescribed centrally active agents. Most ASMs act by modulation of voltage-gated ion channels; by enhancement of gamma aminobutyric acid-mediated inhibition; through interactions with elements of the synaptic release machinery; by blockade of ionotropic glutamate receptors; or by combinations of these mechanisms. Because of differences in their mechanisms of action, most ASMs do not suppress all types of seizures, so appropriate treatment choices are important. The goal of epilepsy therapy is the complete elimination of seizures; however, this is not achievable in about one-third of patients. Both in vivo and in vitro models of seizures and epilepsy are used to discover ASMs that are more effective in patients with continued drug-resistant seizures. Furthermore, therapies that are specific to epilepsy etiology are being developed. Currently, ~ 30 new compounds with diverse antiseizure mechanisms are in the preclinical or clinical drug development pipeline. Moreover, therapies with potential antiepileptogenic or disease-modifying effects are in preclinical and clinical development. Overall, the world of epilepsy therapy development is changing and evolving in many exciting and important ways. However, while new epilepsy therapies are developed, knowledge of the pharmacokinetics, antiseizure efficacy and spectrum, and adverse effect profiles of currently used ASMs is an essential component of treating epilepsy successfully and maintaining a high quality of life for every patient, particularly those receiving polypharmacy for drug-resistant seizures.

Pharmacology of Cenobamate: Mechanism of Action, Pharmacokinetics, Drug-Drug Interactions and Tolerability.

Cenobamate is one of the latest antiseizure medications (ASMs) developed for the treatment of focal onset seizures in adult patients. The recommended starting dose is 12.5 mg/day, titrated gradually to the target daily dose of 200 mg, which may be increased to a maximum of 400 mg/day based on clinical response. Although the high rate of seizure freedom observed in randomized, placebo-controlled clinical trials has resulted in exciting expectations, further clinical studies are needed to better define its clinical profile. Cenobamate is characterized by a peculiar pharmacology regarding both pharmacodynamics and pharmacokinetics. The mechanism of action has only partly been described, with the drug acting on voltage-gated sodium channels through a pronounced action on persistent rather than transient currents. Cenobamate also acts as a positive allosteric modulator of GABAA receptors independently from the benzodiazepine binding site. The bioavailability of cenobamate is not influenced by other drugs, except phenytoin; it can inhibit cytochrome P450 (CYP) 2C19 and induce CYP3A4 and 2B6, and hence can potentially interact with many drugs (e.g. dose adjustments may be required for lamotrigine, carbamazepine and clobazam). The pharmacokinetics of cenobamate are not linear and dosage increases imply a disproportional increase in plasma levels, particularly at doses higher than 300 mg. The most common and dose-related adverse effects associated with cenobamate include central nervous system-related symptoms, mainly somnolence, dizziness, diplopia, and disturbances in gait and coordination. A somewhat higher incidence of adverse events has been observed in patients concomitantly treated with sodium channel blockers. The most relevant safety issues are currently represented by the risk of severe skin reactions (apparently avoidable by a slow titration) and QT shortening (the drug is contraindicated in patients with familial short QT syndrome or taking QT-shortening drugs). Overall, cenobamate is a promising ASM with an intriguing and not fully understood mechanism of action; pharmacokinetic issues need to be considered in clinical practice.

Efficacy and safety of cenobamate in patients with uncontrolled focal seizures: A meta-analysis.

OBJECTIVE: To investigate the efficacy and safety of adjunctive cenobamate for treatment of uncontrolled focal seizures. METHODS: We performed a systematic search of Web of Science, MEDLINE (Ovid and PubMed), Cochrane Library, EMBASE and Google Scholar to identify eligible studies. We included randomized placebo-controlled trials (RCTs) for uncontrolled focal seizures. We calculated the risk ratio (RR) of ≥50%, ≥75% and 100% reduction in seizure frequency from baseline, as well as dropout and serious adverse events related to treatment. Quality of included trials was assessed using the Cochrane Collaboration's tool. RESULTS: Two RCTs with a total of 658 patients were included. A significantly larger proportion of patients allocated to cenobamate achieved 50% seizure reduction (RR 2.06, 95% CI 1.70-2.51, p < 0.001) as compared to placebo, subgroup analysis demonstrated that the most effective dose was at 400 mg (RR 2.28, 95% CI 1.57-3.32, p < 0.001). Patients achieving seizure-freedom during the treatment period were 14.9% with cenobamate and 4.5% with placebo (RR 5.32, 95% CI 2.94-9.62, p < 0.001). Dropouts (RR 1.40, 95% CI 1.01-1.94, p = 0.05) and incidence of serious adverse events (RR 1.48, 95% CI 0.93-2.33, p = 0.1) were not significantly higher in patients receiving cenobamate. However, subgroup analyses based on doses suggested that patients exposed to 400 mg cenobamate were more likely to dropout than placebo (RR 2.09, 95% CI 1.17- 3.71, p = 0.012). CONCLUSION: Cenobamate demonstrated favourable efficacy for treatment of uncontrolled focal seizures and showed a dose-related fashion. Cenobamate could be well tolerated, the most common adverse events associated with cenobamate were dizziness, somnolence, fatigue, headache and nausea. Nevertheless, majority of them were mild to moderate in severity.

Cenobamate tablets as a treatment for focal-onset seizures in adults.

Introduction: Despite the introduction of numerous new antiseizure medications (ASMs) still about one-third of epilepsies remain drug-resistant. Therefore, new compounds with advanced efficacy are urgently needed. Cenobamate (CNB) is a new ASM that has been recently introduced in the United States for the treatment of adults with focal-onset seizures. The approval in Europe is under way.Areas covered: This review covers the pharmacological profile of CNB, the proof-of-concept trial, the two double-blind, placebo-controlled phase 2 trials investigating adjunct CNB in adults with focal-onset seizures, one open-label safety trial, and a variety of published abstract material that provided additional post hoc data.Expert opinion: In two placebo-controlled randomized multicenter phase 2 trials adjunct CNB showed unusually high efficacy with rates of seizure-free people with epilepsy (PWE) partially beyond 20%. However, during the clinical program cases of drug-related reactions with eosinophilia and systemic symptoms (DRESS syndrome) occurred. Therefore, an open-label safety study was performed in more than 1300 PWE with particularly slower titration schedules which did not add more cases with similar reactions. Taking into consideration the promising efficacy and the safety experience from the open-label trial, CNB applied according to the meanwhile recommended titration strategy, might offer a new prospect.

Dinámica contráctil inducida por p-clorofenol alcanforado en anillos aórticos de ratas Wistar / Dinâmica contrátil induzida por cânfora-clorofenol em anéis aórticos de ratos Wistar / Camphorated p-chlorophenol-induced contractile dynamics in aortic rings of Wistar rats

Introducción: El p-clorofenol alcanforado es un derivado clorofenólico de uso común como medicación intraconducto en Endodoncia. Son escasos los reportes científicos sobre sus efectos en la musculatura lisa vascular arterial y la regulación del flujo sanguíneo local. Objetivo: Determinar el efecto del p-clorofenol alcanforado sobre la dinámica contráctil del músculo liso vascular arterial en el tiempo. Método: Se realizó una investigación experimental preclínica utilizando 14 anillos de aorta obtenidos de ratas Wistar. Los anillos se colocaron en baño de órganos y se preactivaron con noradrenalina, registrándose luego la tensión desarrollada por el músculo liso vascular tras la adición de p-clorofenol alcanforado durante diferentes intervalos de tiempo. Resultados: El 51,4 porciento de la musculatura lisa vascular se relajó por la acción del p-clorofenol alcanforado. El mayor descenso del tono vascular se produjo entre el tercer y quinto minuto de añadido el medicamento. Las pruebas de Wilcoxon de los rangos con signos evidenciaron diferencias significativas entre la tensión base inicial y la registrada en los diferentes intervalos de tiempo estudiados. Conclusiones: el p-clorofenol alcanforado, induce in vitro, relajación del músculo liso arterial a través de un acoplamiento excitación-contracción de tipo farmacomecánico, la cual se incrementa en función del tiempo(AU).

Introduction: Camphorated p-chlorophenol is a chlorophenolic derivative commonly used as an intra-oral medication in endodontics. Scientific reports on its effects in arterial vascular smooth muscle and local blood flow regulation are scarce. Objective: To determine the effect of camphorated p-chlorophenol on the contractile dynamics of arterial vascular smooth muscle. Method: An experimental and preclinical research was conducted with the use of 14 aortic rings of Wistar rats. The rings were placed in an organ bath and preactivated with noradrenaline, and the tension developed by the vascular smooth muscle at different time intervals was recorded after induction of camphorated p-chlorophenol. Results: Most of the vascular smooth muscle (51.4 percent) relaxed with the use of camphorated p-chlorophenol. The greatest decrease in vascular tone occurred between the third and fifth minute after use the drug. Wilcoxon rank tests showed significant differences between tension observed at baseline and those recorded at the different time intervals studied. Conclusions: Camphorated p-chlorophenol, induces in vitro, relax the arterial smooth muscle through a pharmacomechanical excitation-contraction link, which increases according to the time(AU).

Introdução: O cânfora-clorofenol é um derivado clorofenólico comumente utilizado como medicamento intracanal em Endodontia. Relatórios científicos sobre seus efeitos no músculo liso vascular arterial e na regulação do fluxo sanguíneo local são escassos. Objetivo: Determinar o efeito da cânfora-clorofenol na dinâmica contrátil do músculo liso vascular arterial ao longo do tempo. Método: Foi realizada investigação experimental pré-clínica com 14 anéis aórticos obtidos de ratos Wistar. Os anéis foram colocados em banho de órgãos e pré-ativados com norepinefrina, em seguida, a tensão desenvolvida pela musculatura lisa vascular foi registrada após a adição de cânfora-clorofenol em diferentes intervalos de tempo. Resultados: 51,4 porcento dos músculos lisos vasculares estavam relaxados pela ação do cânfora-clorofenol. A maior diminuição do tônus vascular ocorreu entre o terceiro e o quinto minuto após a adição do medicamento. Os testes de Wilcoxon das faixas com sinais mostraram diferenças significativas entre a tensão base inicial e a registrada nos diferentes intervalos de tempo estudados. Conclusões: O cânfora-clorofenol induz, in vitro, relaxamento da musculatura lisa arterial por meio de um acoplamento excitação-contração do tipo farmacomecânico, que aumenta em função do tempo(AU).

Adjunctive cenobamate for the treatment of focal onset seizures in adults with epilepsy: a critical review.

INTRODUCTION: Uncontrolled epilepsy has persisted despite development of numerous antiseizure medications (ASMs) over the past 25 years, and more effective treatments are needed. Cenobamate is a new ASM approved in the US for treatment of adults with focal onset seizures. AREAS COVERED: This review outlines cenobamate study results from preclinical animal models through phase 2 and 3 clinical studies. Topics include mechanisms of action, pharmacokinetics, efficacy, and safety of cenobamate. Information on dosing, tolerability, and special populations are included to help healthcare providers understand this new ASM. EXPERT OPINION: Adjunctive cenobamate shows a high level of efficacy in patients with refractory focal epilepsy compared to that reported for other ASMs. Most notable are reductions in monthly seizure frequency (up to 55%) and unprecedented seizure-free rates (up to 28%) with cenobamate in patients with refractory epilepsy despite the concomitant use of 1-3 ASMs. Cenobamate was generally safe and well-tolerated, with a safety profile similar to other ASMs. Due to 3 early cases of DRESS, however, the cenobamate starting dose was lowered and titration rate slowed; no additional cases occurred. If efficacy responses in real-world use reflect what have been observed in clinical studies, cenobamate would be a welcome new treatment option.

Cenobamate for the treatment of focal epilepsies.

INTRODUCTION: Antiseizure drugs (ASDs) play a central and crucial role in the treatment of epilepsy patients because the majority require anticonvulsant treatment for an extended period of time. Due to the fact that 30% of patients are refractory to medical treatment, new therapeutic options are necessary. Cenobamate is the latest approved antiepileptic drug in focal epilepsy, and its mode of action is thought to be mediated by blocking voltage-gated sodium channels and interaction with the GABAergic system. AREAS COVERED: This article reviews animal studies, pharmacokinetics, pharmacodynamics, and the phase 1 to 3 trials and open-label extension data on cenobamate. EXPERT OPINION: Cenobamate has the potential to perform as an important ASD because trial data are indicative of remarkable responder and seizure freedom rates so far not seen with other ASDs. Cenobamate demonstrated significant efficacy at a dosage between 100 and 400 mg per day. The side-effect profile of this drug is comparable to other ASDs and is mainly CNS related; in particular, somnolence, dizziness, headache, diplopia, and nystagmus. However, slow titration is mandatory to decrease the risk of drug rash with eosinophilia and systemic symptoms (DRESS) that was observed in several patients with fast uptitration schemes.

Adjunctive Cenobamate for Focal-Onset Seizures in Adults: A Systematic Review and Meta-Analysis.

BACKGROUND: Cenobamate is a novel tetrazole-derived carbamate compound with a dual mechanism of action. This drug can enhance the inactivated state of voltage-gated sodium channels, preferentially inhibiting the persistent component of the sodium channel current, and acts as a positive allosteric modulator of GABAA receptors, binding at a non-benzodiazepine site. OBJECTIVE: We assessed the efficacy and safety of adjunctive cenobamate for the treatment of focal-onset seizures in adult patients with epilepsy using meta-analytical techniques. METHODS: We systematically searched (May, week 4, 2020) MEDLINE (accessed by PubMed), the Cochrane Central Register of Controlled Trials (CENTRAL), and the US National Institutes of Health Clinical Trials Registry ( http://www.clinicaltrials.gov ). There were no date limitations or language restrictions. Randomized, placebo-controlled, single or double-blinded, add-on trials of cenobamate in adult patients with uncontrolled focal-onset seizures were identified. Main outcomes included the proportion of patients with ≥ 50 and 100% reduction in seizure frequency during the maintenance treatment period compared with baseline and the incidence of treatment withdrawal and adverse events (AEs). Risk ratio (RR) with 95% confidence interval (CI) was estimated for each outcome. RESULTS: Two trials were included, overall enrolling 659 patients (442 for the add-on cenobamate group and 217 for the add-on placebo group). Seizure frequency reduction by at least 50% occurred during the maintenance phase in 50.1% of the patients randomized to cenobamate and 23.5% of the placebo-treated participants (RR 2.18, 95% CI 1.67-2.85; p < 0.001). The pooled estimated RR to achieve seizure freedom for the cenobamate group in comparison with placebo was 3.71 (95% CI 1.93-7.14; p < 0.001). Withdrawal from randomized treatment occurred in 16.7 and 11.1% of participants receiving cenobamate and placebo, respectively (RR 1.34, 95% CI 0.85-2.09; p = 0.205). Treatment was discontinued due to AEs in 12.2 and 4.1% of the patients in the active and control arms (RR 2.27, 95% CI 1.08-4.79; p = 0.031). AEs were reported in 76.9 and 66.8% of the patients during treatment with cenobamate and placebo (RR 1.14, 95% CI 1.02-1.26; p = 0.021). The cenobamate-associated AEs included somnolence, dizziness, fatigue, balance disorder, and diplopia. CONCLUSIONS: Adjunctive cenobamate in adult patients with uncontrolled focal-onset seizures is associated with a greater reduction in seizure frequency and a higher rate of AEs than placebo.

Cenobamate (YKP3089) as adjunctive treatment for uncontrolled focal seizures in a large, phase 3, multicenter, open-label safety study.

OBJECTIVE: During the development of cenobamate, an antiseizure medication (ASM) for focal seizures, three cases of drug reaction with eosinophilia and systemic symptoms (DRESS) occurred. To mitigate the rate of DRESS, a start-low, go-slow approach was studied in an ongoing, open-label, multicenter study. Also examined were long-term safety of cenobamate and a method for managing the pharmacokinetic interaction between cenobamate, a 2C19 inhibitor, and concomitant phenytoin or phenobarbital. METHODS: Patients 18-70 years old with uncontrolled focal seizures taking stable doses of one to three ASMs were enrolled. Cenobamate 12.5 mg/d was initiated and increased at 2-week intervals to 25, 50, 100, 150, and 200 mg/d. Additional biweekly 50 mg/d increases to 400 mg/d were allowed. During titration, patients taking phenytoin or phenobarbital could not have their cenobamate titration rate or other concomitant ASMs adjusted; phenytoin/phenobarbital doses could be decreased by 25%-33%. RESULTS: At data cutoff (median treatment duration = 9 months), 1347 patients were enrolled, of whom 269 (20.0%) discontinued, most commonly due to adverse events (n = 137) and consent withdrawn for reason other than adverse event (n = 74); 1339 patients received ≥1 treatment dose (median modal dose = 200 mg). The most common treatment-emergent adverse events (TEAEs) were somnolence (28.1%), dizziness (23.6%), and fatigue (16.6%). Serious TEAEs occurred in 108 patients (8.1%), most commonly seizure (n = 14), epilepsy (n = 5), and pneumonia, fall, and dizziness (n = 4 each). No cases of DRESS were identified. In the phenytoin/phenobarbital groups, 43.4% (36/114) and 29.7% (11/51) of patients, respectively, had their doses decreased. At the end of titration, mean plasma phenytoin/phenobarbital levels were generally comparable to baseline. SIGNIFICANCE: No cases of DRESS were identified in 1339 patients exposed to cenobamate using a start-low (12.5 mg/d), go-slow titration approach. Cenobamate was generally well tolerated in the long term, with no new safety issues found. Phenytoin/phenobarbital dose reductions (25%-33%), when needed during cenobamate titration, maintained stable plasma levels.

Randomized phase 2 study of adjunctive cenobamate in patients with uncontrolled focal seizures.

OBJECTIVE: To evaluate the efficacy and safety of adjunctive cenobamate 200 mg/d in patients with uncontrolled focal (partial-onset) seizures despite treatment with 1 to 3 antiepileptic drugs. METHODS: In this multicenter, double-blind, placebo-controlled study, adults 18 to 65 years of age with focal seizures were randomized 1:1 (cenobamate:placebo) after an 8-week baseline period. The 12-week double-blind treatment period consisted of a 6-week titration phase and a 6-week maintenance phase. The primary outcome was percent change in seizure frequency (from baseline) per 28 days during double-blind treatment. RESULTS: Two hundred twenty-two patients were randomized; 113 received cenobamate and 109 received placebo; and 90.3% and 90.8% of patients, respectively, completed double-blind treatment. Median baseline seizure frequency was 6.5 in 28 days (range 0-237). Compared to placebo, cenobamate conferred a greater median percent seizure reduction (55.6% vs 21.5%; p < 0.0001) The responder rate (≥50% reduction in seizure frequency) was 50.4% for cenobamate and 22.2% for placebo (p < 0.0001). Focal seizures with motor component, impaired awareness, and focal to bilateral tonic-clonic seizures were significantly reduced with cenobamate vs placebo. During maintenance, 28.3% of cenobamate-treated and 8.8% of placebo-treated patients were seizure-free. Treatment-emergent adverse events reported in >10% in either group (cenobamate vs placebo) were somnolence (22.1% vs 11.9%), dizziness (22.1% vs 16.5%), headache (12.4% vs 12.8%), nausea (11.5% vs 4.6%), and fatigue (10.6% vs 6.4%). CONCLUSION: Adjunctive treatment with cenobamate 200 mg/d significantly improved seizure control in adults with uncontrolled focal seizures and was well tolerated. CLINICALTRIALSGOV IDENTIFIER: NCT01397968. CLASSIFICATION OF EVIDENCE: This study provides Class I evidence that, for patients with uncontrolled focal seizures, adjunctive cenobamate reduces seizures.

An Ex Vivo Evaluation of Cenobamate Administered via Enteral Tubes.

BACKGROUND: Cenobamate is a new, Food and Drug Administration (FDA)-approved oral antiepileptic drug for treatment of focal seizures in adults. This study examined recovery of cenobamate from suspensions administered through ex vivo enteral feeding tubes. METHODS: Suspensions containing 100 and 200 mg of cenobamate were prepared (five duplicates for each dose), passed through five vertically standing tubes, and collected into flasks. The flasks containing the suspensions were rinsed with deionized water, and this content was also injected into the tubes and collected in the flasks. Acetonitrile, isopropyl alcohol, and trifluoroacetic acid were added to the flasks, followed by deionized water to a concentration of 500 (100-mg cenobamate) and 400 (200-mg cenobamate) µg/mL. A 3-mL aliquot from each suspension was placed into a 10-mL flask, diluted to volume, and mixed, resulting in final concentrations of 150 and 120 µg/mL, respectively. All suspensions were analyzed by high-performance liquid chromatography (LC). The % LC recovery of cenobamate was calculated for each suspension, and mean % LC for duplicates. RESULTS: The % LC recovery of cenobamate from the 100-mg suspensions ranged from 96.2 to 99.1%, with mean % LC recovery between 96.3 and 98.3%. The % LC recovery of cenobamate from the 200-mg suspensions ranged from 97.1 to 102.6%, with mean % LC recovery between 98.5 and 101.7%. CONCLUSION: The mean % LC recovery of cenobamate was within the predetermined acceptable range of 90.0-110.0%, suggesting no adhesion or adsorption of cenobamate to enteral feeding tubes. Delivery of cenobamate suspension via enteral feeding tubes may be a viable route of administration for patients who cannot swallow tablets.

Mass Balance, Metabolism, and Excretion of Cenobamate, a New Antiepileptic Drug, After a Single Oral Administration in Healthy Male Subjects.

BACKGROUND AND OBJECTIVE: Cenobamate is an antiepileptic drug for the treatment of partial-onset seizures. The current study was designed to assess the mass balance and the metabolic profiling of cenobamate in humans. METHODS: Absorption, metabolism, and excretion of cenobamate were investigated in healthy male subjects after a single oral dose of 400 mg of cenobamate containing 50 µCi of [14C]-cenobamate as capsule formulation. RESULTS: Cenobamate was rapidly (median time to maximum plasma concentration of 1.25 h) and extensively (≥ 88% of dose) absorbed. The mean cenobamate plasma concentration-time profile revealed a multiphasic elimination profile whereas the mean plasma/blood concentration-time curve for total radioactivity did not appear to be multiphasic, suggesting that elimination mechanisms for cenobamate and its metabolites may be different. Blood/plasma ratios observed for the area under the concentration-time curve (AUC) and peak concentration (both ~ 0.60) suggest a limited penetration of cenobamate and metabolites into red blood cells (RBCs). Eight cenobamate metabolites were identified across plasma, urine, and feces. Cenobamate was the main plasma radioactive component and M1 was the only metabolite detected in plasma (> 98% and < 2% total radioactivity AUC, respectively). All detected metabolites were found in urine, with M1 as the major radioactive component (mean cumulative recovery 37.7% of dose); unchanged cenobamate accounted for 6%. Metabolites comprised ~ 88% of the dose recovered in urine, indicating extensive metabolism by the kidneys and/or metabolites formed in the liver were rapidly eliminated from the bloodstream. However, cenobamate metabolites appear to be formed slowly. Minor amounts of cenobamate (0.48%) and five metabolites (≤ 1.75% each; M1, M3, M6, M7, M11) were recovered in feces. CONCLUSION: This study indicates that cenobamate is primarily eliminated in urine as metabolites. Cenobamate is the major circulating component in plasma after oral administration and has a limited penetration into RBCs.

Pharmacokinetics of Cenobamate: Results From Single and Multiple Oral Ascending-Dose Studies in Healthy Subjects.

Cenobamate (YKP3089) is an antiepileptic drug recently approved by the Food and Drug Administration for the treatment of focal (partial-onset) seizures in adults. The objectives of a first-in-human single-ascending-dose study and 3 multiple-ascending-dose studies were to characterize the pharmacokinetics, safety, and tolerability of cenobamate after single-dose and multiple-dose administration in healthy subjects. The 4 randomized, placebo-controlled, double-blind studies were conducted in 210 healthy subjects receiving single (5 to 750 mg) or multiple (50 to 600 mg/day) oral doses of cenobamate or placebo using capsule formulation. Safety assessments included treatment-emergent adverse events (TEAEs) and laboratory evaluations. Maximum plasma concentrations of cenobamate were observed between 0.8 and 4.0 hours after oral administration. Cmax increased in a dose-proportional manner for single- and multiple-dose administration across all tested doses. Although the AUC of cenobamate increased in a more than dose-proportional manner after single-dose administration, a dose-proportional increase in cenobamate AUCτ was observed after multiple dosing from 50 to 500 mg/day. Cenobamate exhibited low oral clearance (decreasing from approximately 1.4 to 0.50 L/h with dose increase) and long terminal half-life (range, approximately 30 to 76 hours with increasing dose). Steady-state was attained after approximately 2 weeks, and the accumulation ratio was approximately 5 over the 50 to 300 mg/day range. The pharmacokinetic characteristics of cenobamate are consistent with once-daily dosing. Most TEAEs were mild in severity, 2 serious TEAEs were reported, and no deaths occurred across all studies. Except for multiple daily doses of 600 mg, all doses were generally well tolerated.