Ethosuximide, sodium valproate or lamotrigine for absence seizures in children and adolescents

Therapeutic Options for Childhood Absence Epilepsy

Childhood absence epilepsy (CAE) is a common pediatric generalized epileptic syndrome. Although it is traditionally considered as a benign self-limited condition, the apparent benign nature of this syndrome has been revaluated in recent years. This is mainly due to the increasing evidence that children with CAE can present invalidating neuropsychological comorbidities that will affect them up to adulthood. Moreover, a percentage of affected children can develop drug-resistant forms of CAE. The purpose of this review is to summarize the most recent studies and new concepts concerning CAE treatment, in particular concerning drug-resistant forms of CAE. A Pubmed search was undertaken to identify all articles concerning management and treatment of CAE, including articles written between 1979 and 2021. Traditional anticonvulsant therapy of CAE that is still in use is based on three antiepileptic drugs: ethosuximide which is the drug of choice, followed by valproic acid and lamotrigine. In the case of first line treatment failure, after two monotherapies it is usual to start a bi-therapy. In the case of absence seizures that are refractory to traditional treatment, other antiepileptic drugs may be introduced such as levetiracetam, topiramate and zonisamide.

Ethosuximide, sodium valproate or lamotrigine for absence seizures in children and adolescents

BACKGROUND

This is an updated version of the Cochrane Review previously published in 2019. Absence seizures (AS) are brief epileptic seizures which present in childhood and adolescence. Depending on clinical features and electroencephalogram (EEG) findings they are divided into typical, atypical absences, and absences with special features. Typical absences are characterised by sudden loss of awareness and an EEG typically shows generalised spike wave discharges at three cycles per second. Ethosuximide, valproate and lamotrigine are currently used to treat absence seizures. This review aims to determine the best choice of antiepileptic drug for children and adolescents with AS.

OBJECTIVES

To review the evidence for the effects of ethosuximide, valproate and lamotrigine as treatments for children and adolescents with absence seizures (AS), when compared with placebo or each other.

SEARCH METHODS

For the latest update we searched the Cochrane Register of Studies (CRS Web, 22 September 2020) and MEDLINE (Ovid, 1946 to September 21, 2020). CRS Web includes randomised or quasi-randomised, controlled trials from PubMed, Embase, ClinicalTrials.gov, the World Health Organization International Clinical Trials Registry Platform (ICTRP), the Cochrane Central Register of Controlled Trials (CENTRAL), and the Specialized Registers of Cochrane Review Groups including Epilepsy. No language restrictions were imposed. In addition, we contacted Sanofi Winthrop, Glaxo Wellcome (now GlaxoSmithKline) and Parke Davis (now Pfizer), manufacturers of sodium valproate, lamotrigine and ethosuximide respectively.

SELECTION CRITERIA

Randomised parallel group monotherapy or add-on trials which include a comparison of any of the following in children or adolescents with AS: ethosuximide, sodium valproate, lamotrigine, or placebo.

DATA COLLECTION AND ANALYSIS

Outcome measures were: 1. proportion of individuals seizure free at one, three, six, 12 and 18 months post randomisation; 2. individuals with a 50% or greater reduction in seizure frequency; 3. normalisation of EEG and/or negative hyperventilation test; and 4. adverse effects. Data were independently extracted by two review authors. Results are presented as risk ratios (RR) with 95% confidence intervals (95% CIs). We used GRADE quality assessment criteria to evaluate the certainty of evidence for the outcomes derived from all included studies.

MAIN RESULTS

On the basis of our selection criteria, we included no new studies in the present review. Eight small trials (total number of participants: 691) were included from the earlier review. Six of them were of poor methodological quality (unclear or high risk of bias) and seven recruited less than 50 participants. There are no placebo-controlled trials for ethosuximide or valproate, and hence, no evidence from randomised controlled trials (RCTs) to support a specific effect on AS for either of these two drugs. Due to the differing methodologies used in the trials comparing ethosuximide, lamotrigine and valproate, we thought it inappropriate to undertake a meta-analysis. One large randomised, parallel double-blind controlled trial comparing ethosuximide, lamotrigine and sodium valproate in 453 children with newly diagnosed childhood absence epilepsy found that at 12 months, seizure freedom was higher in patients taking ethosuximide (70/154, 45%) than in patients taking lamotrigine (31/146, 21%; P < 0.001), with no difference between valproate (64/146, 44%) and ethosuximide (70/154, 45%; P > 0.05). In this study, the frequency of treatment failures due to intolerable adverse events was significantly different among the treatment groups, with the largest proportion of adverse events in the valproic acid group (48/146, 33%) compared to the ethosuximide (38/154, 25%) and the lamotrigine (29/146, 20%) groups (P < 0.037). Overall, this large study demonstrates the superior effectiveness of ethosuximide and valproic acid compared to lamotrigine as initial monotherapy aimed to control seizures without intolerable adverse effects in children with childhood absence epilepsy. This study provided high certainty of the evidence for outcomes for which data were available. However, the certainty of the evidence provided by the other included studies was low, primarily due to risk of bias and imprecise results because of the small sample sizes. Hence, conclusions regarding the efficacy of ethosuximide, valproic acid and lamotrigine derive mostly from this single study.

AUTHORS' CONCLUSIONS

Since the last version of this review was published, we have found no new studies. Hence, the conclusions remain the same as the previous update. With regards to both efficacy and tolerability, ethosuximide represents the optimal initial empirical monotherapy for children and adolescents with AS. However, if absence and generalised tonic-clonic seizures coexist, valproate should be preferred, as ethosuximide is probably inefficacious on tonic-clonic seizures.

Ethosuximide, sodium valproate or lamotrigine for absence seizures in children and adolescents

BACKGROUND

This is an updated version of the Cochrane Review previously published in 2017.Absence seizures (AS) are brief epileptic seizures which present in childhood and adolescence. Depending on clinical features and electroencephalogram (EEG) findings they are divided into typical, atypical absences, and absences with special features. Typical absences are characterised by sudden loss of awareness and an EEG typically shows generalised spike wave discharges at three cycles per second. Ethosuximide, valproate and lamotrigine are currently used to treat absence seizures. This review aims to determine the best choice of antiepileptic drug for children and adolescents with AS.

OBJECTIVES

To review the evidence for the effects of ethosuximide, valproate and lamotrigine as treatments for children and adolescents with absence seizures (AS), when compared with placebo or each other.

SEARCH METHODS

For the latest update we searched the Cochrane Register of Studies (CRS Web, 29 May 2018), which includes the Cochrane Epilepsy Group's Specialized Register and the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (Ovid, 1946 to 29 May 2018), ClinicalTrials.gov (29 May 2018) and the WHO International Clinical Trials Registry Platform (ICTRP, 29 May 2018). Previously we searched Embase (1988 to March 2005) and SCOPUS (1823 to 31 March 2014), but this is no longer necessary because randomised controlled trials (RCTs) and quasi-RCTs in Embase and SCOPUS are now included in CENTRAL. No language restrictions were imposed. In addition, we contacted Sanofi Winthrop, Glaxo Wellcome (now GlaxoSmithKline) and Parke Davis (now Pfizer), manufacturers of sodium valproate, lamotrigine and ethosuximide respectively.

SELECTION CRITERIA

Randomised parallel group monotherapy or add-on trials which include a comparison of any of the following in children or adolescents with AS: ethosuximide, sodium valproate, lamotrigine, or placebo.

DATA COLLECTION AND ANALYSIS

Outcome measures were: (1) proportion of individuals seizure free at one, three, six, 12 and 18 months post randomisation; (2) people with a 50% or greater reduction in seizure frequency; (3) normalisation of EEG and/or negative hyperventilation test; and (4) adverse effects. Data were independently extracted by two review authors. Results are presented as risk ratios (RR) with 95% confidence intervals (95% CIs). We used GRADE quality assessment criteria to evaluate the certainty of evidence derived from all included studies.

MAIN RESULTS

On the basis of our selection criteria, we included no new studies in the present review. Eight small trials (total number of participants: 691) were included from the earlier review. Six of them were of poor methodological quality (unclear or high risk of bias) and seven recruited less than 50 participants. There are no placebo-controlled trials for ethosuximide or valproate, and hence, no evidence from RCTs to support a specific effect on AS for either of these two drugs. Due to the differing methodologies used in the trials comparing ethosuximide, lamotrigine and valproate, we thought it inappropriate to undertake a meta-analysis. One large randomised, parallel double-blind controlled trial comparing ethosuximide, lamotrigine and sodium valproate in 453 children with newly diagnosed childhood absence epilepsy found that at 12 months, the freedom-from-failure rates for ethosuximide and valproic acid were similar and were higher than the rate for lamotrigine. The frequency of treatment failures due to lack of seizure control (P < 0.001) and intolerable adverse events (P < 0.037) was significantly different among the treatment groups, with the largest proportion of lack of seizure control in the lamotrigine cohort, and the largest proportion of adverse events in the valproic acid group. Overall, this large study demonstrates the superior effectiveness of ethosuximide and valproic acid compared to lamotrigine as initial monotherapy aimed to control seizures without intolerable adverse effects in children with childhood absence epilepsy. The risk of bias for this study was low. We rated the overall certainty of the evidence available from the included studies to be moderate or high.

AUTHORS' CONCLUSIONS

Since the last version of this review was published, we have found no new studies. Hence, the conclusions remain the same as the previous update. With regards to both efficacy and tolerability, ethosuximide represents the optimal initial empirical monotherapy for children and adolescents with AS. However, if absence and generalised tonic-clonic seizures coexist, valproate should be preferred, as ethosuximide is probably inefficacious on tonic-clonic seizures.

Ethosuximide, sodium valproate or lamotrigine for absence seizures in children and adolescents

BACKGROUND

This is an updated version of the original Cochrane review originally published in 2003, Issue 3, and updated in 2005, Issue 4.Absence seizures are brief epileptic seizures which present in childhood and adolescence. Depending on clinical features and electroencephalogram (EEG) findings they are divided into typical, atypical absences, and absences with special features. Typical absences are characterised by sudden loss of awareness and an EEG typically shows generalised spike wave discharges at three cycles per second. Ethosuximide, valproate and lamotrigine are currently used to treat absence seizures. This review aims to determine the best choice of antiepileptic drug for children and adolescents with typical absence seizures.

OBJECTIVES

To review the evidence for the effects of ethosuximide, valproate and lamotrigine as treatments for children and adolescents with absence seizures, when compared with placebo or each other.

SEARCH METHODS

We searched the Cochrane Epilepsy Group's Specialized Register (1 September 2016), the Cochrane Central Register of Controlled Trials (CENTRAL) via the Cochrane Register of Studies Online (CRSO, 1 September 2016), MEDLINE (Ovid, 1946 to 1 September 2016), ClinicalTrials.gov (1 September 2016) and the WHO International Clinical Trials Registry Platform ICTRP (1 September 2016). Previously we searched Embase (1988 to March 2005) and SCOPUS (1823 to 31 March 2014). No language restrictions were imposed. In addition, we contacted Sanofi Winthrop, Glaxo Wellcome (now GlaxoSmithKline) and Parke Davis (now Pfizer), manufacturers of sodium valproate, lamotrigine and ethosuximide respectively.

SELECTION CRITERIA

Randomised parallel group monotherapy or add-on trials which include a comparison of any of the following in children or adolescents with absence seizures: ethosuximide; sodium valproate; lamotrigine; or placebo.

DATA COLLECTION AND ANALYSIS

Outcome measures were: (1) proportion of individuals seizure free at one, three, six, 12 and 18 months post randomisation; (2) people with a 50% or greater reduction in seizure frequency; (3) normalisation of EEG and/or negative hyperventilation test; and (4) adverse effects. Data were independently extracted by two review authors. Results are presented as risk ratios (RR) with 95% confidence intervals (95% CIs).

MAIN RESULTS

Eight small trials were found (three of them not included in the previous version of the review). Six of them were of poor methodological quality and seven recruited less than 50 participants. There are no placebo-controlled trials for ethosuximide or valproate, and hence, no evidence from randomised controlled trials to support a specific effect on absence seizures for either of these two drugs. Due to the differing methodologies used in the trials comparing ethosuximide, lamotrigine and valproate, we thought it inappropriate to undertake a meta-analysis. One large randomised, parallel double-blind controlled trial comparing ethosuximide, lamotrigine and sodium valproate in children with newly diagnosed childhood absence epilepsy found that at 12 months, the freedom-from-failure rates for ethosuximide and valproic acid (VPA) were similar and were higher than the rate for lamotrigine. The frequency of treatment failures due to lack of seizure control (P < 0.001) and intolerable adverse events (P < 0.037) was significantly different among the treatment groups, with the largest proportion of lack of seizure control in the lamotrigine cohort, and the largest proportion of adverse events in the VPA group. Overall, this large study demonstrates the superior effectiveness of ethosuximide and VPA compared to lamotrigine as initial monotherapy aimed to control seizures without intolerable adverse effects in children with childhood absence epilepsy.

AUTHORS' CONCLUSIONS

With regards to both efficacy and tolerability, ethosuximide represents the optimal initial empirical monotherapy for children and adolescents with absence seizures. However, if absence and generalised tonic-clonic seizures coexist, valproate should be preferred, as ethosuximide is probably inefficacious on tonic-clonic seizures.

Valproate as a mainstay of therapy for pediatric epilepsy

This article reviews relevant pharmacologic and clinical information gathered for valproate since it was introduced into clinical practice 37 years ago and the application of this information for the treatment of childhood epilepsy. Valproate is available for oral and parenteral use. Oral forms are almost completely bioavailable but the rate of absorption varies between formulations. The Chrono tablet formulation has not been adapted for children aged <6 years, in whom the oral solution or syrup, requiring two or three daily administrations, has been used until recently. A new formulation specifically adapted for children, Chronosphere, administrated once or twice daily, is a modified-release formulation of valproate that minimizes fluctuations in serum drug concentrations during a dosage interval. Plasma protein binding is 80-94% and tends to decrease with increasing drug concentration. Valproate elimination is markedly decreased in newborns compared with older children and adults. Elimination by glucuronidation only becomes fully effective by the age of 3-4 years. In children aged 2-10 years receiving valproate, plasma clearances are 50% higher than those in adults. Over the age of 10 years, pharmacokinetic parameters approximate those of adults. Valproate can increase plasma concentrations of concomitant drugs, such as phenobarbital and lamotrigine, by inhibiting their metabolism. As a result of its broad spectrum of efficacy in a wide range of seizure types and epilepsy syndromes, valproate is a drug of choice for children with newly diagnosed epilepsy (focal or generalized), idiopathic generalized epilepsy, epilepsies with prominent myoclonic seizures or with multiple seizure types, and photosensitive epilepsies. In the group of cognitive epilepsies, in which severe spike and wave discharges are accompanied by cognitive deterioration, valproate, ethosuximide, or both should be tested before using corticosteroids. In comparative trials with carbamazepine, phenytoin, and phenobarbital in focal epilepsy and with ethosuximide in absence epilepsy, valproate was as effective and showed a favorable tolerability profile, with minimal adverse cognitive and CNS effects. The low potential for paradoxical seizure aggravation and the long-term efficacy of the drug are additional important factors that contribute to its excellent profile. Intravenous valproate may be effective for the treatment of convulsive and non-convulsive status epilepticus that is refractory to conventional drugs. In infants, potential benefits should be carefully weighed against the risk of liver toxicity. Gastrointestinal intolerance is a relatively frequent, dose-related adverse effect of the drug in children. Bodyweight increase and tremor may be observed in older children and adolescents. Despite the challenge of newer drugs, valproate remains a gold standard antiepileptic drug for the treatment of children.

[Typical absence seizure: epidemiological and clinical characteristics and outcome]

OBJECTIVE

To analyze the epidemiological and clinical characteristics and outcome of absence epilepsy in the pediatric age group with the aim of facilitating its diagnosis in clinical practice.

PATIENTS AND METHODS

Information on epidemiological and clinical characteristics, complementary investigations, and outcome was collected from the medical records of 51 children with absence epilepsy. The criteria defined by the International League Against Epilepsy (ILAE) were used in the diagnosis.

RESULTS

Fifty-one percent of the patients had simple absence seizures and 49% had complex absence seizures. A total of 70.6% of the patients were school-aged children and the prevalence was greater among girls (72.5%). The mean age at onset was 7.5 +/- 2.7 years. In 80%, there were multiple seizures per day with a mean duration of 12 seconds. School performance was impaired in 19.6%. Ictal electroencephalogram showed generalized 3 Hz spike and slow wave complexes in 84.3%. Hyperventilation was positive in 98%, and intermittent photic stimulation was positive in 15.7%. The seizures were controlled by sodium valproate (mean dosage: 26 mg/kg/day) in 84.3% of the patients. In 43 patients antiepileptic drugs were withdrawn (mean duration: 3.3 +/- 0.6 years) but 3 patients relapsed.

CONCLUSIONS

Typical absences are a common type of epilepsy in the pediatric age group and generally begin in school-aged children. Absences may be difficult to detect and can impair learning. Treatment response is excellent. Nevertheless, because absences may be the first manifestation of severe forms of epilepsy syndromes, strict follow-up of these patients is essential.

Effects of the combination of valproate and ethosuximide on spike wave discharges in WAG/Rij rats

OBJECTIVE

We studied the interaction between valproate (VPA) and ethosuximide (ESM) in diminishing the incidence of absence-like spike-wave discharges (SWDs) in the EEG of WAG/Rij rats.

METHODS

VPA, ESM, their combination and saline were evaluated in 16 rats. The doses of VPA ranged from 0 to 280 mg/kg and the doses of ESM ranged from 0 to 40 mg/kg. For the drug combination, a fixed weight ratio of 7/1 VPA/ESM was used. The incidence of SWDs in the EEG was determined for the period of 15-75 min after injection and compared to the incidence of SWDs prior to injection. The sigmoid-E(max) equation was fitted to the data. Isobolic analysis, on 50% effect, was used to assess the character of the drug interaction.

RESULTS

The parameters for diminishing the incidence of the SWDs were: VPA: ED(50): 121mg/kg; ESM: ED(50): 21.5mg/kg; VPA/ESM: ED(50): 112/16 mg/kg. Isobolic analysis showed that a higher drug load was needed of the combination than of the individual drugs to achieve a 50% reduction of SWDs: factor 1.67; P = 0.012.

CONCLUSION

The interaction between valproate and ethosuximide was shown to be infra-additive in diminishing the incidence of SWDs in WAG/Rij rats.