Third generation antiepileptic drug monotherapies in adults with epilepsy

Replacement of Valproic Acid with New Anti-Seizure Medications in Idiopathic Generalized Epilepsy

Background: Little is known regarding the non-inferiority of new anti-seizure medications (ASMs) in terms of replacing valproic acid (VPA) in patients with idiopathic generalized epilepsy (IGE). We hypothesized that replacement of VPA with new ASMs would offer non-inferior or better control of seizure frequency. The purpose of this study was to compare epileptic seizure frequency between the subset of patients with IGE who were on VPA and the subset of patients with IGE who replaced VPA with new ASMs. Methods: Patients with IGE who were on or had been on VPA between January 2016 and March 2022 were divided into a group that replaced VPA with new ASMs (VPA-replace group) and a group that remained on VPA (VPA-continue group). We then compared the groups in terms of seizure frequency and myoclonus. Results: Of the 606 patients on VPA between January 2016 and March 2022, 156 patients with IGE were enrolled to this study (VPA-replace group, n = 68; VPA-continue group, n = 88). The VPA-replace group included significantly more females than the VPA-continue group (p < 0.001). The VPA-replace group also showed significantly higher seizure frequency before replacement (p < 0.001), but not after replacement (p = 0.074). Patients on monotherapy displayed improved seizure frequency with new ASMs (p < 0.001). Among the new ASMs, perampanel (PER) significantly improved seizure frequency (p = 0.002). Forty-two patients in the VPA-replace group who had myoclonus achieved significant improvements (p < 0.001). Among these, patients on PER monotherapy (p < 0.001) or PER + lamotrigine (0.016) showed significantly improved myoclonus scale scores. Conclusions: This study shows the non-inferiority of new ASMs compared to VPA, with better seizure control using new ASMs in subsets of patients with IGE on monotherapy.

Antiepileptic drug monotherapy for epilepsy: a network meta-analysis of individual participant data

BACKGROUND

This is an updated version of the original Cochrane Review published in 2017. Epilepsy is a common neurological condition with a worldwide prevalence of around 1%. Approximately 60% to 70% of people with epilepsy will achieve a longer-term remission from seizures, and most achieve that remission shortly after starting antiepileptic drug treatment. Most people with epilepsy are treated with a single antiepileptic drug (monotherapy) and current guidelines from the National Institute for Health and Care Excellence (NICE) in the United Kingdom for adults and children recommend carbamazepine or lamotrigine as first-line treatment for focal onset seizures and sodium valproate for generalised onset seizures; however, a range of other antiepileptic drug (AED) treatments are available, and evidence is needed regarding their comparative effectiveness in order to inform treatment choices.

OBJECTIVES

To compare the time to treatment failure, remission and first seizure of 12 AEDs (carbamazepine, phenytoin, sodium valproate, phenobarbitone, oxcarbazepine, lamotrigine, gabapentin, topiramate, levetiracetam, zonisamide, eslicarbazepine acetate, lacosamide) currently used as monotherapy in children and adults with focal onset seizures (simple focal, complex focal or secondary generalised) or generalised tonic-clonic seizures with or without other generalised seizure types (absence, myoclonus).

SEARCH METHODS

For the latest update, we searched the following databases on 12 April 2021: the Cochrane Register of Studies (CRS Web), which includes PubMed, Embase, ClinicalTrials.gov, the World Health Organization International Clinical Trials Registry Platform (ICTRP), the Cochrane Central Register of Controlled Trials (CENTRAL), the Cochrane Epilepsy Group Specialised Register and MEDLINE (Ovid, 1946 to April 09, 2021). We handsearched relevant journals and contacted pharmaceutical companies, original trial investigators and experts in the field.

SELECTION CRITERIA

We included randomised controlled trials of a monotherapy design in adults or children with focal onset seizures or generalised onset tonic-clonic seizures (with or without other generalised seizure types).

DATA COLLECTION AND ANALYSIS

This was an individual participant data (IPD) and network meta-analysis (NMA) review. Our primary outcome was 'time to treatment failure', and our secondary outcomes were 'time to achieve 12-month remission', 'time to achieve six-month remission', and 'time to first seizure post-randomisation'. We performed frequentist NMA to combine direct evidence with indirect evidence across the treatment network of 12 drugs. We investigated inconsistency between direct 'pairwise' estimates and NMA results via node splitting. Results are presented as hazard ratios (HRs) with 95% confidence intervals (CIs) and we assessed the certainty of the evidence using the CiNeMA approach, based on the GRADE framework. We have also provided a narrative summary of the most commonly reported adverse events.

MAIN RESULTS

IPD were provided for at least one outcome of this review for 14,789 out of a total of 22,049 eligible participants (67% of total data) from 39 out of the 89 eligible trials (43% of total trials). We could not include IPD from the remaining 50 trials in analysis for a variety of reasons, such as being unable to contact an author or sponsor to request data, data being lost or no longer available, cost and resources required to prepare data being prohibitive, or local authority or country-specific restrictions. No IPD were available from a single trial of eslicarbazepine acetate, so this AED could not be included in the NMA. Network meta-analysis showed high-certainty evidence that for our primary outcome, 'time to treatment failure', for individuals with focal seizures; lamotrigine performs better than most other treatments in terms of treatment failure for any reason and due to adverse events, including the other first-line treatment carbamazepine; HRs (95% CIs) for treatment failure for any reason for lamotrigine versus: levetiracetam 1.01 (0.88 to 1.20), zonisamide 1.18 (0.96 to 1.44), lacosamide 1.19 (0.90 to 1.58), carbamazepine 1.26 (1.10 to 1.44), oxcarbazepine 1.30 (1.02 to 1.66), sodium valproate 1.35 (1.09 to 1.69), phenytoin 1.44 (1.11 to 1.85), topiramate 1.50 (1.23 to 1.81), gabapentin 1.53 (1.26 to 1.85), phenobarbitone 1.97 (1.45 to 2.67). No significant difference between lamotrigine and levetiracetam was shown for any treatment failure outcome, and both AEDs seemed to perform better than all other AEDs. For people with generalised onset seizures, evidence was more limited and of moderate certainty; no other treatment performed better than first-line treatment sodium valproate, but there were no differences between sodium valproate, lamotrigine or levetiracetam in terms of treatment failure; HRs (95% CIs) for treatment failure for any reason for sodium valproate versus: lamotrigine 1.06 (0.81 to 1.37), levetiracetam 1.13 (0.89 to 1.42), gabapentin 1.13 (0.61 to 2.11), phenytoin 1.17 (0.80 to 1.73), oxcarbazepine 1.24 (0.72 to 2.14), topiramate 1.37 (1.06 to 1.77), carbamazepine 1.52 (1.18 to 1.96), phenobarbitone 2.13 (1.20 to 3.79), lacosamide 2.64 (1.14 to 6.09). Network meta-analysis also showed high-certainty evidence that for secondary remission outcomes, few notable differences were shown for either seizure type; for individuals with focal seizures, carbamazepine performed better than gabapentin (12-month remission) and sodium valproate (six-month remission). No differences between lamotrigine and any AED were shown for individuals with focal seizures, or between sodium valproate and other AEDs for individuals with generalised onset seizures. Network meta-analysis also showed high- to moderate-certainty evidence that, for 'time to first seizure,' in general, the earliest licensed treatments (phenytoin and phenobarbitone) performed better than the other treatments for individuals with focal seizures; phenobarbitone performed better than both first-line treatments carbamazepine and lamotrigine. There were no notable differences between the newer drugs (oxcarbazepine, topiramate, gabapentin, levetiracetam, zonisamide and lacosamide) for either seizure type. Generally, direct evidence (where available) and network meta-analysis estimates were numerically similar and consistent with confidence intervals of effect sizes overlapping. There was no important indication of inconsistency between direct and network meta-analysis results. The most commonly reported adverse events across all drugs were drowsiness/fatigue, headache or migraine, gastrointestinal disturbances, dizziness/faintness and rash or skin disorders; however, reporting of adverse events was highly variable across AEDs and across studies.

AUTHORS' CONCLUSIONS

High-certainty evidence demonstrates that for people with focal onset seizures, current first-line treatment options carbamazepine and lamotrigine, as well as newer drug levetiracetam, show the best profile in terms of treatment failure and seizure control as first-line treatments. For people with generalised tonic-clonic seizures (with or without other seizure types), current first-line treatment sodium valproate has the best profile compared to all other treatments, but lamotrigine and levetiracetam would be the most suitable alternative first-line treatments, particularly for those for whom sodium valproate may not be an appropriate treatment option. Further evidence from randomised controlled trials recruiting individuals with generalised tonic-clonic seizures (with or without other seizure types) is needed.

Liquid chromatographic methods for determination of the new antiepileptic drugs stiripentol, retigabine, rufinamide and perampanel: A comprehensive and critical review

The new antiepileptic drugs perampanel, retigabine, rufinamide and stiripentol have been recently approved for different epilepsy types. Being them an innovation in the antiepileptics armamentarium, a lot of investigations regarding their pharmacological properties are yet to be performed. Besides, considering their broad anticonvulsant activities, an extension of their therapeutic indications may be worthy of investigation, especially regarding other seizure types as well as other central nervous system disorders. Although different liquid chromatographic (LC) methods coupled with ultraviolet, fluorescence, mass or tandem-mass spectrometry detection have already been developed for the determination of perampanel, retigabine, rufinamide and stiripentol, new and more cost-effective methods are yet required. Therefore, this review summarizes the main analytical aspects regarding the liquid chromatographic methods developed for the analysis of perampanel, retigabine (and its main active metabolite), rufinamide and stiripentol in biological samples and pharmaceutical dosage forms. Furthermore, the physicochemical and stability properties of the target compounds will also be addressed. Thus, this review gathers, for the first time, important background information on LC methods that have been developed and applied for the determination of perampanel, retigabine, rufinamide and stiripentol, which should be considered as a starting point if new (bio)analytical techniques are aimed to be implemented for these drugs.

Potential anti-epileptic phytoconstituents: An updated review

ETHNOPHARMACOLOGICAL RELEVANCE

Epilepsy is one of the most commonly occurring non-communicable neurological disorder that affects people of all age groups. Around 50 million people globally are epileptic, with 80% cases in developing countries due to lack of access to treatments determined by high cost and poor availability or it can be defined by the fraction of active epileptic patients who are not appropriately being treated. The availability of antiepileptic drugs and their adjuvant therapy in such countries is less than 50% and these are highly susceptible to drug interactions and severe adverse effects. As a result, the use of herbal medicine is increasingly becoming popular.

AIM OF THE STUDY

To provide pharmacological information on the active constituents evaluated in the preclinical study to treat epilepsy with potential to be used as an alternative therapeutic option in future. It also provides affirmation for the development of novel antiepileptic drugs derived from medicinal plants.

MATERIALS AND METHODS

Relevant information on the antiepileptic potential of phytoconstituents in the preclinical study (in-vitro, in-vivo) is provided based on their effect on screening parameters. Besides, relevant information on pharmacology of phytoconstituents, the traditional use of their medicinal plants related to epilepsy and status of phytoconstituents in the clinical study were derived from online databases, including PubMed, Clinicaltrial. gov, The Plant List (TPL, www.theplantlist.org), Science Direct. Articles identified using preset searching syntax and inclusion criteria are presented.

RESULTS

More than 70% of the phytoconstituents reviewed in this paper justified the traditional use of their medicinal plant related to epilepsy by primarily acting on the GABAergic system. Amongst the phytoconstituents, only cannabidiol and tetrahydrocannabinol have been explored for clinical application in epilepsy.

CONCLUSION

The preclinical and clinical data of the phytoconstituents to treat epilepsy and its associated comorbidities provides evidence for the discovery and development of novel antiepileptic drugs from medicinal plants. In terms of efficacy and safety, further randomized and controlled clinical studies are required to understand the complete pharmacodynamic and pharmacokinetic picture of phytoconstituents. Also, specific botanical source evaluation is needed.

Seizures, Edema, Thrombosis, and Hemorrhages: An Update Review on the Medical Management of Gliomas

Patients affected with gliomas develop a complex set of clinical manifestations that deeply impact on quality of life and overall survival. Brain tumor-related epilepsy is frequently the first manifestation of gliomas or may occur during the course of disease; the underlying mechanisms have not been fully explained and depend on both patient and tumor factors. Novel treatment options derive from the growing use of third-generation antiepileptic drugs. Vasogenic edema and elevated intracranial pressure cause a considerable burden of symptoms, especially in high-grade glioma, requiring an adequate use of corticosteroids. Patients with gliomas present with an elevated risk of tumor-associated venous thromboembolism whose prophylaxis and treatment are challenging, considering also the availability of new oral anticoagulant drugs. Moreover, intracerebral hemorrhages can complicate the course of the illness both due to tumor-specific characteristics, patient comorbidities, and side effects of antithrombotic and antitumoral therapies. This paper aims to review recent advances in these clinical issues, discussing the medical management of gliomas through an updated literature review.

Effects of long-term antiepileptic polytherapy on bone biochemical markers in ambulatory children and adolescents and possible benefits of vitamin D supplementation: a prospective interventional study

PURPOSE

Our aim was to investigate any adverse effects of long-term polytherapy (VPA and add-on-therapy) on bone biochemical markers in ambulatory children and adolescents with epilepsy and the possible benefits of vitamin D supplementation on the same markers.

METHODS

In this prospective interventional study, the levels of 25(OH)D and the bone turnover markers of CrossLaps (CTX), total alkaline phosphatase (tALP), osteoprotegerin (OPG), and the receptor activator for nuclear factor kB (RANK) ligand (sRANKL) were determined in forty-two ambulatory children with epilepsy on polytherapy (valproic acid + one or more other from levetiracetam, topiramate, lamotrigine, or rufinamide). The same markers were assessed after a year's supplementation of vitamin D (400 IU/d) and were compared with those of clinically healthy controls. The respective mean (±SD) ages were 11.9 ± 4.6 and 11.4 ± 4.4 yrs.

RESULTS

The basal mean 25(OH)D levels in the patients did not differ from controls (23.9 ± 11.5 vs 27.4 ± 13.3 ng/ml), but increased significantly after the vitamin D intake (31.1 ± 13.3 ng/ml, p < 0.01). In parallel, basal serum CTX levels were found to be significantly lower in the patients than controls (0.89 ± 0.63 vs 1.22 ± 0.58 ng/ml, p < 0.02), but not tALP. Osteoprotegerin was higher in the patients (5.7 ± 7.7 pmol/L vs 2.6 ± 1.0 pmol/L, p < 0.03), while sRANKL did not differ. After vitamin D, the CTX levels increased to comparable levels in controls (0.99 ± 0.57 ng/ml), and those of OPG decreased to levels that did not differ from controls (4.9 ± 5.1 pmol/L). The ratio of OPG/sRANKL was higher in patients than controls before treatment (0.030 ± 0.045 vs 0.009 ± 0.005, p < 0.03), but decreased (0.026 ± 0.038) to comparable values in controls later.

CONCLUSIONS

These findings imply a lower bone turnover in the young patients on long-term polytherapy (VPA and add-on-therapy), but after one year's vitamin D intake, bone biochemical markers improved.

What has been the impact of new drug treatments on epilepsy?

PURPOSE OF REVIEW

Nearly two dozen antiseizure medications (ASMs) with different mechanisms of action have been introduced over the past three decades with the aim of providing better efficacy or safety profile than the previous drugs. Several new ASMs with improvement on a classic drug family or have novel mechanisms of action have been recently approved for epilepsy. The present review explored recent studies or guidelines on new agents and discussed the potential impact of these novel treatments on epilepsy management and future directions of research.

RECENT FINDINGS

Long-term cohort studies showed that, collectively, the second-generation did not improve the overall prognosis of epilepsy. Individual monotherapy studies showed similar efficacy of second-generation (levetiracetam and zonisamide) and third-generation (eslicarbazepine acetate and lacosamide) ASMs compared to controlled-release carbamazepine for the treatment of focal epilepsy. However, there appears to be no evidence to support any second-generation or third-generation ASMs to be as efficacious as valproate monotherapy for generalized and unclassified epilepsies. Cannabidiol adjunctive treatments were found to be efficacious for Dravet syndrome and Lennox-Gastaut syndrome. Although most newer generation ASMs are less prone to drug-drug interactions, stiripentol and cannabidiol can elevate the plasma concentration of N-desmethylclobazam, the active metabolite of clobazam. Generally speaking, the second-generation ASMs have lower teratogenic risk than the older drugs but there is scant study on neurodevelopmental effect of third-generation ASMs.

SUMMARY

Although the newer generation ASMs may not have improved the overall seizure control they have advantages in terms of drug-drug interactions and teratogenicity, and thus offer valuable individualized options in the treatment of epilepsy.

Comparative economic outcomes in patients with focal seizures initiating eslicarbazepine acetate versus brivaracetam as their first adjunctive ASD

AIMS

To study the association between initiation of first adjunctive therapy with eslicarbazepine acetate (ESL) vs. brivaracetam (BRV) on healthcare resource utilization (HCRU) and charges among patients with treated focal seizures (FS).

MATERIALS AND METHODS

Symphony Health's Integrated Dataverse (IDV) claims data (1 April 2015 to 30 June 2018) were used to identify two cohorts as first adjunctive therapy with ESL or BRV following a generic anti-seizure drug (ASD). The index date was the earliest claim for a new ESL or BRV prescription. Key inclusion criteria were only 1 generic ASD in the 12 months before the index date; ≥1 medical claim with an FS diagnosis. Unit of analysis was the 90-day person-time-block. Changes in HCRU and charges were assessed using a difference-in-differences framework. Both unadjusted and adjusted analyses were performed. The adjusted model utilized person-specific fixed effects and propensity score-based weighting to control for differences in baseline covariates. Bias-corrected bootstrap confidence intervals (CIs) were calculated for charge outcomes.

RESULTS

208 and 137 patients initiated first adjunctive therapy with ESL (43.7 years, 51.9% female) or BRV (39.3 years, 51.8% female). Patients in the ESL cohort had numerically larger reductions in all-cause and FS-related inpatient hospitalizations and outpatient visits and FS-related emergency department visits. Compared to patients initiating BRV, patients treated with ESL had significantly larger reductions in total charges (-$3,446, CI: -$13,716, -$425), all-cause (-$3,166, CI: -$13,991, -$323) and FS-related (-$2,969, CI: -$21,547, -$842) medical charges, all-cause (-$3,397, CI: -$15,676, -$818) and FS-related (-$2,863, CI: -$19,707, -$787) outpatient charges, and non-ASD-related prescription charges (-$420, CI: -$1,058, -$78).

LIMITATIONS

Claims may be missing, or miscoded; outcomes may be influenced by variables not accounted for in the analysis; only information on submitted charges was included.

CONCLUSIONS

Among patients with FS, initiation of first adjunctive therapy with ESL was associated with significantly larger reductions in medical and non-ASD-related prescriptions charges compared to BRV.

Emerging drugs for focal epilepsy

INTRODUCTION

Epilepsy is one of the most serious neurological conditions, affecting almost 50 million people around the world. Despite more than 20 antiepileptic drugs (AEDs) available, seizures are still uncontrolled in one third of patients. Areas covered: The present paper reviews current compounds in preclinical and clinical development for the treatment of focal epilepsies and new potential molecular targets recently identified. Expert opinion: 1OP-2198, Cannabidavirin, Everolimus, FV-082, Ganaxolone, Minocycline, NAX 810-2, Padsevonil and Selurampanel seem to be particularly promising in focal epilepsy. Some of them, Everolimus and Ganaxolone, are already completing Phase III development while others are still at a preclinical stage. Everolimus represents the first example of precision-medicine in epilepsy and the first generation of disease-modifying agents but data on long-term safety are needed. Among AEDs in Phase II development, Cannabidavirin, Padsevonil and Selurampanel may represent a promising fourth generation of compounds for focal epilepsies if they successfully proceed to subsequent stages. Data on general tolerability, effects of cognition and behavior as well as the potential for interactions in polytherapy will be key element for the success or decline of these drugs.

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.

Carbamazepine-loaded solid lipid nanoparticles and nanostructured lipid carriers: Physicochemical characterization and in vitro/in vivo evaluation

Solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) represent promising alternatives for drug delivery to the central nervous system. In the present work, four different nanoformulations of the antiepileptic drug Carbamazepine (CBZ) were designed and prepared by the homogenization/ultrasonication method, with encapsulation efficiencies ranging from 82.8 to 93.8%. The formulations remained stable at 4 °C for at least 3 months. Physicochemical and microscopic characterization were performed by photon correlation spectroscopy (PCS), transmission electron microscopy (TEM), atomic force microscopy (AFM); thermal properties by differential scanning calorimetry (DSC), thermogravimetry (TGA) and X-ray diffraction analysis (XRD). The results indicated the presence of spherical shape nanoparticles with a mean particle diameter around 160 nm in a narrow size distribution; the entrapped CBZ displayed an amorphous state. The in vitro release profile of CBZ fitted into a Baker-Lonsdale model for spherical matrices and almost the 100% of the encapsulated drug was released in a controlled manner during the first 24 h. The apparent permeability of CBZ-loaded nanoparticles through a cell monolayer model was similar to that of the free drug. In vivo experiments in a mice model of seizure suggested protection by CBZ-NLC against seizures for at least 2 h after intraperitoneal administration. The developed CBZ-loaded lipid nanocarriers displayed optimal characteristics of size, shape and drug release and possibly represent a promising tool to improve the treatment of refractory epilepsy linked to efflux transporters upregulation.

Eslicarbazepine acetate in epilepsies with focal and secondary generalised seizures: systematic review of current evidence

INTRODUCTION

Eslicarbazepine acetate (ESL) is a third-generation antiepileptic drug (AED) approved for adjunctive treatment in adults, children, and adolescents with focal-onset seizures. Recently ESL was approved for initial monotherapy in adults. The intention of this article is to review current evidence for ESL and to summarise its pharmacological profile in comparison to other AEDs of the dibenzazepine group. Areas covered: We performed a systematic literature search in electronic databases (MEDLINE database, Cochrane Central Register of Controlled Trials, Excerpta Medica dataBASE) using a combined search strategy including the following keywords: eslicarbazepine, epilepsy and seizure. The search was performed from 2000 until December 2017. Using a standardised assessment form, information on the study design, methodological framework, data sources and efficacy and adverse events attributed to ESL were extracted from each publication and systematically reported. Expert commentary: ESL is an effective, safe and well tolerated third-generation AED for the treatment of focal epilepsies. During therapy, especially serum sodium levels and possible interactions with other substances have to be monitored. As of yet, long-term experience is still needed to make severe late-occurring adverse events unlikely and to obtain data regarding its use in pregnancy.

Pharmacodynamics and common drug-drug interactions of the third-generation antiepileptic drugs

INTRODUCTION

Anticonvulsants that belong to the third generation are considered as 'newer' antiepileptic drugs, including: eslicarbazepine acetate, lacosamide, perampanel, brivaracetam, rufinamide and stiripentol. Areas covered: This article reviews pharmacodynamics (i.e. mechanisms of action) and clinically relevant drug-drug interactions of the third-generation antiepileptic drugs. Expert opinion: Newer antiepileptic drugs have mechanisms of action which are not shared with the first and the second generation anticonvulsants, like inhibition of neurotransmitters release, blocking receptors for excitatory amino acids and new ways of sodium channel inactivation. New mechanisms of action increase chances of controlling forms of epilepsy resistant to older anticonvulsants. Important advantage of the third-generation anticonvulsants could be their little propensity for interactions with both antiepileptic and other drugs observed until now, making prescribing much easier and safer. However, this may change with new studies specifically designed to discover drug-drug interactions. Although the third-generation antiepileptic drugs enlarged therapeutic palette against epilepsy, 20-30% of patients with epilepsy is still treatment-resistant and need new pharmacological approach. There is great need to explore all molecular targets that may directly or indirectly be involved in generation of seizures, so a number of candidate compounds for even newer anticonvulsants could be generated.

Indirect comparison of third-generation antiepileptic drugs as adjunctive treatment for uncontrolled focal epilepsy

PURPOSE

Eslicarbazepine (ESL), Lacosamide (LAC), Perampanel (PER) and Brivaracetam (BRV), have recently been marketed as third-generation antiepileptic drugs (AEDs). We conducted a meta-analysis to indirectly compare overall efficacy and tolerability between third-generation AEDs in uncontrolled focal epilepsy.

METHODS

We performed an online database search using Pubmed, Embase, Cochrane Online Library, and Clinicaltrial.gov for all available randomized controlled trials (RCTs) that investigated the therapeutic effects over a range of AED doses versus placebo. We then compared clinical efficacy and tolerability between these newer AEDs using Indirect Treatment Comparison software.

RESULTS

Nineteen RCTs with a total of 7245 patients were included in our study. There were no significant differences in the risk difference of 50% responder rates and seizure free rates between third generation AEDs, regardless of dose. The risk of treatment emergent adverse events was significantly higher with ESL and PER treatment compared to BRV at all doses combined. Withdrawal rates due to adverse events were also significantly higher in patients treated with the highest doses of LAC and PER versus BRV, while treatment with ESL or LAC was related to higher withdrawal rates versus BRV when all doses were combined.

CONCLUSIONS

Our analysis suggested there were no significant differences in efficacy between third generation AEDs in uncontrolled focal epilepsy. BRV may have the best tolerability profile. The other AEDs were associated with a higher risk for intolerable adverse, especially when taken at a high doses. The results from these indirect comparisons warrant further examination and verification through future well-designed trials.

Evaluation of brivaracetam efficacy as monotherapy in adult patients with focal seizures

Brivaracetam is a selective, high-affinity ligand for synaptic vesicle protein 2A, recently approved as adjunctive therapy in the treatment of focal (partial-onset) seizures in patients 16 years of age and older with epilepsy. The goal of the present analysis was to determine if the dose-response of brivaracetam as monotherapy would fall within the range associated with brivaracetam efficacy as adjunctive therapy. An existing brivaracetam population pharmacokinetic model consisting of first-order absorption, single compartment distribution, and first-order elimination components was extended by estimating the clearance changes due to co-administration of 12 widely prescribed AEDs. Data for the population pharmacokinetic analysis originated from three Phase III add-on trials and two terminated Phase III monotherapy trials. An existing population model of daily seizure rate versus brivaracetam daily average concentration was applied to the data from the three add-on trials. Simulations allowed the assessment of the combined impact of covariate effects on both the pharmacokinetics and the pharmacodynamics of brivaracetam, and indicated that in the absence of other AEDs, only marginal changes in the overall dose-response relationship would be expected. This suggests that brivaracetam can be used as monotherapy without dose modifications.

Newer antiepileptic drugs compared to levetiracetam as adjunctive treatments for uncontrolled focal epilepsy: An indirect comparison

PURPOSE

Newer antiepileptic drugs (AEDs), such as Eslicarbazepine (ESL), Lacosamide (LAC), Perampanel (PER) and Brivaracetam (BRV), have been marketed as adjunctive treatments for partial-onset seizures. Our aim was to compare the efficacy and tolerability of newer AEDs with Levetiracetam (LEV), when used as add-on treatments for uncontrolled focal epilepsy.

METHOD

We conducted an online database search on PubMed, Embase, Cochrane Online Library and Clinicaltrials.gov for all available randomized controlled trials (RCTs) investigating the therapeutic effects of newer AEDs or LEV vs placebo. Indirect comparisons for clinical efficacy and tolerability at different doses between the newer AEDs and LEV were then performed using Indirect Treatment Comparison (ITC) software.

RESULTS

Twenty-four RCTs with a total of 8540 patients were included. Compared to LEV, ESL, LAC and BRV did not showed significant difference in efficacy at all dose level. PER showed lower 50% response rates and seizure-free rates at the highest effective recommended dosages. Treatment-emergent adverse events (TEAEs) and withdrawal rates due to adverse events (AEs) of LAC and PER were higher than LEV at the highest effective recommended dosages, and overall AE rates from ESL were higher than LEV.

CONCLUSIONS

Indirect comparisons suggested that ESL, LAC and BRV were not inferior to LEV in efficacy. ESL, LAC and PER may have a possible worse tolerability profile compared to LEV at high dose. But BRV may exhibit a similar tolerability to LEV. Newer AEDs cannot exceed the LEV on efficacy and tolerability.

Achyranthes aspera Attenuates epilepsy in experimental animals: possible involvement of GABAergic mechanism

The present study was aimed to examine the possible anticonvulsant property of aerial parts of Achyranthes aspera using various experimental models of epilepsy in mice. Petroleum ether extract of aerial parts of A. aspera (PeAA), methanolic eAA (MeAA) and aqueous eAA (AeAA) was initially evaluated against six-hertz seizure model in mice, based on the outcomes the effective extract was further evaluated against maximal electroshock (MES) and pentylenetetrazole (PTZ) models in mice. In addition, the potent extract was evaluated against the PTZ model by co-administering with flumazenil (FMZ), and also evaluated for its effect on GABA levels in brain and NMDA-induced lethality in mice. Furthermore, the probable locomotor deficit-inducing property of the extract was evaluated by actophotometer test in mice. In results, only MeAA showed protection against six-hertz-induced seizures in mice, based on these outcomes only MeAA was evaluated in MES and PTZ models. Notably, the MeAA (200, 400 and 800 mg/kg) has offered mild and dose dependent protection against MES and PTZ-induced seizures in mice. Alongside, the MeAA (400 mg/kg) showed a significant increase in GABA levels in the brain compared to control, and in line with these findings the anti-PTZ effect of MeAA (400 mg/kg, p.o.) was blocked when co-administered with flumazenil (5 mg/kg, i.p.). However, the MeAA has not shown significant protection against NMDA-induced mortality and also did not cause significant change in locomotor activity compared to before treatment. These findings suggest that MeAA possess mild anticonvulsant activity and the outcomes further confirmed the involvement of GABAergic mechanism behind the anticonvulsant activity of MeAA.

Efficacy and Tolerability of Second and Third Generation Anti-epileptic Drugs in Refractory Epilepsy: A Network Meta-Analysis

This study was proposed to compare the relative efficacy and tolerability of the second and third generation AEDs for refractory epilepsy. The 50% responder rate (RR) was selected as the efficacy outcome whereas the incidence of dizziness and somnolence were considered to evaluate the tolerability of AEDs. Odds ratio (OR) and their 95% credible interval (CrI) were obtained using a consistency model and surface under the cumulative ranking curve (SUCRA) value was calculated to rank AEDs. Topiramate appeared to be significantly more effective than placebo, eslicarbazepine acetate, perampanel, pregabalin, zonisamide, gabapentin and lamotrigine with respect to the 50% RR (all OR > 1). Patients who were managed by eslicarbazepine acetate, perampanel, oxcarbazepine, topiramate and pregabalin were more likely to suffer from dizziness compared to those who receive placebo (all OR > 1). Perampanel, topiramate and pregabalin were related to elevated risks of somnolence compared to placebo (all OR > 1). Moreover, topiramate ranked highest with respect to 50% RR (SUCRA = 0.968) whereas levetiracetam appeared to have balanced efficacy and tolerability (SUCRA = 0.769, 0.743, 0.604 and 0.659). In conclusion, topiramate was the most efficacious AED, while levetiracetam was able to provide patients with balanced efficacy and tolerability.

Ameliorative potential of Colebrookea oppositifolia methanolic root extract against experimental models of epilepsy: Possible role of GABA mediated mechanism

BACKGROUND

Colebrookea oppositifolia Smith is one of the commonly used plants to treat epilepsy by various folk medicine communities like nomadic Gujjars, Tharu and Bhoxa in sub-Himalayan regions of India.

PURPOSE

The present study was undertaken to evaluate the anticonvulsant activity of roots of Colebrookea oppositifolia using various experimental models of epilepsy in mice.

METHODS

Petroleum ether extract of roots of C. Oppositifolia (PeCO), methanolic eCO (MeCO) and aqueous eCO (AeCO) was initially evaluated in six-hertz-seizure test in mice, the effective extract was further evaluated against maximal electroshock (MES) and pentylenetetrazole (PTZ) models in mice. In addition, the potent extract was evaluated against the PTZ model by co-administering with flumazenil (FMZ), and also evaluated for its effect on brain GABA levels in brain and NMDA-induced lethality in mice. Furthermore, the possible locomotor deficit-inducing property of the extract was evaluated by actophotometer test in mice.

RESULTS

In six-hertz-seizure test the MeCO (25, 50, 100 and 200mg/kg) and AeCO (50, 100, 200, 400 and 800mg/kg) showed significant protection compared to control group, and MeCO was more potent than AeCO. Based on these outcomes, only MeCO was evaluated in MES and PTZ models. Notably, the MeCO (25, 50, 100 and 200mg/kg) has offered significant and dose- dependent protection against MES and PTZ-induced seizures in mice. Alongside, the MeCO (100 and 200mg/kg) showed a significant increase in GABA levels in the brain compared to control. In line with these findings, the anti-PTZ effect of MeCO (100mg/kg, p.o.) was blocked when co-administered with flumazenil (3mg/kg, i.p.),and in NMDA-induced mortality test, the MeCO has shown only 50% protection at 200mg/kg dose, thus confirmed the significant role of GABA pathway. Interestingly, the MeCO did not cause significant change in locomotor activity compared to before treatment.

CONCLUSION

These findings suggest that MeCO possess significant anticonvulsant activity and the outcomes further confirmed the involvement of GABAergic mechanisms behind the anticonvulsant activity of MeCO.