Brivaracetam, a selective high-affinity synaptic vesicle protein 2A (SV2A) ligand with preclinical evidence of high brain permeability and fast onset of action

Narrative Review of Brivaracetam: Preclinical Profile and Clinical Benefits in the Treatment of Patients with Epilepsy

One third of patients with epilepsy will continue to have uncontrolled seizures despite treatment with antiseizure medications (ASMs). There is therefore a need to develop novel ASMs. Brivaracetam (BRV) is an ASM that was developed in a major drug discovery program aimed at identifying selective, high-affinity synaptic vesicle protein 2A (SV2A) ligands, the target molecule of levetiracetam. BRV binds to SV2A with 15- to 30-fold higher affinity and greater selectivity than levetiracetam. BRV has broad-spectrum antiseizure activity in animal models of epilepsy, a favorable pharmacokinetic profile, few clinically relevant drug-drug interactions, and rapid brain penetration. BRV is available in oral and intravenous formulations and can be initiated at target dose without titration. Efficacy and safety of adjunctive BRV (50-200 mg/day) treatment of focal-onset seizures was demonstrated in three pivotal phase III trials (NCT00490035/NCT00464269/NCT01261325), including in patients who had previously failed levetiracetam. Efficacy and safety of adjunctive BRV were also demonstrated in adult Asian patients with focal-onset seizures (NCT03083665). In several open-label trials (NCT00150800/NCT00175916/NCT01339559), long-term safety and tolerability of adjunctive BRV was established, with efficacy maintained for up to 14 years, with high retention rates. Evidence from daily clinical practice highlights BRV effectiveness and tolerability in specific epilepsy patient populations with high unmet needs: the elderly (≥ 65 years of age), children (< 16 years of age), patients with cognitive impairment, patients with psychiatric comorbid conditions, and patients with acquired epilepsy of specific etiologies (post-stroke epilepsy/brain tumor related epilepsy/traumatic brain injury-related epilepsy). Here, we review the preclinical profile and clinical benefits of BRV from pivotal trials and recently published evidence from daily clinical practice.

Assessment of cerebral drug occupancy in humans using a single PET-scan: A [11C]UCB-J PET study

PURPOSE

Here, we evaluate a PET displacement model with a Single-step and Numerical solution in healthy individuals using the synaptic vesicle glycoprotein (SV2A) PET-tracer [11C]UCB-J and the anti-seizure medication levetiracetam (LEV). We aimed to (1) validate the displacement model by comparing the brain LEV-SV2A occupancy from a single PET scan with the occupancy derived from two PET scans and the Lassen plot and (2) determine the plasma LEV concentration-SV2A occupancy curve in healthy individuals.

METHODS

Eleven healthy individuals (five females, mean age 35.5 [range: 25-47] years) underwent two 120-min [11C]UCB-J PET scans where an LEV dose (5-30 mg/kg) was administered intravenously halfway through the first PET scan to partially displace radioligand binding to SV2A. Five individuals were scanned twice on the same day; the remaining six were scanned once on two separate days, receiving two identical LEV doses. Arterial blood samples were acquired to determine the arterial input function and plasma LEV concentrations. Using the displacement model, the SV2A-LEV target engagement was calculated and compared with the Lassen plot method. The resulting data were fitted with a single-site binding model.

RESULTS

SV2A occupancies and VND estimates derived from the displacement model were not significantly different from the Lassen plot (p = 0.55 and 0.13, respectively). The coefficient of variation was 14.6% vs. 17.3% for the Numerical and the Single-step solution in Bland-Altman comparisons with the Lassen plot. The average half maximal inhibitory concentration (IC50), as estimated from the area under the curve of the plasma LEV concentration, was 12.5 µg/mL (95% CI: 5-25) for the Single-Step solution, 11.8 µg/mL (95% CI: 4-25) for the Numerical solution, and 6.3 µg/mL (95% CI: 0.08-21) for the Lassen plot. Constraining Emax to 100% did not significantly improve model fits.

CONCLUSION

Plasma LEV concentration vs. SV2A occupancy can be determined in humans using a single PET scan displacement model. The average concentration of the three computed IC50 values ranges between 6.3 and 12.5 µg/mL. The next step is to use the displacement model to evaluate LEV occupancy and corresponding plasma concentrations in relation to treatment efficacy.

CLINICAL TRIAL REGISTRATION

NCT05450822. Retrospectively registered 5 July 2022 https://clinicaltrials.gov/ct2/results? term=NCT05450822&Search=Search.

An analysis of suicidal and self-injurious behavior reports with antiseizure medications in the FDA adverse event database

BACKGROUND

Pharmacovigilance systems such as the FDA Adverse Event Reporting System (FAERS), are established models for adverse event surveillance that may have been missed during clinical trials. We aimed to analyze twenty-five anti-seizure medications (ASMs) in FAERS to assess for increased reporting of suicidal and self-injurious behavior.

METHODS

Twenty-five ASMs were analyzed: brivaracetam, cannabidiol, carbamazepine, clobazam, clonazepam, diazepam, eslicarbazepine, felbamate, gabapentin, lacosamide, lamotrigine, levetiracetam, oxcarbazepine, perampanel, phenobarbital, phenytoin, pregabalin, primidone, rufinamide, stiripentol, tiagabine, topiramate, valproate, vigabatrin, zonisamide. Reports of "suicidal and self-injurious behavior" were collected from January 1, 2004, to December 31, 2020, using OpenVigil 2.1 tool with indication as "Epilepsy". Relative reporting ratio, proportional reporting ratio, and reporting odds ratio were calculated utilizing all other drug reports for epilepsy patients as a control.

RESULTS

Significant relative operating ratio, ROR (greater than 1, p<0.05) were observed for diazepam (2.909), pregabalin (2.739), brivaracetam (2.462), gabapentin (2.185), clonazepam (1.649), zonisamide (1.462), lacosamide (1.333), and levetiracetam (1.286).

CONCLUSIONS

Of the 25 ASMs that were analyzed in this study, 4 (16%) were identified to have been linked with a likely true adverse event. These drugs included diazepam, brivaracetam, gabapenetin, and pregabalin. Although several limitations are present with the FAERS database, it is imperative to closely monitor patient comorbidities for increased risk of suicidality with the use of several ASMs.

Brivaracetam exposure-response predictions in pediatric patients from age 1 month: Extrapolation of levetiracetam adult-pediatric scaling to brivaracetam

BACKGROUND

An adult population pharmacokinetic/pharmacodynamic (PK/PD) model for the antiseizure medication (ASM) brivaracetam (BRV) was previously extended to children aged 4-16 years by using a pediatric BRV population PK model. Effects were scaled using information from a combined adult-pediatric PK/PD model of a related ASM, levetiracetam (LEV).

OBJECTIVE

To scale an existing adult population PK/PD model for BRV to children aged 1 month to < 4 years using information from a combined adult-pediatric PK/PD model for LEV, and to predict the effective dose of BRV in children aged 1 month to < 4 years using the adult BRV PK/PD model modified for the basal seizure rate in children.

MATERIAL AND METHODS

An existing adult population PK/PD model for BRV was scaled to children aged from 1 month to < 4 years using information from a combined adult-pediatric PK/PD model for LEV, an ASM binding to the same target protein as BRV. An existing adult-pediatric PK/PD model for LEV was extended using data from UCB study N01009 (NCT00175890) to include children as young as 1 month of age. The BRV population PK model was updated with data up to 180 days after first administration from BRV pediatric studies N01263 (NCT00422422) and N01266 (NCT01364597). PK and PD simulations for BRV were performed for a range of mg/kg doses to predict BRV effect in pediatric participants, and to provide dosing recommendations.

RESULTS

The extended adult-pediatric LEV PK/PD model was able to describe the adult and pediatric data using the same PD model parameters in adults and children and supported the extension of the adult BRV PK/PD model to pediatric patients aged 1 month to < 4 years. Simulations predicted exposures similar to adults receiving BRV 100 mg twice daily (b.i.d.), when using 3 mg/kg b.i.d. for weight < 10 kg, 2.5 mg/kg b.i.d. for weight ≥ 10 kg and < 20 kg, and 2 mg/kg b.i.d. for weight ≥ 20 kg in children aged 1 month to < 4 years. PK/PD simulations show that maximum BRV response is expected to occur with 2-3 mg/kg b.i.d. dosing of BRV in children aged 1 month to < 4 years, with an effective dose of 1 mg/kg b.i.d. for some participants.

CONCLUSION

Development of an adult-pediatric BRV PK/PD model allowed characterization of the exposure-response relationship of BRV in children aged 1 to < 4 years, providing a maximal dose allowance based on weight.

Development of SV2A Ligands for Epilepsy Treatment: A Review of Levetiracetam, Brivaracetam, and Padsevonil

Epilepsy is a common neurological disorder that is primarily treated with antiseizure medications (ASMs). Although dozens of ASMs are available in the clinic, approximately 30% of epileptic patients have medically refractory seizures; other limitations in most traditional ASMs include poor tolerability and drug-drug interactions. Therefore, there is an urgent need to develop alternative ASMs. Levetiracetam (LEV) is a first-line ASM that is well tolerated, has promising efficacy, and has little drug-drug interaction. Although it is widely accepted that LEV acts through a unique therapeutic target synaptic vesicle protein (SV) 2A, the molecular basis of its action remains unknown. Even so, the next-generation SV2A ligands against epilepsy based on the structure of LEV have achieved clinical success. This review highlights the research and development (R&D) process of LEV and its analogs, brivaracetam and padsevonil, to provide ideas and experience for the R&D of novel ASMs.

Brivaracetam use in clinical practice: a Delphi consensus on its role as first add-on therapy in focal epilepsy and beyond

BACKGROUND

Antiseizure medications remain the cornerstone of treatment for epilepsy, although a proportion of individuals with the condition will continue to experience seizures despite appropriate therapy. Treatment choices for epilepsy are based on variables related to both the individual patient and the available medications. Brivaracetam is a third-generation agent antiseizure medication.

METHODS

We carried out a Delphi consensus exercise to define the role of brivaracetam in clinical practice and to provide guidance about its use as first add-on ASM and in selected clinical scenarios. A total of 15 consensus statements were drafted by an expert panel following review of the literature and all were approved in the first round of voting by panelists. The consensus indicated different clinical scenarios for which brivaracetam can be a good candidate for treatment, including first add-on use.

RESULTS

Overall, brivaracetam was considered to have many advantageous characteristics that render it a suitable option for patients with focal epilepsy, including a fast onset of action, favorable pharmacokinetic profile with few drug-drug interactions, broad-spectrum activity, and being well tolerated across a range of doses. Brivaracetam is also associated with sustained clinical response and good tolerability in the long term.

CONCLUSIONS

These characteristics also make it suitable as an early add-on for the elderly and for patients with post-stroke epilepsy or status epilepticus as highlighted by the present Delphi consensus.

Development of a physiologically based pharmacokinetic model for levetiracetam in patients with renal impairment to guide dose adjustment based on steady-state peak/trough concentrations

Levetiracetam may cause acute renal failure and myoclonic encephalopathy at high plasma levels, particularly in patients with renal impairment. The aim of this study was to develop a physiologically based pharmacokinetic (PBPK) model to predict levetiracetam pharmacokinetics in Chinese adults with epilepsy and renal impairment and define appropriate levetiracetam dosing regimen.PBPK models for healthy subjects and epilepsy patients with renal impairment were developed, validated, and adapted. Furthermore, we predicted the steady-state trough and peak concentrations of levetiracetam in patients with renal impairment using the final PBPK model, thereby recommending appropriate levetiracetam dosing regimens for different renal function stages. The predicted maximum plasma concentration (Cmax), time to maximum concentration (Tmax), area under the plasma concentration-time curve (AUC) were in agreement (0.8 ≤ fold error ≤ 1.2) with the observed, and the fold error of the trough concentrations in end-stage renal disease (ESRD) was 0.77 - 1.22. The prediction simulations indicated that the recommended doses of 1000, 750, 500, and 500 mg twice daily for epilepsy patients with mild, moderate, severe renal impairment, and ESRD, respectively, were sufficient to achieve the target plasma concentration of levetiracetam.

Current advances in rodent drug-resistant temporal lobe epilepsy models: Hints from laboratory studies

Anti-seizure drugs (ASDs) are the first choice for the treatment of epilepsy, but there is still one-third of patients with epilepsy (PWEs) who are resistant to two or more appropriately chosen ASDs, named drug-resistant epilepsy (DRE). Temporal lobe epilepsy (TLE), a common type of epilepsy usually associated with hippocampal sclerosis (HS), shares the highest proportion of drug resistance (approximately 70%). In view of the key role of the temporal lobe in memory, emotion, and other physiological functions, patients with drug-resistant temporal lobe epilepsy (DR-TLE) are often accompanied by serious complications, and surgical procedures also yield extra considerations. The exact mechanisms for the genesis of DR-TLE remain unillustrated, which makes it hard to manage patients with DR-TLE in clinical practice. Animal models of DR-TLE play an irreplaceable role in both understanding the mechanism and searching for new therapeutic strategies or drugs. In this review article, we systematically summarized different types of current DR-TLE models, and then recent advances in mechanism investigations obtained in these models were presented, especially with the development of advanced experimental techniques and tools. We are deeply encouraged that novel strategies show great therapeutic potential in those DR-TLE models. Based on the big steps reached from the bench, a new light has been shed on the precise management of DR-TLE.

Value of drug level concentrations of brivaracetam, lacosamide, and perampanel in care of people with epilepsy

OBJECTIVE

The aim of this study was to determine whether clinical efficacy and reported adverse effects (AEs) of the newer antiseizure medications (ASMs) brivaracetam (BRV), lacosamide (LCM), and perampanel (PER) have been associated with plasma levels of these ASMs. We also investigated whether plasma levels outside the reference range has led to dose adjustments.

METHODS

Plasma levels of 300 people with epilepsy (PWE) seen at our tertiary epilepsy center were determined by liquid chromatography-tandem mass spectrometry. PWE received BRV (n = 100), LCM (n = 100), or PER (n = 100), in most cases in polytherapy. Demographic and clinical data were retrospectively analyzed and related to plasma levels. Clinical efficacy of BRV, LCM, or PER was assessed retrospectively by comparing seizure frequency at the time of current blood draw with seizure frequency at the time of first administration. AEs were also recorded and, if reported, compared retrospectively with the time of first administration.

RESULTS

No significant associations were found between plasma levels of BRV, LCM, or PER and seizure freedom (BRV, p = 1.000; LCM, p = .243; PER, p = .113) or responder status (BRV, p = .118; LCM, p = .478; PER, p = .069) at presentation. There was also no pattern between plasma levels and the occurrence of AEs. In the majority of cases, drug levels outside the reference ranges have not led to adjustments in the daily doses of BRV (93.5%), LCM (93.9%), or PER (89.1%).

SIGNIFICANCE

Plasma levels at a given time point did not allow conclusions to be drawn about seizure control or the occurrence of AEs. Our findings indicate that efficacy and tolerability cannot be predicted based on averaged data from a single plasma measurement due to high interindividual variability. Instead, individual reference values should be established when sufficient clinical data are available, in line with the 2008 International League Against Epilepsy position paper on therapeutic drug monitoring.

Brivaracetam as add-on therapy in children with developmental epileptic encephalopathies: A study of 42 patients

OBJECTIVE

Here we present a multicenter series of patients with developmental epileptic encephalopathies (DEE) who were treated with brivaracetam (BRV) as add-on therapy.

METHODS

Medical records of 42 patients with DEE treated with add-on BRV seen at four pediatric neurology centers in Argentina between January 2021 and July 2023 were retrospectively analyzed.

RESULTS

We included 42 patients (26 males, 16 females) with a mean age of 7 years (SD, ± 3.8; median, 9; range, 2-16). The children had different types of childhood-onset treatment-resistant DEEs and received BRV as add-on therapy for a mean period of 2 years (SD, ± 1.3 years; median, 1.5 years; range, 0.5-3 years). Thirty-three patients received levetiracetam (LEV) before the introduction of BRV. In nine patients, BRV was started without prior LEV because of behavioral disturbances. Three patients (9.5 %) became seizure free and 26/42 patients (62.1 %) had a greater than 50 % decrease in seizures after a mean follow-up of 21 months. Ten patients (23.8 %) had a 25-50 % seizure reduction, while seizure frequency remained unchanged in two (4.7 %) and increased in one patient (2.4 %). The interictal EEG abnormalities improved in all the responders. Adverse effects, consisting of drowsiness, irritability, and decreased appetite, were observed in seven patients (16.6 %), but did not lead to treatment discontinuation.

CONCLUSION

Brivaracetam was found to be effective, safe, and well tolerated in children with DEE. In patients on LEV with behavioral disturbances, BRV may be tried. BRV may also be given without a previous trial with LEV in patients with behavioral problems.

The real-world effectiveness of intravenous brivaracetam as a second-line treatment in status epilepticus

PURPOSE

Status epilepticus (SE) is defined by abnormally prolonged seizures that may lead to brain damage and death. Our aim was to evaluate the efficacy and tolerability (effectiveness) of intravenous brivaracetam (BRV) as a second-line treatment.

METHODS

Twenty-one patients (median age 68 years ± 17.28) were prospectively recruited between June 2019 and December 2022. Patients were treated with BRV (50-200 mg) as a second-line add-on therapy for SE. We evaluated the response of SE to the administration of BRV in terms of SE termination and recurrence of epileptic seizures at 6, 12, and 24 h, also monitoring safety. The first-line therapy was represented by intravenous benzodiazepines (mainly diazepam).

RESULTS

Almost a quarter of patients had generalized seizures, whereas the vast majority (76.2%) presented focal seizures. In 52.4% of patients, the underlying cause was cerebrovascular. Fourteen (66.7%) patients displayed a good early response in the subsequent 6 h. At 12 and 24 h, 8 (38%) and 11 (52.4%) patients, respectively, did not present seizures.

CONCLUSION

The present study highlights the potential of BRV when used as an early add-on therapy in SE, further confirming its good safety profile.

Pharmacokinetics, Safety, and Tolerability of Brivaracetam in Healthy Elderly Participants

The pharmacokinetics, metabolism, safety, and tolerability of the antiseizure medication brivaracetam (BRV) were characterized in 16 healthy elderly participants (8 men/8 women) aged 65-78 years who received a single 200-mg oral dose of BRV on day 1, followed by 200 mg twice daily from day 3 until day 12. BRV and three metabolites were determined in plasma and urine. Adverse events, vital signs, electrocardiograms, laboratory tests, general and neurological examinations, and psychometric rating scales were recorded at regular intervals. No clinically relevant changes or abnormalities were detected. The adverse events were similar to those observed in pivotal trials. Rating scales indicated transiently increased sedation and decreased alertness. BRV pharmacokinetics and metabolism were unchanged relative to younger populations. Based on our observations in this healthy elderly population receiving oral BRV 200 mg twice daily (twice the maximum recommended dose), dose reductions are not warranted relative to other, younger populations. Further investigations may be necessary in frail elderly populations aged >80 years.

Real-life evidence about the use of intravenous brivaracetam in urgent seizures: The BRIV-IV study

PURPOSE

Urgent seizures are a medical emergency for which new therapies are still needed. This study evaluated the use of intravenous brivaracetam (IV-BRV) in an emergency setting in clinical practice.

METHODS

BRIV-IV was a retrospective, multicenter, observational study. It included patients ≥18 years old who were diagnosed with urgent seizures (including status epilepticus (SE), acute repetitive seizures, and high-risk seizures) and who were treated with IV-BRV according to clinical practice in 14 hospital centers. Information was extracted from clinical charts and included in an electronic database. Primary effectiveness endpoints included the rate of IV-BRV responder patients, the rate of patients with a sustained response without seizure relapse in 12 h, and the time between IV-BRV administration and clinical response. Primary safety endpoints were comprised the percentage of patients with adverse events and those with adverse events leading to discontinuation.

RESULTS

A total of 156 patients were included in this study. The mean age was 57.7 ± 21.5 years old with a prior diagnosis of epilepsy for 57.1% of patients. The most frequent etiologies were brain tumor-related (18.1%) and vascular (11.2%) epilepsy. SE was diagnosed in 55.3% of patients. The median time from urgent seizure onset to IV treatment administration was 60.0 min (range: 15.0-360.0), and the median time from IV treatment to IV-BRV was 90.0 min (range: 30.0-2400.0). Regarding dosage, the mean bolus infusion was 163.0 ± 73.0 mg and the mean daily dosage was 195.0 ± 87.0 mg. A total of 77.6% of patients responded to IV-BRV (66.3% with SE vs. 91% other urgent seizures) with a median response time of 30.0 min (range: 10.0-60.0). A sustained response was achieved in 62.8% of patients. However, adverse events were reported in 14.7%, which were predominantly somnolence and fatigue, with 4.5% leading to discontinuation. Eighty-six percent of patients were discharged with oral brivaracetam.

CONCLUSION

IV-BRV in emergency settings was effective, and tolerability was good for most patients. However, a larger series is needed to confirm the outcomes.

Perioperative perampanel administration for early seizure prophylaxis in brain tumor patients

Background

The efficacy of perioperative prophylactic antiepileptic drug therapy in "seizure-naïve" patients with brain tumor, including glioblastoma (GBM), remains controversial. This study investigated whether perampanel (PER) is effective and safe for preventing perioperative onset of epileptic seizures, so-called early seizure, in patients with brain tumors.

Methods

Forty-five patients underwent tumor resection through craniotomy for a primary supratentorial brain tumor at Ehime University Hospital between April 2021 and July 2022. PER was administered from the 1st to the 6th day after surgery for seizure prophylaxis. Occurrence of early seizure, hematological toxicities, and various side effects were recorded on postoperative days 7 and 14. In addition, the clinical course of these patients was compared with 42 brain tumor patients under the same treatment protocol who received levetiracetam (LEV) for seizure prophylaxis between April 2017 and October 2018.

Results

In 45 patients with brain tumor, including GBM, who received PER administration, no early seizures were identified within 7 days postoperatively. No adverse drug reactions such as hematological toxicity, liver or kidney dysfunction, or exanthematous drug eruption were observed in any cases. As side effects, somnolence was reported in 14 patients (31.1%), vertigo in 3 patients (6.7%), and headache in 3 patients (6.7%). Although somnolence and vertigo were difficult to assess in the case of intraparenchymal tumors, particularly GBM, these side effects were not identified in patients with extraparenchymal tumors such as meningiomas, epidermoid cysts, and pituitary adenomas. In addition, no significant differences were identified compared to patients who received LEV.

Conclusion

The efficacy and safety of PER in preventing early seizures among patients with brain tumors were retrospectively evaluated. Perioperative administration of PER to patients with brain tumors may reduce the risk of early seizures without incurring serious side effects, showing no significant differences compared to patients who received LEV.

Modulating Hyperpolarization-Activated Cation Currents through Small Molecule Perturbations: Magnitude and Gating Control

The hyperpolarization-activated cation current (Ih) exhibits a slowly activating time course of the current (Ih) when the cell membrane is hyperpolarized for an extended duration. It is involved in generating electrical activity in various excitable cells. Numerous structurally distinct compounds or herbal drugs have the potential to impact both the magnitude and gating kinetics of this current. Brivaracetam, a chemical analog of levetiracetam known to be a ligand for synaptic vesicle protein 2A, could directly suppress the Ih magnitude. Carisbamate, an anticonvulsant agent, not only inhibited the Ih amplitude but also reduced the strength of voltage-dependent hysteresis (Hys(V)) associated with Ih. Cilobradine, similar to ivabradine, inhibited the amplitude of Ih; however, it also suppressed the amplitude of delayed-rectifier K+ currents. Dexmedetomidine, an agonist of α2-adrenergic receptor, exerted a depressant action on Ih in a concentration-dependent fashion. Suppression of Ih amplitude was observed when GAL-021, a breathing control modulator, was present at a concentration exceeding 30 μM. Lutein, one of the few xanthophyll carotenoids, was able to suppress the Ih amplitude as well as to depress Hys(V)'s strength of Ih. Pirfenidone, a pyridine derivative known to be an anti-fibrotic agent, depressed the Ih magnitude in a concentration- and voltage-dependent fashion. Tramadol, a synthetic centrally active analgesic, was shown to reduce the Ih magnitude, independent of its interaction with opioid receptors. Various herbal drugs, including ent-kaurane-type diterpenoids from Croton tonkinensis, Ganoderma triterpenoids, honokiol, and pterostilbene, demonstrated efficacy in reducing the magnitude of Ih. Conversely, oxaliplatin, a platinum-based chemotherapeutic compound, was observed to effectively increase the Ih amplitude. Collectively, the regulatory effects of these compounds or herbal drugs on cellular function can be partly attributed to their perturbations on Ih.

Safety and efficacy of brivaracetam in children epilepsy: a systematic review and meta-analysis

Background

Epilepsy is one of the most common neurological diseases, affecting people of any age. Although the treatments of epilepsy are more and more diverse, the uncertainty regarding efficacy and adverse events still exists, especially in the control of childhood epilepsy.

Methods

We performed a systematic review and meta- analysis following the Cochrane Handbook and preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. Four databases including PubMed, Embase, Web of Science and Cochrane library were searched. Studies reporting the use of brivaracetam monotherapy or adjuvant therapy in children (aged ≤18 years) were eligible for inclusion. Each stage of the review was conducted by two authors independently. Random-effects models were used to combine effect sizes for the estimation of efficacy and safety.

Results

A total of 1884 articles were retrieved, and finally 9 articles were included, enrolling 503 children with epilepsy. The retention rate of BRV treatment was 78% (95% CI: 0.64-0.91), the responder rate (reduction of seizure frequency ≥ 50%) was 35% (95% CI: 0.24-0.47), the freedom seizure rate (no seizure) was 18% (95% CI: 0.10-0.25), and the incidence rate of any treatment-emergent adverse events (TEAE) was 39% (95% CI: 0.09-0.68). The most common TEAE was somnolence, which had an incidence rate of 9% (95% CI: 0.07-0.12). And the incidence rate of mental or behavioral disorders was 12% (95% CI: 0.06-0.17).

Conclusion

Our systematic review and meta-analysis showed that BRV seemed to be safe and effective in the treatment of childhood epilepsy.

Treatment of pediatric convulsive status epilepticus

Status epilepticus is one of the most common life-threatening neurological emergencies in childhood with the highest incidence in the first 5 years of life and high mortality and morbidity rates. Although it is known that a delayed treatment and a prolonged seizure can cause permanent brain damage, there is evidence that current treatments may be delayed and the medication doses administered are insufficient. Here, we summarize current knowledge on treatment of convulsive status epilepticus in childhood and propose a treatment algorithm. We performed a structured literature search via PubMed and ClinicalTrails.org and identified 35 prospective and retrospective studies on children <18 years comparing two and more treatment options for status epilepticus. The studies were divided into the commonly used treatment phases. As a first-line treatment, benzodiazepines buccal/rectal/intramuscular/intravenous are recommended. For status epilepticus treated with benzodiazepine refractory, no superiority of fosphenytoin, levetirazetam, or phenobarbital was identified. There is limited data on third-line treatments for refractory status epilepticus lasting >30 min. Our proposed treatment algorithm, especially for children with SE, is for in and out-of-hospital onset aids to promote the establishment and distribution of guidelines to address the treatment delay aggressively and to reduce putative permanent neuronal damage. Further studies are needed to evaluate if these algorithms decrease long-term damage and how to treat refractory status epilepticus lasting >30 min.

Rapid intravenous loading of brivaracetam during invasive and non-invasive video-EEG monitoring

PURPOSE

The pharmacokinetics of Brivaracetam (BRV) and its ability to penetrate the blood-brain barrier quickly make it a suitable drug for emergencies. In this study, our aim was to investigate the tolerability, safety, and acute efficacy of rapid intravenous (IV) loading of BRV during invasive and non-invasive video-EEG monitoring in patients with drug-resistant focal epilepsy (DRFE).

METHODS

Eleven adult patients, six during stereo-electroencephalography (SEEG) and five in scalp video-EEG evaluation, received a 10-minute IV infusion of BRV 100 mg after a period of total withdrawal from antiseizure medications (ASMs). The ictal and interictal EEG activity was assessed through visual and spectrographic analysis before and after intravenous BRV administration. Patients completed the Liverpool Adverse Events Profile (LAEP) scale to evaluate tolerability and adverse events.

RESULTS

Rapid BRV IV infusion was well tolerated in all patients. The mean LAEP values showed no significant differences (p = 0.40). Loading BRV resulted in a reduction in interictal activity in six patients. The mean seizure frequency significantly decreased five hours after BRV administration (a 79.2 % reduction across the entire group, p = 0.027). A significant change in spectral band analysis was observed ten minutes after BRV administration.

CONCLUSION

Our data suggest that rapid BRV IV infusion has a favorable safety profile and is effective in controlling seizure series in the short term. The electrophysiological changes observed ten minutes after the BRV load correlate with its effects on brain dynamics after blood-brain barrier diffusion.

Investigating anti-inflammatory and immunomodulatory properties of brivaracetam and lacosamide in experimental autoimmune encephalomyelitis (EAE)

PURPOSE

Inflammation plays a role in drug-resistant epilepsy (DRE). We have previously reported an increased proportion of CD4 T cells displaying a pro-inflammatory profile in the peripheral blood of adults with DRE. Specific anti-epileptic drugs (AEDs) exhibit immunomodulatory properties that could increase the risk of infections but also contribute to their beneficial impact on DRE and other neurological diseases. The impact of novel generation AEDs on the profile of immune cells and on neuroinflammatory processes remains unclear.

METHODS

We compared the influence of brivaracetam and lacosamide on the activation of human and murine peripheral immune cells in vitro and in vivo in active experimental autoimmune encephalomyelitis (EAE), a common mouse model of central nervous system inflammation.

RESULTS

We found that brivaracetam and lacosamide at 2.5 μg/ml did not impair the survival and activation of human immune cells, but a higher dose of 25 μg/ml decreased mitogen-induced proliferation of CD8 T cells in vitro. Exposure to high doses of brivaracetam, and to a lesser extent lacosamide, reduced the proportion of CD25⁺ and CD107a⁺ CD8⁺ human T cells in vitro, and the frequency of CNS-infiltrating CD8⁺ T cells at EAE onset and CD11b⁺ myeloid cells at peak in vivo. Prophylactic administration of brivaracetam or lacosamide did not delay EAE onset but significantly improved the clinical course in the chronic phase of EAE compared to control.

CONCLUSION

Novel generation AEDs do not impair the response to immunization with MOG peptide but improve the course of EAE, possibly through a reduction of neuroaxonal damage.

Beyond monoamines: I. Novel targets and radiotracers for Positron emission tomography imaging in psychiatric disorders

With the emergence of positron emission tomography (PET) in the late 1970s, psychiatry had access to a tool capable of non-invasive assessment of human brain function. Early applications in psychiatry focused on identifying characteristic brain blood flow and metabolic derangements using radiotracers such as [¹⁵ O]H₂ O and [¹⁸ F]FDG. Despite the success of these techniques, it became apparent that more specific probes were needed to understand the neurochemical bases of psychiatric disorders. The first neurochemical PET imaging probes targeted sites of action of neuroleptic (dopamine D₂ receptors) and psychoactive (serotonin receptors) drugs. Based on the centrality of monoamine dysfunction in psychiatric disorders and the measured success of monoamine-enhancing drugs in treating them, the next 30 years witnessed the development of an armamentarium of PET radiopharmaceuticals and imaging methodologies for studying monoamines. Continued development of monoamine-enhancing drugs over this time however was less successful, realizing only modest gains in efficacy and tolerability. As patent protection for many widely prescribed and profitable psychiatric drugs lapsed, drug development pipelines shifted away from monoamines in search of novel targets with the promises of improved efficacy, or abandoned altogether. Over this period, PET radiopharmaceutical development activities closely paralleled drug development priorities resulting in the development of new PET imaging agents for non-monoamine targets. Part one of this review will briefly survey novel PET imaging targets with relevance to the field of psychiatry, which include the metabotropic glutamate receptor type 5 (mGluR5), purinergic P₂ X₇ receptor, type 1 cannabinoid receptor (CB₁ ), phosphodiesterase 10A (PDE10A), and describe radiotracers developed for these and other targets that have matured to human subject investigations. Current limitations of the targets and techniques will also be discussed.

Drug characteristics derived from kinetic modeling: combined 11C-UCB-J human PET imaging with levetiracetam and brivaracetam occupancy of SV2A

BACKGROUND

Antiepileptic drugs, levetiracetam (LEV) and brivaracetam (BRV), bind to synaptic vesicle glycoprotein 2A (SV2A). In their anti-seizure activity, speed of brain entry may be an important factor. BRV showed faster entry into the human and non-human primate brain, based on more rapid displacement of SV2A tracer ¹¹C-UCB-J. To extract additional information from previous human studies, we developed a nonlinear model that accounted for drug entry into the brain and binding to SV2A using brain ¹¹C-UCB-J positron emission tomography (PET) data and the time-varying plasma drug concentration, to assess the kinetic parameter K₁ (brain entry rate) of the drugs.

METHOD

Displacement (LEV or BRV p.i. 60 min post-tracer injection) and post-dose scans were conducted in five healthy subjects. Blood samples were collected for measurement of drug concentration and the tracer arterial input function. Fitting of nonlinear differential equations was applied simultaneously to time-activity curves (TACs) from displacement and post-dose scans to estimate 5 parameters: K₁ (drug), K₁(¹¹C-UCB-J, displacement), K₁(¹¹C-UCB-J, post-dose), free fraction of ¹¹C-UCB-J in brain (f_ND(¹¹C-UCB-J)), and distribution volume of ¹¹C-UCB-J (V_T(UCB-J)). Other parameters (K_D(drug), K_D(¹¹C-UCB-J), f_P(drug), f_P(¹¹C-UCB-J, displacement), f_P(¹¹C-UCB-J, post-dose), f_ND(drug), k_off(drug), k_off(¹¹C-UCB-J)) were fixed to literature or measured values.

RESULTS

The proposed model described well the TACs in all subjects; however, estimates of drug K₁ were unstable in comparison with ¹¹C-UCB-J K₁ estimation. To provide a conservative estimate of the relative speed of brain entry for BRV vs. LEV, we determined a lower bound on the ratio BRV K₁/LEV K₁, by finding the lowest BRV K₁ or highest LEV K₁ that were statistically consistent with the data. Specifically, we used the F test to compare the residual sum of squares with fixed BRV K₁ to that with floating BRV K₁ to obtain the lowest possible BRV K₁; the same analysis was performed to find the highest LEV K₁. The lower bound of the ratio BRV K₁/LEV K₁ was ~ 7.

CONCLUSIONS

Under appropriate conditions, this advanced nonlinear model can directly estimate entry rates of drugs into tissue by analysis of PET TACs. Using a conservative statistical cutoff, BRV enters the brain at least sevenfold faster than LEV.

Physiologically based pharmacokinetic modeling of brivaracetam and its interactions with rifampin based on CYP2C19 phenotypes

Brivaracetam (BRV), a third-generation antiepileptic drug (AED), is primarily metabolized through amidase hydrolysis and CYP2C19-mediated hydroxylation in vivo. This study utilized physiologically based pharmacokinetic (PBPK) modeling to explore the pharmacokinetics of BRV and drug interactions between BRV and rifampin (RIF), a CYP2C19 inducer, based on CYP2C19 genetic polymorphisms. A PBPK model of BRV was developed in the general population and in individuals with different CYP2C19 phenotypes by adjusting catalytic rate constants (k_cat), and the model was validated with observed clinical data. The model was then extrapolated to predict BRV steady-state plasma concentration in individuals with different CYP2C19 phenotypes, with or without coadministration of RIF. The developed model adequately described BRV exposure in the abovementioned populations. The predicted steady-state area under the curve (AUC_τ-ss) increases by 20% in heterozygous extensive metabolizers (hEMs) and 55% in poor metabolizers (PMs), compared to homozygous extensive metabolizer (EMs). When coadministered with RIF, the model predicted the most significant magnitude of drug-drug interaction (DDI) in EMs, while the exposure change of BRV was minimal in PMs. Referencing the recommended concentration for therapeutic drug monitoring (TDM), we concluded that the current clinical maintenance dose of BRV is acceptable regardless of CYP2C19 polymorphisms and coadministration with RIF.

Levetiracetam Mechanisms of Action: From Molecules to Systems

Epilepsy is a chronic disease that affects millions of people worldwide. Antiepileptic drugs (AEDs) are used to control seizures. Even though parts of their mechanisms of action are known, there are still components that need to be studied. Therefore, the search for novel drugs, new molecular targets, and a better understanding of the mechanisms of action of existing drugs is still crucial. Levetiracetam (LEV) is an AED that has been shown to be effective in seizure control and is well-tolerable, with a novel mechanism of action through an interaction with the synaptic vesicle protein 2A (SV2A). Moreover, LEV has other molecular targets that involve calcium homeostasis, the GABAergic system, and AMPA receptors among others, that might be integrated into a single mechanism of action that could explain the antiepileptogenic, anti-inflammatory, neuroprotective, and antioxidant properties of LEV. This puts it as a possible multitarget drug with clinical applications other than for epilepsy. According to the above, the objective of this work was to carry out a comprehensive and integrative review of LEV in relation to its clinical uses, structural properties, therapeutical targets, and different molecular, genetic, and systemic action mechanisms in order to consider LEV as a candidate for drug repurposing.

In Vitro and In Vivo Bioequivalence Study of 3D-Printed Instant-Dissolving Levetiracetam Tablets and Subsequent Personalized Dosing for Chinese Children Based on Physiological Pharmacokinetic Modeling

Recently, the development of Binder Jet 3D printing technology has promoted the research and application of personalized formulations, which are especially useful for children’s medications. Additionally, physiological pharmacokinetic (PBPK) modeling can be used to guide drug development and drug dose selection. Multiple technologies can be used in combination to increase the safety and effectiveness of drug administration. In this study, we performed in vivo pharmacokinetic experiments in dogs with preprepared 3D-printed levetiracetam instant-dissolving tablets (LEV-IDTs). Bioequivalence analysis showed that the tablets were bioequivalent to commercially available preparations (Spritam^®) for dogs. Additionally, we evaluated the bioequivalence of 3D-printed LEV-IDTs with Spritam^® by a population-based simulation based on the established PBPK model of levetiracetam for Chinese adults. Finally, we established a PBPK model of oral levetiracetam in Chinese children by combining the physiological parameters of children, and we simulated the PK (pharmacokinetics) curves of Chinese children aged 4 and 6 years that were administered the drug to provide precise guidance on adjusting the dose according to the effective dose range of the drug. Briefly, utilizing both Binder jet 3D printing technology and PBPK models is a promising route for personalized drug delivery with various age groups.

Positron Emission Computed Tomography Imaging of Synaptic Vesicle Glycoprotein 2A in Alzheimer's Disease

Alzheimer's disease (AD) is the most common neurodegenerative disorder seen in age-dependent dementia. There is currently no effective treatment for AD, which may be attributed in part to lack of a clear underlying mechanism. Early diagnosis of AD is of great significance to control the development of the disease. Synaptic loss is an important pathology in the early stage of AD, therefore the measurement of synaptic density using molecular imaging technology may be an effective way to early diagnosis of AD. Synaptic vesicle glycoprotein 2A (SV2A) is located in the presynaptic vesicle membrane of virtually all synapses. SV2A Positron Emission Computed Tomography (PET) could provide a way to measure synaptic density quantitatively in living humans and to track changes in synaptic density in AD. In view of the fact that synaptic loss is the pathology of both epilepsy and AD, this review summarizes the potential role of SV2A in the pathogenesis of AD, and suggests that SV2A should be used as an important target molecule of PET imaging agent for the early diagnosis of AD.

Efficacy of Brivaracetam in children with epilepsy

BACKGROUND AND OBJECTIVES

To determine the efficacy, tolerance, and safety of BRV in children with epilepsy.

METHODS

A retrospective study of patients with epilepsy who received treatment with BRV before age 16 years and underwent a minimum follow-up of 3 months.

METHOD AND RESULTS

Sixty-six patients were included in the study. Patients received BRV at a mean age of 8.8 years (range 1-16 years). The majority (93.4 %) had refractory epilepsy, 27 with epileptic encephalopathy. The median maximum dose used was 4.3 mg/kg/day. In 30.3 % of the cases, seizure frequency was reduced by over 50 %, and 9 % remained seizure-free. Greater efficacy was observed in those patients who received higher doses and when a direct switch from levetiracetam (LEV) to BRV was performed. The ineffectiveness of LEV was not related to a failure to respond to BRV treatment. Side effects were identified in 24.2 % of the cases, the most frequent being irritability and drowsiness.

CONCLUSIONS

BRV appears to be an effective, safe, and well-tolerated AED in children with refractory epilepsy.

Preclinical In Vitro and In Vivo Characterization of Synaptic Vesicle 2A-Targeting Compounds Amenable to F-18 Labeling as Potential PET Radioligands for Imaging of Synapse Integrity

PURPOSE

Current synaptic vesicle 2A (SV2A) positron emission tomography (PET) imaging agents include the nanomolar affinity probes [¹¹C]UCB-J and [¹⁸F]UCB-H derived from the anti-epileptic drug levitaracetam (Keppra®). An industry-utilized "de-risking" approach was used to carry out initial pharmacological characterization and to assess potential next-generation candidates amenable to F-18 radiolabeling for preliminary evaluation.

PROCEDURES

Radioligand binding methods were employed in mammalian brain homogenates to determine the SV2A affinity (K_d) and maximal binding capacity (B_max) of [³H]UCB-J. Novel leads were then screened to identify compounds minimally with comparable binding affinities with UCB-J in order to select a F-18-labeled candidate for subsequent in vivo assessment in rat. In parallel, mammalian brain tissue section autoradiography was performed to assess specific SV2A distribution.

RESULTS

[³H]UCB-J bound with high affinity to a single population of sites in the rat brain (K_d = 2.6 ± 0.25 nM; B_max = 810 ± 25 fmol/mg protein) and control human cortex (K_d = 2.9 ± 0.54 nM; B_max = 10,000 ± 640 fmol/mg protein). Distribution of specific SV2A binding was shown to be homogeneous throughout the rodent brain and primarily in gray matter regions of rodent and human brain sections. Analog screening identified MNI-1038, MNI-1126/SDM-8, and SDM-2 as having comparable binding affinities with the currently available PET ligands. Subsequent [¹⁸F]MNI-1126/[¹⁸F]SDM-8 dynamic micro-PET imaging in rats revealed in vivo uptake and accumulation in the brain with favorable kinetics. Chase studies using 30 mg/kg levetiracetam confirmed that in vivo brain uptake of [¹⁸F]MNI-1126/[¹⁸F]SDM-8 was reversible.

CONCLUSIONS

Taken together, these data suggest [¹⁸F]MNI-1126/[¹⁸F]SDM-8 (since renamed as [¹⁸F]SynVesT-1) characterized via an in vitro screening cascade provided a measurable in vivo SV2A specific signal in the rodent brain. This tracer as well as the close analog [¹⁸F]SDM-2 (since renamed as [¹⁸F]SynVesT-2) is currently undergoing further evaluation in preclinical and clinical studies.

[Pharmacotherapy and intensive care aspects of status epilepticus: update 2020/2021]

Die gezielte Therapie epileptischer Ereignisse und im Speziellen des Status epilepticus (SE) setzt das sichere Erkennen der Krankheitsbilder voraus, wofür gerade bei Formen mit vorwiegend nichtmotorischen Symptomen klinische und elektroenzephalographische Expertise notwendig ist. Die im Jahr 2020 erfolgte Fortschreibung der deutschen Leitlinie zur Behandlung des SE hält an der streng stufengerechten Therapie fest, die eskalierend die Anwendung von Benzodiazepinen, spezifischen Antiepileptika und Anästhetika vorsieht. Bisher ist die Eingrenzung eines in den allermeisten Fällen wirksamen sowie zugleich sicheren und interaktionsfreien Antiepileptikums nicht gelungen. Individuelle Vorerkrankungen und aktuelle Begleitumstände gehen daher genauso wie Erfahrungen des Behandlerteams in die differenzierte Behandlung des SE ein. Insbesondere bei therapierefraktären Formen des SE erweist sich die Therapie als durchaus kompliziert und hat regelhaft intensivmedizinische Implikationen. Mithin ergeben sich im Zuge der modernen SE-Behandlung zahlreiche interdisziplinäre Schnittstellen. Zukünftige wissenschaftliche Fragstellungen werden sich u. a. mit der optimalen Therapie des nonkonvulsiven SE und hier v. a. dem Ausmaß und dem Zeitpunkt von adäquaten Therapieschritten sowie mit assoziierten ethischen Fragen einer Therapieeskalation beschäftigen.

The Synaptic Vesicle Protein 2A Interacts With Key Pathogenic Factors in Alzheimer's Disease: Implications for Treatment

Alzheimer’s disease (AD), a serious neurodegenerative disease, is pathologically characterized by synaptic loss and dysfunction. Synaptic vesicle protein 2A (SV2A) is an indispensable vesicular protein specifically expressed in synapses and can be used as a biomarker for synaptic density. We found that the expression of SV2A was down-regulated in the hippocampus of AD patients, yet the relation of SV2A to other hallmarks of AD pathology such as amyloid precursor protein (APP), β-amyloid (Aβ), and Tau protein is not thoroughly clear. In addition, SV2A colocalized with APP and was down-regulated at Aβ deposition. Moreover, we found that SV2A deficiency leads to a simultaneous increase in Aβ and Tau hyperphosphorylation, while SV2A overexpression was associated with downregulation of β-site APP cleaving enzyme 1 and apolipoprotein E genes. In addition, evidence gained in the study points to the phosphatidylinositol 3-kinase signaling pathway as a possible mediator in SV2A regulation influencing the incidence and development of AD. With limited effective diagnostic methods for AD, a close interplay between SV2A and AD-related proteins demonstrated in our study may provide novel and innovative diagnostic and therapeutic opportunities.

Super-Refractory Status Epilepticus: Prognosis and Recent Advances in Management

Super-refractory status epilepticus (SRSE) is a life-threatening neurological emergency with high morbidity and mortality. It is defined as “status epilepticus (SE) that continues or recurs 24 hours or more after the onset of anesthesia, including those cases in which SE recurs on the reduction or withdrawal of anesthesia.” This condition is resistant to normal protocols used in the treatment of status epilepticus and exposes patients to increased risks of neuronal death, neuronal injury, and disruption of neuronal networks if not treated in a timely manner. It is mainly seen in patients with severe acute onset brain injury or presentation of new-onset refractory status epilepticus (NORSE). The mortality, neurological deficits, and functional impairments are significant depending on the duration of status epilepticus and the resultant brain damage. Research is underway to find the cure for this devastating neurological condition. In this review, we will discuss the wide range of therapies used in the management of SRSE, provide suggestions regarding its treatment, and comment on future directions. The therapies evaluated include traditional and alternative anesthetic agents with antiepileptic agents. The other emerging therapies include hypothermia, steroids, immunosuppressive agents, electrical and magnetic stimulation therapies, emergent respective epilepsy surgery, the ketogenic diet, pyridoxine infusion, cerebrospinal fluid drainage, and magnesium infusion. To date, there is a lack of robust published data regarding the safety and effectiveness of various therapies, and there continues to be a need for large randomized multicenter trials comparing newer therapies to treat this refractory condition.

Alzheimer's Disease and Epilepsy: A Perspective on the Opportunities for Overlapping Therapeutic Innovation

Early-onset Alzheimer's disease (AD) is associated with variants in amyloid precursor protein (APP) and presenilin (PSEN) 1 and 2. It is increasingly recognized that patients with AD experience undiagnosed focal seizures. These AD patients with reported seizures may have worsened disease trajectory. Seizures in epilepsy can also lead to cognitive deficits, neuroinflammation, and neurodegeneration. Epilepsy is roughly three times more common in individuals aged 65 and older. Due to the numerous available antiseizure drugs (ASDs), treatment of seizures has been proposed to reduce the burden of AD. More work is needed to establish the functional impact of seizures in AD to determine whether ASDs could be a rational therapeutic strategy. The efficacy of ASDs in aged animals is not routinely studied, despite the fact that the elderly represents the fastest growing demographic with epilepsy. This leaves a particular gap in understanding the discrete pathophysiological overlap between hyperexcitability and aging, and AD more specifically. Most of our preclinical knowledge of hyperexcitability in AD has come from mouse models that overexpress APP. While these studies have been invaluable, other drivers underlie AD, e.g. PSEN2. A diversity of animal models should be more frequently integrated into the study of hyperexcitability in AD, which could be particularly beneficial to identify novel therapies. Specifically, AD-associated risk genes, in particular PSENs, altogether represent underexplored contributors to hyperexcitability. This review assesses the available studies of ASDs administration in clinical AD populations and preclinical studies with AD-associated models and offers a perspective on the opportunities for further therapeutic innovation.

The pharmacokinetics of [18F]UCB-H revisited in the healthy non-human primate brain

Background

Positron Emission Tomography (PET) imaging of the Synaptic Vesicle glycoprotein (SV) 2A is a new tool to quantify synaptic density. [¹⁸F]UCB-H was one of the first promising SV2A-ligands to be labelled and used in vivo in rodent and human, while limited information on its pharmacokinetic properties is available in the non-human primate. Here, we evaluate the reliability of the three most commonly used modelling approaches for [¹⁸F]UCB-H in the non-human cynomolgus primate, adding the coupled fit of the non-displaceable distribution volume (V_ND) as an alternative approach to improve unstable fit. The results are discussed in the light of the current state of SV2A PET ligands.

Results

[¹⁸F]UCB-H pharmacokinetic data was optimally fitted with a two-compartment model (2TCM), although the model did not always converge (large total volume of distribution (V_T) or large uncertainty of the estimate). 2TCM with coupled fit K₁/k₂ across brain regions stabilized the quantification, and confirmed a lower specific signal of [¹⁸F]UCB-H compared to the newest SV2A-ligands. However, the measures of V_ND and the influx parameter (K₁) are similar to what has been reported for other SV2A ligands. These data were reinforced by displacement studies using [¹⁹F]UCB-H, demonstrating only 50% displacement of the total [¹⁸F]UCB-H signal at maximal occupancy of SV2A. As previously demonstrated in clinical studies, the graphical method of Logan provided a more robust estimate of V_T with only a small bias compared to 2TCM.

Conclusions

Modeling issues with a 2TCM due to a slow component have previously been reported for other SV2A ligands with low specific binding, or after blocking of specific binding. As all SV2A ligands share chemical structural similarities, we hypothesize that this slow binding component is common for all SV2A ligands, but only hampers quantification when specific binding is low.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13550-021-00777-8.

The Integrated Effects of Brivaracetam, a Selective Analog of Levetiracetam, on Ionic Currents and Neuronal Excitability

Brivaracetam (BRV) is recognized as a novel third-generation antiepileptic drug approved for the treatment of epilepsy. Emerging evidence has demonstrated that it has potentially better efficacy and tolerability than its analog, Levetiracetam (LEV). This, however, cannot be explained by their common synaptic vesicle-binding mechanism. Whether BRV can affect different ionic currents and concert these effects to alter neuronal excitability remains unclear. With the aid of patch clamp technology, we found that BRV concentration dependently inhibited the depolarization-induced M-type K⁺ current (I_K(M)), decreased the delayed-rectifier K⁺ current (I_K(DR)), and decreased the hyperpolarization-activated cation current in GH3 neurons. However, it had a concentration-dependent inhibition on voltage-gated Na⁺ current (I_Na). Under an inside-out patch configuration, a bath application of BRV increased the open probability of large-conductance Ca²⁺-activated K⁺ channels. Furthermore, in mHippoE-14 hippocampal neurons, the whole-cell I_Na was effectively depressed by BRV. In simulated modeling of hippocampal neurons, BRV was observed to reduce the firing of the action potentials (APs) concurrently with decreases in the AP amplitude. In animal models, BRV ameliorated acute seizures in both OD-1 and lithium-pilocarpine epilepsy models. However, LEV had effects in the latter only. Collectively, our study demonstrated BRV’s multiple ionic mechanism in electrically excitable cells and a potential concerted effect on neuronal excitability and hyperexcitability disorders.

Intravenous brivaracetam in status epilepticus: A multicentric retrospective study in Italy

PURPOSE

to evaluate the use, effectiveness, and adverse events of intravenous brivaracetam (BRV) in status epilepticus (SE).

METHODS

a retrospective multicentric study involving 24 Italian neurology units was performed from March 2018 to June 2020. A shared case report form was used across participating centres to limit biases of retrospective data collection. Diagnosis and classification of SE followed the 2015 ILAE proposal. We considered a trial with BRV a success when it was the last administered drug prior the clinical and/or EEG resolution of seizures, and the SE did not recur during hospital observation. In addition, we considered cases with early response, defined as SE resolved within 6 h after BRV administration.

RESULTS

56 patients were included (mean age 62 years; 57 % male). A previous diagnosis of epilepsy was present in 21 (38 %). Regarding SE etiology classification 46 % were acute symptomatic, 18 % remote and 16 % progressive symptomatic. SE episodes with prominent motor features were the majority (80 %). BRV was administered as first drug after benzodiazepine failure in 21 % episodes, while it was used as the second or the third (or more) drug in the 38 % and 38 % of episodes respectively. The median loading dose was 100 mg (range 50-300 mg). BRV was effective in 32 cases (57 %). An early response was documented in 22 patients (39 % of the whole sample). The use of the BRV within 6 h from SE onset was independently associated to an early SE resolution (OR 32; 95 % CI 3.39-202; p = 0.002). No severe treatment emergent adverse events were observed.

CONCLUSION

BRV proved to be useful and safe for the treatment of SE. Time to seizures resolution appears shorter when it is administered in the early phases of SE.

Insights into neurological dysfunction of critically ill COVID-19 patients

Novel coronavirus spread rapidly around the world infecting millions of people. It was thus declared a pandemic. This new virus damages the lungs. In the most severe cases, it leads to acute respiratory failure that requires intensive care treatment. However, many clinical reports have listed different neurological symptoms, leading to increased interest in the neurological involvement of COVID-19. Various pathophysiological mechanisms have been proposed to explain these neurological aspects. Direct viral invasion of the nervous system, systemic cytokine storm and severe hypoxemia are key factors in the development of symptoms. Critically ill patients present several additional risk factors for nervous system damage. Reasons for these include deep sedation and extended muscular paralysis, bed rest for several days, and the inability to receive proper physical rehabilitation. After ICU treatment, COVID-19 patients generally require an extensive rehabilitation program. However, distancing restrictions mean that in many cases physiotherapists are unable to enter ICUs, delaying the process of rehabilitation. The role of telemedicine should be considered as an adjunctive tool in the rehabilitation of critically ill COVID-19 patients.

Potential role of brivaracetam in pediatric epilepsy

Brivaracetam (BRV) is a new antiseizure medication (ASM) that is currently approved for adjunctive treatment in patients with focal onset seizures. Similarly to levetiracetam (LEV), BRV works by binding SV2A vesicles with a high affinity and a linear pharmacokinetic profile. Retrospective studies and randomized clinical trials have already proven the efficacy of BRV, even in patients who failed treatment with LEV. Most studies about the efficacy and tolerability conducted so far were performed in adult cohorts, whereas few studies have been performed in children; however, BRV was proven to be a useful ASM for pediatric focal epilepsies, with fewer studies and conflicting results among patients with generalized epilepsies and epileptic syndromes. Retention rates were high in the cohorts analyzed, and no serious treatment-emergent adverse events were reported in the majority of patients, with somnolence, drowsiness, irritability, aggression, and decreased appetite being the most frequently reported side effects. Although there are few original papers published on the subject so far, the analysis of the literature data demonstrated the efficacy and safety of BRV in pediatric patients, with more evidence for children aged 4-16 years with an onset of focal seizures. However, a positive response was also achieved in patients affected by encephalopathic epilepsies (eg, Jeavons' epilepsy, Dravet syndrome, Lennox-Gastaut syndrome, and juvenile myoclonic epilepsy), and ongoing studies are now testing BRV in order to widen its application to other forms of epilepsy and to test its effectiveness when used in monotherapy. This review aims to provide a comprehensive analysis of the literature surrounding the efficacy and tolerability of BRV for pediatric patients.

A novel lipase from Aspergillus oryzae WZ007 catalyzed synthesis of brivaracetam intermediate and its enzymatic characterization

Brivaracetam is a structural derivative of the chiral drug levetiracetam and has been approved for the adjuvant treatment of partial epilepsy. As a new antiepileptic drug, it is widely used in a variety of epilepsy models. In this study, a novel lipase M16 derived from Aspergillus oryzae WZ007 was cloned, expressed, and used for chiral resolution. Lipase M16 has a high enantioselectivity to the racemic substrate (R,S)-methyl 2-propylsuccinate 4-tert-butyl ester, and the intermediate (R)-2-propylsuccinic acid 4-tert-butyl ester of brivaracetam was obtained efficiently. Under optimal conditions, the enantiomeric excess of substrate was up to 99.26%, and the e.e._p was 96.23%. The conversion and apparent E value were 50.63% and 342.48, respectively. This study suggests a new biocatalytic resolution via lipase M16 for preparing the brivaracetam chiral intermediate and its potential application in the pharmaceutical industry.

Intravenous brivaracetam for the management of refractory focal non-convulsive status epilepticus

Diagnosis and management of status epilepticus (SE), including non-convulsive status epilepticus (NCSE), is challenging, with a reported 30%–50% of epilepticus patients not responding to available antiseizure medications (ASMs). Injectable benzodiazepines, fosphenytoin, valproate, levetiracetam, lacosamide and phenobarbital are commonly used for treating SE. Brivaracetam, a new ASM, with higher affinity and greater selectivity for the synaptic vesicle glycoprotein 2A than levetiracetam, has been approved as monotherapy or adjunct for treatment of focal onset seizures. Brivaracetam may have a role in the management of SE. However, limited data exist on brivaracetam’s efficacy in SE. We describe a patient case with focal NCSE refractory to levetiracetam, fosphenytoin, lacosamide and valproate who demonstrated clinical and electrographic improvement on continuous electroencephalography monitoring after brivaracetam administration.

Comparison of the safety of brivaracetam at various doses among patients with epilepsy: A network meta-analysis of randomized controlled trials

The present study aimed to compare the safety of brivaracetam (BRV) at various doses among patients with epilepsy through a network meta-analysis. Randomized controlled trials (RCTs) were retrieved from different databases, which were then pooled for a network analysis for calculating the odds ratios (ORs), together with the corresponding 95% confidence intervals (CIs) and surface under the cumulative ranking curve (SUCRA). A total of 9 RCTs were included in the final analysis. Compared with placebo, BRV at a dose of 50 mg daily led to a markedly increased risk of nervous system disorders (OR, 0.62; 95% CI, 0.43-0.90; P=0.01) and evidently increased the risk of psychiatric disorders (OR, 0.16; 95% CI, 0.04-0.64; P=0.022). However, BRV treatment was not associated with a statistically significant change in the prevalence of infectious diseases. SUCRA analysis suggested that treatment with BRV at 50 mg/day posed the highest risk of nervous system disorders and psychiatric disorders compared with placebo or other doses of BRV. In conclusion, BRV treatment at a dose of 50 mg/day may increase the risk of nervous system diseases and psychosis disorders compared with the placebo group. However, more high-quality clinical studies are warranted to validate these results.

Levetiracetam vs. phenytoin as 2nd-line treatment for status epilepticus: A systematic review and meta-analysis

OBJECTIVE

The objective of the study was to perform a systematic review and meta-analysis to evaluate the efficacy and safety of levetiracetam (LEV) or phenytoin (PHT) as second-line treatment for status epilepticus (SE).

METHODS

PubMed, Cumulative Index to Nursing and Allied Health Literature (CINAHL), Latin American and Caribbean Health Sciences Literature (LILACS), Scopus, the Cochrane Database of Systematic Reviews, the Cochrane Central Register of Controlled Trials, and Google Scholar were assessed for prospective randomized trials comparing LEV with PHT as second-line treatment of SE published from inception until December 18th, 2019. The primary outcome was seizure cessation. Data were analyzed using a random-effects model. Quality analysis was performed using version 2 of the Cochrane risk-of-bias tool (RoB 2). The study protocol was registered on PROSPERO (CRD42020136417).

RESULTS

Nine studies with a total of 1732 patients were included. Overall, seizure cessation occurred in 657 of 887 (74%) of patients in the LEV group and 600 of 845 (71%) in the PHT group. Treatment success did not differ significantly between groups, and the relative risk (RR) was 1.05 (95% confidence interval (CI): 0.98-1.12; I² = 53%). Six of the studies were at low risk of bias, one study had some risk, and two studies had high risk.

CONCLUSIONS

The use of LEV or PHT as second-line agents after benzodiazepine (BZD) for the treatment of SE was not associated with a difference in seizure cessation. Because there are minimal differences in efficacy at this time, clinicians should consider alternative factors when deciding on an antiepileptic drug (AED).

Brivaracetam for the treatment of focal-onset seizures: pharmacokinetic and pharmacodynamic evaluations

INTRODUCTION

The goal of pharmacologic therapy with antiseizure medications (ASMs) is to achieve a seizure-free state with minimal side effects. About one third of patients treated with available ASMs continue to experience uncontrolled seizures. There is still need for new ASMs with enhanced effectiveness and tolerability.

AREAS COVERED

The present manuscript is based on an extensive Internet and PubMed search from 1999 to 2020. It is focused on the clinical and pharmacological properties of brivaracetam (BRV) in the treatment of epilepsy.

EXPERT OPINION

BRV is approved as add-on or monotherapy (in US) for the treatment of focal-onset seizures with or without secondary generalization. BRV is a high affinity synaptic vesicle glycoprotein 2A ligand, with 15-30-fold higher affinity than levetiracetam. The selectivity of BRV may be associated with fewer clinical adverse effects. BRV shares many of the pharmacokinetic characteristics of an ideal ASMs. Additionally, BRV has a low potential for clinically relevant drug-drug interactions. Its pharmacokinetic profile makes BRV a promising agent for the treatment of status epilepticus (SE). Although BRV is not approved for the treatment of SE, it has demonstrated promising preliminary results. Further studies are needed to explore the efficacy and tolerability of BRV in SE.

Human Positron Emission Tomography Neuroimaging

Neuroimaging with positron emission tomography (PET) is the most powerful tool for understanding pharmacology, neurochemistry, and pathology in the living human brain. This technology combines high-resolution scanners to measure radioactivity throughout the human body with specific, targeted radioactive molecules, which allow measurements of a myriad of biological processes in vivo. While PET brain imaging has been active for almost 40 years, the pace of development for neuroimaging tools, known as radiotracers, and for quantitative analytical techniques has increased dramatically over the past decade. Accordingly, the fundamental questions that can be addressed with PET have expanded in basic neurobiology, psychiatry, neurology, and related therapeutic development. In this review, we introduce the field of human PET neuroimaging, some of its conceptual underpinnings, and motivating questions. We highlight some of the more recent advances in radiotracer development, quantitative modeling, and applications of PET to the study of the human brain.

Quantification of [18F]UCB-H Binding in the Rat Brain: From Kinetic Modelling to Standardised Uptake Value

PURPOSE

[¹⁸F]UCB-H is a specific positron emission tomography (PET) biomarker for the Synaptic Vesicle protein 2A (SV2A), the binding site of the antiepileptic drug levetiracetam. With a view to optimising acquisition time and simplifying data analysis with this radiotracer, we compared two parameters: the distribution volume (Vt) obtained from Logan graphical analysis using a Population-Based Input Function, and the Standardised Uptake Value (SUV).

PROCEDURES

Twelve Sprague Dawley male rats, pre-treated with three different doses of levetiracetam were employed to develop the methodology. Three additional kainic acid (KA) treated rats (temporal lobe epilepsy model) were also used to test the procedure. Image analyses focused on: (i) length of the dynamic acquisition (90 versus 60 min); (ii) correlations between Vt and SUV over 20-min consecutive time-frames; (iii) and (iv) evaluation of differences between groups using the Vt and the SUV; and (v) preliminary evaluation of the methodology in the KA epilepsy model.

RESULTS

A large correlation between the Vt issued from 60 to 90-min acquisitions was observed. Further analyses highlighted a large correlation (r > 0.8) between the Vt and the SUV. Equivalent differences between groups were detected for both parameters, especially in the 20-40 and 40-60-min time-frames. The same results were also obtained with the epilepsy model.

CONCLUSIONS

Our results enable the acquisition setting to be changed from a 90-min dynamic to a 20-min static PET acquisition. According to a better image quality, the 20-40-min time-frame appears optimal. Due to its equivalence to the Vt, the SUV parameter can be considered in order to quantify [¹⁸F]UCB-H uptake in the rat brain. This work, therefore, establishes a starting point for the simplification of SV2A in vivo quantification with [¹⁸F]UCB-H, and represents a step forward to the clinical application of this PET radiotracer.