Rational polytherapy

Epilepsy medication management: Addressing common treatment barriers to adopting cenobamate and other new antiseizure medications

Seizure freedom is an important therapeutic goal for people with epilepsy and is associated with improved quality of life and reduced morbidity and mortality. Yet despite the use of multiple antiseizure medications (ASMs; either as monotherapy or in combination), seizures persist in approximately one third of patients. Third-generation ASMs, such as lacosamide, eslicarbazepine, perampanel, and brivaracetam, have demonstrated good efficacy in terms of reductions in the frequency of focal seizures. The newest ASM, cenobamate, which is indicated for the treatment of focal seizures in adults, has demonstrated notable rates of seizure freedom for some patients with drug-resistant epilepsy. In long-term, open-label clinical studies of adjunctive cenobamate, between 18.4% and 36.3% of patients achieved seizure freedom for a consecutive ≥12-month duration, and 1-year retention rates ranged from 73% to 83%. This article reviews some of the potential treatment barriers encountered during the medication management of patients with epilepsy that may impede the use and optimization of newer ASMs like cenobamate. These include treatment complacency, inadequate trial of new adjunctive therapies ("last in, first out"), pitfalls of rational polytherapy, and restricting the use of newer drugs. Although treatment must always be tailored to the specific patient, clinicians should consider the potential benefits of newer therapies and continue to reassess and optimize ASM treatment to achieve the best outcomes for their patients.

Does treatment in an epilepsy clinic affect epilepsy-related admissions?

BACKGROUND

Epilepsy-related emergency hospitalizations are associated with risks to patients. Neurologist ambulatory care can improve seizure control and decrease the rates of ED visits and emergency hospitalizations.

AIMS

To evaluate the etiologies for emergency epilepsy-related admissions in patients with and without prior epilepsy clinic follow-up, and to identify possible factors that may influence admission rates.

METHODS

A retrospective review of the computerized database and the medical records of all the people with epilepsy who presented to our outpatient epilepsy clinic following an epilepsy-related admission during a 10-year period (2012 - 2021).

RESULTS

The study group included 134 patients with epilepsy aged 18- 85 years who presented to our outpatient epilepsy clinic following an epilepsy-related admission. Patients with pre-admission follow up in the epilepsy clinic (n = 67) were less likely to have epilepsy-related admissions during subsequent post-admission follow-up (p = 0.024), had fewer prior admissions related to antiseizure medication (ASM) discontinuation, ASM nonadherence or sub-therapeutic ASM serum levels (p = 0.038), were more likely to continue epilepsy clinic follow-up (p = 0.036), and received more ASMs before admission (p = 0.0001), at the first post-admission visit (p = 0.0001) and at last follow-up (p = 0.015).

CONCLUSIONS

Epilepsy clinic follow-up may affect the rate of epilepsy and ASM related admissions. Further studies are needed to evaluate the effects of ASM polytherapy and possibly higher doses of ASMs on the rates of epilepsy-related admissions.

Optimizing ketogenic diet therapy for childhood epilepsy: Identifying key factors for seizure control and psychomotor enhancement

OBJECTIVE

To identify key factors influencing the therapeutic efficacy of the ketogenic diet (KD) for children with drug-resistant epilepsy and elucidate their interconnected relationships to optimize clinical practice.

METHODS

Participants were selected from children receiving KD treatment at West Second University Hospital of Sichuan University from September 2015 to October 2023. Clinical factors pre-KD and post-KD (at the third month) were analyzed systematically using an analytical framework. Descriptive analyses, univariate analyses, and multivariate regression analyses were performed for the entire cohort and subgroups of genetic and non-genetic (i.e., structural and unknown) etiologies. Thereby, the most significant predictors were identified for each relevant dependent variable. Path analysis diagrams were used for visual representation.

RESULTS

Of 156 patients, genetic etiology was prevalent (38.5%). In the genetic subgroup, channelopathies predicted lower baseline seizure frequency and increased chance of seizure freedom with KD. Frequent seizures and complex history of anti-seizure medications (ASMs) predicted severe baseline psychomotor abnormalities. Younger age at KD initiation benefited psychomotor improvement. In the non-genetic subgroup, lower baseline seizure frequency increased the likelihood of seizure freedom post-KD. Concurrent use of multiple ASMs helped achieve ≥50% seizure reduction. Boys were more likely to experience psychomotor improvement. A significant correlation was found between ≥50% seizure reduction and psychomotor improvement in both subgroups. Delayed KD initiation (longer epilepsy duration at KD start) was related to a greater number of ASMs used, infrequent seizures, and older age at epilepsy onset. In addition, patients with channelopathies had delayed initiation of KD.

SIGNIFICANCE

Children with genetic epilepsy display more pronounced characteristics of epileptic encephalopathy. Early KD intervention is crucial for channelopathies, notably SCN1A variants. For other drug-resistant epilepsy cases, KD alongside diverse ASMs may improve seizure control and developmental outcomes. However, the patient population benefiting most from early KD tends to start the treatment later, urging a re-evaluation of KD decision-making paradigms.

Retention Rates and Successful Treatment with Antiseizure Medications in Newly-Diagnosed Epilepsy Patients

PURPOSE

Treatment for epilepsy primarily involves antiseizure medications (ASMs), which can be characterized using the clinical data warehouse (CDW) database. In this study, we compared retention rates and time to successful treatment for various ASMs to reflect both efficacy and adverse effects in patients with newly diagnosed epilepsy.

MATERIALS AND METHODS

We identified newly diagnosed epilepsy patients with ASM treatment for more than 12 months using CDW of a tertiary referral hospital. Clinical characteristics were compared between groups with successful and unsuccessful treatment. Cox regression analysis was performed to evaluate independent variables of age, sex, comorbidities, and attributes of ASM regimens.

RESULTS

Of 2515 eligible participants, 46.2% were successfully treated with the first ASM regimen, and 74.7% with all ASM regimens with the median time-to-treatment success of 14 months. Participants with second-generation ASM as the first ASM were more likely to be successfully treated with the first regimen compared to those with first-generation ASM (51.6% vs. 42.3%, p<0.001) and more successfully treated [hazard ratio (HR)=1.26; 95% confidence interval (CI): 1.15-1.39]. Overall, valproic acid was the most common ASM across a wide range of ages under 65 years, while levetiracetam in patients aged over 65 years or lamotrigine in female adult patients. Clinical factors associated with less favorable treatment outcomes included renal disease (HR=0.78; 95% CI: 0.66-0.92), liver disease (HR=0.65; 95% CI: 0.52-0.81), depression (HR=0.70; 95% CI: 0.57-0.84), and mechanical ventilation (HR=0.58; 95% CI: 0.50-0.67).

CONCLUSION

Second-generation ASMs have the advantage of more successful treatment with fewer ASM regimen changes compared with first-generation drugs. Various comorbid conditions as well as age and sex should be considered when selecting ASMs.

Cenobamate enhances the anticonvulsant effect of other antiseizure medications in the DBA/2 mouse model of reflex epilepsy

Clinical studies documented that cenobamate (CNB) has a marked efficacy compared to other antiseizure medications (ASMs) in reducing focal seizures. To date, different aspects of CNB need to be clarified, including its efficacy against generalized seizures. Similarly, the pattern of drug-drug interactions between CNB and other ASMs also compels further investigation. This study aimed to detect the role of CNB on generalized seizures using the DBA/2 mouse model. We have also studied the effects of an adjunctive CNB treatment on the antiseizure properties of some ASMs against reflex seizures. The effects of this adjunctive treatment on motor performance, body temperature, and brain levels of ASMs were also evaluated. CNB was able to antagonize seizures in DBA/2 mice. CNB, at 5 mg/kg, enhanced the antiseizure activity of ASMs, such as diazepam, clobazam, levetiracetam, perampanel, phenobarbital, topiramate, and valproate. No synergistic effects were observed when CNB was co-administered with some Na+ channel blockers. The increase in antiseizure activity was associated with a comparable intensification in motor impairment; however, the therapeutic index of combined treatment of ASMs with CNB was more favorable than the combination with vehicle except for carbamazepine, phenytoin, and oxcarbazepine. Since CNB did not significantly influence the brain levels of the ASMs studied, we suggest that pharmacokinetic interactions seem not probable. Overall, this study shows the ability of CNB to counteract generalized reflex seizures in mice. Moreover, our data documented an evident synergistic antiseizure effect for the combination of CNB with ASMs including phenobarbital, benzodiazepines, valproate, perampanel, topiramate, and levetiracetam.

Dosage, time, and polytherapy dependent effects of different levetiracetam regimens on cognitive function

OBJECTIVE

Cognitive impairment is a potential drawback of antiseizure medications. This study aimed to evaluate the impact of different levetiracetam drug regimens on cognitive function.

METHODS

A retrospective analysis identified 221 patients diagnosed with seizures who underwent cognitive screening. Patients were categorized into four groups: no medications, non-levetiracetam medications, high and low dose levetiracetam. Composite scores determined low and high levetiracetam groups whereby one point was added for each increment in dosage, duration since uptake, and concurrent anti-seizure medication. Variables known to affect cognition were recorded and classified as demographic, seizure-related, diagnosis-related, and psychopathology. Logistic regression was used to identify variables associated with cognitive scores below cut-off.

RESULTS

Multivariable analysis found being male, non-active in the community, less than 12 years of education, left temporal lobe epilepsy, high seizure frequency, and depression were associated with poor cognitive performance. In a final regression analysis, the high levetiracetam group exhibited a 4.5-fold higher likelihood of scoring below cut-off than the medication-free group (OR 4.5, CI 1.5-13.6, p<.08). Depression (OR 2.1, CI 1.1-3.9, p<.03), being male (OR 2.2, CI 1.1-4.3, p<.02), and not being active in the community (OR 3.8, 1.6-8.7, p <.003) remained significant contributors to the model. Language (p<.05), attention (p<.05), and delayed recall (p<.001) were the most affected cognitive domains.

SIGNIFICANCE

When taken in small doses, for brief periods as monotherapy, levetiracetam minimally influences cognition. At higher doses, as part of long-term seizure management, in conjunction with multiple ASMs, LEV is associated with cognitive impairment.

The burden of chronic drug-refractory focal onset epilepsy: Can it be prevented?

Despite the many therapeutic options for epilepsy available today, a third of patients still have poorly controlled epilepsy. Over the years, their transition through lines of treatment exposes them to increased risk of disease progression, mortality, morbidity, mental distress, and not least significantly impaired quality of life (QoL). The present review explores the multiple factors contributing to the impairment of health-related QoL in PWE-including both seizure-related and non seizure-related. The analysis aims to identify potential areas of intervention and strategies for a more holistic approach to epilepsy care and inform policy-makers and healthcare providers in their approach to this condition.

The pharmacological treatment of epilepsy in adults

The pharmacological treatment of epilepsy entails several critical decisions that need to be based on an individual careful risk-benefit analysis. These include when to initiate treatment and with which antiseizure medication (ASM). With more than 25 ASMs on the market, physicians have opportunities to tailor the treatment to individual patients´ needs. ASM selection is primarily based on the patient's type of epilepsy and spectrum of ASM efficacy, but several other factors must be considered. These include age, sex, comorbidities, and concomitant medications to mention the most important. Individual susceptibility to adverse drug effects, ease of use, costs, and personal preferences should also be taken into account. Once an ASM has been selected, the next step is to decide on an individual target maintenance dose and a titration scheme to reach this dose. When the clinical circumstances permit, a slow titration is generally preferred since it is associated with improved tolerability. The maintenance dose is adjusted based on the clinical response aiming at the lowest effective dose. Therapeutic drug monitoring can be of value in efforts to establish the optimal dose. If the first monotherapy fails to control seizures without significant adverse effects, the next step will be to gradually switch to an alternative monotherapy, or sometimes to add another ASM. If an add-on is considered, combining ASMs with different modes of action is usually recommended. Misdiagnosis of epilepsy, non-adherence and suboptimal dosing are frequent causes of treatment failure and should be excluded before a patient is regarded as drug-resistant. Other treatment modalities, including epilepsy surgery, neuromodulation, and dietary therapies, should be considered for truly drug-resistant patients. After some years of seizure freedom, the question of ASM withdrawal often arises. Although successful in many, withdrawal is also associated with risks and the decision needs to be based on careful risk-benefit analysis.

The efficacy and safety of first-line anti-seizure medications as substitution therapy for children with drug-resistant epilepsy: a randomized controlled trial protocol

Although many anti-seizure medications (ASMs) are available, treatment failure, known as drug-resistant epilepsy (DRE), still occurs in around 30% of children with epilepsy. Second-line ASMs are usually used as substitution therapy in DRE to control seizures, although international consensus is not available yet. Previous studies focus on comparing the ASMs, whether as add-on or substitution therapy, mainly conducted in newly diagnosed epilepsy. However, the study that investigated first-line ASMs as substitution therapy compared to second-line ones, particularly among DRE children, is still lacking. A randomized controlled trial (RCT) enrolling 102 participants, aged 1-18, at three referral hospitals in Indonesia will be conducted, dividing them into intervention and control groups. The intervention group will be treated with first-line ASMs as the substitution therapy, while the other in the control group will get second-line ASMs. The primary outcome measure is the proportion difference of responders between groups who get first-line and second-line ASMs in 14 weeks of intervention. Clinical trial registration: ClinicalTrials.gov, identifier NCT05697614.

Cost-effectiveness of cenobamate for focal seizures in people with drug-resistant epilepsy

OBJECTIVE

This study was undertaken to estimate the cost-effectiveness of add-on cenobamate in the UK when used to treat drug-resistant focal seizures in adults who are not adequately controlled with at least two prior antiseizure medications, including at least one used adjunctively.

METHODS

We estimated the cost per quality-adjusted life-year (QALY) for cenobamate compared to brivaracetam, eslicarbazepine, lacosamide, and perampanel in the UK National Health Service over a lifetime time horizon. We used a Markov cohort structure to determine response to treatment, using pooled data from three long-term studies of cenobamate. A network meta-analysis informed the likelihood of response to therapy with brivaracetam, eslicarbazepine, lacosamide, and perampanel relative to cenobamate. Once individuals discontinued treatment, they transitioned to subsequent treatment health states, including other antiseizure medicines, surgery, and vagus nerve stimulation. Costs included treatment, administration, routine monitoring, event management, and adverse events. Published evidence and expert opinion informed the likelihood of response to subsequent treatments, associated adverse events, and costs. Utility data were based on Short-Form six-dimension form utility. Discounting was applied at 3.5% per annum as per National Institute for Health and Care Excellence guidance. Uncertainty was explored through deterministic and probabilistic sensitivity analyses.

RESULTS

In the base case, cenobamate led to cost savings of £51 967 (compared to brivaracetam), £21 080 (compared to eslicarbazepine), £33 619 (compared to lacosamide), and £28 296 (compared to perampanel) and increased QALYs of 1.047 (compared to brivaracetam), 0.598 (compared to eslicarbazepine), 0.776 (compared to lacosamide), and 0.703 (compared to perampanel) per individual over a lifetime time horizon. Cenobamate also dominated the four drugs across most sensitivity analyses. Differences were due to reduced seizure frequency with cenobamate relative to comparators.

SIGNIFICANCE

Cenobamate improved QALYs and was less costly than brivaracetam, eslicarbazepine, lacosamide, and perampanel. Therefore, cenobamate may be considered as a cost-effective adjunctive antiseizure medication for people with drug-resistant focal seizures.

Scoping review of rational polytherapy in patients with drug-resistant epilepsy

There is a paucity of literature regarding the optimal selection of combination antiseizure medications (ASMs) for drug-resistant epilepsy (DRE). The aim of this scoping review is to evaluate current evidence related to "rational polytherapy" among adults with DRE. Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses for Scoping Reviews (PRISMA-SCr) guidelines, PubMed, ProQuest, CINAHL, and Cochrane databases were searched using DRE- and polytherapy-related keywords. The exclusion criteria applied included: non-English; non-human studies; non-research studies; participants less than 18 years; status epilepticus; ASM monotherapy; and certain ASMs. In Covidence, two researchers independently reviewed articles for inclusion at each phase, with a third resolving conflicts. Data were extracted, with quality appraisal using the Mixed Methods Appraisal Tool (MMAT). Of the 6477 studies imported for screening, 33 studies were included. Clinical, humanistic, and economic outcomes were reported by 26, 12, and one study, respectively. Common efficacy-related clinical outcomes included ≥50% reduction in seizure frequency (n = 14), seizure freedom (n = 14), and percent reduction in seizure frequency (n = 8). Common humanistic outcomes included quality of life (n = 4), medication adherence (n = 2), sleep-related outcomes (n = 2), and physician and patient global assessments (n = 2). The economic study reported quality-adjusted life years. The median MMAT score was 80 (range: 60-100). Two studies referenced the standard definition of DRE, whereas five studies did not specifically define DRE. Gaps in the literature include limited generalizability, minimal reports in pregnancy, and lack of optimal ASM combinations, among others. Strengths of the evidence include addressing a variety of outcomes. Inconsistent definitions of DRE, small sample sizes, and heterogeneity among studies limit the ability to draw meaningful conclusions. Optimal combinations of ASMs for rational polytherapy for DRE is unclear.

Synergistic effects of the galanin analog 810-2 with the antiseizure medication levetiracetam in rodent seizure models

OBJECTIVE

The use of many antiseizure medications (ASMs) is limited due to pharmacoresistance and dose-limiting side effects, suggesting an unmet need for novel therapeutic approaches. The neuropeptide galanin reduces seizures in several preclinical seizure and epilepsy models, but its clinical utility is limited due to rapid metabolism and poor blood-brain barrier penetration. The lead galanin analog 810-2 is systemically bioavailable and reduces seizures when administered alone. Further development of this analog, with the potential for use as an add-on therapy in patients with epilepsy, requires a better understanding of the use of this analog in combination with approved ASMs. We sought to evaluate 810-2 in combination with commonly used ASMs in rodent models of seizures.

METHODS

The mouse 6-Hz seizure assay was used to test efficacy of 810-2 in combination with levetiracetam (LEV), valproic acid (VPA), or lacosamide (LCM) using a 1:1 dose ratio in isobolographic studies. Further characterization was performed for the combination of 810-2 and LEV in the mouse corneal kindling and rat 6-Hz assays.

RESULTS

Whereas the combination of 810-2 with VPA and LCM yielded additive interactions, the combination of 810-2 with LEV demonstrated a synergistic interaction in the mouse 6-Hz assay. Supra-additive effects were also observed in the mouse corneal kindling and rat 6-Hz assays for this combination.

SIGNIFICANCE

The combination of 810-2 with LEV suggests the potential for this galanin analog to be further developed as an add-on therapy for patients with epilepsy, particularly when coadministered with LEV.

Trio-Drug Combination of Sodium Valproate, Baclofen and Thymoquinone Exhibits Synergistic Anticonvulsant Effects in Rats and Neuro-Protective Effects in HEK-293 Cells

Epilepsy is a chronic brain disorder, with anti-epileptic drugs (AEDs) providing relief from hyper-excitability of neurons, but largely failing to restrain neurodegeneration. We investigated a progressive preclinical trial in rats, whereby the test drugs; sodium valproate (SVP; 150 and 300 mg/kg), baclofen (BFN; 5 and 10 mg/kg), and thymoquinone (THQ; 40 and 80 mg/kg) were administered (i.p, once/day for 15 days) alone, and as low dose combinations, and subsequently tested for antiseizure and neuroprotective potential using electrical stimulation of neurons by Maximal electroshock (MES). The seizure stages were monitored, and hippocampal levels of m-TOR, IL-1β, IL-6 were measured. Hippocampal histopathology was also performed. Invitro and Insilco studies were run to counter-confirm the results from rodent studies. We report the synergistic effect of trio-drug combination; SVP (150 mg/kg), BFN (5 mg/kg) and THQ (40 mg/kg) against generalized seizures. The Insilco results revealed that trio-drug combination binds the Akt active site as a supramolecular complex, which could have served as a delivery system that affects the penetration and the binding to the new target. The potential energy of the ternary complex in the Akt active site after dynamics simulation was found to be -370.426 Kcal/mol, while the supramolecular ternary complex alone was -38.732 Kcal/mol, with a potential energy difference of -331.694 Kcal/mol, which favors the supramolecular ternary complex at Akt active site binding. In addition, the said combination increased cell viability by 267% and reduced morphological changes induced by Pentylenetetrazol (PTZ) in HEK-293 cells, which indicates the neuroprotective property of said combination. To conclude, we are the first to report the anti-convulsant and neuroprotective potential of the trio-drug combination.

Effect of Anti-seizure Medications on Functional Anatomy of Language: A Perspective From Language Functional Magnetic Resonance Imaging

Background

In epilepsy, cognitive difficulties are common, partly a consequence of anti-seizure medications (ASM), and cognitive side-effects are often considered to be more disabling than seizures and significantly affect quality of life. Functional MRI during verbal fluency tasks demonstrated impaired frontal activation patterns and failed default mode network deactivation in people taking ASM with unfavourable cognitive profiles. The cognitive effect of ASMs given at different dosages in monotherapy, or in different combinations, remains to be determined.

Methods

Here, we compared the effects of different drug loads on verbal fluency functional MRI (fMRI) in people (i) taking dual therapy of ASMs either considered to be associated with moderate (levetiracetam, lamotrigine, lacosamide, carbamazepine/oxcarbazepine, eslicarbazepine, valproic acid; n = 119, 56 females) or severe (topiramate, zonisamide) side-effects; n = 119, 56 females), (ii) taking moderate ASMs in either mono-, dual- or triple-therapy (60 subjects in each group), or (iii) taking different dosages of ASMs with moderate side-effect profiles (n = 180). “Drug load” was defined as a composite value of numbers and dosages of medications, normalised to account for the highest and lowest dose of each specific prescribed medication.

Results

In people taking “moderate” ASMs (n = 119), we observed higher verbal-fluency related to left inferior frontal gyrus and right inferior parietal fMRI activations than in people taking “severe” ASMs (n = 119). Irrespective of the specific ASM, people on monotherapy (n = 60), showed greater frontal activations than people taking two (n = 60), or three ASMs (n = 60). People on two ASMs showed less default mode (precuneus) deactivation than those on monotherapy. In people treated with “moderate” ASMs (n = 180), increased drug load correlated with reduced activation of language-related regions and the right piriform cortex.

Conclusion

Our study delineates the effects of polytherapy and high doses of ASMs when given in monotherapy on the functional anatomy of language. Irrespective of the cognitive profile of individual ASMs, each additional ASM results in additional alterations of cognitive activation patterns. Selection of ASMs with moderate cognitive side effects, and low doses of ASMs when given in polytherapy, could reduce the cognitive effect.

How much can medical management alone improve the outcome of adult drug-resistant epilepsy? An exploratory study on possibilities and limitations of combining multiple therapeutic actions

PURPOSE

Failure to control epileptic seizures with two medications, adequately chosen and dosed, indicates drug-resistant epilepsy (DRE). The chance of pharmacologically controlling seizures is low for patients with DRE and uncontrolled seizures who are not candidates for surgery, who have already undergone surgery, or who already had a vagus nerve stimulator (VNS) placed. Patients experiencing these conditions must instead rely on medical management of their seizures, and there is no breakthrough solution on the horizon. Medical care of DRE might be optimized by systematically considering factors that promote and inhibit breakthrough seizures. For example, seizure control could be enhanced through measures such as increasing the frequency of follow-up visits, tracking treatment plan compliance, treating sleep disorders, rational polypharmacy, adjusting drug administration to achieve higher levels when seizures are more likely and educating patients on seizure triggers. A systematic and simultaneous implementation of all of these measures is likely to yield a sizable, clinically relevant, improvement. This paper presents an exploratory study on the effects of implementing such an approach, specifically evaluating this method's impact on seizure frequency.

METHODS

I performed a retrospective chart review of 659 consecutive adult patients with epilepsy followed up at the University of Utah and at the Salt Lake City VA Medical center using the multimodal approach described above. I identified 27 patients who had DRE and uncontrolled seizures and in whom a medical management optimization protocol was implemented. I measured these patients' seizure frequency at the beginning and the end of the study period and compared the results with those of a matching control group of 48 patients.

RESULTS

The optimization protocol did not increase the number of seizure-free patients with DRE; however, it was effective in minimizing seizure frequency in patients whose seizures remained uncontrolled. Among these patients, the median seizure frequency dropped by 64% in the optimization group but did not change in the control group.

CONCLUSIONS

Despite the high occurrence of DRE, there is no accepted protocol for the related medical management. This paper describes an effective approach that can be implemented in a clinically relevant and readily achievable manner.

Understanding mechanisms of drug resistance in epilepsy and strategies for overcoming it

INTRODUCTION

The present evidence indicates that approximately 70% of patients with epilepsy can be successfully treated with antiepileptic drugs (AEDs). A significant proportion of patients are not under sufficient control, and pharmacoresistant epilepsy is clearly associated with poor quality of life and increased morbidity and mortality. There is a great need for newer therapeutic options able to reduce the percentage of drug-resistant patients.

AREAS COVERED

A number of hypotheses trying to explain the development of pharmacoresistance have been put forward. These include: target hypothesis (altered AED targets), transporter (overexpression of brain efflux transporters), pharmacokinetic (overexpression of peripheral efflux transporters in the intestine or kidneys), intrinsic severity (initial high seizure frequency), neural network (aberrant networks), and gene variant hypothesis (genetic polymorphisms).

EXPERT OPINION

A continuous search for newer AEDs or among non-AEDs (blockers of efflux transporters, interleukin antagonists, cyclooxygenase inhibitors, mTOR inhibitors, angiotensin II receptor antagonists) may provide efficacious drugs for the management of drug-resistant epilepsy. Also, combinations of AEDs exerting synergy in preclinical and clinical studies (for instance, lamotrigine + valproate, levetiracetam + valproate, topiramate + carbamazepine) might be of importance in this respect. Preclinically antagonistic combinations must be avoided (lamotrigine + carbamazepine, lamotrigine + oxcarbazepine).

Survey on Antiepileptic Drug Therapy in Patients with Drug Resistant Epilepsy

Background and Purpose

Individualized anti-epileptic drug (AED) selection in patient with epilepsy is crucial. However, there is no unified opinion in treating patients with drug resistant epilepsy (DRE). This survey aimed to make a consolidate consensus with epileptologists’ perspectives of the treatment for Korean DRE patients by survey responses.

Methods

The survey was conducted with Korean epilepsy experts who have experience prescribing AEDs via e-mail. Survey questionnaires consisted of six items regarding prescription patterns and practical questions in treating patients with DRE in Korea. The research period was from February 2021 to March 2021.

Results

The survey response rate was 83.3% (90/108). Most (77.8%) of the responders are neurologists. The proportion of patients whose seizures were not controlled by the second AED was 26.9%. The proportion of patients who had taken five or more AEDs is 13.9%, and those who are currently taking five or more AEDs are 7.3%, of which 54.5% and 37.9% reported positive effects on additional AED, respectively. The majority (91.1%) of respondents answered that the mechanism of action was the top priority factor when adding AED. Regarding data priority, responders considered that expert opinion should have the top priority, followed by clinical experiences, reimbursement guidelines and clinical evidence. Responders gave 64.9 points (range from 0 to 100) about overall satisfaction on reimbursement system of Health Insurance Review and Assessment Service for AED.

Conclusions

This study on AED therapy for DRE patients is the first nationwide trial in Korean epilepsy experts. In five drug failure, the top priorities on AED selection are mechanism of action and expert opinion. These findings might help to achieve consensus and recognize the insight on optimal therapy of AED in DRE.

Critical Appraisal of Cenobamate as Adjunctive Treatment of Focal Seizures in Adults

Cenobamate (CNB) is the latest antiseizure medication (ASM) authorized for the treatment of focal-onset seizures in adults. Although the precise mechanism of action of CNB is not yet fully understood, this drug inhibits the persistent, rather than transient, voltage-gated sodium channel currents and is a positive allosteric modulator of synaptic and extrasynaptic GABA_A receptors, differently from benzodiazepines. CNB has a non-linear pharmacokinetic with a terminal half-life range of about 50/60 hours within the therapeutic dose range, which allows once daily administration. Cenobamate inhibits cytochrome P450 (CYP) 2C19 and induces CYP3A4 and 2B6, and hence can potentially interact with ASMs (eg, phenytoin, carbamazepine and clobazam) and no-ASMs drugs. In two randomized, double-blind, placebo-controlled trials in patients with focal epilepsies, CNB has shown a particularly good efficacy with a rate of seizure freedom of about 20% during the maintenance period in participants treated with the dose of 400 mg/day. The most common treatment-emergent adverse effects include central nervous system-related symptoms, like dizziness, diplopia, somnolence, and gait disturbances. Safety issues of particular interest are severe skin reactions (drug reaction with eosinophilia and systemic symptoms) and QT shortening, which contraindicates its use in subjects with familial short QT syndrome or in combination with other QT-shortening drugs. The recommended starting dose is 12.5 mg/day, which can be gradually titrated to the target dose (200 mg/day) and further increased up to 400 mg/day. There are several aspects of CNB that need to be still addressed, including the long-term efficacy and the efficacy in patients with generalized seizures. Ongoing studies will clarify these issues. The clinical relevance of the peculiar pharmacokinetics and the pattern of drug-drug interactions also require further investigation.

Developing precision treatments for epilepsy using patient and animal models

Introduction: Phenytoin was the first antiepileptic drug (AED) discovered in an animal model of seizures whose clinical efficacy was subsequently confirmed. This clearly indicated that a search for other AEDs had to consider animal studies.Areas covered: Main seizure tests used for the evaluation of possible anticonvulsive activity of potential anticonvulsants and their predictive values have been reviewed. Procedures used for the estimation of antiepileptogenic effects have been also included.Expert opinion: First-line seizure models comprise maximal electroshock (MES)-, pentylenetetrazol (PTZ)- and kindling-induced convulsions in rodents. The MES test may be considered as a convenient and easy model of generalized tonic-clonic seizures, PTZ test - as a model of generalized myoclonic seizures and to a certain degree - absence seizures. Kindled seizures (for example, from amygdala) may be regarded as a model of focal seizures. Some tests have been suggested for the search of AEDs effective in drug-resistant seizures - for instance, 6 Hz (44 mA) test or intrahippocampal kainate model of mesial temporal lobe epilepsy. There are also recommendations from experimental epileptology on synergistic AED combinations for patients with drug-resistant seizures. The clinical evidence on this issue is scarce and favors a combined treatment with valproate + lamotrigine.

Starting a new anti-seizure medication in drug-resistant epilepsy: Add-on or substitute?

OBJECTIVES

Randomized studies in drug-resistant epilepsy (DRE) typically involve addition of a new anti-seizure medication (ASM). However, in clinical practice, if the patient is already taking multiple ASMs, then substitution of one of the current ASMs commonly occurs, despite little evidence supporting this approach.

METHODS

Longitudinal prospective study of seizure outcome after commencing a previously untried ASM in patients with DRE. Multivariable time-to-event and logistic regression models were used to evaluate outcomes by whether the new ASM was introduced by addition or substitution.

RESULTS

A total of 816 ASM changes in 436 adult patients with DRE between 2010 and 2018 were analyzed. The new ASM was added on 407 (50.1%) occasions and substituted on 409 (49.9%). Mean patient follow-up was 3.2 years. Substitution was more likely if the new ASM was enzyme-inducing or in patients with a greater number of concurrent ASMs. ASM add-on was more likely if a γ-aminobutyric acid (GABA) agonist was introduced or if the patient had previously trialed a higher number of ASMs. The rate of discontinuation due to lack of tolerability was similar between the add-on and substitution groups. No difference between the add-on and substitution ASM introduction strategies was observed for the primary outcome of ≥50% seizure reduction at 12 months.

SIGNIFICANCE

Adding or substituting a new ASM in DRE has the same influence on seizure outcomes. The findings confirm that ASM alterations in DRE can be individualized according to concurrent ASM therapy and patient characteristics.

Anticonvulsant Effectiveness and Neurotoxicity Profile of 4-butyl-5-[(4-chloro-2-methylphenoxy)methyl]-2,4-dihydro-3H-1,2,4-triazole-3-thione (TPL-16) in Mice

Protective (antiseizure) effects of 4-butyl-5-[(4-chloro-2-methylphenoxy)-methyl]-2,4-dihydro-3H-1,2,4-triazole-3-thione (TPL-16) and acute neurotoxic effects were determined in the tonic-clonic seizure model and rotarod test in mice. The interaction profile of four classic antiepileptic drugs (carbamazepine, phenobarbital, phenytoin and valproate) with TPL-16 was also determined in the tonic-clonic seizure model in mice. The protective effects of TPL-16 from tonic-clonic seizures (as ED₅₀ values) and acute neurotoxic effects of TPL-16 (as TD₅₀ values) were determined in 4 pretreatment times (15, 30, 60 and 120 min after its i.p. administration), in adult male albino Swiss mice. The interaction profile of TPL-16 with carbamazepine, phenobarbital, phenytoin and valproate in the tonic-clonic seizure model was determined with isobolographic analysis. Total concentrations of carbamazepine, phenobarbital, phenytoin and valproate were measured in the mouse brain homogenates. The candidate for novel antiepileptic drug (TPL-16) administered separately 15 min before experiments, has a beneficial profile with protective index (as ratio of TD₅₀ and ED₅₀ values) amounting to 5.58. The combination of TPL-16 with valproate produced synergistic interaction in the tonic-clonic seizure model in mice. The combinations of TPL-16 with carbamazepine, phenobarbital and phenytoin produced additive interaction in terms of protection from tonic-clonic seizures in mice. None of the total brain concentrations of classic AEDs were changed significantly after TPL-16 administration in mice. Synergistic interaction for TPL-16 with valproate and the additive interaction for TPL-16 with carbamazepine, phenobarbital and phenytoin in the tonic-clonic seizures in mice allows for recommending TPL-16 as the promising drug for further experimental and clinical testing.

Electro-clinical analysis of epilepsy patients with generalized seizures on adjunctive perampanel treatment

Quantifying epileptiform discharges before and after the initiation of treatment can be useful for evaluating the efficacy of antiepileptic drugs in generalized epilepsy. The aim of this study was to determine if the selective α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptor antagonist perampanel alters the electroencephalographic signals in patients with drug resistant generalized seizures (primary or secondary). We also assessed the clinical efficacy, safety and tolerability of perampanel as an adjunctive treatment for patients with refractory generalized seizures after 3, 6 and 12 months of treatment to determine if there is an electro-clinical correlation. We carried out a 1-year retrospective, unicentric, observational, descriptive and non-interventional study to analyze changes in epileptiform discharges, seizure frequency and adverse effects in patients with generalized seizures taking perampanel as an add-on treatment. Perampanel significantly reduced the total number, total duration, maximal duration and average duration of epileptiform discharges in patients with primary generalized epilepsy (n = 44). In patients with focal onset epilepsy and secondary generalized seizures (n = 8) significant decreases in the maximal duration and average duration of epileptiform discharges were found. These findings correlate with the significant decrease in seizure frequency and clinical improvement observed after taking perampanel as an adjunctive therapy for 3, 6 and 12 months. To our knowledge, this is the first study to show that perampanel reduces epileptiform activity, and that this effect correlates with patients' clinical improvement. Analysing patients' electroencephalographic activity in response to perampanel could be useful for assessing the drug's efficacy and optimising adjunctive treatments.

Treatment of epilepsy in adults: Expert opinion in South Korea

OBJECTIVE

The aim of this study was to gather the expert opinions of Korean epileptologists regarding the treatment of adult patients with epilepsy.

METHODS

A total of 42 neurologists who specialized in epilepsy were surveyed. They completed an online questionnaire describing multiple patient scenarios. Using these scenarios, they evaluated treatment strategies and gave their preference for specific antiepileptic drugs (AEDs) used to treat genetically mediated generalized epilepsy and focal epilepsy.

RESULTS

Initial AED monotherapy, followed by a second form of alternative monotherapy or an add-on combination therapy, was the preferred treatment strategy. The experts reached consensus for 87.2% of the items. The most commonly selected AEDs for the initial monotherapy for patients with generalized epilepsy were levetiracetam or valproate. For those with focal epilepsy, levetiracetam, oxcarbazepine, or lamotrigine were the most popular selections. Ethosuximide was the treatment of choice only for patients with generalized epilepsy with prominent absence seizures. Levetiracetam was preferred as an add-on therapy for both generalized and focal epilepsy. For special populations of patients, such as elderly adults or those with comorbid diseases, levetiracetam or lamotrigine was selected as the treatment of choice.

CONCLUSION

Most of the survey results were in accordance with the US expert opinion survey published in 2016. This survey can assist clinicians in making clinical decisions when treating individual adult patients with epilepsy.

Pharmacodynamic interactions of antiepileptic drugs: From bench to clinical practice

BACKGROUND

Approximately 50% of patients do not achieve seizure control with antiepileptic drug (AED) monotherapy, and polytherapy, with more than one AED, is often required. To date, no evidence-based criteria on how to combine AEDs exist.

OBJECTIVE

This narrative review aimed to provide critical findings of the available literature about the role of pharmacodynamic AEDs' interactions in patients whose epilepsies were treated with polytherapy.

METHODS

Electronic databases, Medical Literature Analysis and Retrieval System Online (MEDLINE) and Excerpta Medica dataBASE (EMBASE), were systematically searched to identify relevant studies on pharmacodynamic AEDs' interactions in patients with epilepsy.

RESULTS AND CONCLUSION

Most data on AED combinations are coming from animal models and preclinical studies. Combining AEDs with different mechanisms of actions seems to have greater effectiveness and lower risk of adverse event development. Conversely, the combination of AEDs may cause pharmacodynamic synergistic effects that may result in not only increased efficacy but also more adverse effects. Despite some AED associations that have been proven to be effective in specific epilepsy/seizure type (e.g., phenobarbital+/phenytoin for tonic seizures and ethosiximide + valproate for absences; lamotrigine + valproate for various epilepsy/seizure types), no clear and definitive evidence exists about AED combinations in humans. Examples of pharmacodynamic interactions that possibly explain the synergistic effects on efficacy or adverse effects include the combination between vigabatrin or pregabalin and sodium channel blockers (supra-additive antiseizure effect) and lacosamide combined with other sodium channel blockers (infra-additive antiseizure effect and neurotoxicity synergistic). The pharmacodynamic lamotrigine-valproate interaction is also supported by synergistic adverse events. Therefore, well-designed double-blind prospective studies recruiting a sufficient number of patients possibly with a crossover design and carefully ascertain the role of pharmacokinetic interactions and variations of AEDs' levels in the blood are needed.

Pharmacological Profile of the Novel Antiepileptic Drug Candidate Padsevonil: Characterization in Rodent Seizure and Epilepsy Models

The antiepileptic drug (AED) candidate, (4R)-4-(2-chloro-2,2-difluoroethyl)-1-{[2-(methoxymethyl)-6-(trifluoromethyl)imidazo[2,1-b][1,3,4]thiadiazol-5-yl]methyl}pyrrolidin-2-one (padsevonil), is the first in a novel class of drugs that bind to synaptic vesicle protein 2 (SV2) proteins and the GABAA receptor benzodiazepine site, allowing for pre- and postsynaptic activity, respectively. In acute seizure models, padsevonil provided potent, dose-dependent protection against seizures induced by administration of pilocarpine or 11-deoxycortisol, and those induced acoustically or through 6 Hz stimulation; it was less potent in the pentylenetetrazol, bicuculline, and maximal electroshock models. Padsevonil displayed dose-dependent protective effects in chronic epilepsy models, including the intrahippocampal kainate and Genetic Absence Epilepsy Rats from Strasbourg models, which represent human mesial temporal lobe and absence epilepsy, respectively. In the amygdala kindling model, which is predictive of efficacy against focal to bilateral tonic-clonic seizures, padsevonil provided significant protection in kindled rodents; in mice specifically, it was the most potent AED compared with nine others with different mechanisms of action. Its therapeutic index was also the highest, potentially translating into a favorable efficacy and tolerability profile in humans. Importantly, in contrast to diazepam, tolerance to padsevonil's antiseizure effects was not observed in the pentylenetetrazol-induced clonic seizure threshold test. Further results in the 6 Hz model showed that padsevonil provided significantly greater protection than the combination of diazepam with either 2S-(2-oxo-1-pyrrolidinyl)butanamide (levetiracetam) or 2S-2-[(4R)-2-oxo-4-propylpyrrolidin-1-yl] butanamide (brivaracetam), both selective SV2A ligands. This observation suggests that padsevonil's unique mechanism of action confers antiseizure properties beyond the combination of compounds targeting SV2A and the benzodiazepine site. Overall, padsevonil displayed robust efficacy across validated seizure and epilepsy models, including those considered to represent drug-resistant epilepsy. SIGNIFICANCE STATEMENT: Padsevonil, a first-in-class antiepileptic drug candidate, targets SV2 proteins and the benzodiazepine site of GABAA receptors. It demonstrated robust efficacy across a broad range of rodent seizure and epilepsy models, several representing drug-resistant epilepsy. Furthermore, in one rodent model, its efficacy extended beyond the combination of drugs interacting separately with SV2 or the benzodiazepine site. Padsevonil displayed a high therapeutic index, potentially translating into a favorable safety profile in humans; tolerance to antiseizure effects was not observed.

Seizures in meningioma

More than one-third of patients with meningiomas will experience seizures at some point in their disease. Despite this, meningioma-associated epilepsy remains significantly understudied, as most investigations focus on tumor progression, extent of resection, and survival. Due to the impact of epilepsy on the patient's quality of life, identifying predictors of preoperative seizures and postoperative seizure freedom is critical. In this chapter, we review previously reported rates and predictors of seizures in meningioma and discuss surgical and medical treatment options. Preoperative epilepsy occurs in approximately 30% of meningioma patients with peritumoral edema on neuroimaging being one of the most significant predictor of seizures. Other associated factors include age <18, male gender, the absence of headache, and non-skull base tumor location. Following tumor resection, approximately 70% of individuals with preoperative epilepsy achieve seizure freedom. Variables associated with persistent seizures include a history of preoperative epilepsy, peritumoral edema, skull base tumor location, tumor progression, and epileptiform discharges on postoperative electroencephalogram. In addition, after surgery, approximately 10% of meningioma patients without preoperative epilepsy experience new seizures. Variables associated with new postoperative seizures include tumor progression, prior radiation exposure, and gross total tumor resection. Both pre- and postoperative meningioma-related seizures are often responsive to antiepileptic drugs (AEDs), although AED prophylaxis in the absence of seizures is not recommended. AED selection is based on current guidelines for treating focal seizures with additional considerations including efficacy in tumor-related epilepsy, toxicities, and potential drug-drug interactions. Continued investigation into medical and surgical strategies for preventing and alleviating epilepsy in meningioma is warranted.

Pharmacotherapy for Pediatric Convulsive Status Epilepticus

Convulsive status epilepticus (CSE) is one of the most common pediatric neurological emergencies. Ongoing seizure activity is a dynamic process and may be associated with progressive impairment of gamma-aminobutyric acid (GABA)-mediated inhibition due to rapid internalization of GABA_A receptors. Further hyperexcitability may be caused by AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) and NMDA (N-methyl-D-aspartic acid) receptors moving from subsynaptic sites to the synaptic membrane. Receptor trafficking during prolonged seizures may contribute to difficulties treating seizures of longer duration and may provide some of the pathophysiological underpinnings of established and refractory SE (RSE). Simultaneously, a practice change toward more rapid initiation of first-line benzodiazepine (BZD) treatment and faster escalation to second-line non-BZD treatment for established SE is in progress. Early administration of the recommended BZD dose is suggested. For second-line treatment, non-BZD anti-seizure medications (ASMs) include valproate, fosphenytoin, or levetiracetam, among others, and at this point there is no clear evidence that any one of these options is better than the others. If seizures continue after second-line ASMs, RSE is manifested. RSE treatment consists of bolus doses and titration of continuous infusions under continuous electro-encephalography (EEG) guidance until electrographic seizure cessation or burst-suppression. Ultimately, etiological workup and related treatment of CSE, including broad spectrum immunotherapies as clinically indicated, is crucial. A potential therapeutic approach for future studies may entail consideration of interventions that may accelerate diagnosis and treatment of SE, as well as rational and early polytherapy based on synergism between ASMs by utilizing medications targeting different mechanisms of epileptogenesis and epileptogenicity.

Refining General Principles of Antiepileptic Drug Treatments for Epilepsy

Antiepileptic drugs (AEDs) are the primary treatment strategy for epilepsy. As the use of AEDs has become more widespread and diverse over the past century, it has become necessary to refine the associated prescription strategies. This prompted the Drug Committee of the Korean Epilepsy Society to perform a systemic review of both international and domestic guidelines as well as literature related to medical treatment of epilepsy, and prepared a series of reviews to provide practical guidelines for clinicians to follow. This article is the first in a series on AED treatments for epilepsy in South Korea.

The role of polytherapy in the management of epilepsy: suggestions for rational antiepileptic drug selection

Introduction: Antiepileptic polytherapy may be indicated in patients experiencing drug-resistant epilepsy. To date, there are no evidence-based criteria on how to combine different antiepileptic drugs (AEDs) together, in order to obtain the best therapeutic response.Areas covered: This paper reviews the available data about the various associations of AEDs in patients undergoing polytherapy, focusing on the most effective and well-tolerated polytherapies. Moreover, some controversial aspects of this topic are addressed.Expert opinion: Nowadays, there are no guidelines on polytherapy in patients with epilepsy; thus, the management of pharmacoresistant epilepsy is still uncertain, except for valproate/lamotrigine combination, which seems to be the only one recommended. Data regarding mechanism of action, pharmacokinetics, tolerability, and, more importantly, the analysis of the valuable clinical studies of drug combinations can help physicians to choose the best and most effective AED association for each patient.

Clinical opinion: Earlier employment of polytherapy in sequential pharmacotherapy of epilepsy

Modern pharmacotherapy for epilepsy consists of orderly, sequential drug trials, in which antiepileptic drugs (AEDs) are chosen under the concept of individual patient-oriented (or - tailored) pharmacotherapy. Although monotherapy has been established as the preferred mode of AEDs therapy in both newly diagnosed and drug resistant epilepsies, there are still lack of evidence to favor either monotherapy or polytherapy in epilepsy, which has generated continuing controversies on the preferred mode of pharmacotherapy. However, each mode of pharmacotherapy may have both advantages and disadvantages, which are different and variable related to individual case scenario. We conducted a brief comparative overview between monotherapy and polytherapy to provide clues for earlier employment of polytherapy in each steps of sequential drug trials. Previous claims about the advantages of monotherapy over polytherapy are not supported but gradually losing its ground by the introduction of a large number of drugs carrying pharmacological advantages for combination therapy. Current evidence stresses the importance of combining drugs having synergistic interactions for better outcome of polytherapy, which has not been considered in previous clinical investigations comparing monotherapy and polytherapy. It is likely that a significant improvement in the outcome of current AEDs therapy is feasible by earlier employment of polytherapy as well as identification of combination drug regimens carrying synergistic interactions. At present, lamotrigine(LTG) and valproate(VPA) combination regimen is the only well documented synergistic regimen, but there are a long-list of candidate regimens requiring future trials in appropriate designs.

Antiepileptic Drug Therapy in Patients with Drug-Resistant Epilepsy

Antiepileptic drug (AED) therapy starts with an accurate diagnosis of epilepsy and is followed by sequential drug trials. Seizure freedom is largely achieved by the first two drug trials; thus, epilepsy that cannot be controlled after appropriately conducted trials of the first two drugs is defined as drug-resistant epilepsy (DRE). It is still unclear which mode of pharmacotherapy, among monotherapy and polytherapy, shows better outcomes in cases of DRE. However, in a recent large hospital cohort study over past two decades, combination therapy was associated with a progressive increase in seizure-free rate than monotherapy in DRE. The benefits of polytherapy in the management of DRE might be related to the recent introduction of many new AEDs with different and novel mechanisms of action and better pharmacokinetic and tolerability profiles. These new AEDs were introduced to the market after they have proven their superiority over placebos in randomized controlled trials (RCTs) on add-on therapy in patients with DRE. Therefore, polytherapy including these new AEDs in the regimen is the approved mode of treatment for cases of DRE; this has prompted physicians to try various combinations of polytherapy to optimize the clinical outcomes. In addition, the significant discrepancies in AED responder rates between RCTs and real-world practice may support the importance of judicious use of new drugs in polytherapy by experienced epileptologists. Most experts now agree to the concept of “rational polytherapy” consisting of mechanistic combinations of AEDs exerting synergistic interactions and to the importance of continuing trials of different rational polytherapy regimens to improve the outcome of the core population of epilepsy patients in the long term.

Chemical space of Escherichia coli dihydrofolate reductase inhibitors: New approaches for discovering novel drugs for old bugs

Escherichia coli Dihydrofolate reductase is an important enzyme that is essential for the survival of the Gram-negative microorganism. Inhibitors designed against this enzyme have demonstrated application as antibiotics. However, either because of poor bioavailability of the small-molecules resulting from their inability to cross the double membrane in Gram-negative bacteria or because the microorganism develops resistance to the antibiotics by mutating the DHFR target, discovery of new antibiotics against the enzyme is mandatory to overcome drug-resistance. This review summarizes the field of DHFR inhibition with special focus on recent efforts to effectively interface computational and experimental efforts to discover novel classes of inhibitors that target allosteric and active-sites in drug-resistant variants of EcDHFR.

Evaluation of long-term antiepileptic drug use in patients with temporal lobe epilepsy: Assessment of risk factors for drug resistance and polypharmacy

PURPOSE

To evaluate risk factors for drug resistance and polypharmacy in patients with temporal lobe epilepsy.

METHODS

Patients with temporal lobe epilepsy, treated for more than 5 years, completed questionnaires on antiepileptic drug use and effect. Logistic regression models were used for analysis of risk factors.

RESULTS

Of 135 patients included in the study, 65% were classified as drug resistant and 41% identified as using polypharmacy. Poor effects associated with first-choice antiepileptic drug were reported by 59% of the patients, and 70% reported poor effects of second-line treatment. The most frequently used first-generation antiepileptic drugs had a similar mean effect to those of second-generation. Univariate regression analyses showed a significant association between drug resistance and mesial temporal sclerosis, seizure onset below 18 years, and lack of family history of epilepsy. However, multivariate regression analysis showed no association with any demographic or clinical features. Unsuccessful treatment with the first antiepileptic drug increased the risk of drug resistance by 18 times, and the risk of poor effect from the second antiepileptic drug by 9 times. Disease duration was associated with annual risk for drug resistance of 7% and for polypharmacy of 5%.

CONCLUSIONS

A poor effect from initial pharmacotherapy is the only early risk factor for drug resistance found in this study. Long disease duration increases the risk of drug resistance and polypharmacy. Second-generation antiepileptic drugs provide no additional effect for poor responders to first-generation drugs.

Antiepileptic drug treatment of generalized tonic-clonic seizures: An evaluation of regulatory data and five criteria for drug selection

BACKGROUND

A generalized tonic-clonic seizure (GTCS) is the most severe form of common epileptic seizure and carries the greatest risk of harm. The aim of this review is to provide an evidence-based guide for the selection of antiepileptic drugs (AEDs) for patients with GTCSs. Eight AEDs are approved in Europe and the USA for the treatment of both primarily GTCSs (PGTCSs) and secondarily GTCSs (SGTCSs) and are considered in this paper.

METHODS

Each AED is evaluated using five criteria: (1) efficacy, by seizure type (a: PGTCSs and b: SGTCSs); (2) adverse effects; (3) interactions; (4) adherence and dosing; and (5) mechanism of action (MOA). To ensure the inclusions of robust data, only efficacy data accepted by regulatory authorities were considered, and data related to adverse effects, interactions, adherence, and MOA were all extracted from UK Summaries of Product Characteristics (SPCs).

RESULTS

(1a) There is class 1 evidence of the efficacy of only four AEDs in controlling PGTCSs (lamotrigine, levetiracetam, perampanel, and topiramate). (1b) There is no class 1 evidence of the efficacy of any AED in SGTCSs although some evidence from pooled/subgroup analyses or meta-analyses supports the use of the four AEDs (levetiracetam, perampanel, topiramate, and with less robust data for lamotrigine). (2) AEDs are associated with different, but to some extent overlapping, common adverse effect profiles but have differing idiosyncratic adverse effects. (3) Pharmacokinetic interactions are seen with most, but not all, AEDs and are most common with carbamazepine and phenytoin. (4) Good adherence is important for seizure control and is influenced by frequency of dosing, among other factors. (5) Mechanism of action is also a consideration in rationalising AED selection when switching or combining AEDs.

CONCLUSION

Ultimately, the choice of AED depends on all these factors but particularly on efficacy and adverse effects. Different patients will weigh the various factors differently, and the role of the treating physician is to provide accurate information to allow patients to make informed choices.

Perampanel, an AMPA receptor antagonist: From clinical research to practice in clinical settings

Epileptic seizures are refractory to treatment in approximately one-third of patients despite the recent introduction of many newer antiepileptic drugs (AEDs). Development of novel AEDs therefore remains a high priority. Perampanel is a first-in-class non-competitive selective AMPA receptor antagonist with a unique mechanism of action. Clinical efficacy and safety of perampanel as adjunctive treatment for focal seizures with/without secondary generalization (±SG) and primary generalized tonic-clonic (PGTC) seizures have been established in five phase 3 randomized controlled trials (RCTs), and a long-term extension study, and perampanel is approved as monotherapy for focal seizures ±SG in the USA. In patients with focal seizures ±SG, add-on perampanel resulted in median percent reduction in seizure frequency 23.3%-34.5% and ≥50% responder rate 28.5%-37.6%; in PGTC seizures, these results were 76.5% and 64.2%, respectively. Efficacy among adolescents (reduction in seizure frequency 34.8%-35.6%; ≥50% responder rate 40.9%-45.0%) and elderly people (reduction in seizure frequency 12.5%-16.9%; ≥50% responder rate 22.2%-42.9%) is similar to those in adults, and results remain comparable between Asian (reduction in seizure frequency 17.3%-38.0%) and global populations. Perampanel has been extensively studied in real-world clinical practice, with similar efficacy and safety results to the RCTs (≥50% responder rate 12.8%-75.0%; adverse events of somnolence/sedation, dizziness, ataxia, and behavioral changes). Real-world observational studies suggest that perampanel tolerability can be improved by slow titration (2 mg every 2-4 weeks), and bedtime administration can mitigate somnolence and dizziness. Counseling about the potential for behavioral changes and close monitoring are recommended.

Prevalence and patterns of anti-epileptic medication prescribing in the treatment of epilepsy in older adults with intellectual disabilities

BACKGROUND

The prevalence of epilepsy is higher in people with intellectual disability (ID) and increases with the degree of ID. Although life expectancy for people with ID is increasing, people with ID coexisting with epilepsy have a higher mortality rate, particularly those who had recent seizures. There have been few observational studies of the prevalence and patterns of anti-epileptic prescribing among older people with ID and epilepsy. The aim of this study was to investigate prevalence and patterns of anti-epileptic prescribing in the treatment of epilepsy in a representative population of older people with ID and epilepsy.

METHODS

This was an observational cross-sectional study from wave 1 (2009/2010) of Intellectual Disability Supplement to the Irish Longitudinal Study on Aging, a nationally representative sample of 753 persons with ID aged between 41 and 90 years. Participants and/or proxies recorded medicines used on a regular basis and reported doctor's diagnosis of epilepsy; medication data were available for 736 (98%). Prescribing of anti-epileptic drugs (AEDs) for epilepsy in those with a doctor's diagnosis of epilepsy (N = 205) was the primary exposure of interest for this study. Participant exposure to these AEDs was then categorised into AED monotherapy and polytherapy. Participants/carers reported seizure frequency, when epilepsy was last reviewed and which practitioner reviewed epilepsy. In addition, medications that may lower the seizure threshold that were listed in the Maudsley prescribing guidelines in psychiatry were examined.

RESULTS

Of the 736 participants with reported medicines use, 38.9% (n = 287) were exposed to AEDs, and 30.6% (225) had a doctor's diagnosis of epilepsy. Of those with epilepsy (n = 225), 90.9% (n = 205) reported concurrent use of AEDs and epilepsy. Of these 205 participants, 50.3% (n = 103) were exposed to AED polytherapy, and 63 different polytherapy regimes were reported. The most frequently reported AEDs were valproic acid (n = 100, 48.7%), carbamazepine (n = 89, 46.3%) and lamotrigine (n = 57, 27.8%). In total, 13.7% had a concurrent psychotropic, which should be avoided in epilepsy, and 32.6% had a psychotropic where caution is required. Antipsychotics with potential epileptogenic potential accounted for 80% of these medications. Of those with AED polytherapy (n = 103), 29.5% (28) reported being seizure free for the previous 2 years.

CONCLUSIONS

Prevalence of epilepsy was high among older people with ID, and half were exposed to two or more AEDs. Despite the use of AED therapy, over half had seizures in the previous 2 years. As the primary goals of optimal AED treatment are to achieve seizure freedom without unacceptable adverse effects, this was not achievable for many older patients with ID and epilepsy. Our findings indicated that people with ID and epilepsy were often exposed to psychotropic medications that may lower the seizure threshold. Regular review of epilepsy and medicines (including medicines that may interact with AEDs or lower the seizure threshold) by multidisciplinary teams working to agreed standards may improve quality of prescribing. Improved exchange of information and coordination of care between specialists and primary care practitioners in line with expert consensus recommendations could bring substantial benefit.

Potent and selective pharmacodynamic synergy between the metabotropic glutamate receptor subtype 2-positive allosteric modulator JNJ-46356479 and levetiracetam in the mouse 6-Hz (44-mA) model

OBJECTIVE

We previously demonstrated that positive allosteric modulators (PAMs) of metabotropic glutamate subtype 2 (mGlu₂ ) receptors have potential synergistic interactions with the antiseizure drug levetiracetam (LEV). The present study utilizes isobolographic analysis to evaluate the combined administration of JNJ-46356479, a selective and potent mGlu₂ PAM, with LEV as well as sodium valproate (VPA) and lamotrigine (LTG).

METHODS

The anticonvulsant efficacy of JNJ-46356479 was evaluated in the 6-Hz model of psychomotor seizures in mice. JNJ-46356479 was administered in combination with LEV using 3 fixed dose-ratio treatment groups in the mouse 6-Hz (44-mA) seizure test. The combination of JNJ-46356479 with LEV was also evaluated in the mouse corneal kindling model. The potential interactions of JNJ-46356479 with the antiseizure drugs VPA and LTG were also evaluated using fixed dose-ratio combinations. Plasma levels were obtained for analysis of potential pharmacokinetic interactions for each combination studied in the mouse 6-Hz model.

RESULTS

JNJ-46356479 was active in the 6-Hz model at both 32-mA and 44-mA stimulus intensities (median effective dose = 2.8 and 10.2 mg/kg, respectively). Using 1:1, 1:3, and 3:1 fixed dose-ratio combinations (LEV:JNJ-46356479), coadministration was significantly more potent than predicted for additive effects, and plasma levels suggest this synergism was not due to pharmacokinetic interactions. Studies in kindled mice further demonstrate the positive pharmacodynamic interaction of LEV with JNJ-46356479. Using 1:1 dose-ratio combinations of JNJ-46356479 with either VPA or LTG, there were no significant differences observed for coadministration.

SIGNIFICANCE

These studies demonstrate a synergistic interaction of JNJ-46356479 with LEV, whereas no such effect occurred for JNJ-46356479 with either VPA or LTG. The synergy seems therefore to be specific to LEV, and the combination LEV/mGlu₂ PAM has the potential to result in a rational polypharmacy approach to treat patients with refractory epilepsy, once it has been confirmed in clinical studies.

The impact of polypharmacy and drug interactions among the elderly population in Western Sicily, Italy

AIM

Primary endpoint was to report polypharmacy distribution in the general population vs ≥65 years old people and to examine the frequency of drug-drug interactions (DDIs) in the Health Local Unit of Palermo, Italy, in relationship with patients' age.

METHODS

Drug prescription data for the year 2014 were extracted from the database of the Local Health Unit of Palermo Province, Italy. Patients were divided into five age groups (0-13, 14-64, 65-69, 70-74, and ≥75 year old). The detection of potential DDIs in polypharmacy profiles was performed with NavFarma software (Infologic srl, Padova, Italia), with DDI classification provided by tool Micromedex Drug Reax (Truven Health Analitics, Michigan, USA).

RESULTS

We analyzed data of 1,324,641 patients, and 15,801,191 medical prescription were recorded; of these, 11,337,796 regarded chronic conditions. The drug prescriptions reached the highest values in the 65-69 and 70-74 age groups (p = 0.005 and p = 0.008 vs age 14-64 respectively). An overall amount of 6,094,373 DDIs were detected, of which 47,173 were contraindicated. Median number of DDIs was higher in 65-69 and 70-74 age groups (p = 0.008 and p = 0.012 vs age 14-64, respectively). Regarding contraindicated DDIs a significant difference was detected comparing 14-64 vs ≥65 age groups (p = 0.010 vs 65-69 group, p = 0.005 vs 70-74 group and ≥75 group).

CONCLUSIONS

Polypharmacy is a phenomenon acquiring increasing dimensions also in our province. It interests particularly the older subjects, and assumes a dramatic accent when it is put in relationship with the frequency of DDIs. A proactive vigilance about potential life threatening drug interactions is mandatory.

Influence of titration schedule and maintenance dose on the tolerability of adjunctive eslicarbazepine acetate: An integrated analysis of three randomized placebo-controlled trials

OBJECTIVE

To examine the influence of titration schedule and maintenance dose on the incidence and type of treatment-emergent adverse events (TEAEs) associated with adjunctive eslicarbazepine acetate (ESL).

METHODS

Data from three randomized, double-blind, placebo-controlled trials were analyzed. Patients with refractory partial-onset seizures were randomized to maintenance doses of ESL 400, 800, or 1200mg QD (dosing was initiated at 400 or 800mg QD) or placebo. The incidence of TEAEs was analyzed during the double-blind period (2-week titration phase; 12-week maintenance phase), according to the randomized maintenance dose and the titration schedule.

RESULTS

1447 patients were included in the analysis. During the first week of treatment, 62% of patients taking ESL 800mg QD had ≥1 TEAE, vs 35% of those taking 400mg QD and 32% of the placebo group; dizziness, somnolence, nausea, and headache were numerically more frequent in patients taking ESL 800mg than those taking ESL 400mg QD. During the double-blind period, the incidences of common TEAEs were lower in patients who initiated ESL at 400mg vs 800mg QD. For the 800 and 1200mg QD maintenance doses, rates of TEAEs leading to discontinuation were lower in patients who began treatment with 400mg than in those who began taking ESL 800mg QD.

CONCLUSIONS

Initiation of ESL at 800mg QD is feasible. However, initiating treatment with ESL 400mg QD for 1 or 2 weeks is recommended, being associated with a lower incidence of TEAEs, and related discontinuations. For some patients, treatment may be initiated at 800mg QD, if the need for more immediate seizure reduction outweighs concerns about increased risk of adverse reactions during initiation.

Basic Mechanisms of Action of the Antiepileptic Drugs

Available antiepileptic drugs interact with a variety of different molecular targets. The mechanism of action of most anticonvulsants is most often complex with a number of affected regions. The combination of mechanisms of action of drugs in particular proportions can possibly determine the showcase of its antiepileptic activity. The common factor between the different supposed mechanisms for a number of drugs includes the possibility for modulating the excitatory and inhibitory neurotransmission through effects upon the voltage-gated ion channels, synaptic plasticity, heterogeneous receptors, and metabolism of neurotransmitters. There are controversial data on the extent to which a specific action can be the reason for the wholesome anticonvulsive characteristics of various medications, as well as the relation with the presence of undesired drug effects. The complexity of the action of some antiepileptic drugs creates conditions for optimal choice during therapy. In many cases, the insufficient familiarity with individual genetic differences and the disease related receptor damages can hinder defining a particular drug action. Characterizing the mechanisms of action of the present antiepileptic medications would increase the understanding for the pathophysiological mechanisms of epileptic seizures, as well as the development of new therapeutic strategies. The development of novel antiepileptic drugs and the ongoing research regarding the mechanism of action of established antiepileptic drugs, are continuously increasing the level of complexity in the spectrum of molecular targets relevant for epilepsy therapy. The current state of knowledge as well as the limitations in our understanding should guide future research aiming for a more detailed elucidation of the impact of genetics and pathophysiological mechanisms on interindividual differences in expression and function of antiepileptic drug targets.

Selecting Rational Drug Combinations in Epilepsy

Monotherapy remains the standard initial therapy of epilepsy, but when the first antiepileptic drug (AED) fails, combination therapy may be considered. The choice of combination therapy should take into consideration pharmacokinetic interactions, as well as pharmacodynamic interactions related to mechanism of action. There is evidence that an AED combination with different mechanisms of action is more likely to be successful than a combination with the same mechanisms. The combination of lamotrigine and valproate has been demonstrated to be synergistic in its efficacy. However, there are limited data to support other synergistic AED combinations.

Evaluation of Safety in Exceeding Maximum Adult Doses of Commonly Used Second-Generation Antiepileptic Drugs in Pediatric Patients

OBJECTIVE

Pediatric patients often require larger doses of antiepileptic drug (AED) than adults in order to attain therapeutic serum concentrations and/or achieve seizure control. Safety and efficacy data are often extrapolated from adult literature; hence, optimal dosage may only be determined anecdotally or based on expert opinion. With limited pediatric dosing guidelines, milligrams per day that are based on weight may exceed the maximum adult dose. The primary objective of this study is to evaluate the safety of exceeding maximum doses as specified by the US Food and Drug Administration or manufacturers of commonly used AEDs in pediatric patients.

METHODS

This study is a single-center, retrospective analysis of all pediatric patients seen in the outpatient clinic between October 2010 and October 2014 who were prescribed a dose that exceeds the maximum approved dose of oxcarbazepine, zonisamide, topiramate, levetiracetam, lamotrigine, or clobazam. Baseline demographics (ie, sex, age, race/ethnicity, weight, height, diagnosis), serum drug concentrations, and appropriate laboratory tests were collected. Side effects were reviewed.

RESULTS

During the 4-year study period, 41,137 prescriptions were included. A total of 2% of prescriptions exceeded the maximum dose of 1 of the included AEDs. The most common AED prescribed above the maximum dose was levetiracetam (53%), whereas lamotrigine was the least common (6%). The largest doses prescribed exceeded the maximum by 3-fold (i.e., levetiracetam dose of 9000 mg/day).

CONCLUSION

It appears safe to use doses exceeding the maximum approved dose of the evaluated AEDs in pediatric patients, with appropriate counseling and monitoring for adverse effects.

Pharmacological Treatment of Drug-Resistant Epilepsy in Adults: a Practical Guide

More than 30 % of adults with epilepsy do not fully control on the currently available antiepileptic drugs (AEDs). For these and many other patients, combinations of agents, often possessing different mechanisms of actions, are employed with the aim of achieving seizure freedom or the best available prognosis in terms of reduced seizure numbers and severity. This review discusses my own approach to optimising outcomes in as many of these patients as possible by adjusting the drug burden using a combination of two, three or sometimes four or more AEDs. Modes of drug action are reviewed and practical strategies for treating different patients with drug-resistant epilepsy have been explored. Only for sodium valproate with lamotrigine is there good evidence of synergism. The final part of this practical paper consists of six individual illustrative cases with appropriate comments.

Adjunctive eslicarbazepine acetate: A pooled analysis of three phase III trials

OBJECTIVE

To assess the safety and efficacy of once-daily (QD) adjunctive eslicarbazepine acetate (ESL).

METHODS

This post-hoc pooled analysis of three randomized, placebo-controlled trials (2093-301, -302, -304) involved adults with refractory partial-onset seizures (POS) receiving 1-3 antiepileptic drugs (AEDs). All studies included 8-week baseline, 2-week titration, and 12-week maintenance periods. Patients were randomized equally to placebo, ESL 400mg (studies 301, 302), 800mg, or 1200mg QD. The primary endpoint was standardized seizure frequency (SSF; per 4weeks); secondary endpoints included responder rates (maintenance period), and incidence of treatment-emergent adverse events (TEAEs), TEAEs leading to discontinuation, serious AEs (SAEs), and deaths.

RESULTS

The safety and efficacy analysis populations totaled 1447 and 1410 patients, respectively. SSF was significantly reduced versus placebo with ESL 800mg (p=0.0001) and 1200mg (p<0.0001) but not 400mg (p=0.81). There were no significant interactions between treatment effect and age, gender, race/ethnicity, geographic region, epilepsy duration, or concomitant AED use. Incidences of TEAEs and TEAEs leading to discontinuation increased with ESL dose. Incidences of the most frequent TEAEs were lower for patients who initiated dosing at 400 versus 800mg QD, regardless of titration regimen and maintenance dose. SAE incidence was <10%; there were 3 deaths (placebo, n=2; ESL 800mg, n=1).

CONCLUSIONS

ESL (800 and 1200mg QD) was effective and well tolerated as adjunctive therapy for adults with refractory POS.

Efficacy of mGlu2 -positive allosteric modulators alone and in combination with levetiracetam in the mouse 6 Hz model of psychomotor seizures

OBJECTIVE

The metabotropic glutamate receptor subtype 2 (mGlu₂ ) possesses both orthosteric and allosteric modulatory sites, are expressed in the frontal cortex and limbic structures, and can affect excitatory synaptic transmission. Therefore, mGlu₂ is a potential therapeutic target in the treatment of epilepsy. The present study seeks to evaluate the anticonvulsant potential of mGlu₂ -acting compounds.

METHODS

The anticonvulsant efficacy of two selective mGlu₂ -positive allosteric modulators (PAMs) (JNJ-42153605 and JNJ-40411813/ADX71149) and one mGlu_2/3 receptor agonist (LY404039) were evaluated alone and in combination with the antiseizure drug levetiracetam (LEV) in the mouse 6 Hz model.

RESULTS

In the 6 Hz (32 mA stimulus intensity) model, median effective dose (ED₅₀ ) values were determined for JNJ-42153605 (3.8 mg/kg), JNJ-40411813 (12.2 mg/kg), and LY404039 (10.9 mg/kg). At the 44 mA stimulus intensity, ED₅₀ values were determined for JNJ-42153605 (5.9 mg/kg), JNJ-40411813 (21.0 mg/kg), LY404039 (14.1 mg/kg), and LEV (345 mg/kg). In addition, subprotective doses of each mGlu₂ -acting compound, administered in combination with various doses of LEV, were able to shift the 6 Hz 44 mA ED₅₀ for LEV by >25-fold. When JNJ-42153605 was administered at varying doses in combination with a single dose of LEV (10 mg/kg), the potency of JNJ-42153605 was increased 3.7-fold. Similarly, when a moderately effective dose of LEV (350 mg/kg) was administered in combination with varying doses of JNJ-40411813, the potency of JNJ-40411813 was increased approximately 14-fold. Plasma levels of JNJ-40411813 and LEV were not different when administered alone or in combination, suggesting that increases in potency are not due to pharmacokinetic effects.

SIGNIFICANCE

These studies suggest a potential positive pharmacodynamic effect of mGlu₂ -acting compounds in combination with LEV. If this effect is translated in a clinical setting, it can support a rational polypharmacy concept in treatment of epilepsy patients.