Post-authorisation study of eslicarbazepine as treatment for drug-resistant epilepsy: preliminary results

Safety, tolerability and effectiveness of transition to eslicarbazepine acetate from carbamazepine or oxcarbazepine in clinical practice

PURPOSE

To assess the efficacy, safety and tolerability of eslicarbazepine acetate (ESL) in patients transitioning from carbamazepine or oxcarbazepine to ESL in clinical practice, by analysing data from the Euro-Esli study.

METHODS

Euro-Esli was a pooled analysis of 14 European clinical practice studies. Effectiveness assessments included responder rate (≥50 % seizure frequency reduction) and seizure freedom rate (seizure freedom at least since prior visit), assessed after 3, 6 and 12 months of ESL treatment, and at the last visit. Safety and tolerability were assessed throughout follow-up by evaluating adverse events (AEs) and ESL discontinuation due to AEs, respectively. Data were analysed for cohorts of patients who transitioned from carbamazepine and oxcarbazepine to ESL either due to lack of efficacy or poor tolerability.

RESULTS

Euro-Esli included 2058 patients, of whom 233 (11.3 %) transitioned from carbamazepine to ESL and 134 (6.5 %) transitioned from oxcarbazepine to ESL. After 12 months of ESL treatment, responder and seizure freedom rates for patients transitioning from carbamazepine due to lack of efficacy (n = 163) were 70.0 % and 30.9 %, respectively. Corresponding values for patients transitioning from oxcarbazepine due to lack of efficacy (n = 90) were 57.1 % and 25.0 %, respectively. Among patients who transitioned from carbamazepine and oxcarbazepine to ESL due to poor tolerability (n = 64 and n = 61, respectively), 26.6 % and 39.5 % experienced AEs, and 8.3 % and 6.8 % discontinued ESL due to AEs, respectively.

CONCLUSION

ESL was efficacious and generally well tolerated in patients transitioning from carbamazepine or oxcarbazepine in clinical practice due to inadequate seizure control or intolerable AEs with these agents.

Effectiveness and Safety/Tolerability of Eslicarbazepine Acetate in Epilepsy Patients Aged ≥ 60 Versus < 60 Years: A Subanalysis from the Euro-Esli Study

Introduction

Clinical practice studies help guide antiepileptic drug (AED) therapy in patient groups routinely excluded from clinical trials, such as the elderly. The Euro-Esli study investigated the effectiveness and safety/tolerability of eslicarbazepine acetate (ESL) when used in everyday clinical practice in Europe. A subanalysis of data from elderly patients (≥ 60 years) included in the Euro-Esli study was conducted to assess these aspects of ESL use in this population.

Methods

Euro-Esli was a pooled analysis of 14 European clinical practice studies. Effectiveness parameters included responder (≥ 50% seizure frequency reduction) and seizure freedom rates after 3, 6 and 12 months of treatment and at last visit. Safety and tolerability were assessed throughout the follow-up by evaluating adverse events (AEs) and ESL discontinuation due to AEs, respectively. Data were compared for patients aged ≥ 60 versus those aged < 60 years at study entry.

Results

Euro-Esli included 2058 patients (mean age 44.0 years). Age at study entry was known for 2057 patients, of whom 358 (17.4%) and 1699 (82.6%) were aged ≥ 60 and < 60 years, respectively. Mean maximum ESL dose was   882.0 and 1008.2 mg/day in patients aged ≥ 60 and < 60 years, respectively  (p < 0.001). At all timepoints, responder and seizure freedom rates were significantly higher in patients aged ≥ 60 versus < 60 years; for example, at 12 months, responder rates were 83.9 and 73.7%, respectively (p = 0.002), and seizure freedom rates were 58.5 and 37.1%, respectively (p < 0.001). The incidence of AEs was significantly higher in patients aged ≥ 60 versus < 60 years (41.4 vs. 32.5%; p = 0.001), but the rate of discontinuation due to AEs was comparable between age groups (16.2 vs 13.1%; p = not significant). The safety/tolerability of ESL in patients aged ≥ 60 years was consistent with its known    profile.

Conclusion

Eslicarbazepine acetate was efficacious and generally well tolerated when used to treat elderly patients with focal epilepsy in clinical practice, with no new or unexpected safety signals emerging in this setting.

Funding

Eisai Ltd.

Eslicarbazepine acetate as monotherapy in clinical practice: Outcomes from Euro-Esli

OBJECTIVES

To assess the effectiveness and safety/tolerability of eslicarbazepine acetate (ESL) monotherapy in clinical practice in Europe.

MATERIALS AND METHODS

Euro-Esli was a pooled analysis of 14 European clinical practice studies. Responder rate (≥50% seizure frequency reduction) and seizure freedom rate (seizure freedom at least since prior visit) were assessed after 3, 6 and 12 months of ESL treatment and at last visit. Adverse events (AEs) and AEs leading to ESL discontinuation were assessed throughout follow-up. A subanalysis was conducted to assess outcomes for patients treated initially with ESL monotherapy and for patients treated at the last visit with ESL monotherapy.

RESULTS

ESL was used as monotherapy in 88/2045 (4.3%) patients initially and in 229/1340 (17.1%) patients at the last visit. At 12 months, responder and seizure freedom rates were 94.1% and 88.2%, respectively, in patients treated initially with ESL monotherapy, and 93.2% and 77.4%, respectively, in patients treated at the last visit with ESL monotherapy. Corresponding values for patients treated initially with ESL adjunctive therapy were 74.8% and 39.0%, respectively; and for patients treated at the last visit with ESL adjunctive therapy, corresponding values were 70.4% and 25.9%, respectively. Safety and tolerability were generally comparable in patients treated with ESL as monotherapy or adjunctive therapy. The most commonly reported AEs (≥5% of patients in any group) were dizziness, somnolence, instability/ataxia, and fatigue.

CONCLUSIONS

These clinical practice data support the use of ESL as monotherapy, as well as adjunctive therapy, for focal-onset seizures, complementing evidence from clinical trials.

Dibenzazepine Agents in Epilepsy: How Does Eslicarbazepine Acetate Differ?

Carbamazepine (CBZ), oxcarbazepine (OXC), and eslicarbazepine acetate (ESL) belong to the dibenzazepine family of antiepileptic drugs and are all thought to primarily act as sodium channel blockers (SCBs). However, ESL is structurally distinct from CBZ and OXC, resulting in differences in metabolism, pharmacokinetics, and pharmacodynamics. Despite a lack of direct comparative data, evidence for potential differences in effectiveness and tolerability within the dibenzazepine family has emerged from studies in which patients being treated with one dibenzazepine agent have received adjunctive treatment with another (having achieved insufficient seizure control with the first) or have transitioned from one dibenzazepine agent to another because of lack of effectiveness or poor tolerability. Most of these studies have been conducted in the real-world clinical practice setting. ESL has been shown to be effective as adjunctive therapy in patients who have previously achieved inadequate seizure control with CBZ, indicating that the use of different dibenzazepine agents in combination can provide additive effectiveness benefits, which may reflect underlying differences in their mechanisms of action. Similarly, ESL monotherapy can be effective in patients who have switched from another dibenzazepine, such as CBZ or OXC, because of inadequate efficacy. There is also considerable evidence to demonstrate that patients transitioning from OXC or CBZ to ESL as a result of adverse events experience improvements in tolerability, which may also be associated with improvements in quality of life, alertness, and/or lipid profiles. Current evidence therefore demonstrates that ESL differs from other dibenzazepine agents in terms of effectiveness and tolerability.

Funding: Eisai Ltd.

Eslicarbazepine Acetate: A New Improvement on a Classic Drug Family for the Treatment of Partial-Onset Seizures

Eslicarbazepine acetate is a new anti-epileptic drug belonging to the dibenzazepine carboxamide family that is currently approved as adjunctive therapy and monotherapy for partial-onset (focal) seizures. The drug enhances slow inactivation of voltage-gated sodium channels and subsequently reduces the activity of rapidly firing neurons. Eslicarbazepine acetate has few, but some, drug–drug interactions. It is a weak enzyme inducer and it inhibits cytochrome P450 2C19, but it affects a smaller assortment of enzymes than carbamazepine. Clinical studies using eslicarbazepine acetate as adjunctive treatment or monotherapy have demonstrated its efficacy in patients with refractory or newly diagnosed focal seizures. The drug is generally well tolerated, and the most common side effects include dizziness, headache, and diplopia. One of the greatest strengths of eslicarbazepine acetate is its ability to be administered only once per day. Eslicarbazepine acetate has many advantages over older anti-epileptic drugs, and it should be strongly considered when treating patients with partial-onset epilepsy.

Eslicarbazepine acetate in the treatment of adults with partial-onset epilepsy: an evidence-based review of efficacy, safety and place in therapy

INTRODUCTION

Up to 30% of the patients diagnosed with epilepsy will continue suffering from seizures despite treatment with antiepileptic drugs, either in monotherapy or polytherapy. Hence, there remains the need to develop new effective and well-tolerated therapies.

AIM

The objective of this article was to review the evidence for the efficacy and safety of eslicarbazepine acetate (ESL) as adjunctive treatment in adult patients with focal onset seizures.

EVIDENCE REVIEW

ESL is the newest, third-generation, single enantiomer member of the dibenzazepine family. Following oral administration, ESL is rapidly and extensively metabolized by hepatic first-pass hydrolysis to the active metabolite eslicarbazepine, which has linear, dose-proportional pharmacokinetics and low potential for drug-drug interactions. Eslicarbazepine works as a competitive blocker of the voltage gated sodium channels; unlike carbamazepine (CBZ) and oxcarbazepine (OXC), it has a lower affinity for the resting state of the channels, and reduces their availability by selectively enhancing slow inactivation. Efficacy and safety of ESL have been assessed in four randomized, Phase III clinical trials: the median relative reduction in standardized seizure frequency was 33.4% and 37.8% in the ESL 800 and 1,200 mg daily dose groups, and the responder rates were 33.8% and 43.1%, respectively. The incidence of treatment-emergent adverse events (TEAEs) increased with raising the dosage (ESL 400 mg: 63.8%, ESL 800 mg: 67.0%, ESL 1,200 mg: 73.1%). The TEAEs were generally mild to moderate in intensity, and the most common were dizziness, somnolence, headache and nausea. Open-label studies confirmed the findings from the pivotal trials and demonstrated sustained therapeutic effect of ESL over time and improvement of tolerability profile in patients switching from OXC/CBZ. No unexpected safety signals emerged over >5 years of follow-up.

CONCLUSION

Once-daily adjunctive ESL at the doses of 800 and 1,200 mg was effective to reduce the seizure frequency and was fairly well tolerated in adults with focal onset epilepsy. Starting treatment at 400 mg/day, followed by 400 mg increments every 7-14 days, could provide the optimal balance of efficacy and tolerability.

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.

Euro-Esli: a European audit of real-world use of eslicarbazepine acetate as a treatment for partial-onset seizures

The Euro-Esli study was an exploratory pooled analysis of data from 14 European clinical practice studies, which was conducted to audit the real-world effectiveness, safety, and tolerability of eslicarbazepine acetate (ESL) as an adjunctive treatment for partial-onset seizures. Retention and effectiveness were assessed after 3, 6, and 12 months of ESL treatment, and at the final visit. Safety and tolerability were assessed throughout ESL treatment by evaluating adverse events (AEs) and ESL discontinuation due to AEs. Data from 2058 patients (52.1% male; mean age 44.0 years) were included. All 2058 patients were assessed for safety and 1975 (96.0%) patients were assessed for effectiveness. After 12 months, retention, responder (≥50% seizure frequency reduction), and seizure freedom rates were 73.4, 75.6, and 41.3%, respectively. AEs were reported for 34.0% of patients and led to discontinuation in 13.6% of patients. The most frequently reported AEs were dizziness (6.7% of patients), fatigue (5.4%), and somnolence (5.1%). No unexpected safety signals emerged over a median duration of follow-up of >5 years. Subgroup analyses revealed that ESL was significantly more effective in patients aged ≥65 versus <65 years, in patients who were not receiving treatment with other sodium channel blockers versus those who were receiving treatment with other sodium channel blockers, and in patients who were receiving <2 versus ≥2 concomitant antiepileptic drugs at baseline. Euro-Esli is the largest ESL clinical practice study conducted to date. This study provides strong and reassuring evidence of ESL’s safety profile, and complements the data from clinical trials.

EARLY-ESLI study: Long-term experience with eslicarbazepine acetate after first monotherapy failure

PURPOSE

Evaluate real-life experience with eslicarbazepine acetate (ESL) after first monotherapy failure in a large series of patients with focal epilepsy.

METHOD

Multicentre, retrospective, 1-year, observational study in patients older than 18 years, with focal epilepsy, who had failed first antiepileptic drug monotherapy and who received ESL. Data from clinical records were analysed at baseline, 3, 6 and 12 months to assess effectiveness and tolerability.

RESULTS

Eslicarbazepine acetate was initiated in 253 patients. The 1-year retention rate was 92.9%, and the final median dose of ESL was 800 mg. At 12 months, 62.3% of patients had been seizure free for 6 months; 37.3% had been seizure free for 1 year. During follow-up, 31.6% of the patients reported ESL-related adverse events (AEs), most commonly somnolence (8.7%) and dizziness (5.1%), and 3.6% discontinued due to AEs. Hyponatraemia was observed in seven patients (2.8%). After starting ESL, 137 patients (54.2%) withdrew the prior monotherapy and converted to ESL monotherapy; 75.9% were seizure free, 87.6% were responders, 4.4% worsened, and 23.4% reported ESL-related AEs.

CONCLUSION

Use of ESL after first monotherapy failure was associated with an optimal seizure control and tolerability profile. Over half of patients were converted to ESL monotherapy during follow-up.

Switching to eslicarbazepine acetate in patients with epilepsy: a field-practice observation

Aim: To provide field-practice information on the safety and efficacy of eslicarbazepine. Patients & methods: Patients who switched from carbamazepine or oxcarbazepine to eslicarbazepine were consecutively and retrospectively identified in two Italian reference centers for the treatment of epilepsy. Results: Eighteen patients with a mean age of 39 ± 16 years were recruited. Mean monthly seizure frequency was 18 ± 22 (range: 2–59) before switching to eslicarbazepine, and decreased to 11 ± 18 (0–56) after switching (p = 0.03). The monthly number of seizures decreased in 16/18 patients (89%) and it remained unchanged in one. Six patients became seizure-free after switching, five of whom had underwent overnight switch. The mean score of the adverse event profile questionnaire before switching was 42.5 ± 9.5 and it decreased to 35.0 ± 6.4 with eslicarbazepine therapy; 8/11 patients (73%) reported improved scores. Conclusion: Although the limited number of patients should be taken into account, switching to eslicarbazepine allowed a reduction of monthly number of seizures in about 55% of patients. Furthermore, eslicarbazepine showed a good safety profile with a potential lower impact on quality of life of patients.

Eslicarbazepine acetate: its effectiveness as adjunctive therapy in clinical trials and open studies

Eslicarbazepine acetate (ESL) is a once-daily antiepileptic drug that is approved as adjunctive therapy in adults with focal-onset seizures. Following oral administration, ESL is rapidly metabolized to its active metabolite, eslicarbazepine, which acts primarily by enhancing slow inactivation of voltage-gated sodium channels. The efficacy and safety/tolerability of ESL in the adjunctive setting were established in a comprehensive Phase III program (n = 1702 randomized patients) and this evidence has been supported by several open studies (n = 864). ESL treatment has demonstrated improvements in health-related quality of life, in both randomized clinical trials and open studies. ESL has also been shown to be usually well tolerated and efficacious when used in the adjunctive setting in elderly patients. The effectiveness of ESL as the only add-on to antiepileptic drug monotherapy has been demonstrated in a multinational study (n = 219), subgroup analyses of which have also shown it to be efficacious and generally well tolerated in patients who had previously not responded to carbamazepine therapy. Open studies have also demonstrated improvements in tolerability in patients switched overnight from oxcarbazepine to ESL. Due to differences in pharmacokinetics, pharmacodynamics, and metabolism, there may be clinical situations in which it is appropriate to consider switching patients from oxcarbazepine or carbamazepine to ESL.

EPICON consensus: recommendations for proper management of switching to eslicarbazepine acetate in epilepsy

INTRODUCTION

The objective of the EPICON Project is to develop a set of recommendations on how to adequately switch from carbamazepine (CBZ) and oxcarbazepine (OXC) to eslicarbazepine acetate (ESL) in some patients with epilepsy.

METHODS

A steering committee drafted a questionnaire of 56 questions regarding the transition from CBZ or OXC to ESL in clinical practice (methodology and change situation). The questionnaire was then distributed to 54 epilepsy experts in 2 rounds using the Delphi method. An agreement/disagreement consensus was defined when a median ≥ 7 points or ≤ 3 was achieved, respectively, and a relative interquartile range ≤ 0.40. We analysed the results obtained to reach our conclusions.

RESULTS

Our main recommendations were the following: switching from CBZ to ESL must be carried out over a period of 1 to 3 weeks with a CBZ:ESL dose ratio of 1:1.3 and is recommended for patients who frequently forget to take their medication, those who work rotating shifts, polymedicated patients, subjects with cognitive problems, severe osteoporosis-osteopaenia, dyslipidaemia, or liver disease other than acute liver failure, as well as for men with erectile dysfunction caused by CBZ. The transition from OXC to ESL can take place overnight with an OXC:ESL dose ratio of 1:1 and it is recommended for patients who frequently forget to take their medication, those who work rotating shifts, polymedicated patients, or those with cognitive problems. The transition was not recommended for patients with prior rash due to CBZ or OXC use.

CONCLUSION

The EPICON Project offers a set of recommendations about the clinical management of switching from CBZ or OXC to ESL, using the Delphi method.

Eslicarbazepine acetate for the treatment of partial epilepsy

INTRODUCTION

Eslicarbazepine acetate (ESL) is a third generation AED structurally related to carbamazepine and oxcarbazepine, but without several of the drawbacks associated with these compounds. ESL is completely metabolized to its eslicarbazpine, which selectively binds inactivated voltage-gated sodium channels and thus selectively reduces the activity of rapidly firing (epileptic) neurons. In addition, ESL has pharmacokinetic properties allowing once daily dosing.

AREAS COVERED

This review summarizes data from the initial phase I to III studies, which demonstrated efficacy of ESL as add-on treatment in partial onset epilepsy, and more recent studies that demonstrate efficacy of ESL as monotherapy. Real-life observational studies are also reviewed, and seem to confirm the notion of ESL as a well-tolerated AED. As a new AED, ESL needs to be subject to close monitoring regarding long-term adverse events. Future independent studies will most likely clarify the role of ESL in the management of partial onset seizures.

EXPERT OPINION

The role of ESL in management of partial onset seizures is discussed, as is the need for close monitoring and evaluation for broad-spectrum pharmacodynamics properties. The characteristics of the molecule and efficacy and safety profiles seem, however, very promising.

Practical Use of Newer Antiepileptic Drugs as Adjunctive Therapy in Focal Epilepsy

This article lays the background for, and discusses the practical issues surrounding, the adjunctive use of the last four antiepileptic drugs (AEDs) to be licensed for the treatment of pharmacoresistant focal seizures in the UK and elsewhere. More than 30% of adolescent and adult patients will not be fully controlled on the currently available therapeutic armamentarium. After not responding to their first three AED schedules, only a handful of patients attained seizure freedom on subsequent regimens. To optimise the response to any new AED in this setting, it is often necessary to reduce the existing drug burden. The pharmacology, tolerability and safety, and everyday use of lacosamide, eslicarbazepine acetate, retigabine (ezogabine) and perampanel will be reviewed and discussed. This will be accompanied by data from prospective audits with each drug undertaken at the Western Infirmary in Glasgow, Scotland, and a report of their successful introduction in an illustrative case. Overall, there is a large variation in the course of refractory epilepsy and the effect of AED therapy on this process seems minimal. Nevertheless, a number of patients will benefit from the introduction of each new AED, with some becoming seizure-free.

Perspectives on treatment options for mesial temporal lobe epilepsy with hippocampal sclerosis

INTRODUCTION

Mesial temporal lobe epilepsy associated with hippocampal sclerosis (MTLE-HS) is a syndrome that is often refractory to drug treatment. The effects on specific syndromes are not currently available from the pre-marketing clinical development of new AEDs; this does not allow the prediction of whether new drugs will be more effective in the treatment of some patients.

AREAS COVERED

We have reviewed all the existing literature relevant to the understanding of a potential effectiveness in MTLE-HS patients for the latest AEDs, namely brivaracetam, eslicarbazepine, lacosamide, perampanel and retigabine also including the most relevant clinical data and a brief description of their pharmacological profile. Records were identified using predefined search criteria using electronic databases (e.g., PubMed, Cochrane Library Database of Systematic Reviews). Primary peer-reviewed articles published up to the 15 June 2015 were included.

EXPERT OPINION

All the drugs considered have the potential to be effective in the treatment of MTLE-HS; in fact, they possess proven efficacy in animal models; currently considered valuable tools for predicting drug efficacy in TLE. Furthermore, for some of these (e.g., lacosamide and eslicarbazepine) data are already available from post-marketing studies while brivaracetam acting on SV2A like levetiracetam might have the same potential effectiveness with the possibility to be more efficacious considering its ability to inhibit voltage gated sodium channels; finally, perampanel and retigabine are very effective drugs in animal models of TLE.

Practical guidance and considerations for transitioning patients from oxcarbazepine or carbamazepine to eslicarbazepine acetate--Expert opinion

There is currently a lack of guidance on methodology and special considerations for transitioning patients from oxcarbazepine (OXC) or carbamazepine (CBZ) to eslicarbazepine acetate (ESL), if deemed clinically necessary. An advisory panel of epilepsy experts was convened to share their experience on the use of adjunctive ESL in clinical practice and to provide practical recommendations to help address this gap. When changing over from OXC to ESL, an OXC:ESL dose ratio of 1:1 should be employed to calculate the ESL target dose, and the changeover can take place overnight. No changes to comedication are required. Since CBZ has a different mechanism of action to ESL and is a stronger inducer of cytochrome P450 (CYP) enzymes, the transitioning of patients from CBZ to ESL requires careful consideration on a patient-by-patient basis. In general, a CBZ:ESL dose ratio of 1:1.3 should be employed to calculate the ESL target dose, and patients should be transitioned over a minimum period of 1-2weeks. Special considerations include adjustment of titration schedule and target dose in elderly patients and those with hepatic or renal impairment and potential adjustment of comedications metabolized by CYP enzymes. In summary, due to structural distinctions between ESL, OXC, and CBZ, which affect mechanism of action and tolerability, there are clinical situations in which it may be appropriate to consider transitioning patients from OXC or CBZ to ESL. Changing patients over from OXC to ESL is generally more straightforward than transitioning patients from CBZ to ESL, which requires careful consideration.

A review of the efficacy and safety of eslicarbazepine acetate in the management of partial-onset seizures

Eslicarbazepine acetate is a is a once-daily antiepileptic drug (AED) that was approved in 2009 by the European Medicines Agency (EMA) (Zebinix™), and in 2013 by the US Food and Drug Administration (FDA) (Aptiom™) as adjunctive therapy in adults with refractory partial-onset seizures, with or without secondary generalization. It is a third-generation member of the dibenzazepine family of AEDs with distinctive mechanism of action, posology and tolerability profile. The eslicarbazepine acetate development program included an initial phase II study (study BIA 2-093) and three subsequent phase III, multicentre, randomized, double-blinded and placebo-controlled clinical trials (studies BIA-2093-301, BIA- 2093-302 and BIA -2093-303). A fourth phase III placebo-controlled trial (study BIA-2093-304) was designed in order to meet specific requirements of the FDA. All performed studies have consistently shown that eslicarbazepine acetate (800 to 1200 mg/day) is effective and well tolerated as adjunctive therapy for adults with partial-onset seizures.

Pharmacogenetics of adverse reactions to antiepileptic drugs

INTRODUCTION

Adverse drug reactions (ADRs) are a major public health concern and a leading cause of morbidity and mortality in the world. In the case of antiepileptic drugs (AEDs), ADRs constitute a barrier to successful treatment since they decrease treatment adherence and impact patients' quality of life of patients. Pharmacogenetics aims to identify genetic polymorphisms associated with drug safety. This article presents a review of genes coding for drug metabolising enzymes and drug transporters, and HLA system genes that have been linked to AED-induced ADRs.

DEVELOPMENT

To date, several genetic variations associated with drug safety have been reported: CYP2C9*2 and *3 alleles, which code for enzymes with decreased activity, have been linked to phenytoin (PHT)-induced neurotoxicity; GSTM1 null alleles with hepatotoxicity induced by carbamazepine (CBZ) and valproic acid (VPA); EPHX1 polymorphisms with teratogenesis; ABCC2 genetic variations with CBZ- and VPA-induced neurological ADRs; and HLA alleles (e.g. HLA-B*15:02, -A*31:01, -B*15:11, -C*08:01) with cutaneous ADRs.

CONCLUSIONS

Published findings show that there are ADRs with a pharmacogenetic basis and a high interethnic variability, which indicates a need for future studies in different populations to gather more useful results for larger number of patients. The search for biomarkers that would allow predicting ADRs to AEDs could improve pharmacotherapy for epilepsy.

Clinical utility of eslicarbazepine: current evidence

Eslicarbazepine acetate (ESL) is a new antiepileptic drug whose mechanism of action is blockade of the voltage-gated sodium channel (VGSC). However, in respect to carbamazepine and oxcarbazepine, the active ESL metabolite (eslicarbazepine) affects slow inactivation of VGSC and has a similar affinity for the inactivated state and a lower affinity for the resting state of the channel. This new antiepileptic drug has been recently approved in Europe (trade name Zebinix) and in the United States (trade name Stedesa) for adjunctive treatment in adult subjects with partial-onset seizures, with or without secondary generalization. Following oral administration, ESL is rapidly and extensively metabolized by hepatic esterases to eslicarbazepine. This active metabolite has a linear pharmacokinetic profile, a low binding to plasma proteins (<40%), and a half-life of 20-24 hours and is mainly excreted by kidneys in an unchanged form or as glucuronide conjugates. ESL is administered once a day and has a low potential for drug-drug interactions. Efficacy and safety of this drug in patients with focal seizures have been assessed in four randomized clinical trials, and responder rates (percentage of patients with a ≥50% improvement of their seizures) ranged between 17% and 43%. Adverse events were usually mild to moderate, and the most common were dizziness, somnolence, diplopia, abnormal coordination, blurred vision, vertigo, headache, fatigue, nausea, and vomiting. ESL may be considered an interesting alternative to current antiepileptic drugs for the treatment of drug-resistant focal epilepsies. Additionally, it is under investigation in children with focal epilepsies, in patients with newly diagnosed focal epilepsies, and also in other neurological and psychiatric disorders.

Cutaneous adverse drug reaction type erythema multiforme major induced by eslicarbazepine

Severe skin reactions occur less frequently with eslicarbazepine (ESL) than with the other aromatic anticonvulsants. We report the first case of cutaneous adverse drug reaction (CADR) to ESL and co-sensitization between ESL and betalactams. A 41-year-old white woman developed focal epilepsy due to a meningioma that was removed. As post-operatory complication, she suffered meningitis as well as a maculo-papular erythema caused by the treatment with meropenem. Subsequently, ESL was started and gradually increased until 800 mg/day. Twenty-five days later, the patient developed an Erythema Multiforme Major (EMM). Strong positive immediate reaction was induced by prick test with carbamazepine (CBZ) and ESL at 0.01 and 0.1% within 15 and 30 minutes; however the delayed reading at 48 hours was negative. The patient was not carrier of the HLA alleles A3101 and B1502 associated with CBZ induced EMM. The hypersensitivity pathogenic mechanism of EMM is unclear and a delayed hypersensitivity process is speculated. However, the patch and intradermal tests in our patient did not show a delayed reaction but an immediate cutaneous one. A first allergic episode may elicit a massive nonspecific activation of the immune system, providing an enhanced expression of co-stimulatory molecules that decreases the level of tolerance to other drugs. When prescribing ESL, we suggest ruling out previous CADR, especially to CBZ and oxcarbazepine but also other chemically unrelated drugs such as beta-lactams.

Eslicarbazepine acetate: a review of its use as adjunctive therapy in refractory partial-onset seizures

Eslicarbazepine acetate (Aptiom(®), Zebinix(®)) is approved for the adjunctive treatment of partial-onset seizures in adults aged ≥18 years. Adjunctive therapy with oral eslicarbazepine acetate 800 or 1,200 mg once daily was associated with a significantly lower standardized seizure frequency (primary endpoint) than placebo in patients aged ≥18 years with refractory partial-onset seizures in three, randomized, double-blind, multinational, phase III trials. In a fourth randomized, double-blind, multinational, phase III trial in patients aged ≥16 years with refractory partial-onset seizures, adjunctive eslicarbazepine acetate 1,200 mg once daily, but not 800 mg once daily, was associated with a significantly lower standardized seizure frequency (primary endpoint). Responder rates were significantly higher with eslicarbazepine acetate 1,200 mg once daily than with placebo in these four trials, and with eslicarbazepine acetate 800 mg once daily than with placebo in two trials. The efficacy of eslicarbazepine acetate was maintained in the longer term, according to the results of 1-year extension studies. Adjunctive therapy with oral eslicarbazepine acetate was generally well tolerated in patients with refractory partial-onset seizures, with most adverse events being of mild to moderate severity. In conclusion, eslicarbazepine acetate is a useful option for the adjunctive treatment of patients with refractory partial-onset seizures.