Pharmacotherapy for Neonatal Seizures: Current Knowledge and Future Perspectives

Enhancing GABAergic Tonic Inhibition Reduces Seizure-Like Activity in the Neonatal Mouse Hippocampus and Neocortex

Approximately one-third of neonatal seizures do not respond to first-line anticonvulsants, including phenobarbital, which enhances phasic inhibition. Whether enhancing tonic inhibition decreases seizure-like activity in the neonate when GABA is mainly depolarizing at this age is unknown. We evaluated if increasing tonic inhibition using THIP [4,5,6,7-tetrahydroisoxazolo(5,4-c)pyridin-3-ol, gaboxadol], a δ-subunit-selective GABAA receptor agonist, decreases seizure-like activity in neonatal C57BL/6J mice (postnatal day P5-8, both sexes) using acute brain slices. Whole-cell patch-clamp recordings showed that THIP enhanced GABAergic tonic inhibitory conductances in layer V neocortical and CA1 pyramidal neurons and increased their rheobase without altering sEPSC characteristics. Two-photon calcium imaging demonstrated that enhancing the activity of extrasynaptic GABAARs decreased neuronal firing in both brain regions. In the 4-aminopyridine and the low-Mg2+ model of pharmacoresistant seizures, THIP reduced epileptiform activity in the neocortex and CA1 hippocampal region of neonatal and adult brain slices in a dose-dependent manner. We conclude that neocortical layer V and CA1 pyramidal neurons have tonic inhibitory conductances, and when enhanced, they reduce neuronal firing and decrease seizure-like activity. Therefore, augmenting tonic inhibition could be a viable approach for treating neonatal seizures.

New GABA-Targeting Therapies for the Treatment of Seizures and Epilepsy: I. Role of GABA as a Modulator of Seizure Activity and Recently Approved Medications Acting on the GABA System

γ-Aminobutyric acid (GABA) is the most prevalent inhibitory neurotransmitter in the mammalian brain and has been found to play an important role in the pathogenesis or the expression of many neurological diseases, including epilepsy. Although GABA can act on different receptor subtypes, the component of the GABA system that is most critical to modulation of seizure activity is the GABAA-receptor-chloride (Cl-) channel complex, which controls the movement of Cl- ions across the neuronal membrane. In the mature brain, binding of GABA to GABAA receptors evokes a hyperpolarising (anticonvulsant) response, which is mediated by influx of Cl- into the cell driven by its concentration gradient between extracellular and intracellular fluid. However, in the immature brain and under certain pathological conditions, GABA can exert a paradoxical depolarising (proconvulsant) effect as a result of an efflux of chloride from high intracellular to lower extracellular Cl- levels. Extensive preclinical and clinical evidence indicates that alterations in GABAergic inhibition caused by drugs, toxins, gene defects or other disease states (including seizures themselves) play a causative or contributing role in facilitating or maintaning seizure activity. Conversely, enhancement of GABAergic transmission through pharmacological modulation of the GABA system is a major mechanism by which different antiseizure medications exert their therapeutic effect. In this article, we review the pharmacology and function of the GABA system and its perturbation in seizure disorders, and highlight how improved understanding of this system offers opportunities to develop more efficacious and better tolerated antiseizure medications. We also review the available data for the two most recently approved antiseizure medications that act, at least in part, through GABAergic mechanisms, namely cenobamate and ganaxolone. Differences in the mode of drug discovery, pharmacological profile, pharmacokinetic properties, drug-drug interaction potential, and clinical efficacy and tolerability of these agents are discussed.

High Effectiveness of Midazolam and Lidocaine in the Treatment of Acute Neonatal Seizures

PURPOSE

To assess the clinical effectiveness of treating acute seizures with midazolam and lidocaine infusion.

METHODS

This single-center historical cohort study included 39 term neonates with electrographic seizures who underwent treatment with midazolam (1st line) and lidocaine (2nd line). Therapeutic response was measured using continuous video-EEG monitoring. The EEG measurements included total seizure burden (minutes), maximum ictal fraction (minutes/hour), and EEG-background (normal/slightly abnormal vs. abnormal). Treatment response was considered good (seizure control with midazolam infusion), intermediate (need to add lidocaine to the control), or no response. Using clinical assessments supplemented by BSID-III and/or ASQ-3 at 2 to 9 years old age, neurodevelopment was classified as normal, borderline, or abnormal.

RESULTS

A good therapeutic response was obtained in 24 neonates, an intermediate response in 15, and no response in any of the neonates. Babies with good response showed lower values in maximum ictal fraction compared with those with intermediate response (95% CI: 5.85-8.64 vs. 9.14-19.14, P = 0.002). Neurodevelopment was considered normal in 24 children, borderline in five, and abnormal in other 10 children. Abnormal neurodevelopment was significantly associated with an abnormal EEG background, maximum ictal fraction >11 minutes, and total seizure burden >25 minutes (odds ratio 95% CI: 4.74-1708.52, P = 0.003; 1.72-200, P = 0.016; 1.72-142.86, P = 0.026, respectively) but not with the therapeutic response. Serious adverse effects were not recorded.

CONCLUSIONS

This retrospective study suggests that the midazolam/lidocaine association could potentially be efficacious in decreasing seizure burden in term neonates with acute seizures. These results would justify testing the midazolam/lidocaine combination as a first-line treatment for neonatal seizures in future clinical trials.

Bumetanide potentiates the anti-seizure and disease-modifying effects of midazolam in a noninvasive rat model of term birth asphyxia

Birth asphyxia and the resulting hypoxic-ischemic encephalopathy (HIE) are highly associated with perinatal and neonatal death, neonatal seizures, and an adverse later-life outcome. Currently used drugs, including phenobarbital and midazolam, have limited efficacy to suppress neonatal seizures. There is a medical need to develop new therapies that not only suppress neonatal seizures but also prevent later-life consequences. We have previously shown that the loop diuretic bumetanide does not potentiate the effects of phenobarbital in a rat model of birth asphyxia. Here we compared the effects of bumetanide (0.3 or 10 mg/kg i.p.), midazolam (1 mg/kg i.p.), and a combination of bumetanide and midazolam on neonatal seizures and later-life outcomes in this model. While bumetanide at either dose was ineffective when administered alone, the higher dose of bumetanide markedly potentiated midazolam's effect on neonatal seizures. Median bumetanide brain levels (0.47-0.53 µM) obtained with the higher dose were in the range known to inhibit the Na-K-Cl-cotransporter NKCC1 but it remains to be determined whether brain NKCC1 inhibition was underlying the potentiation of midazolam. When behavioral and cognitive alterations were examined over three months after asphyxia, treatment with the bumetanide/midazolam combination, but not with bumetanide or midazolam alone, prevented impairment of learning and memory. Furthermore, the combination prevented the loss of neurons in the dentate hilus and aberrant mossy fiber sprouting in the CA3a area of the hippocampus. The molecular mechanisms that explain that bumetanide potentiates midazolam but not phenobarbital in the rat model of birth asphyxia remain to be determined.

The loop diuretic torasemide but not azosemide potentiates the anti-seizure and disease-modifying effects of midazolam in a rat model of birth asphyxia

Loop diuretics such as furosemide and bumetanide, which act by inhibiting the Na-K-2Cl cotransporter NKCC2 at the thick ascending limb of the loop of Henle, have been shown to exert anti-seizure effects. However, the exact mechanism of this effect is not known. For bumetanide, it has been suggested that inhibition of the NKCC isoform NKCC1 in the membrane of brain neurons may be involved; however, NKCC1 is expressed by virtually all cell types in the brain, which makes any specific targeting of neuronal NKCC1 by bumetanide impossible. In addition, bumetanide only poorly penetrates the brain. We have previously shown that loop diuretics azosemide and torasemide also potently inhibit NKCC1. In contrast to bumetanide and furosemide, azosemide and torasemide lack a carboxylic group, which should allow them to better penetrate through biomembranes by passive diffusion. Because of the urgent medical need to develop new treatments for neonatal seizures and their adverse outcome, we evaluated the effects of azosemide and torasemide, administered alone or in combination with phenobarbital or midazolam, in a rat model of birth asphyxia and neonatal seizures. Neither diuretic suppressed the seizures when administered alone but torasemide potentiated the anti-seizure effect of midazolam. Brain levels of torasemide were below those needed to inhibit NKCC1. In addition to suppressing seizures, the combination of torasemide and midazolam, but not midazolam alone, prevented the cognitive impairment of the post-asphyxial rats at 3 months after asphyxia. Furthermore, aberrant mossy fiber sprouting in the hippocampus was more effectively prevented by the combination. We assume that either an effect on NKCC1 at the blood-brain barrier and/or cells in the periphery or the NKCC2-mediated diuretic effect of torasemide are involved in the present findings. Our data suggest that torasemide may be a useful option for improving the treatment of neonatal seizures and their adverse outcome.

Midazolam Prevents the Adverse Outcome of Neonatal Asphyxia

OBJECTIVE

Birth asphyxia (BA) is the most frequent cause of neonatal death as well as central nervous system (CNS) injury. BA is often associated with neonatal seizures, which only poorly respond to anti-seizure medications and may contribute to the adverse neurodevelopmental outcome. Using a non-invasive rat model of BA, we have recently reported that the potent benzodiazepine, midazolam, prevents neonatal seizures in ~50% of rat pups. In addition to its anti-seizure effect, midazolam exerts anti-inflammatory actions, which is highly relevant for therapeutic intervention following BA. The 2 major aims of the present study were to examine (1) whether midazolam reduces the adverse outcome of BA, and (2) whether this effect is different in rats that did or did not exhibit neonatal seizures after drug treatment.

METHODS

Behavioral and cognitive tests were performed over 14 months after asphyxia, followed by immunohistochemical analyses.

RESULTS

All vehicle-treated rats had seizures after asphyxia and developed behavioral and cognitive abnormalities, neuroinflammation in gray and white matter, neurodegeneration in the hippocampus and thalamus, and hippocampal mossy fiber sprouting in subsequent months. Administration of midazolam (1 mg/kg i.p.) directly after asphyxia prevented post-asphyctic seizures in ~50% of the rats and resulted in the prevention or decrease of neuroinflammation and the behavioral, cognitive, and neurodegenerative consequences of asphyxia. Except for neurodegeneration in the thalamus, seizures did not seem to contribute to the adverse outcome of asphyxia.

INTERPRETATION

The disease-modifying effect of midazolam identified here strongly suggests that this drug provides a valuable option for improving the treatment and outcome of BA. ANN NEUROL 2023;93:226-243.

Neonatal Hypoxic-Ischemic Encephalopathy: Perspectives of Neuroprotective and Neuroregenerative Treatments

Hypoxic-ischemic encephalopathy (HIE) is a serious condition that could have deleterious neurological outcomes, such as cerebral palsy, neuromotor disability, developmental disability, epilepsy, and sensitive or cognitive problems, and increase the risk of death in severe cases. Once HIE occurs, molecular cascades are triggered favoring the oxidative stress, excitotoxicity, and inflammation damage that promote cell death via apoptosis or necrosis. Currently, the therapeutic hypothermia is the standard of care in HIE; however, it has a small window of action and only can be used in children of more than 36 gestational weeks; for this reason, it is very important to develop new therapies to prevent the progression of the hypoxic-ischemic injury or to develop neuroregenerative therapies in severe HIE cases. The objective of this revision is to describe the emerging treatments for HIE, either preventing cell death for oxidative stress, excitotoxicity, or exacerbated inflammation, as well as describing a new therapeutic approach for neuroregeneration, such as mesenchymal stem cells, brain-derived neurotrophic factor, and gonadotropin realizing hormone agonists.

Comparing the effect of different loading doses of phenobarbitone on serum phenobarbitone levels in babies with neonatal seizures and effect of therapeutic hypothermia on phenobarbitone levels

BACKGROUND

With current recommendation for phenobarbitone dosing, we have noted that babies are extremely sedated with elevated serum phenobarbitone levels. We postulate that asphyxiated neonates with hypoxic liver injury have impaired drug metabolism and renal injury affects drug elimination, thus elevating serum drug levels. Therapeutic hypothermia (TH) could further affect the drug levels.

OBJECTIVE

To determine the serum levels of the phenobarbitone in babies receiving different loading doses of phenobarbitone for neonatal seizures and to study the effect of asphyxia and TH on drug levels.

DESIGN

Prospective observational cohort study.

MATERIAL AND METHODS

Term neonates with seizures of any cause were given phenobarbitone up to a maximum loading of 40 mg/kg followed by maintenance dose of 5 mg/kg/day. Serum phenobarbitone levels were assessed after 4 h of the initial loading dose and subsequently at 24, 48 and 72 h from the time after maximum loading dose. Babies were divided into three groups Group 1 (HIE + TH-hypoxic ischemic encephalopathy undergoing TH), Group 2 (HIE - TH-hypoxic ischemic encephalopathy without TH) and Group 3 (non-HIE group).

RESULTS

A total of 47 babies completed the study. Twenty-three (49%) received 20 mg/kg, 14 (30%) received 30 mg/kg and 10 (21%) received 40 mg per kg of phenobarbitone as loading dose. HIE was the major cause of seizures 28 (59%) followed by hypoglycemia 7 (14%), cerebral malformations 4 (8%), inborn errors of metabolism 2 (4%) and hypocalcemia 1 (2%) while the cause of seizures was not known in 6 (13%). Median (IQR) Phenobarbitone levels at 72 h in babies who received 20 mg/kg loading dose of phenobarbitone was 46.72 (44.02-50.49) mcg/ml in HIE + TH group, 40.53 (28.66-65.09) mcg/ml in HIE - TH group and 49 (37-65) mcg/ml in non-HIE group. After a loading dose of 30 mg/kg, phenobarbitone level was 63.76 (59.5-65.94) mcg/ml in HIE + TH group, 42.5 (34.75-48.75) mcg/ml in HIE - TH group and 42.07 (40-49.05) mcg/ml in non-HIE group. After 40 mg/kg loading dose, it was 62.3 (60.2-64.9) mcg/ml in HIE + TH group, 57.0 (49.8-60.2) mcg/ml in HIE - TH group and 48.15 (40.8-50.97) mcg/ml in non-HIE group. In babies who received >20 mg/kg loading dose, 100% of HIE + TH, 80% of HIE - TH and 60% of non-HIE had supratherapeutic levels of phenobarbitone.

CONCLUSION

At higher loading doses of 30 and 40 mg/kg, steady state concentration of serum phenobarbitone is higher in babies with hypoxic ischemic encephalopathy who underwent TH than in babies with non-HIE causes of seizures. Loading dose beyond 20 mg/kg should be used with close monitoring of serum drug level.

Diagnosis and Management of Seizures in the Preterm Infant

The risk of seizure is increased in premature neonates compared to full term infants, with a distinct profile of etiologies, timing and character. Despite improvements in neonatal care, preterm infants with seizure continue to have higher risk of abnormal neurodevelopmental outcomes when compared to preterm infants without seizures, or to full term infants with seizures. Very limited evidence guides the care of this challenging population, therefore, management of the preterm neonate with seizure is largely extrapolated from the care of full-term neonates. A critical need exists for well-designed clinical trials investigating and validating the safety, efficacy, and outcomes of seizure management in this vulnerable population.

Topiramate Is Safe for Refractory Neonatal Seizures: A Multicenter Retrospective Cohort Study of Necrotizing Enterocolitis Risk

BACKGROUND

A previously published, single-institution, case series suggested an association between topiramate administration in neonates and subsequent development of necrotizing enterocolitis (NEC). This contradicted our more extensive experiences using topiramate in this population. We therefore studied safety and tolerability of topiramate for treating refractory neonatal seizures, hypothesizing that the risk of developing NEC following topiramate exposure was low and that most infants tolerate topiramate.

METHODS

This multicenter retrospective cohort study included seventy-five neonates who received topiramate to treat seizures from January 2011 to October 2019 at three geographically diverse level IV neonatal intensive care units affiliated with pediatric tertiary hospitals. Data included demographics, birth history, seizure etiology, treatment response, side effects, and occurrence and details of NEC.

RESULTS

Three of seventy-five infants (4%) developed NEC following topiramate exposure. These infants did not differ in gestational age, birth weight, seizure etiology, postmenstrual age, weight when topiramate was initiated, or dosing of topiramate. Topiramate was well tolerated. Only three infants (4%) discontinued due to side effects. The most common side effect (20%) was weight loss (typically <5%). Topiramate was felt to be efficacious (61%). Most infants (72%) continued topiramate when discharged.

CONCLUSIONS

Our multicenter, 75-infant study demonstrated that development of NEC after treatment with topiramate was rare (4%) and refutes prior literature suggesting an association. Topiramate was felt to be efficacious and was well tolerated. Although limited by retrospective design, study data are broadly applicable and support thoughtful use of topiramate as a safe, reasonable option for treating refractory neonatal seizures.

Neonatal Seizures: Core Concepts

Seizures are the abnormal, excessive, synchronous discharge of cortical neurons that results in injury to the brain. Seizures presenting in the neonatal period may be the first and only clue to underlying neurological pathology. Despite advances in care, the mortality rate for infants experiencing neonatal seizures is still as high as 20 percent, with up to 65 percent of infants with seizures demonstrating significant morbidity. Early identification and treatment of the seizure or modifiable underlying etiology greatly reduces the extent of morbidity associated with neonatal seizures. Literature, including journal articles and relevant textbooks, was reviewed and condensed into a practical guide to neonatal seizures which includes the pathophysiology of injury associated with neonatal seizures, clinical manifestations, methods of diagnosis, and various options available for treatment.

Evaluation of an ex-vivo neonatal extracorporeal membrane oxygenation circuit on antiepileptic drug sequestration

Antiepileptic dosing information used to manage neonatal patients receiving extracorporeal membrane oxygenation (ECMO) is limited. The objective of this study is to quantify the extent of sequestration of various antiepileptic drugs using an ex-vivo neonatal ECMO circuit. Two neonatal closed-loop ECMO circuits were prepared using a Rotaflow centrifugal pump, custom polyvinylchloride tubing and a Quadrox-i Neonatal membrane oxygenator. After 5 minutes of circuit priming and stabilization with normal saline/albumin or expired human whole blood, single boluses of levetiracetam (200 mg), lacosamide (20 mg), and phenytoin (200 mg) were injected into the circuit. To account for spontaneous drug degradation, two polyvinylchloride beakers were filled with normal saline/albumin or expired human whole blood and equivalent antiepileptic drug doses were prepared. Simultaneous pharmacokinetic samples were collected from the control solution and the pre-centrifugal pump, pre-oxygenator, and post-oxygenator sampling ports from each circuit. Similar drug recovery profiles were observed among the three sampling sites investigated. Percent drug sequestration after a 24-hour circuit flow period was relatively similar between the two different circuits and ranged between 5.5%-13.2% for levetiracetam, 18.4%-22.3% for lacosamide, and 24.5%-30.2% for phenytoin. A comparison at 12 and 24 hours demonstrated similar percent drug sequestration across all three drugs in each circuit. Percent drug sequestrations for levetiracetam and lacosamide were less than 20% and for phenytoin were as high as 30% based on the sampling following single bolus dose administration into a neonatal ECMO circuit. Careful consideration of patient clinical status should be taken in consideration when optimizing antiepileptic therapy in neonates receiving ECMO.

Carbonic anhydrase inhibitors suppress seizures in a rat model of birth asphyxia

OBJECTIVE

Seizures are common in neonates recovering from birth asphyxia but there is general consensus that current pharmacotherapy is suboptimal and that novel antiseizure drugs are needed. We recently showed in a rat model of birth asphyxia that seizures are triggered by the post-asphyxia recovery of brain pH. Here our aim was to investigate whether carbonic anhydrase inhibitors (CAIs), which induce systemic acidosis, block the post-asphyxia seizures.

METHODS

The CAIs acetazolamide (AZA), benzolamide (BZA), and ethoxzolamide (EZA) were administered intraperitoneally or intravenously to 11-day-old rats exposed to intermittent asphyxia (30 min; three 7+3 min cycles of 9% and 5% O₂ at 20% CO₂ ). Electrode measurements of intracortical pH, Po₂ , and local field potentials (LFPs) were made under urethane anesthesia. Convulsive seizures and blood acid-base parameters were examined in freely behaving animals.

RESULTS

The three CAIs decreased brain pH by 0.14-0.17 pH units and suppressed electrographic post-asphyxia seizures. AZA, BZA, and EZA differ greatly in their lipid solubility (EZA > AZA > BZA) and pharmacokinetics. However, there were only minor differences in the delay (range 0.8-3.7 min) from intraperitoneal application to their action on brain pH. The CAIs induced a modest post-asphyxia elevation of brain Po₂ that had no effect on LFP activity. AZA was tested in freely behaving rats, in which it induced a respiratory acidosis and decreased the incidence of convulsive seizures from 9 of 20 to 2 of 17 animals.

SIGNIFICANCE

AZA, BZA, and EZA effectively block post-asphyxia seizures. Despite the differences in their pharmacokinetics, they had similar effects on brain pH, which indicates that their antiseizure mode of action was based on respiratory (hypercapnic) acidosis resulting from inhibition of blood-borne and extracellular vascular carbonic anhydrases. AZA has been used for several indications in neonates, suggesting that it can be safely repurposed for the treatment of neonatal seizures as an add-on to the current treatment regimen.

Rapid infusion of excessive phenytoin: A newborn autopsy case

The patient was a two-day-old female infant. The patient's mother was a primigravid in her 20 s who developed premature abruption of the normal placenta on the first day of the 33rd week of gestation. The infant was born by emergency cesarean section with severe neonatal asphyxia with a birth weight of 1928 g. Spontaneous circulation was returned 11 min after birth. The infant was treated under mechanical ventilation in the neonatal intensive care unit, and phenobarbital was administered for repeated seizures. On day 2, spontaneous respiration was observed; however, the patient developed seizures repeatedly. The dose of phenobarbital reached the maximum and was switched to midazolam. In the early morning of day 3, while midazolam was administered up to the maximum dose, the infant developed status epilepticus, and the anticonvulsant drug was changed to phenytoin. Due to a calculation error, the intravenous administration of phenytoin was started at 400 mg/30 min, which is 10-fold of the normal dose. Six minutes later, after 80 mg was administered, the administration was stopped due to a drop in blood pressure; however, the infant died of cardiac arrest. An autopsy, which was performed approximately 25 h after death, revealed the blood phenytoin concentration in the heart was 63.85 μg/mL. The cause of death was determined to be acute phenytoin toxicity. This is the first fatal case reported of the blood concentration of phenytoin caused by rapid intravenous administration.

A combination of phenobarbital and the bumetanide derivative bumepamine prevents neonatal seizures and subsequent hippocampal neurodegeneration in a rat model of birth asphyxia

OBJECTIVES

Bumetanide was suggested as an adjunct to phenobarbital for suppression of neonatal seizures. This suggestion was based on the idea that bumetanide, by reducing intraneuronal chloride accumulation through inhibition of the Na-K-2Cl cotransporter NKCC1, may attenuate or abolish depolarizing γ-aminobutyric acid (GABA) responses caused by birth asphyxia. However, a first proof-of-concept clinical trial failed. This could have had several reasons, including bumetanide's poor brain penetration, the wide cellular NKCC1 expression pattern in the brain, and problems with the general concept of NKCC1's role in neonatal seizures. We recently replicated the clinical failure of bumetanide to potentiate phenobarbital's effect in a novel rat model of birth asphyxia. In this study, a clinically relevant dose (0.3 mg/kg) of bumetanide was used that does not lead to NKCC1-inhibitory brain levels. The aim of the present experiments was to examine whether a much higher dose (10 mg/kg) of bumetanide is capable of potentiating phenobarbital in this rat model. Furthermore, the effects of the two lipophilic bumetanide derivatives, the ester prodrug N,N-dimethylaminoethylester of bumetanide (DIMAEB) and the benzylamine derivative bumepamine, were examined at equimolar doses.

METHODS

Intermittent asphyxia was induced for 30 min by exposing male and female P11 rat pups to three 7 + 3 min cycles of 9% and 5% O₂ at constant 20% CO₂ . All control pups exhibited neonatal seizures after the asphyxia.

RESULTS

Even at 10 mg/kg, bumetanide did not potentiate the effect of a submaximal dose (15 mg/kg) of phenobarbital on seizure incidence, whereas a significant suppression of neonatal seizures was determined for combinations of phenobarbital with DIMAEB or, more effectively, bumepamine, which, however, does not inhibit NKCC1. Of interest, the bumepamine/phenobarbital combination prevented the neurodegenerative consequences of asphyxia and seizures in the hippocampus.

SIGNIFICANCE

Both bumepamine and DIMAEB are promising tools that may help to develop more effective lead compounds for clinical trials.

Treating the symptom or treating the disease in neonatal seizures: a systematic review of the literature

Aim

The existing treatment options for neonatal seizures have expanded over the last few decades, but no consensus has been reached regarding the optimal therapeutic protocols. We systematically reviewed the available literature examining neonatal seizure treatments to clarify which drugs are the most effective for the treatment of specific neurologic disorders in newborns.

Method

We reviewed all available, published, literature, identified using PubMed (published between August 1949 and November 2020), that focused on the pharmacological treatment of electroencephalogram (EEG)-confirmed neonatal seizures.

Results

Our search identified 427 articles, of which 67 were included in this review. Current knowledge allowed us to highlight the good clinical and electrographic responses of genetic early-onset epilepsies to sodium channel blockers and the overall good response to levetiracetam, whose administration has also been demonstrated to be safe in both full-term and preterm newborns.

Interpretation

Our work contributes by confirming the limited availability of evidence that can be used to guide the use of anticonvulsants to treat newborns in clinical practice and examining the efficacy and potentially harmful side effects of currently available drugs when used to treat the developing newborn brain; therefore, our work might also serve as a clinical reference for future studies.

Reply to the commentary by Ben-Ari and Delpire: Bumetanide and neonatal seizures: Fiction versus reality

In this response to a commentary by Ben-Ari and Delpire on our recent study on the pharmacology of neonatal seizures in a novel, physiologically validated rat model of birth asphyxia, we wish to rectify their inaccurate descriptions of our model and data. Furthermore, because Ben-Ari and Delpire suggest that negative data on bumetanide from preclinical and clinical trials of neonatal seizures have few implications for (alleged) bumetanide actions on neurons in other brain disorders, we will discuss this topic as well. Based on the poor brain penetration of bumetanide, combined with the extremely wide cellular expression patterns of the target protein NKCC1, it is obvious that the numerous actions of systemically applied bumetanide described in the literature are not mediated by the drug's effects on central neurons.

Neonatal Seizures Revisited

Seizures are the most common neurological disorder in newborns and are most prevalent in the neonatal period. They are mostly caused by severe disorders of the central nervous system (CNS). However, they can also be a sign of the immaturity of the infant’s brain, which is characterized by the presence of specific factors that increase excitation and reduce inhibition. The most common disorders which result in acute brain damage and can manifest as seizures in neonates include hypoxic-ischemic encephalopathy (HIE), ischemic stroke, intracranial hemorrhage, infections of the CNS as well as electrolyte and biochemical disturbances. The therapeutic management of neonates and the prognosis are different depending on the etiology of the disorders that cause seizures which can lead to death or disability. Therefore, establishing a prompt diagnosis and implementing appropriate treatment are significant, as they can limit adverse long-term effects and improve outcomes. In this review paper, we present the latest reports on the etiology, pathomechanism, clinical symptoms and guidelines for the management of neonates with acute symptomatic seizures.

Efficacy of Fosphenytoin as First-Line Antiseizure Medication for Neonatal Seizures Compared to Phenobarbital

Currently used treatment protocols for neonatal seizures vary among centers with limited evidence to support the choice of a given antiseizure medication. Because of concerns about the potential negative impact of phenobarbital on long-term neurodevelopment outcomes, our unit transitioned to fosphenytoin as the first-line antiseizure medication. A retrospective observational cohort study was conducted to compare the acute and long-term outcomes of fosphenytoin and phenobarbital as first-line antiseizure medication for neonatal seizure treatment. The 2 study groups had similar baseline characteristics for neonatal variables as well as maternal antenatal complications. We did not find any differences in the acute outcomes between the 2 groups. However, significantly fewer infants in the fosphenytoin group had moderate-to-severe neurodevelopmental delay at the 18- and 24-month assessments. In conclusion, although both medications were equally efficacious for acute neonatal seizure control, fosphenytoin had the potential for significantly better neurodevelopmental outcomes at 18-24 months of age.

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.

Perinatal Brain Injury and Inflammation: Lessons from Experimental Murine Models

Perinatal brain injury or neonatal encephalopathy (NE) is a state of disturbed neurological function in neonates, caused by a number of different aetiologies. The most prominent cause of NE is hypoxic ischaemic encephalopathy, which can often induce seizures. NE and neonatal seizures are both associated with poor neurological outcomes, resulting in conditions such as cerebral palsy, epilepsy, autism, schizophrenia and intellectual disability. The current treatment strategies for NE and neonatal seizures have suboptimal success in effectively treating neonates. Therapeutic hypothermia is currently used to treat NE and has been shown to reduce morbidity and has neuroprotective effects. However, its success varies between developed and developing countries, most likely as a result of lack of sufficient resources. The first-line pharmacological treatment for NE is phenobarbital, followed by phenytoin, fosphenytoin and lidocaine as second-line treatments. While these drugs are mostly effective at halting seizure activity, they are associated with long-lasting adverse neurological effects on development. Over the last years, inflammation has been recognized as a trigger of NE and seizures, and evidence has indicated that this inflammation plays a role in the long-term neuronal damage experienced by survivors. Researchers are therefore investigating the possible neuroprotective effects that could be achieved by using anti-inflammatory drugs in the treatment of NE. In this review we will highlight the current knowledge of the inflammatory response after perinatal brain injury and what we can learn from animal models.

Phenobarbital and midazolam suppress neonatal seizures in a noninvasive rat model of birth asphyxia, whereas bumetanide is ineffective

OBJECTIVE

Neonatal seizures are the most frequent type of neurological emergency in newborn infants, often being a consequence of prolonged perinatal asphyxia. Phenobarbital is currently the most widely used antiseizure drug for treatment of neonatal seizures, but fails to stop them in ~50% of cases. In a neonatal hypoxia-only model based on 11-day-old (P11) rats, the NKCC1 inhibitor bumetanide was reported to potentiate the antiseizure activity of phenobarbital, whereas it was ineffective in a human trial in neonates. The aim of this study was to evaluate the effect of clinically relevant doses of bumetanide as add-on to phenobarbital on neonatal seizures in a noninvasive model of birth asphyxia in P11 rats, designed for better translation to the human term neonate.

METHODS

Intermittent asphyxia was induced for 30 minutes by exposing the rat pups to three 7 + 3-minute cycles of 9% and 5% O₂ at constant 20% CO₂ . Drug treatments were administered intraperitoneally either before or immediately after asphyxia.

RESULTS

All untreated rat pups had seizures within 10 minutes after termination of asphyxia. Phenobarbital significantly blocked seizures when applied before asphyxia at 30 mg/kg but not 15 mg/kg. Administration of phenobarbital after asphyxia was ineffective, whereas midazolam (0.3 or 1 mg/kg) exerted significant antiseizure effects when administered before or after asphyxia. In general, focal seizures were more resistant to treatment than generalized convulsive seizures. Bumetanide (0.3 mg/kg) alone or in combination with phenobarbital (15 or 30 mg/kg) exerted no significant effect on seizure occurrence.

SIGNIFICANCE

The data demonstrate that bumetanide does not increase the efficacy of phenobarbital in a model of birth asphyxia, which is consistent with the negative data of the recent human trial. The translational data obtained with the novel rat model of birth asphyxia indicate that it is a useful tool to evaluate novel treatments for neonatal seizures.

Hydrolytic biotransformation of the bumetanide ester prodrug DIMAEB to bumetanide by esterases in neonatal human and rat serum and neonatal rat brain-A new treatment strategy for neonatal seizures?

OBJECTIVES

The loop diuretic bumetanide has been proposed previously as an adjunct treatment for neonatal seizures because bumetanide is thought to potentiate the action of γ-aminobutyric acid (GABA)ergic drugs such as phenobarbital by preventing abnormal intracellular accumulation of chloride and the subsequent "GABA shift." However, a clinical trial in neonates failed to demonstrate such a synergistic effect of bumetanide, most likely because this drug only poorly penetrates into the brain. This prompted us to develop lipophilic prodrugs of bumetanide, such as the N,N-dimethylaminoethyl ester of bumetanide (DIMAEB), which rapidly enter the brain where they are hydrolyzed by esterases to the parent compound, as demonstrated previously by us in adult rodents. However, it is not known whether esterase activity in neonates is sufficient to hydrolyze ester prodrugs such as DIMAEB.

METHODS

In the present study, we examined whether esterases in neonatal serum of healthy term infants are capable of hydrolyzing DIMAEB to bumetanide and whether this activity is different from the serum of adults. Furthermore, to extrapolate the findings to brain tissue, we performed experiments with brain tissue and serum of neonatal and adult rats.

RESULTS

Serum from 1- to 2-day-old infants was capable of hydrolyzing DIMAEB to bumetanide at a rate similar to that of serum from adult individuals. Similarly, serum and brain tissue of neonatal rats rapidly hydrolyzed DIMAEB to bumetanide.

SIGNIFICANCE

These data provide a prerequisite for further evaluating the potential of bumetanide prodrugs as add-on therapy to phenobarbital and other antiseizure drugs as a new strategy for improving pharmacotherapy of neonatal seizures.

Therapeutic Drug Monitoring Is a Feasible Tool to Personalize Drug Administration in Neonates Using New Techniques: An Overview on the Pharmacokinetics and Pharmacodynamics in Neonatal Age

Therapeutic drug monitoring (TDM) should be adopted in all neonatal intensive care units (NICUs), where the most preterm and fragile babies are hospitalized and treated with many drugs, considering that organs and metabolic pathways undergo deep and progressive maturation processes after birth. Different developmental changes are involved in interindividual variability in response to drugs. A crucial point of TDM is the choice of the bioanalytical method and of the sample to use. TDM in neonates is primarily used for antibiotics, antifungals, and antiepileptic drugs in clinical practice. TDM appears to be particularly promising in specific populations: neonates who undergo therapeutic hypothermia or extracorporeal life support, preterm infants, infants who need a tailored dose of anticancer drugs. This review provides an overview of the latest advances in this field, showing options for a personalized therapy in newborns and infants.

Lidocaine as treatment for neonatal seizures: Evaluation of previously developed population pharmacokinetic models and dosing regimen

AIMS

Lidocaine is used to treat neonatal seizures refractory to other anticonvulsants. It is effective, but also associated with cardiac toxicity. Previous studies have reported on the pharmacokinetics of lidocaine in preterm and term neonates and proposed a dosing regimen for effective and safe lidocaine use. The objective of this study was to evaluate the previously developed pharmacokinetic models and dosing regimen. As a secondary objective, lidocaine effectiveness and safety were assessed.

METHODS

Data from preterm neonates and (near-)term neonates with and without therapeutic hypothermia receiving lidocaine were included. Pharmacokinetic analyses were performed using non-linear mixed effects modelling. Simulations were performed to evaluate the proposed dosing regimen. Lidocaine was considered effective if no additional anticonvulsant was required and safe if no cardiac adverse events occurred.

RESULTS

Data were available for 159 neonates; 50 (31.4%) preterm and 109 term neonates, of whom 49 (30.8%) were treated with therapeutic hypothermia. Lidocaine clearance increased with postmenstrual age by 0.69%/day (95% confidence interval 0.54-0.84%). During therapeutic hypothermia (33.5°C), lidocaine clearance was reduced by 21.8% (7.26%/°C, 95% confidence interval 1.63-11.2%) compared to normothermia (36.5°C). Simulations demonstrated that the proposed dosing regimen leads to adequate average lidocaine plasma concentrations. Effectiveness and safety were assessed in 92 neonates. Overall effectiveness was 53.3% (49/92) and 56.5% (13/23) for neonates receiving the proposed dosing regimen. No cardiac toxicity was observed.

CONCLUSION

Lidocaine pharmacokinetics was adequately described across the entire neonatal age range. With the proposed dosing regimen, lidocaine can provide effective and safe treatment for neonatal seizures.

Efficacy of antiepileptic drugs in neonatal seizures: a systematic review protocol

INTRODUCTION

Seizures are one of the most common neurological disorders of neonates, which is also an emergency in the neonatal intensive care unit. For neonates, the recommended first-line antiepileptic drugs (AEDs) include phenobarbitone, which may be effective in only 50% of seizures. Some new AEDs, such as levetiracetam, have been shown to be effective in adults and older children. However, their efficacy for neonatal seizures remains uncertain. The aim of this investigation is to conduct a systematic review to evaluate the efficacy of all AEDs in neonates. Additionally, the long-term outcomes following neonatal seizures, in relation to the development of cerebral palsy and epilepsy, will be studied.

METHOD

We will perform a systematic review including randomised controlled studies (RCTs), cohort studies, case-controlled studies and case series studies which evaluated the efficacy of AEDs and short-term and long-term outcomes in neonatal seizures. PubMed, Embase, Web of Science, Cochrane Library and Clinical trial.gov will be searched. There will be no language restriction. Risk bias in RCTs will be evaluated by the Cochrane risk-of-bias tool, while cohort and case-control studies will be evaluated by the Newcastle-Ottawa Scale. A network meta-analysis will be performed by the Bayesian model using WinBUGS V.1.4.3 and R software if there is a high degree of homogeneity among studies. Otherwise, we will perform a narrative review without pooling. Subgroup analyses will be performed in different AEDs and dosage groups.

OUTCOME

The primary outcomes will be seizure cessation confirmed by electroencephalogram and long-term neurodevelopmental outcome. Secondary outcomes will be neonatal mortality during hospitalisation and suspected drug toxicity.

ETHICS AND DISSEMINATION

Formal ethical approval is not required as no primary data are collected. This systematic review will be disseminated through a peer-reviewed publication.

Pharmacotherapy for Focal Seizures in Children and Adolescents

Focal-onset seizures are among the most common forms of seizures in children and adolescents and can be caused by a wide diversity of acquired or genetic etiologies. Despite the increasing array of antiseizure drugs available, treatment of focal-onset seizures in this population remains problematic, with as many as one-third of children having seizures refractory to medications. This review discusses contemporary concepts in focal seizure classification and pathophysiology and describes the antiseizure medications most commonly chosen for this age group. As antiseizure drug efficacy is comparable in children and adults, here we focus on pharmacokinetic aspects, drug-drug interactions, and side effect profiles. Finally, we provide some suggestions for choosing the optimal medication for the appropriate patient.

Preparation and Physicochemical Stability of Liquid Oral Dosage Forms Free of Potentially Harmful Excipient Designed for Pediatric Patients

Dexamethasone, hydrochlorothiazide, spironolactone, and phenytoin are commonly used in neonates, but no age-appropriate formulation containing these active pharmaceutical ingredients (APIs) is commercially available. Thus, pharmaceutical compounding of the liquid oral dosage form is required to enable newborn administration. A problem common to the compounded preparations described in the literature is that they include potentially harmful excipients (PHEs). Therefore, the aim of this study was to evaluate the feasibility of compounding oral liquid dosage forms free of PHE, containing dexamethasone, hydrochlorothiazide, phenytoin, or spironolactone and to assess their physicochemical stability. Due to the poor water solubility of the targeted APIs, oral suspensions were compounded using Syrspend® SF-PH4 Dry, a suspending vehicle free of PHE. Four HPLC coupled to UV spectrometry (HPLC-UV) stability-indicating methods were developed and validated according to international guidelines to assay the strength of the targeted APIs. Whatever storage condition was used (5 ± 3 °C or 22 ± 4 °C), no significant degradation of API occurred in compounded oral suspensions. Overall, the results attest to the physical and chemical stability of the four oral liquid dosage forms over 60 days under regular storage temperatures. Finally, the use of the proposed oral suspensions provides a reliable solution to reduce the exposure of children to potentially harmful excipients.

Taurine potentiates the anticonvulsive effect of the GABAA agonist muscimol and pentobarbital in the immature mouse hippocampus

OBJECTIVE

The high incidence of epileptic seizures in neonates and their frequent refractoriness to pharmacologic therapies require identification of new therapeutical options. Therefore, we investigated whether the modulatory effect of taurine on γ-aminobutyric acid (GABA)_A receptors can enhance the anticonvulsive potential of the GABA_A receptor agonist muscimol and of the barbiturate pentobarbital.

METHODS

We performed field potential recordings in in toto hippocampus preparations of immature (postnatal days 4-7) C57Bl/6 mouse pups. Spontaneous epileptiform activity was induced by the continuous presence of the potassium channel blocker 4-aminopyridine and the glycinergic antagonist strychnine in Mg²⁺ -free solutions.

RESULTS

Bath application of 0.1 μmol/L muscimol increases the occurrence of recurrent epileptiform discharges, whereas they are significantly attenuated in a dose-dependent manner by muscimol in concentrations between 0.5 and 5 μmol/L. Taurine at concentrations between 0.1 and 0.5 mmol/L induces a proconvulsive effect, but upon coapplication, it significantly augments the anticonvulsive effect of moderate muscimol doses (0.5-1 μmol/L). In addition, the anticonvulsive effect of 100 and 200 μmol/L pentobarbital is increased significantly in the presence of 0.5 μmol/L taurine.

SIGNIFICANCE

These observations demonstrate that taurine can indeed enhance the anticonvulsive effects of muscimol and pentobarbital, suggesting that taurine may act as a positive modulator on GABA_A receptors. Thus, interfering with the modulatory taurine binding site of GABA_A receptors or the interstitial taurine concentration may provide new therapeutical options for anticonvulsive therapies in neonates.

Outcome in preterm infants with seizures

Most neonatal seizures in preterm newborns are of acute symptomatic origin with a prevalence higher than in full-term infants. To date, recommendations for management of seizures in preterm newborns are scarce and do not differ from those in full-term newborns. Mortality in preterm newborns with seizures has significantly declined over the last decades, from figures of 84%-94% in the 1970s and 1980s to 22%-45% in the last years. However, mortality is significantly higher in those with a birth weight<1000g and a gestational age<28 weeks. Seizures are a strong predictor of unfavorable outcomes, including not only cerebral palsy, epilepsy, and intellectual disability, but also vision, hearing impairment, and microcephaly. The majority of patients with developmental delay are severely affected and this is usually associated with cerebral palsy. Furthermore, the incidence of epilepsy after neonatal seizures seems to be lower in preterm than in full-term infants but the risk is approximately 40 times greater than in the general population. Clinical studies cannot disentangle the specific and independent contributions of seizure-induced functional changes and the role of etiology and brain damage severity in determining the long-term outcomes in these newborns.

Symptomatic seizures in preterm newborns: a review on clinical features and prognosis

Neonatal seizures are the most common neurological event in newborns, showing higher prevalence in preterm than in full-term infants. In the majority of cases they represent acute symptomatic phenomena, the main etiologies being intraventricular haemorrhage, hypoxic-ischemic encephalopathy, central nervous system infections and transient metabolic derangements.Current definition of neonatal seizures requires detection of paroxysmal EEG-changes, and in preterm newborns the incidence of electrographic-only seizures seems to be particularly high, further stressing the crucial role of electroencephalogram monitoring in this population. Imaging work-up includes an integration of serial cranial ultrasound and brain magnetic resonance at term-equivalent age. Unfavourable outcomes following seizures in preterm infants include death, neurodevelopmental impairment, epilepsy, cerebral palsy, hearing and visual impairment. As experimental evidence suggests a detrimental role of seizures per se in determining subsequent outcome, they should be promptly treated with the aim to reduce seizure burden and long-term disabilities. However, neonatal seizures show low response to conventional anticonvulsant drugs, and this is even more evident in preterm newborns, due to intrinsic developmental factors. As a consequence, as literature does not provide any specific guidelines, due to the lack of robust evidence, off-label medications are often administered in clinical practice.

What is new: Talk about status epilepticus in the neonatal period

Nowadays, no general consensus was achieved regarding neonatal status epilepticus and its definition. Indeed, different criteria (mainly based on seizure duration) were used. Whereas a recent proposal has been developed to define status epilepticus in older ages, it seems that the peculiar characteristics of neonatal seizures and of the immature brain make difficult to find a tailored definition for this period of life. Achieving a consensus on this entity would mean to make the first step toward a targeted therapeutic strategy of intervention.

Acute symptomatic neonatal seizures in preterm neonates: etiologies and treatments

Acute symptomatic neonatal seizures in preterm newborns are a relevant clinical challenge due to the presence of many knowledge gaps. Etiology-wise, acute symptomatic seizures have an age-specific epidemiology, with intraventricular hemorrhage and its complications representing the first cause in extremely and very preterm neonates, whereas other etiologies have similar occurrence rates as in full-term infants. Specific treatment strategies for the premature neonates are not yet available. Studies suggest a similarly low response rate with even more unfavorable prognosis than in full-term infants. Pharmacodynamic and pharmacokinetic changes are likely under way during the preterm period, with the potential to affect both effectiveness and safety of antiepileptic drugs in these patients. However, due to the lack of clear evidence to guide prioritization of second-line drugs, off-label medications are frequently indicated by review papers and flow-charts, and are prescribed in clinical practice. We therefore conclude by exploring potential future lines of research.

Acute symptomatic seizures in term neonates: Etiologies and treatments

Acute symptomatic seizures caused by either diffuse or focal perinatal hypoxic-ischemic insults and intracranial hemorrhage in term newborns make up the large majority of all neonatal seizures. Acute seizures are one of the most common neurological disorders in term newborns who require admission to the neonatal intensive care unit. Despite elucidation of seizure pathogenesis in this population using animal models, treatment is limited by a lack of good evidence-based guidelines because of a paucity of rigorously conducted clinical trials or prospective studies in human newborns. A result of this knowledge gap is that management, particularly drug choice, is guided by clinical experience rather than by data informing drug efficacy and safety. This review summarizes the common etiologies and pathogenesis of acute symptomatic seizures, and the current data informing their treatment, including potential novel drugs, together with a suggested treatment algorithm.

Efficacy of levetiracetam for neonatal seizures in preterm infants

Background

Neonatal seizures remain a significant clinical problem, and therapeutic options are still not diverse with limited efficacy. Levetiracetam (LEV) is a relatively new and wide spectrum anti-seizure medication with favorable pharmacokinetics and safety profile. In the recent decades, LEV has been increasingly used for the treatment of neonatal seizures. The aim of this study was to describe the experience of using LEV as the first line anti-seizure medication for preterm infants.

Methods

A retrospective analysis of 37 preterm infants who were treated with LEV as the first-line anti-seizure medication was performed.

Results

Mean gestational age of the 37 preterm infants was 31.5 ± 1.9 weeks (range, 26 to 36^+ 6 weeks). Twenty-one infants (57%) were seizure-free while given LEV at the end of the first week, and no additional anti-seizure medication was required. Loading doses of LEV ranged from 40 to 60 mg/kg (mean 56 mg/kg) and the maintenance dose ranged from 20 to 30 mg/kg (mean 23 mg/kg). No adverse effect was observed.

Conclusions

Levetiracetam can be a good and safe choice for treatment of neonatal seizures in preterm infants. Prospective double blind controlled studies are needed in the future.

Drug Treatment of Seizures and Epilepsy in Newborns and Children

The mainstay of treatment of childhood epilepsy is to administer antiepileptic drugs (AEDs). This article provides an overview of the clinical approach to drug treatment of childhood epilepsy, focusing on general principles of therapy and properties of recently introduced medications. Initiation and cessation of therapy, adverse medication effects, drug interactions, indications for the various AEDs, and off-label use of AEDs are reviewed. The distinct challenges in treatment of epileptic spasms and neonatal seizures are addressed. Finally, ideas for the future of drug treatment of childhood epilepsy are presented, with particular attention to precision medicine.

Vasopressin excites interneurons to suppress hippocampal network activity across a broad span of brain maturity at birth

During birth in mammals, a pronounced surge of fetal peripheral stress hormones takes place to promote survival in the transition to the extrauterine environment. However, it is not known whether the hormonal signaling involves central pathways with direct protective effects on the perinatal brain. Here, we show that arginine vasopressin specifically activates interneurons to suppress spontaneous network events in the perinatal hippocampus. Experiments done on the altricial rat and precocial guinea pig neonate demonstrated that the effect of vasopressin is not dependent on the level of maturation (depolarizing vs. hyperpolarizing) of postsynaptic GABA_A receptor actions. Thus, the fetal mammalian brain is equipped with an evolutionarily conserved mechanism well-suited to suppress energetically expensive correlated network events under conditions of reduced oxygen supply at birth.

The use of phenobarbital and other anti-seizure drugs in newborns

Neonatal seizures constitute the most frequent presenting neurologic sign encountered in the neonatal intensive care unit. Despite limited efficacy and safety data, phenobarbital continues to be used near-universally as the first-line anti-seizure drug (ASD) in neonates. The choice of second-line ASDs varies by provider and institution, and is still not supported by sufficient scientific evidence. In this review, we discuss the available evidence supporting the efficacy, mechanism of action, potential adverse effects, key pharmacokinetic characteristics such as interaction with therapeutic hypothermia, logistical issues, and rationale for use of neonatal ASDs. We describe the widely used neonatal ASDs, namely phenobarbital, phenytoin, midazolam, and levetiracetam, in addition to potential ASDs, including lidocaine, topiramate, and bumetanide.

Effects of P2X7 receptor antagonists on hypoxia-induced neonatal seizures in mice

Neonatal seizures are a common consequence of hypoxic/ischemic encephalopathy (HIE). Phenobarbital remains the frontline treatment for neonatal seizures but is often ineffective. The P2X7 receptor (P2X7R) is a cell surface-expressed ionotropic receptor activated by high amounts of ATP which may be released during seizures or as a consequence of tissue injury. Here, we explored the role of the P2X7R in a mouse model of neonatal seizures induced by hypoxia. Exposure of postnatal day 7 (P7) mouse pups to global hypoxia (5% O₂ for 15 min) produced electrographically-defined seizures with behavioural correlates that persisted after restitution of normoxia. Expression of the P2X7R showed age-dependent increases in the hippocampus and neocortex of developing mice and was present in human neonatal brain. P2X7R transcript and protein levels were increased 24 h after neonatal hypoxia-induced seizures in mouse pups. EEG recordings in pups determined that injection of the P2X7R antagonist A-438079 (25 mg/kg^-1, intraperitoneal) reduced electrographic seizure number, EEG power and spiking during hypoxia. A-438079 did not reduce post-hypoxia seizures. Caspase-1 processing and molecular markers of inflammation and microglia were reduced in A438079-treated mice. Electrographic seizure-suppressive effects were also observed with a second P2X7R antagonist, JNJ-47965567, in the same model. The present study shows hypoxia-induced seizures alter expression of purinergic and neuroinflammatory signalling components and suggest potential applications but also limitations of the P2X7R as a target for the treatment of HIE and other causes of neonatal seizures.

Different response to antiepileptic drugs according to the type of epileptic events in a neonatal ischemia-reperfusion model

Perinatal arterial stroke is the most frequent form of cerebral infarction in children. Neonatal seizures are the most frequent symptom during the neonatal period. The current management of perinatal stroke is based on supportive care. It is currently unknown if treatment of the seizures modifies the outcome, and no clinical studies have focused on seizures during neonatal stroke. We studied the effect of phenobarbital and levetiracetam on an ischemic-reperfusion stroke model in P7 rats using prolonged electroencephalographic recordings and a histologic analysis of the brain (24h after injury). The following two types of epileptic events were observed: 1) bursts of high amplitude spikes during ischemia and the first hours of reperfusion and 2) organized seizures consisting in discharges of a 1-2Hz spike-and-wave. Both phenobarbital and levetiracetam decreased the total duration of the bursts of high amplitude spikes. Phenobarbital also delayed the start of seizures without changing the total duration of epileptic discharges. The markedly limited efficacy of the antiepileptic drugs studied in our neonatal stroke rat model is frequently observed in human neonatal seizures. Both drugs did not modify the stroke volume, which suggests that the modification of the quantity of bursts of high amplitude spikes does not influence the infarct size. In the absence of a reduction in seizure burden by the antiepileptic drugs, we increased the seizure burden and stroke volume by combining our neonatal stroke model with a lithium-pilocarpine-induced status epilepticus. Our data suggest that the reduction of burst of spikes did not influence the stroke volume. The presence of organized seizure with a pattern close to what is observed in human newborns seems related to the presence of the infarct. Further research is required to determine the relationship between seizure burden and infarct volume.