Review

Authors: R L Macdonald, K M Kelly

Established antiepileptic drugs (AEDs) decrease membrane excitability by interacting with neurotransmitter receptors or ion channels. AEDs developed before 1980 appear to act on sodium channels, gamma-aminobutyric acid type A (GABAA) receptors, or calcium channels. Benzodiazepines and barbiturates enhance GABAA receptor-mediated inhibition. Phenytoin (PHT), carbamazepine (CBZ), and possibly valproate (VPA) decrease high-frequency repetitive firing of action potentials by enhancing sodium-channel inactivation. Ethosuximide (ESM) and VPA reduce a low threshold (T-type) calcium-channel current. The mechanisms of action of the new AEDs are not fully established. Gabapentin (GBP) binds to a high-affinity site on neuronal membranes in a restricted regional distribution of the central nervous system. This binding site may be related to a possible active transport process of GBP into neurons; however, this has not been proven, and the mechanism of action of GBP remains uncertain. Lamotrigine (LTG) decreases sustained high-frequency repetitive firing of voltage-dependent sodium action potentials that may result in a preferential decreased release of presynaptic glutamate. The mechanism of action of oxcarbazepine (OCBZ) is not known; however, its similarity in structure and clinical efficacy to CBZ suggests that its mechanism of action may involve inhibition of sustained high-frequency repetitive firing of voltage-dependent sodium action potentials. Vigabatrin (VGB) irreversibly inhibits GABA transaminase, the enzyme that degrades GABA, thereby producing greater available pools of presynaptic GABA for release in central synapses. Increased activity of GABA at postsynaptic receptors may underline the clinical efficacy of VGB.

Topics: Acetates; Action Potentials; Amines; Animals; Anticonvulsants; Barbiturates; Benzodiazepines; Calcium Channels; Carbamazepine; Central Nervous System; Cyclohexanecarboxylic Acids; Epilepsy; Gabapentin; Humans; Ion Channels; Lamotrigine; Phenytoin; Rats; Receptors, GABA; Receptors, N-Methyl-D-Aspartate; Receptors, Neurotransmitter; Sodium Channels; Triazines; Trimethadione; Valproic Acid; Vigabatrin; gamma-Aminobutyric Acid

PubMed: 8784210
DOI: 10.1111/j.1528-1157.1995.tb05996.x

Review

Authors: Sudha Kilaru Kessler, Emily McGinnis

Childhood absence epilepsy (CAE) is a common pediatric epilepsy syndrome with distinct seizure semiology, electroencephalography (EEG) features, and treatment. A diagnosis of CAE can be obtained during an office visit with a careful history, physical exam including prolonged hyperventilation, and a routine EEG. The treatment of choice for CAE with absence seizures only is ethosuximide. Valproic acid and lamotrigine are also effective treatments for many patients, but when compared to ethosuximide, valproic acid has more adverse effects and lamotrigine is less effective. Attention to predictors of response to treatment, including clinical, electrographic, and genetic factors, is increasing. Refractory CAE occurs in fewer than half of patients, and treatment strategies are available, though efficacy data are lacking. Careful assessment and treatment of psychosocial comorbidities is essential in caring for patients with CAE.

Topics: Anticonvulsants; Child; Child, Preschool; Drug-Related Side Effects and Adverse Reactions; Electroencephalography; Epilepsy, Absence; Ethosuximide; Female; Humans; Lamotrigine; Male; Practice Guidelines as Topic; Seizures; Treatment Outcome; Valproic Acid

PubMed: 30734897
DOI: 10.1007/s40272-019-00325-x

Authors: Debopam Samanta

Angelman Syndrome (AS) is characterized by severe developmental delays including marked speech impairment, movement abnormalities(ataxia, tremor), and unique behaviors such as frequent laughter and is caused by dysfunctional maternal UBE3A gene (maternal 15q11-13 deletions, maternal specific UBE3A mutation, uniparental disomy, and imprinting defect). Intractable epileptic seizures since early childhood with characteristic EEG abnormalities are present in 80-90% patients with AS. Underlying pathophysiology may involve neocortical and thalamocortical hyperexcitability secondary to severe reduction of GABAergic input, as well as dysfunctional synaptic plasticity, deficient synaptogenesis, and neuronal morphological immaturity. The onset of epilepsy is most prevalent between 1 and 3 years of age; however, approximately 25% of patients developed epilepsy before one year of age. Various types of generalized seizures are most prevalent, with most common types are myoclonic and atypical absence.More than 95% of epilepsy patients may have daily seizures at least for a limited time during early childhood, and two-third patients develop disabling seizures. Fever provoked seizures, and frequent occurrence of nonconvulsive status epilepticus are two unique features. Seizures are frequently pharmacoresistant. Considering underlying prominent GABAergic dysfunction, clinicians had used AEDs that target GABAergic signaling such as valproate, phenobarbital, and clonazepam as first-line therapies for AS. However, due to the unfavorable side effect profile of these AEDs, a recent treatment approach involves priority use of levetiracetam, clobazam, topiramate, lamotrigine, ethosuximide, VNS, and carbohydrate-restricted diets. Besides symptomatic management, there has been recent progress to find a curative treatment with the following approaches: 1. Gene/protein replacement therapy (Adeno and lentiviral vector therapy to deliver a gene or secretory protein); 2. Activation of the intact but silent paternal copy of UBE3A (antisense oligonucleotide therapy and artificial transcription factors); and 3. Downstream therapies (OV101/gaboxadol, ketone supplement, novel compounds/peptides, anti-inflammatory/regenerative therapy).

Topics: Angelman Syndrome; Anticonvulsants; Child; Child, Preschool; Electroencephalography; Epilepsy; Female; Humans; Infant; Infant, Newborn; Male; Seizures; Status Epilepticus; Ubiquitin-Protein Ligases; Valproic Acid

PubMed: 32893075
DOI: 10.1016/j.braindev.2020.08.014

Review

Authors: Sarah A Kelley, Eric H Kossoff

Doose syndrome, otherwise traditionally known as myoclonic-astatic epilepsy, was first described as a unique epilepsy syndrome by Dr Hermann Doose in 1970. In 1989, the International League Against Epilepsy classified it formally as a symptomatic generalized epilepsy, and 20 years later it was renamed 'epilepsy with myoclonic-atonic seizures'. In this review, we discuss the components of this unique disorder including its incidence, clinical features, and electroencephalographic findings. Recent evidence has suggested possible genetic links to the GEFS+ (generalized epilepsy with febrile seizures plus) family, and, additionally, some children with structural brain lesions can mimic the Doose syndrome phenotype. Treatment strategies such as corticosteroids, ethosuximide, and valproate have been described as only partially effective, but newer anticonvulsants, such as levetiracetam and zonisamide, may provide additional seizure control. The most effective treatment reported to date appears to be the ketogenic diet. Prognosis is quite varied in this disorder; however, many children can have a remarkably normal neurodevelopmental outcome.

Topics: Anticonvulsants; Electroencephalography; Epilepsies, Myoclonic; History, 20th Century; History, 21st Century; Humans; Mutation; NAV1.9 Voltage-Gated Sodium Channel; Neuropeptides; Prognosis; Receptors, GABA-A; Sodium Channels

PubMed: 20722665
DOI: 10.1111/j.1469-8749.2010.03744.x

Review

Authors: Adam Strzelczyk, Susanne Schubert-Bast

The developmental and epileptic encephalopathies encompass a group of rare syndromes characterised by severe drug-resistant epilepsy with onset in childhood and significant neurodevelopmental comorbidities. The latter include intellectual disability, developmental delay, behavioural problems including attention-deficit hyperactivity disorder and autism spectrum disorder, psychiatric problems including anxiety and depression, speech impairment and sleep problems. Classical examples of developmental and epileptic encephalopathies include Dravet syndrome, Lennox-Gastaut syndrome and tuberous sclerosis complex. The mainstay of treatment is with multiple anti-seizure medications (ASMs); however, the ASMs themselves can be associated with psychobehavioural adverse events, and effects (negative or positive) on cognition and sleep. We have performed a targeted literature review of ASMs commonly used in the treatment of developmental and epileptic encephalopathies to discuss the latest evidence on their effects on behaviour, mood, cognition, sedation and sleep. The ASMs include valproate (VPA), clobazam, topiramate (TPM), cannabidiol (CBD), fenfluramine (FFA), levetiracetam (LEV), brivaracetam (BRV), zonisamide (ZNS), perampanel (PER), ethosuximide, stiripentol, lamotrigine (LTG), rufinamide, vigabatrin, lacosamide (LCM) and everolimus. Bromide, felbamate and other sodium channel ASMs are discussed briefly. Overall, the current evidence suggest that LEV, PER and to a lesser extent BRV are associated with psychobehavioural adverse events including aggressiveness and irritability; TPM and to a lesser extent ZNS are associated with language impairment and cognitive dulling/memory problems. Patients with a history of behavioural and psychiatric comorbidities may be more at risk of developing psychobehavioural adverse events. Topiramate and ZNS may be associated with negative effects in some aspects of cognition; CBD, FFA, LEV, BRV and LTG may have some positive effects, while the remaining ASMs do not appear to have a detrimental effect. All the ASMs are associated with sedation to a certain extent, which is pronounced during uptitration. Cannabidiol, PER and pregabalin may be associated with improvements in sleep, LTG is associated with insomnia, while VPA, TPM, LEV, ZNS and LCM do not appear to have detrimental effects. There was variability in the extent of evidence for each ASM: for many first-generation and some second-generation ASMs, there is scant documented evidence; however, their extensive use suggests favourable tolerability and safety (e.g. VPA); second-generation and some third-generation ASMs tend to have the most robust evidence documented over several years of use (TPM, LEV, PER, ZNS, BRV), while evidence is still being generated for newer ASMs such as CBD and FFA. Finally, we discuss how a variety of factors can affect mood, behaviour and cognition, and untangling the associations between the effects of the underlying syndrome and those of the ASMs can be challenging. In particular, there is enormous heterogeneity in cognitive, behavioural and developmental impairments that is complex and can change naturally over time; there is a lack of standardised instruments for evaluating these outcomes in developmental and epileptic encephalopathies, with a reliance on subjective evaluations by proxy (caregivers); and treatment regimes are complex involving multiple ASMs as well as other drugs.

Topics: Autism Spectrum Disorder; Bromides; Cannabidiol; Clobazam; Cognition; Ethosuximide; Everolimus; Felbamate; Fenfluramine; Humans; Lacosamide; Lamotrigine; Levetiracetam; Pregabalin; Spasms, Infantile; Sulfides; Topiramate; Valproic Acid; Vigabatrin; Zinc Compounds; Zonisamide

PubMed: 36194365
DOI: 10.1007/s40263-022-00955-9

Meta-Analysis Review

Authors: Hongyuan Chu, Xinyu Zhang, Jie Shi...

OBJECTIVES

To compare the efficacy and safety of antiseizure medications (ASMs), both as monotherapies and adjunctive therapies, for idiopathic generalized epilepsies (IGEs) and related entities.

METHODS

Two reviewers independently searched PubMed, Embase, and the Cochrane Library for relevant randomized controlled trials from December 2022 to February 2023. Studies on the efficacy and safety of ASM monotherapies or adjunctive therapies for IGEs and related entities-including juvenile myoclonic epilepsy, childhood absence epilepsy (CAE), juvenile absence epilepsy, or generalized tonic-clonic seizures alone (GTCA)-were included. Efficacy outcomes were the proportions of patients remaining seizure free for 1, 3, 6, and 12 months; safety outcomes were the proportions of any treatment-emergent adverse event (TEAE) and TEAEs leading to discontinuation. Network meta-analyses were performed in a random-effects model to obtain odds ratios and 95% confidence intervals. Rankings of ASMs were based on the surface under the cumulative ranking curve (SUCRA). This study is registered with PROSPERO (No. CRD42022372358).

RESULTS

Twenty-eight randomized controlled trials containing 4282 patients were included. As monotherapies, all ASMs were more effective than placebo, and valproate and ethosuximide were significantly better than lamotrigine. According to the SUCRA for efficacy, ethosuximide ranked first for CAE, whereas valproate ranked first for other types of IGEs. As adjunctive therapies, topiramate ranked best for GTCA as well as overall for IGEs, while levetiracetam ranked best for myoclonic seizures. For safety, perampanel ranked best (measured by any TEAE).

CONCLUSIONS

All of the studied ASMs were more effective than placebo. Valproate monotherapy ranked best overall for IGEs, whereas ethosuximide ranked best for CAE. Adjunctive topiramate and levetiracetam were most effective for GTCA and myoclonic seizures, respectively. Furthermore, perampanel had the best tolerability.

Topics: Humans; Child; Valproic Acid; Topiramate; Network Meta-Analysis; Levetiracetam; Ethosuximide; Anticonvulsants; Epilepsy, Generalized; Seizures; Randomized Controlled Trials as Topic

PubMed: 37378757
DOI: 10.1007/s00415-023-11834-8

Review

Authors: Gerald W Zamponi, Joerg Striessnig, Alexandra Koschak...

Voltage-gated calcium channels are required for many key functions in the body. In this review, the different subtypes of voltage-gated calcium channels are described and their physiologic roles and pharmacology are outlined. We describe the current uses of drugs interacting with the different calcium channel subtypes and subunits, as well as specific areas in which there is strong potential for future drug development. Current therapeutic agents include drugs targeting L-type Ca(V)1.2 calcium channels, particularly 1,4-dihydropyridines, which are widely used in the treatment of hypertension. T-type (Ca(V)3) channels are a target of ethosuximide, widely used in absence epilepsy. The auxiliary subunit α2δ-1 is the therapeutic target of the gabapentinoid drugs, which are of value in certain epilepsies and chronic neuropathic pain. The limited use of intrathecal ziconotide, a peptide blocker of N-type (Ca(V)2.2) calcium channels, as a treatment of intractable pain, gives an indication that these channels represent excellent drug targets for various pain conditions. We describe how selectivity for different subtypes of calcium channels (e.g., Ca(V)1.2 and Ca(V)1.3 L-type channels) may be achieved in the future by exploiting differences between channel isoforms in terms of sequence and biophysical properties, variation in splicing in different target tissues, and differences in the properties of the target tissues themselves in terms of membrane potential or firing frequency. Thus, use-dependent blockers of the different isoforms could selectively block calcium channels in particular pathologies, such as nociceptive neurons in pain states or in epileptic brain circuits. Of important future potential are selective Ca(V)1.3 blockers for neuropsychiatric diseases, neuroprotection in Parkinson's disease, and resistant hypertension. In addition, selective or nonselective T-type channel blockers are considered potential therapeutic targets in epilepsy, pain, obesity, sleep, and anxiety. Use-dependent N-type calcium channel blockers are likely to be of therapeutic use in chronic pain conditions. Thus, more selective calcium channel blockers hold promise for therapeutic intervention.

Topics: Calcium Channel Blockers; Calcium Channels; Calcium Channels, L-Type; Calcium Channels, N-Type; Calcium Channels, T-Type; Cardiovascular Diseases; Cyclic AMP-Dependent Protein Kinases; GTP-Binding Proteins; Hearing Disorders; Humans; Metabolic Diseases; Nervous System Diseases; Night Blindness; Phospholipids; Receptor Protein-Tyrosine Kinases

PubMed: 26362469
DOI: 10.1124/pr.114.009654

Authors: Torbjörn Tomson, Dina Battino, Rebecca Bromley...

We carried out a systematic review of published information on transfer of antiseizure medications (ASMs) into breastmilk, ASM serum concentrations in breastfed infants, and the wellbeing of infants breastfed by mothers on ASM treatment. Information was extracted from 85 relevant articles. No data on ASM levels in breastmilk or in breastfed infants was identified for cannabidiol, cenobamate, clobazam, eslicarbazepine-acetate, everolimus, felbamate, fenfluramine, retigabine, rufinamide, stiripentol, tiagabine, and vigabatrin. For ASMs, with available information on levels in breastfed infants, very low concentrations (in the order of 10% or less of maternal serum concentrations) were reported for carbamazepine, gabapentin, levetiracetam, oxcarbazepine, phenytoin, valproate, and clonazepam. Slightly higher levels (up to approximately 30% of maternal serum concentrations) have been observed with lamotrigine and topiramate, and in single case reports for brivaracetam, lacosamide, and perampanel. High infant levels (30% up to 100% of maternal serum concentrations) have been reported with ethosuximide, phenobarbital and zonisamide. Adverse infant effects during breastfeeding by mothers on ASMs appear to be rare regardless of the type of ASM, but systematic study is limited. Prospective long-term follow-up studies of developmental outcomes among children who have been breastfed by mothers taking ASMs are sparse and have mainly involved children whose mothers were taking carbamazepine, lamotrigine, levetiracetam, phenytoin or valproate as monotherapy while breastfeeding. Although these studies have not indicated poorer outcome among breastfed children compared with those who were not breastfed, further data on long-term outcomes are needed to draw firm conclusions. It is concluded that breastfeeding should in general be encouraged in women taking ASMs, given the well-established benefits of breastfeeding with regard to both short- and long-term infant health in the general population. Counselling needs to be individualized including information on the current knowledge regarding the woman's specific ASM treatment.

Topics: Breast Feeding; Cannabidiol; Carbamazepine; Child; Clobazam; Clonazepam; Epilepsy; Ethosuximide; Everolimus; Felbamate; Female; Fenfluramine; Gabapentin; Humans; Infant; Lacosamide; Lamotrigine; Levetiracetam; Oxcarbazepine; Phenobarbital; Phenytoin; Prospective Studies; Tiagabine; Topiramate; Valproic Acid; Vigabatrin; Zonisamide

PubMed: 36193017
DOI: 10.1684/epd.2022.1492