Comprehensive overview: efficacy, tolerability, and cost-effectiveness of clobazam in Lennox-Gastaut syndrome

Disproportionality analysis of the safety profile of rufinamide in the real world: an evaluation of the FDA Adverse Event Reporting System database

BACKGROUND

Rufinamide (RUF) is an antiepileptic drug recently introduced for managing seizures in Lennox-Gastaut syndrome (LGS), but its adverse reactions are not well understood. This study aims to evaluate RUF's safety profile using data from the FDA Adverse Event Reporting System (FAERS).

METHODS

Disproportionality analysis was conducted to assess RUF-associated adverse drug events (ADEs), using reporting odds ratio (ROR), proportional reporting ratio (PRR), Bayesian confidence propagation neural network (BCPNN), and multi-item gamma-Poisson shrinker (MGPS).

RESULTS

We collected 338 ADE reports related to RUF. Nervous system disorders were the most frequently reported signals, and several new ADEs were detected, including atonic seizures, sudden unexplained death in epilepsy, seizure clusters, multi-drug resistance, and Stevens-Johnson syndrome. Nearly half of the ADEs in pediatric patients were psychological or neurological. Disproportionality analysis within 4 weeks of treatment showed high RORs for QT shortening, sudden death, and atonic seizures.

CONCLUSIONS

Our study revealed prospective signals of new ADEs linked to RUF as well as revealed that both prescribers and patients were more conscious of the risks involved in its clinical use.

The bee venom active compound melittin protects against bicuculline-induced seizures and hippocampal astrocyte activation in rats

Epilepsy is a chronic neuropathology characterized by an abnormal hyperactivity of neurons that generate recurrent, spontaneous, paradoxical and synchronized nerve impulses, leading or not to seizures. This neurological disorder affects around 70 million individuals worldwide. Pharmacoresistance is observed in about 30% of the patients and long-term use of antiepileptics may induce serious side effects. Thus, there is an interest in the study of the therapeutic potential of bioactive substances isolated from natural products in the treatment of epilepsy. Arthropod venoms contain neurotoxins that have high affinity for molecular structures in the neural tissue such as receptors, transporters and ion channels both in glial and neuronal membranes. This study evaluated the potential neuroprotective effect of melittin (MEL), an active compound of bee venom, in the bicuculline-induced seizure model (BIC) in rats. Male Wistar rats (3 months, 250-300 g) were submitted to surgery for the implantation of a unilateral cannula in the lateral ventricle. After the recovery period, rats received a microinjection of saline solution or MEL (0.1 mg per animal). Firstly, rats were evaluated in the open field (20 min) and in the elevated plus maze (5 min) tests after received microinjection of saline or MEL. After, 30 min later animals received BIC (100 mg/ml) or saline, and their behaviors were analyzed for 20 min in the open field according to a seizure scale. At the end, rats were euthanized, brains collected and processed to glial fibrillary acidic protein (GFAP) immunohistochemistry evaluation. No changes were observed in MEL-treated rats in the open field and elevated plus maze. However, 90% of MEL-treated animals were protected against seizures induced by BIC. There was an increase in the latency for the onset of seizures, accompanied by a reduction of GFAP-immunoreactivity cells in the dentate gyrus and CA1. Thus, our study suggests that MEL has an anticonvulsant potential, and further studies are needed to elucidate the mechanisms involved in this action.

Functional characterization of the antiepileptic drug candidate, padsevonil, on GABAA receptors

OBJECTIVE

The antiepileptic drug candidate, padsevonil, is the first in a novel class of drugs designed to interact with both presynaptic and postsynaptic therapeutic targets: synaptic vesicle 2 proteins and γ-aminobutyric acid type A receptors (GABA_A Rs), respectively. Functional aspects of padsevonil at the postsynaptic target, GABA_A Rs, were characterized in experiments reported here.

METHODS

The effect of padsevonil on GABA-mediated Cl^- currents was determined by patch clamp on recombinant human GABA_A Rs (α1β2γ2) stably expressed in a CHO-K1 cell line and on native GABA_A Rs in cultured rat primary cortical neurons. Padsevonil selectivity for GABA_A R subtypes was evaluated using a two-electrode voltage clamp on recombinant human GABA_A Rs (α1-5/β2/γ2) in Xenopus oocytes.

RESULTS

In recombinant GABA_A Rs, padsevonil did not evoke Cl^- currents in the absence of the agonist GABA. However, when co-administered with GABA at effective concentration (EC)₂₀ , padsevonil potentiated GABA responses by 167% (EC₅₀ 138 nmol/L) and demonstrated a relative efficacy of 41% compared with zolpidem, a reference benzodiazepine site agonist. Similarly, padsevonil demonstrated GABA-potentiating activity at native GABA_A Rs (EC₅₀ 208 nmol/L) in cultured rat cortical neurons. Padsevonil also potentiated GABA (EC₂₀ ) responses in GABA_A Rs expressed in oocytes, with higher potency at α1- and α5-containing receptors (EC₅₀ 295 and 281 nmol/L) than at α2- and α3-containing receptors (EC₅₀ 1737 and 2089 nmol/L). Compared with chlordiazepoxide-a nonselective, full GABA_A R agonist-the relative efficacy of padsevonil was 60% for α1β2γ2, 26% for α2β2γ2, 56% for α3β2γ2, and 41% for α5β2γ2; no activity was observed at benzodiazepine-insensitive α4β2γ2 receptors.

SIGNIFICANCE

Results of functional investigations on recombinant and native neuronal GABA_A Rs show that padsevonil acts as a positive allosteric modulator of these receptors, with a partial agonist profile at the benzodiazepine site. These properties may confer better tolerability and lower potential for tolerance development compared with classic benzodiazepines currently used in the clinic.

Why we urgently need improved epilepsy therapies for adult patients

PURPOSE

Up to a third of patients with epilepsy suffer from recurrent seizures despite therapeutic advances.

RESULTS

Current epilepsy treatments are limited by experiential data from treating different types of epilepsy. For example, we lack evidence-based approaches to efficacious multi-drug therapies or identifying potentially serious or disabling adverse events before medications are initiated. Despite advances in neuroscience and genetics, our understanding of epilepsy pathogenesis and mechanisms of treatment-resistance remains limited. For most patients with epilepsy, precision medicine for improved seizure control and reduced toxicity remains a future goal.

CONCLUSION

A third of epilepsy patients suffer from ongoing seizures and even more suffer from adverse effects of treatment. There is a critical need for more effective and safer therapies for epilepsy patients with frequent comorbitidies, including depression, anxiety, migraine, and cognitive impairments, as well as special populations (e.g., women, elderly). Advances from genomic sequencing techniques may identify new genes and regulatory elements that influence both the depth of the epilepsies' roots within brain circuitry as well as ASD resistance. Improved understanding of epilepsy mechanisms, identification of potential new therapeutic targets, and their assessment in randomized controlled trials are needed to reduce the burden of refractory epilepsy. 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'.

Lennox-Gastaut syndrome: a comprehensive review

Lennox-Gastaut syndrome (LGS) is considered an epileptic encephalopathy and is defined by a triad of multiple drug-resistant seizure types, a specific EEG pattern showing bursts of slow spike-wave complexes or generalized paroxysmal fast activity, and intellectual disability. The prevalence of LGS is estimated between 1 and 2% of all patients with epilepsy. The etiology of LGS is often divided into two groups: identifiable (genetic-structural-metabolic) in 65 to 75% of the patients and LGS of unknown cause in others. Lennox-Gastaut syndrome may be considered as secondary network epilepsy. The seizures in LGS are usually drug-resistant, and complete seizure control with resolution of intellectual and psychosocial dysfunction is often not achievable. Reduction in frequency of the most incapacitating seizures (e.g., drop attacks and tonic-clonic seizures) should be the major objective. Valproate, lamotrigine, and topiramate are considered to be the first-line drugs by many experts. Other effective antiepileptic drugs include levetiracetam, clobazam, rufinamide, and zonisamide. The ketogenic diet is an effective and well-tolerated treatment option. For patients with drug resistance, a further therapeutic option is surgical intervention. Corpus callosotomy is a palliative surgical procedure that aims at controlling the most injurious seizures. Finally, vagus nerve stimulation offers reasonable seizure improvement. The long-term outcome for patients with LGS is generally poor. This syndrome is often associated with long-term adverse effects on intellectual development, social functioning, and independent living.

The Pharmacology and Toxicology of Third-Generation Anticonvulsant Drugs

Epilepsy is a neurologic disorder affecting approximately 50 million people worldwide, or about 0.7% of the population [1]. Thus, the use of anticonvulsant drugs in the treatment of epilepsy is common and widespread. There are three generations of anticonvulsant drugs, categorized by the year in which they were developed and released. The aim of this review is to discuss the pharmacokinetics, drug-drug interactions, and adverse events of the third generation of anticonvulsant drugs. Where available, overdose data will be included. The pharmacokinetic properties of third-generation anticonvulsant drugs include relatively fewer drug-drug interactions, as well as several unique and life-threatening adverse events. Overdose data are limited, so thorough review of adverse events and knowledge of drug mechanism will guide expectant management of future overdose cases. Reporting of these cases as they occur will be necessary to further clarify toxicity of these drugs.

Treatment issues for children with epilepsy transitioning to adult care

This is the third of three papers that summarize the second symposium on Transition in Epilepsies held in Paris in June 2016. This paper focuses on treatment issues that arise during the course of childhood epilepsy and make the process of transition to adult care more complicated. Some AEDs used during childhood, such as stiripentol, vigabatrin, and cannabidiol, are unfamiliar to adult epilepsy specialists. In addition, new drugs are being developed for treatment of specific childhood onset epilepsy syndromes and have no indication yet for adults. The ketogenic diet may be effective during childhood but is difficult to continue in adult care. Regional adult epilepsy diet clinics could be helpful. Polytherapy is common for patients transitioning to adult care. Although these complex AED regimes are difficult, they are often possible to simplify. AEDs used in childhood may need to be reconsidered in adulthood. Rescue medications to stop prolonged seizures and clusters of seizures are in wide home use in children and can be continued in adulthood. Adherence/compliance is notoriously difficult for adolescents, but there are simple clinical approaches that should be helpful. Mental health issues including depression and anxiety are not always diagnosed and treated in children and young adults even though effective treatments are available. Attention deficit hyperactivity disorder and aggressive behavior disorders may interfere with transition and successful adulthood but these can be treated. For the majority, the adult social outcome of children with epilepsy is unsatisfactory with few proven interventions. The interface between pediatric and adult care for children with epilepsy is becoming increasingly complicated with a need for more comprehensive transition programs and adult epileptologists who are knowledgeable about special treatments that benefit this group of patients.

Clobazam and Its Use in Epilepsy

Clobazam (CLB) is an older anti-epileptic drug, with a slightly different chemical structure from that of the classic benzodiazepines currently used in the treatment of epilepsy, which confers less sedative properties in terms of negative adverse effects. It is also thought to be better tolerated than other anti-epileptic drugs, whilst maintaining a very similar level of efficacy. It has been tested extensively in over 50 studies on more than 3000 patients with epilepsy and is now approved as an adjunctive treatment of epilepsy in >100 countries. The aim of this review is to evaluate several existing studies on the effectiveness of CLB as an adjunctive therapy in the treatment of epilepsy and whether this therapy is more useful in particular types of epilepsy or seizure prevention. This is not a systematic review but a general overview of some of the most recent studies on the effectiveness of CLB as an adjunctive therapy. Additionally, the benefits of having an oral suspension of CLB will be evaluated with regards to patient groups benefiting from this formulation. The last issue addressed is that of the importance of prescribing CLB by brand, along with the benefits and risks of not doing so.

Emerging Antiepileptic Drugs for Severe Pediatric Epilepsies

The medical management of the epilepsy syndromes of early childhood (eg, infantile spasms, Dravet syndrome, and Lennox-Gastaut syndrome) is challenging; and requires careful evaluation, classification, and treatment. Pharmacologic therapy continues to be the mainstay of management for these children, and as such it is important for the clinician to be familiar with the role of new antiepileptic drugs. This article reports the clinical trial data and personal experience in treating the severe epilepsies of childhood with the recently Food and Drug Administration-approved new antiepileptic drugs (vigabatrin, rufinamide, perampanel, and clobazam) and those in clinical trials (cannabidiol, stiripentol, and fenfluramine). Genetic research has also identified an increasing number of pediatric developmental and seizure disorders that are possibly treatable with targeted drug therapies, focused on correcting underlying neural dysfunction. We highlight recent genetic advances, and how they affect our treatment of some of the genetic epilepsies, and speculate on the use of targeted genetic treatment (precision medicine) in the future.