Practice guideline update summary: Efficacy and tolerability of the new antiepileptic drugs II: Treatment-resistant epilepsy

Current role of carbamazepine and oxcarbazepine in the management of epilepsy

Epilepsy is one of the most common neurological disorders, affecting approximately 50 million people worldwide. Despite a dramatic increase in treatment options over the past 30 years, it still ranks fourth in the world's disease burden. There are now close to 30 antiepileptic drugs (AEDs), with more than two thirds introduced to the market after carbamazepine (CBZ) and one third after its derivative, oxcarbazepine (OXC). Following the introduction of these newer AEDs, the role of CBZ and OXC in the therapeutic armamentarium for seizure control and effective epilepsy management needs to be reviewed. The main guidelines list both CBZ and OXC as first-line options or second-line alternatives for the treatment of focal-onset epilepsy and primary generalized tonic-clonic seizures. While evidence suggests that overall AEDs have similar efficacy, some newer AEDs may be better tolerated than CBZ. In line with this, there have been changes in treatment patterns, with many variations across different countries. However, CBZ remains among the two or three most prescribed drugs for focal epilepsy in many countries, and is widely used across Europe, Africa, South America, and Asia, where it represents a good compromise between cost, availability, and effectiveness. OXC is among the first-choice options for the initial treatment of focal-onset seizures in several countries, including the US and China, where the oral suspension is commonly prescribed. This review provides guidance on the optimal use of these two drugs in clinical practice, including in children, the elderly, and in pregnancy.

Experience with Eslicarbazepine Acetate Treatment at a Pediatric Epilepsy Center

Eslicarbazepine acetate (ESL) is a novel, once-daily antiseizure medication. We evaluated the efficacy and safety profile of ESL treatment in epilepsy patients at a single tertiary epilepsy center. In this retrospective observational study, we included 32 patients with pharmacologically intractable epilepsy receiving ESL at Boston Children's Hospital from June 2014 to June 2018. We assessed treatment outcome in terms of efficacy and tolerability at first and last follow-up (f/u). Median age was 17 (interquartile range: 10.8–20.7; range: 6.5–36) years. Twelve (37.5%) patients, including three with seizure freedom, were responders at last f/u. Eleven patients discontinued ESL due to seizure worsening (9, 28%), adverse events (AEs) (2, 6%) or both (4, 12%). Responders showed greater seizure reduction at last f/u with fewer AEs as compared with nonresponders. Ten (31%) patients developed AEs, the most common being sleep problems (5, 15%). One-year retention rate with ESL treatment was 54%. In conclusion, ESL had a good response rate in patients with pharmacologically intractable epilepsy, with about one-third of patients developing AEs.

Comparison of clinical efficacy of oxcarbazepine and lamotrigine combined with escitalopram, and impact on prognostic quality of life in treating patients with epilepsy and depressive disorder

This study aimed to investigate the clinical efficacy of oxcarbazepine and lamotrigine combined with escitalopram in treating patients with epilepsy and depressive disorder, and their influence on the prognostic quality of life. A total of 108 patients with epilepsy and depression were selected as research participants. Among them, 53 patients were treated by oxcarbazepine combined with escitalopram (group A) and 55 patients were treated by lamotrigine combined with escitalopram (group B). Following six-month treatment, efficacy, epilepsy frequency and duration, Hamilton Depression Rating (HAMD) and Montgomery-Asberg Depression Rating (MADRS) scores, adverse reactions, improvement of electroencephalogram (EEG) epileptic discharge, quality of life, 1-year drug retention rate and withdrawal reasons of the two groups were compared. There was no remarkable difference in the total efficacy rate between both groups. The number and duration of epileptic seizures, improvement of EEG epileptic discharge and quality of life in the two groups significantly improved after treatment, with no marked difference. HAMD and MADRS scores of patients from group B were significantly lower after treatment compared with those of patients from group A. The incidence rate of adverse reactions in group B was dramatically lower compared with group A, and the 1-year drug retention rate of group B was dramatically higher compared with that in group A. Both oxcarbazepine and lamotrigine combined with escitalopram exhibited good efficacy in patients with epilepsy and depressive disorder, and they may effectively improve the prognostic quality of life of patients. Lamotrigine combined with escitalopram presented with a better antidepressant effect and safety, with higher patient tolerance.

Digoxin enhances the effect of antiepileptic drugs with different mechanism of action in the pentylenetetrazole-induced seizures in mice

The worldwide prevalence of epilepsy with high percentage of multidrug-resistant patients make it urgent to find new approaches to treating, including the use of combinations of classic anticonvulsants with drugs that have an exclusively original mechanism of action, in particular digoxin. The aim of this work was to investigate the influence of low-dose digoxin on the anticonvulsant effect of sodium valproate, topiramate, levetiracetam, phenobarbital and clonazepam. A basic model of pentylenetetrazole-induced seizures in mice was used. Antiepileptic drugs were administered intragastrically in conditionally effective (ED₅₀) and sub-effective (½ ED₅₀) doses at 30 min, digoxin - subcutaneously at a dose of 0.8 mg/kg (¹/₁₀ LD₅₀) at 10-15 min before seizures induction. Pentylenetetrazole at a dose of 80 mg/kg was administered subcutaneously. Experimental data demonstrates that cardiac glycoside digoxin enhances the anticonvulsant activity of sodium valproate, topiramate, levetiracetam, phenobarbital and clonazepam in the model of pentylenetetrazole-induced seizures, providing a clear protective effect of their sub-effective doses. Digoxin may be a valuable component of adjuvant pharmacotherapy for epilepsy, as it reduces the doses of the classic AEDs without compromising the effectiveness of treatment.

Impact of Early Initiation of Eslicarbazepine Acetate on Economic Outcomes Among Patients with Focal Seizure: Results from Retrospective Database Analyses

INTRODUCTION

This study assessed the association between early initiation of eslicarbazepine acetate (ESL) as first-line therapy (1L cohort) or as first adjunctive regimen to either levetiracetam (LEV) or lamotrigine (LTG) (add-on cohort), and healthcare resource utilization (HCRU) and charges among adults with treated focal seizures (FS).

METHODS

This retrospective, longitudinal cohort analysis used Symphony Health's Integrated Dataverse (IDV®) claims data to identify patients aged ≥ 18 years with a diagnosis of FS who had a new prescription for ESL between April 2015 and June 2018. Baseline was the 90-day period immediately prior to the date of the first-dispensed claim for ESL (index date) with a follow-up of 1-4 consecutive 90-day periods. Linear regression models were estimated to assess changes in HCRU and charge outcomes.

RESULTS

There were 274 and 153 patients who received ESL in the 1L cohort and add-on cohort, respectively. The 1L cohort experienced significant reductions from baseline during follow-up in all-cause inpatient (IP; P < 0.0001), emergency room (ER; P < 0.0001), and outpatient (OP; P < 0.0001) visits; FS-related IP (P = 0.006) and OP (P < 0.0001) visits; total, medical, all-cause ER and OP, and FS-related medical charges (P < 0.05); and significant increases in total prescription and anti-seizure drug (ASD)-related prescription (P < 0.001) charges. The add-on cohort experienced significant reductions in all-cause IP (P = 0.009) and all-cause and FS-related OP visits (P < 0.0001 for both) and significant increases in total prescription and ASD-related prescription (P < 0.001) charges during the follow-up period. In both cohorts, the increases in prescription charges were smaller than the reduction in total medical charges.

CONCLUSION

Early initiation of ESL as 1L or add-on therapy was associated with statistically significant reductions in all-cause IP and all-cause and FS-related OP visits during follow-up compared to baseline. The 1L cohort also had statistically significant reductions in all-cause ER visits, FS-related IP visits, and total, medical, all-cause ER and OP, and FS-related medical charges. Knowledge of healthcare resource utilization (HCRU) and costs of care in patients taking anti-seizure drugs (ASDs) is required to inform prescribing and formulary decision-making. Levetiracetam (LEV) and lamotrigine (LTG) are the most widely used first-line (1L) ASDs in the USA. Eslicarbazepine acetate (ESL), a third-generation ASD with sodium channel-modulating activity, is typically used in later lines of therapy. Sodium channel-blocking anti-seizure drugs may represent an effective treatment option for patients with epilepsy in the 1L setting. This study assessed the association between early initiation of ESL as 1L therapy (1L cohort) or as first adjunctive therapy to either LEV or LTG (add-on cohort), and HCRU and charges among adults with treated focal seizures (FS). The results showed that following ESL initiation the 1L cohort experienced significant reductions in all-cause inpatient (IP), emergency room (ER), and outpatient (OP) visits; FS-related IP and OP visits; and total, medical, all-cause ER and OP, and FS-related medical charges, and significant increases in total prescription and ASD-related prescription charges. The add-on cohort showed significant reductions in all-cause IP and all-cause and FS-related OP visits and significant increases in total prescription and ASD-related prescription charges. In both cohorts, the increases in prescription charges were smaller than the reduction in total medical charges. These data imply that use of ESL as 1L therapy in adult patients with FS could help conserve scarce healthcare resources and reduce the burden on healthcare budgets. These findings may inform selection of ASD therapy in this patient population.

Effects of levetiracetam and lacosamide on therapeutic efficacy and neural function in patients with epilepsy

The present study aimed to investigate the effects of levetiracetam tablets and lacosamide (LCM) on therapeutic efficacy and neural function in patients with epilepsy. We assigned 252 patients with refractory partial seizures admitted to our hospital to receive either levetiracetam tablets [120 patients, the control group (CG)] or levetiracetam tablets combined with LCM [132 patients, the joint group (JG)]. The bone mineral density and neural function between the two groups at 6 months before and after treatment were compared. The total response rate was higher in the JG than in the CG (P<0.05). There was no significant difference in the comparison of the multiple indexes between the two groups before treatment (P>0.05). The frequency of seizures was reduced after treatment in the two groups, however, it was lower in the JG compared with the CG (P<0.05). The levels of neurological indicators were significantly reduced after treatment in the two groups (P<0.05), however, the reduction was more marked in the JG than in the CG. The bone mineral density (BMD) of the femoral neck decreased after treatment in the two groups (P<0.05), but there was no difference between the two groups after treatment (P>0.05). The calcium content decreased after treatment in the two groups (P<0.05), but there was no difference between the two groups after treatment (P>0.05). The comparison of other bone metabolism markers between the two groups exhibited no significant differences. The combination therapy greatly increased the quality of life score and the 1-year drug retention rate. To sum up, levetiracetam tablets combined with LCM significantly enhanced the therapeutic effect and improved the neural function in patients with refractory partial seizures, however this therapy may cause a slight adverse effect on BMD and bone metabolism in the short term.

Expert opinion: Proposed diagnostic and treatment algorithms for Lennox-Gastaut syndrome in adult patients

Lennox-Gastaut syndrome (LGS) is a severe developmental epileptic encephalopathy diagnosed in childhood that persists through adolescence and into adulthood. While the characteristics of LGS in pediatric patients are well defined, including "drop attacks", interictal slow spike and wave electroencephalogram (EEG) activity, and intellectual disability, these features can evolve over time, and different EEG activities may be present in adult patients with LGS. This may result in missed diagnoses in these patients and subsequent challenges for the adequate treatment of their seizures. Based on discussions held during the LGS Transition of Care advisory board meeting and thereafter, we developed proposed diagnostic and treatment algorithms for LGS in adult patients. We highlight readily available assessments to facilitate diagnosis of LGS, based on past medical history and physical examination. The LGS diagnostic algorithm recommends that clinicians consider the occurrence of wider seizure types and abnormal EEG activities to be potentially indicative of LGS. Seizure types may include atypical absence seizures, myoclonic seizures, focal seizures, and tonic-clonic seizures, and EEG may demonstrate background slowing, focal or multifocal epileptiform discharges, and diffuse fast rhythms during sleep, among other activities. Extended EEG during sleep and video-EEG should be used in equivocal cases. Treatment of LGS in adult patients should incorporate both antiseizure drug (ASD) therapy and nonpharmacologic approaches. Frequent reassessment of patients is considered a central aspect. ASDs were categorized based on order of preference for use in the treatment of LGS; Tier 1 comprises recommended first-line ASDs, and includes valproate, clobazam, lamotrigine, rufinamide, topiramate, and cannabidiol. Other treatment options include diet, neurostimulation, and surgical approaches. Developments with the potential to improve diagnosis in the future include genetic screening, while novel ASDs and advances in neurostimulation techniques may provide valuable treatment options. These algorithms should be frequently revisited to incorporate improved techniques and therapies.

Eslicarbazepine Acetate: A Review in Focal-Onset Seizures

Eslicarbazepine acetate (Zebinix^®), a voltage-gated sodium channel blocker, is a once-daily, orally administered anti-seizure medication available in the EU for use as monotherapy in adults with newly diagnosed focal-onset seizures and as adjunctive therapy in adults, adolescents and children aged > 6 years with focal-onset seizures. In adult patients, adjunctive eslicarbazepine acetate was generally associated with a significant decrease in seizure frequency and an increase in responder rate compared with placebo. The drug was also an effective monotherapy agent in adult patients, demonstrating noninferiority to controlled-release carbamazepine, in terms of seizure freedom rates. In paediatric patients, eslicarbazepine acetate provided seizure control when administered as adjunctive therapy, with the benefits appearing to be dependent on age and dose. The antiepileptic efficacy of eslicarbazepine acetate as adjunctive therapy or as monotherapy was maintained during longer-term extension studies, with each extension study period being up to 2 years. Oral eslicarbazepine acetate was generally well tolerated when administered as adjunctive therapy or monotherapy in adult patients and when administered as adjunctive therapy in paediatric patients, with most adverse events being of mild or moderate intensity. In conclusion, with the convenience of once-daily administration, eslicarbazepine acetate is an effective and generally well-tolerated treatment option for adults, adolescents and children aged > 6 years with focal-onset seizures.

Clinical Data for the Use of Cannabis-Based Treatments: A Comprehensive Review of the Literature

Objective:

To compile and synthesize the available literature describing medical cannabis use across various disease states.

Data Sources:

PubMed, EBSCO, and Google Scholar searches were conducted using MeSH and/or keywords.

Study Selection and Data Extraction:

Studies were included if they described the use of cannabis-based products and medications in the treatment of a predefined list of disease states in humans and were published in English. The extraction period had no historical limit and spanned through April 2019.

Data Synthesis:

Evidence was compiled and summarized for the following medical conditions: Alzheimer disease, amyotrophic lateral sclerosis, autism, cancer and cancer-associated adverse effects, seizure disorders, human immunodeficiency virus, inflammatory bowel disease, multiple sclerosis (MS), nausea, pain, posttraumatic stress disorder, and hospice care.

Relevance to Patient Care and Clinical Practice:

Based on identified data, the most robust evidence suggests that medical cannabis may be effective in the treatment of chemotherapy-induced nausea and vomiting, seizure disorders, MS-related spasticity, and pain (excluding diabetic neuropathy). Overall, the evidence is inconsistent and generally limited by poor quality. The large variation in cannabis-based products evaluated in studies limits the ability to make direct comparisons. Regardless of the product, a gradual dose titration was utilized in most studies. Cannabis-based therapies were typically well tolerated, with the most common adverse effects being dizziness, somnolence, dry mouth, nausea, and euphoria.

Conclusions:

As more states authorize medical cannabis use, there is an increasing need for high-quality clinical evidence describing its efficacy and safety. This review is intended to serve as a reference for clinicians, so that the risks and realistic benefits of medical cannabis are better understood.

Polygonogram and isobolographic analysis of interactions between various novel antiepileptic drugs in the 6-Hz corneal stimulation-induced seizure model in mice

Pharmacotherapy with two antiepileptic drugs in combination is usually prescribed to epilepsy patients with refractory seizures. The choice of antiepileptic drugs in combination should be based on synergistic cooperation of the drugs with respect to suppression of seizures. The selection of synergistic interactions between antiepileptic drugs is challenging issue for physicians, especially, if 25 antiepileptic drugs are currently available and approved to treat epilepsy patients. The aim of this study was to determine all possible interactions among 5 second-generation antiepileptic drugs (gabapentin (GBP), lacosamide (LCM), levetiracetam (LEV), pregabalin (PGB) and retigabine (RTG)) in the 6-Hz corneal stimulation-induced seizure model in adult male albino Swiss mice. The anticonvulsant effects of 10 various two-drug combinations of antiepileptic drugs were evaluated with type I isobolographic analysis associated with graphical presentation of polygonogram to visualize the types of interactions. Isobolographic analysis revealed that 7 two-drug combinations of LEV+RTG, LEV+LCM, GBP+RTG, PGB+LEV, GBP+LEV, PGB+RTG, PGB+LCM were synergistic in the 6-Hz corneal stimulation-induced seizure model in mice. The additive interaction was observed for the combinations of GBP+LCM, GBP+PGB, and RTG+LCM in this seizure model in mice. The most beneficial combination, offering the highest level of synergistic suppression of seizures in mice was that of LEV+RTG, whereas the most additive combination that protected the animals from seizures was that reporting additivity for RTG+LCM. The strength of interaction for two-drug combinations can be arranged from the synergistic to the additive, as follows: LEV+RTG > LEV+LCM > GBP+RTG > PGB+LEV > GBP+LEV > PGB+RTG > PGB+LCM > GBP+LCM > GBP+PGB > RTG+LCM.

Persistence of pregabalin treatment in Taiwan: a nation-wide population-based study

Background

Pregabalin is approved for the treatment of neuropathic pain, fibromyalgia, and seizure disorders, although the pivotal trials were mostly carried out in Europe or North America. The prescribing patterns among different indications in Asia have rarely been explored.

Methods

This was a population-based retrospective cohort study based on the National Health Insurance Research Database in Taiwan. Prescriptions of pregabalin were identified, and data regarding demographics, indications, co-existing diagnoses, and concomitant medications were extracted. Pregabalin users were followed for at least one year, and factors associated with persistence at one year were determined by using multivariate logistic regression analysis.

Results

Between June 2012 and December 2016, 114,437 pregabalin users (mean age 60.7 ± 15.4 years, 57.8% female) were identified. The indications included post-herpetic neuralgia (PHN) (30.5%), musculoskeletal diseases other than fibromyalgia (21.2%), fibromyalgia (18.4%), diabetic peripheral neuropathic pain (DPNP) (11.7%) and epilepsy (2.9%). Overall, 62.5% and 6.4% of patients achieved a maximum dose of ≥150 and ≥ 300 mg/day, respectively. The median duration of persistent pregabalin use was 28 days (interquartile range 14–118 days). The one-year persistence rate was 12.1%, and the indications associated with the highest and lowest persistence rates were epilepsy (42.4%) and PHN (6.1%), respectively. Male gender (odds ratio [OR] 1.14, 95% confidence interval [CI] 1.09–1.18), older age (OR 1.01 per year, 95% CI 1.01–1.01), indications other than PHN, especially epilepsy (OR 8.04, 95% CI 7.33–8.81, PHN as reference), and a higher initial dose (OR 1.12 per 75 mg, 95% CI = 1.10–1.15) were associated with persistence at one year, whereas the initial concomitant use of antiviral agents decreased the likelihood (OR 0.41, 95% CI 0.35–0.47).

Conclusions

Pregabalin prescriptions for pain disorders were limited to short-term use, which is consistent around the world. However, the average prescribed dose in Taiwan was lower than those in Western countries, and was frequently below the recommended ranges. Potential causes included the duration of natural history of PHN, and off-label prescriptions for pain in acute herpes zoster, rather than PHN, as well as intolerance to the side effects.

The Prevalence and Factors Associated with Antiepileptic Drug Use in US Nursing Home Residents

BACKGROUND

Antiepileptic drugs (AEDs) are commonly used by nursing home residents, both on- and off-label. The landscape of AED use has changed over the past two decades; however, despite this, contemporaneous research on AED use in US nursing home residents is scant.

OBJECTIVE

The aim of this study was to estimate the prevalence of AED use, describe prescribing patterns, identify factors associated with AED use, and assess whether these factors differ among AEDs with expanded indications in older adults (i.e. gabapentin, pregabalin, topiramate, and lamotrigine).

METHODS

We conducted a cross-sectional study among 549,240 long-stay older residents who enrolled in fee-for-service Medicare and lived in 15,111 US nursing homes on 1 September 2016. Demographics and conditions associated with AED indications, epilepsy comorbidities, and safety data came from the Minimum Data Set Version 3.0 (MDS 3.0). Medicare Part D claims were used to identify AED use. Robust Poisson models and multinomial logistic models for clustered data estimated adjusted prevalence ratios (aPR), adjusted odds ratios (aOR), and 95% confidence intervals (CIs).

RESULTS

Overall, 24.0% used AEDs (gabapentin [13.3%], levetiracetam [4.7%], phenytoin [1.9%], pregabalin [1.8%], and lamotrigine [1.2%]). AED use was associated with epilepsy (aPR 3.73, 95% CI 3.69-3.77), bipolar disorder (aPR 1.20, 95% CI 1.18-1.22), pain (aPR_{moderate/severe vs. no pain} 1.42, 95% CI 1.40-1.44), diabetes (aPR 1.27, 95% CI 1.26-1.28), anxiety (aPR 1.12, 95% CI 1.11-1.13), depression (aPR 1.17, 95% CI 1.15-1.18), or stroke (aPR 1.08, 95% CI 1.06-1.09). Residents with advancing age (aPR_{85+ vs. 65-74 years} 0.73, 95% CI 0.73-0.74), Alzheimer's disease/dementia (aPR 0.87, 95% CI 0.86-0.88), or cognitive impairment (aPR_{severe vs. no impairment} 0.62, 95% CI 0.61-0.63) had decreased AED use. Gabapentinoid use was highly associated with pain (aOR_{moderate/severe vs. no pain} 2.07, 95% CI 2.01-2.12) and diabetes (aOR 1.79, 95% CI 1.76-1.82), but not with an epilepsy indication.

CONCLUSIONS

AED use was common in nursing homes, with gabapentin most commonly used (presumably for pain). That multiple comorbidities were associated with AED use underscores the need for future studies to investigate the safety and effectiveness of AED use in nursing home residents.

Understanding the challenge of comparative effectiveness research in focal epilepsy: A review of network meta-analyses and real-world evidence on antiepileptic drugs

OBJECTIVE

Head-to-head randomized controlled trials (RCTs) are the gold standard for assessing comparative treatment effects. In the absence of direct comparisons between all possible antiepileptic drugs (AEDs), however, clinical decision-making in focal (partial onset) epilepsy relies on alternative evidence borne from indirect comparisons including network meta-analyses (NMAs) and from real-world evidence (RWE) studies. We review NMAs and observational RWE studies comparing AEDs in the adjunctive setting to compare the robustness of these methods and to formulate recommendations for future evidence development.

METHODS

A literature review identified NMAs and RWE studies comparing AEDs for the adjunctive treatment of focal seizures published between January 2008 and October 2018. NMAs were evaluated for robustness using a framework based on guidelines from the National Institute for Health and Care Excellence Decision Support Unit and the International Society for Pharmacoeconomics and Outcomes Research. RWE studies were evaluated using the GRACE checklist.

RESULTS

From a total of 1993 records, 11 NMAs and six RWE studies were eligible. Key limitations identified in the NMAs include nonsystematic selection of RCTs, unexplored heterogeneity between included RCTs in terms of study and patient characteristics, and selection of AEDs and AED doses or dosing strategies that are not reflective of clinical practice. The main limitations of RWE studies concern sample size, design, and analysis methods. Approximately 90% of comparisons between individual AEDs were nonsignificant in the NMAs. None of the RWE studies adjusted for baseline differences between comparator groups; therefore, they lack the validity to make comparative conclusions.

SIGNIFICANCE

Current NMAs and RWE studies provide only nominal comparative evidence for AED treatments in focal epilepsy, and should be used with caution for decision-making due to their methodological limitations. To overcome these hurdles, adherence to methodological guidelines and concerted efforts to collect relevant outcome data in the real world are needed.

Update on Antiepileptic Drugs 2019

PURPOSE OF REVIEW

This article is an update from the article on antiepileptic drug (AED) therapy published in the last Continuum issue on epilepsy and is intended to cover the vast majority of agents currently available to the neurologist in the management of patients with epilepsy. Treatment of epilepsy starts with AED monotherapy. Knowledge of the spectrum of efficacy, clinical pharmacology, and modes of use for individual AEDs is essential for optimal treatment for epilepsy. This article addresses AEDs individually, focusing on key pharmacokinetic characteristics, indications, and modes of use.

RECENT FINDINGS

Since the previous version of this article was published, three new AEDs, brivaracetam, cannabidiol, and stiripentol, have been approved by the US Food and Drug Administration (FDA), and ezogabine was removed from the market because of decreased use as a result of bluish skin pigmentation and concern over potential retinal toxicity.Older AEDs are effective but have tolerability and pharmacokinetic disadvantages. Several newer AEDs have undergone comparative trials demonstrating efficacy equal to and tolerability at least equal to or better than older AEDs as first-line therapy. The list includes lamotrigine, oxcarbazepine, levetiracetam, topiramate, zonisamide, and lacosamide. Pregabalin was found to be less effective than lamotrigine. Lacosamide, pregabalin, and eslicarbazepine have undergone successful trials of conversion to monotherapy. Other newer AEDs with a variety of mechanisms of action are suitable for adjunctive therapy. Most recently, the FDA adopted a policy that a drug's efficacy as adjunctive therapy in adults can be extrapolated to efficacy in monotherapy. In addition, efficacy in adults can be extrapolated for efficacy in children 4 years of age and older. Both extrapolations require data demonstrating that an AED has equivalent pharmacokinetics between its original approved use and its extrapolated use. In addition, the safety of the drug in pediatric patients has to be demonstrated in clinical studies that can be open label. Rational AED combinations should avoid AEDs with unfavorable pharmacokinetic interactions or pharmacodynamic interactions related to mechanism of action.

SUMMARY

Knowledge of AED pharmacokinetics, efficacy, and tolerability profiles facilitates the choice of appropriate AED therapy for patients with epilepsy.

Safety and Efficacy of Supratherapeutic Doses of Clobazam

Clobazam is a commonly used long-acting benzodiazepine approved by the US Food and Drug Administration (FDA) to treat seizures associated with Lennox Gastaut syndrome. The FDA approved maximum dosage of clobazam is 1 mg/kg/d or a total of 40 mg a day. Many providers exceed this dosage but there is limited data on the safety, tolerability, and efficacy of supratherapeutic doses. We reviewed retrospective data at our institution and compared patients on supratherapeutic doses to patients on therapeutic doses. A total of 133 patients met inclusion criteria (65 supratherapeutic, 67 therapeutic). There was no statistically significant difference in terms of seizure control, health care utilization, or side effects between patients on supratherapeutic doses and those on therapeutic doses. This study lends further support to the safety and tolerability of supratherapuetic doses of clobazam.

The value of human epileptic tissue in the characterization and development of novel antiepileptic drugs: The example of CERC-611 and KRM-II-81

The need for improved antiepileptics is clearly mandated despite the existence of multiple existing medicines from different chemical and mechanistic classes. Standard of care agents do not fully control epilepsies and have a variety of side-effect and safety issues. Patients typically take multiple antiepileptic drugs and yet many continue to have seizures. Antiepileptic-unresponsive seizures are life-disrupting and life-threatening. One approach to seizure control is surgical resection of affected brain tissue and associated neural circuits. Although non-human brain studies can provide insight into novel antiepileptic mechanisms, human epileptic brain is the bottom-line biological substrate. Human epileptic brain can provide definitive information on the presence or absence of the putative protein targets of interest in the patient population, the potential changes in these proteins in the epileptic state, and the engagement of novel molecules and their functional impact in target tissue. In this review, we discuss data on two novel potential antiepileptic drugs. CERC-611 (LY3130481) is an AMPA receptor antagonist that selectively blocks AMPA receptors associated with the auxiliary protein TARP γ-8 and is in clinical development. KRM-II-81 is a positive allosteric modulator of GABA_A receptors selectively associated with protein subunits α2 and α 3. Preclinical data on these compounds argue that patient-based biological data increase the probability that a newly discovered molecule will translate its antiepileptic potential to patients.