Combination therapy in epilepsy: when and what to use

Selecting Rational Drug Combinations in Epilepsy

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

Beneficial Combination of Lacosamide with Retigabine in Experimental Animals: An Isobolographic Analysis

BACKGROUND/AIM

To isobolographically determine the types of interactions that occur between retigabine and lacosamide (LCM; two third-generation antiepileptic drugs) with respect to their anticonvulsant activity and acute adverse effects (sedation) in the maximal electroshock-induced seizures (MES) and chimney test (motor performance) in adult male Swiss mice.

METHODS

Type I isobolographic analysis for nonparallel dose-response effects for the combination of retigabine with LCM (at the fixed-ratio of 1:1) in both the MES and chimney test in mice was performed. Brain concentrations of retigabine and LCM were measured by high-pressure liquid chromatography (HPLC) to characterize any pharmacokinetic interactions occurring when combining these drugs.

RESULTS

Linear regression analysis revealed that retigabine had its dose-response effect line nonparallel to that of LCM in both the MES and chimney tests. The type I isobolographic analysis illustrated that retigabine combined with LCM (fixed-ratio of 1:1) exerted an additive interaction in the mouse MES model and sub-additivity (antagonism) in the chimney test. With HPLC, retigabine and LCM did not mutually change their total brain concentrations, thereby confirming the pharmacodynamic nature of the interaction.

CONCLUSION

LCM combined with retigabine possesses a beneficial preclinical profile (benefit index ranged from 2.07 to 2.50) and this 2-drug combination is worth recommending as treatment plan to patients with pharmacoresistant epilepsy.

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

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

Comparative analysis of monotherapy versus duotherapy antiseizure drug management for postoperative seizure control in patients undergoing an awake craniotomy

OBJECTIVE Postoperative seizures are a common complication in patients undergoing an awake craniotomy, given the cortical manipulation during tumor resection and the electrical cortical stimulation for brain mapping. However, little evidence exists about the efficacy of postoperative seizure prophylaxis. This study aims to determine the most appropriate antiseizure drug (ASD) management regimen following an awake craniotomy. METHODS The authors performed a retrospective analysis of data pertaining to patients who underwent an awake craniotomy for brain tumor from 2007 to 2015 performed by a single surgeon. Patients were divided into 2 groups, those who received a single ASD (the monotherapy group) and those who received 2 types of ASDs (the duotherapy group). Patient demographics, symptoms, tumor characteristics, hospitalization details, and seizure outcome were evaluated. Multivariable logistic regression was used to evaluate numerous clinical variables associated with postoperative seizures. RESULTS A total of 81 patients underwent an awake craniotomy for tumor resection of an eloquent brain lesion. Preoperative baseline characteristics were comparable between the 2 groups. The postoperative seizure rate was 21.7% in the monotherapy group and 5.7% in the duotherapy group (p = 0.044). Seizure outcome at 6 months' follow-up was assessed with the Engel classification scale. The duotherapy group had a significantly higher proportion of seizure-free (Engel Class I) patients than the monotherapy group (90% vs 60%, p = 0.027). The length of stay was similar, 4.02 days in the monotherapy group and 4.51 days in the duotherapy group (p = 0.193). The 90-day readmission rate was higher for the monotherapy group (26.1% vs 8.5% in the duotherapy group, p = 0.044). Multivariate logistic regression showed that preoperative seizure history was a significant predictor for postoperative seizures following an awake craniotomy (OR 2.08, 95% CI 0.56-0.90, p < 0.001). CONCLUSIONS Patients with a preoperative seizure history may be at a higher risk for postoperative seizures following an awake craniotomy and may benefit from better postoperative seizure control with postoperative ASD duotherapy.

Treatment issues for children with epilepsy transitioning to adult care

This is the third of three papers that summarize the second symposium on Transition in Epilepsies held in Paris in June 2016. This paper focuses on treatment issues that arise during the course of childhood epilepsy and make the process of transition to adult care more complicated. Some AEDs used during childhood, such as stiripentol, vigabatrin, and cannabidiol, are unfamiliar to adult epilepsy specialists. In addition, new drugs are being developed for treatment of specific childhood onset epilepsy syndromes and have no indication yet for adults. The ketogenic diet may be effective during childhood but is difficult to continue in adult care. Regional adult epilepsy diet clinics could be helpful. Polytherapy is common for patients transitioning to adult care. Although these complex AED regimes are difficult, they are often possible to simplify. AEDs used in childhood may need to be reconsidered in adulthood. Rescue medications to stop prolonged seizures and clusters of seizures are in wide home use in children and can be continued in adulthood. Adherence/compliance is notoriously difficult for adolescents, but there are simple clinical approaches that should be helpful. Mental health issues including depression and anxiety are not always diagnosed and treated in children and young adults even though effective treatments are available. Attention deficit hyperactivity disorder and aggressive behavior disorders may interfere with transition and successful adulthood but these can be treated. For the majority, the adult social outcome of children with epilepsy is unsatisfactory with few proven interventions. The interface between pediatric and adult care for children with epilepsy is becoming increasingly complicated with a need for more comprehensive transition programs and adult epileptologists who are knowledgeable about special treatments that benefit this group of patients.

[Anticonvulsant add-on therapy with Eslicarbazepine acetate : Results of the EPOS-study in adults in Germany]

BACKGROUND

Due to inadequate seizure control achieved with antiepileptic drug (AED) monotherapy and the considerable side effects at high required doses, patients with partial-onset seizures (POS) often require AED combination therapy. Eslicarbazepine acetate (ESL) is licensed as an add-on therapy for POS and has a favorable tolerability profile.

OBJECTIVES

To investigate retention, utilization, reported efficacy, safety and tolerability as well as effects on health-related quality of life using ESL as an add-on treatment to an established monotherapy in a real-world adult population with POS in Germany.

PATIENTS AND METHODS

A subgroup analysis was performed on the data derived from the German study sites that had participated in an international, non-interventional, open-label study conducted in eight European countries (eslicarbazepine acetate in partial-onset seizures, EPOS). Adult patients with POS whose physician had decided to prescribe add-on treatment with ESL to an established monotherapy were followed over a total period of approximately six months (three visits: baseline and after periods of approximately three and six months). Data collection included patient retention, reported efficacy, safety and tolerability as well as quality of life (QOLIE-10).

RESULTS AND DISCUSSION

The subgroup analysis included 104 patients which had been enrolled at 38 German study sites. After 6 months, retention of ESL add-on therapy was 86.5 %, with 44.7 % of patients reporting seizure freedom over the 3 months prior to this visit. The overall tolerability of ESL add-on therapy was favorable: 32 adverse events (AE) were reported in 20 patients (19.2 %), while only two events in two patients were considered serious. No new safety signals were detected.

Correlation between prescribed daily dose, seizure freedom and defined daily dose in antiepileptic drug treatment

Background Although defined daily doses (DDD) for antiepileptic drugs (AED) have been assigned only in combination therapy, based on the literature, most patients take them in monotherapy. Furthermore, discrepancies between DDD and prescribed daily dose (PDD) were observed. Objective First, to determine PDDs of AEDs and to reveal PDD/DDD ratio among seizure free versus not seizure free patients in everyday clinical practice. Second, to test the applicability of 75% cut-off of DDD to achieve seizure freedom. Furthermore, to find out what factors might influence PDD. Setting Outpatient data files at a Hungarian university hospital were studied. Methods A retrospective, 20-year cross-sectional database was compiled from 1282 epileptic outpatients' files. Main outcome measure Seizure freedom and PDD were used as outcome measures. Results The mean DDD% of all prescribed AEDs increased steadily from monotherapy, through bitherapy towards polytherapy (p < 0.0001). Most seizure free patients took AEDs in doses in the range of ≤75% of DDDs in monotherapy and bitherapy. Older AEDs (carbamazepine and valproate) were given in a significantly higher mean dose in bitherapy in the seizure free group. Among the newer types, only levetiracetam and lamotrigine had a significantly higher DDD% in mono-, bi-, and polytherapy. Confirmed by logistic regression analysis, gender, age, type of epilepsy, and number of AEDs had a significant impact on the value of 75% DDD. Conclusion No significant unfavourable impact of the lower ratio of PDD/DDD on the outcome of achieving seizure freedom has been confirmed. As a measure of seizure freedom, 75% of DDD may be used, although individual therapy must be emphasised. Precisely quantified DDD would provide a more accurate calculation of other derived values.

Additive interactions between retigabine and oxcarbazepine in the chimney test and the model of generalized tonic-clonic seizures in mice

Introduction. Patients with pharmacoresistant epilepsy are usually treated with two or more antiepileptic drugs (AEDs). The search for therapeutically efficacious AED combinations is still a challenging issue for clinicians and epileptologists throughout the world.

Aim. To determine the interaction profile for the combination of retigabine (RTG) and oxcarbazepine (OXC) in both, the model of tonic-clonic seizures, the maximal electroshock (MES)-induced seizure model and chimney test (motor performance) in adult male albino Swiss mice.

Methods. Isobolographic analysis (type I) was applied to characterize interactions for the combination of RTG with OXC with respect to its anticonvulsant and acute side (neurotoxic) effects, as determined in the MES and chimney tests, respectively.

Results. The combination of RTG with OXC at the fixed-ratios of 1:3, 1:1 and 3:1 produced additive interactions in the MES test in mice. Similarly, the combination of RTG with OXC at the fixed-ratio of 1:1 produced additive interaction with a tendency towards sub-additivity in the chimney test in mice. Measurement of total brain concentrations of both AEDs revealed that RTG did not affect total brain concentrations of OXC and inversely, OXC had no impact on RTG’s total brain concentrations, confirming pharmacodynamic interaction between the drugs.

Conclusions. The additive pharmacodynamic interactions in both the MES and chimney tests in mice were observed for the combination of RTG with OXC.

Real-world data on eslicarbazepine acetate as add-on to antiepileptic monotherapy

Objective

To assess retention, tolerability, and safety, efficacy and effects on quality of life (QoL) of eslicarbazepine acetate (ESL) add‐on treatment over 6 months in a real‐world adult population with partial‐onset seizures.

Methods

This non‐interventional, multicenter, prospective study was performed in eight European countries. Adult patients (n = 247) for whom the physician had decided to initiate ESL as add‐on to an existing antiepileptic drug (AED) monotherapy were invited to participate. The study comprised three visits: baseline, and after 3 and 6 months. Data on ESL retention, efficacy, tolerability, safety, and QoL were collected.

Results

After 6 months, the retention rate of ESL was 82.2%, and 81.8% of patients reported a reduction of seizure frequency of at least 50%; 39.2% of patients reported seizure freedom at this time. The mean QOLIE‐10 score improved from 2.9 (SD ± 0.8) at baseline to 2.1 (SD ± 0.8) after 6 months. 109 adverse events (AEs) were reported in 57 patients (26.0%); the majority were rated as related to ESL by the investigator and led to a discontinuation of ESL in 25 patients (11.4%). Eight patients (3.7%) suffered at least one serious AE. The most frequently reported AEs were dizziness, headache, convulsion, and fatigue.

Conclusions

This study shows that ESL was well tolerated and efficacious as add‐on therapy to one baseline AED. The use of ESL in patients less refractory than those included in previous clinical trials led to higher responder and seizure freedom rates. No new safety issues were observed.

Pharmacodynamic and pharmacokinetic interaction of Panchagavya Ghrita with phenytoin and carbamazepine in maximal electroshock induced seizures in rats

Introduction:

Traditionally, Panchagavya Ghrita (PG) has been used for the management of epilepsy, anxiety, fever and jaundice. It consists of five components of cow products namely, cow milk, clarified butter from cow milk, cow urine, curd from cow milk, and cow dung juice.

Aim:

To evaluate the effect of PG in maximal electroshock (MES) induced seizures model and its pharmacodynamic and pharmacokinetic interaction with phenytoin (PHT) and carbamazepine (CBZ) in rats.

Materials and Methods:

Male Wistar rats were administered PG 500, 1000, 2000, and 4000 mg/kg orally for 7 days and seizures were induced by MES. For interaction studies, PG (4000 mg/kg) was administered along with a sub-therapeutic dose of PHT (20 mg/kg, p.o.) and CBZ (10 mg/kg, p.o.). Behavioral parameters were assessed. Oxidative stress markers and serum levels of PHT and CBZ were estimated.

Results:

Tonic hind limb extension, cognitive impairment, and oxidative stress produced by MES were reversed by PG (4000 mg/kg). Co-administration of PG (4000 mg/kg) with a sub-therapeutic dose of PHT and CBZ potentiated antiepileptic effect and ameliorated cognitive impairment as well as oxidative stress. Although, there was a slight increase in serum levels of PHT and CBZ on co-administration with PG, it was statistically insignificant.

Conclusion:

Co-administration of PG with low doses of PHT and CBZ caused complete seizure protection. This suggests the potential of PG as an adjunct in epilepsy with improved efficacy and tolerability.

[Algorithms of mono- and polytherapy in clinical epileptology]

The large number of antiepileptic drugs (AEDs) at the physician's disposal provides not only a broad therapeutic potential in the treatment of epilepsy (EP), but creates difficulties in the adequate choice of AED. The sufficient experience in the management of patients with epilepsy has been gained so far in the world, based on which the International League Against Epilepsy (ILAE), updated classification, adopted the basic definition of efficiency, remission, resistance, evidence of research on the effectiveness of AED therapy, and introduced the concept of "resolved" epilepsy. In this article, a group of Russian experts suggest recommendations on the main steps in the choice of therapy in epilepsy. Possible drug interactions between different AEDs and other drugs as well as main characteristics of mono- and polytherapy of epilepsy are described. Some features of the use of AEDs in the elderly, characteristics of the "female" epilepsy related to the reproductive function and basic requirements for the therapy of epilepsy in children are presented.

[Algorithms of mono- and polytherapy in clinical epileptology. Part 1. General principles of drug choice]

The large number of antiepileptic drugs (AEDs) at the physician's disposal provides not only a broad therapeutic potential in the treatment of epilepsy (EP), but creates difficulties in the adequate choice of AED. The sufficient experience in the management of patients with epilepsy has been gained so far in the world, based on which the International League Against Epilepsy (ILAE), updated classification, adopted the basic definition of efficiency, remission, resistance, evidence of research on the effectiveness of AED therapy, and introduced the concept of "resolved" epilepsy. In this article, a group of Russian experts suggest recommendations on the main steps in the choice of therapy in epilepsy. Possible drug interactions between different AEDs and other drugs as well as main characteristics of mono- and polytherapy of epilepsy are described. Some features of the use of AEDs in the elderly, characteristics of the "female" epilepsy related to the reproductive function and basic requirements for the therapy of epilepsy in children are presented.

Retention, dosing, tolerability and patient reported seizure outcome of Zonisamide as only add-on treatment under real-life conditions in adult patients with partial onset seizures: Results of the observational study ZOOM

PURPOSE

Zonisamide is licensed for adjunctive therapy for partial-onset seizures with or without secondary generalisation in patients 6 years and older and as monotherapy for the treatment of partial seizures in adult patients with newly diagnosed epilepsy, and shows a favourable pharmacokinetic profile with low interaction potential with other drugs. The aim of the present study was to gather real-life data on retention and modalities of zonisamide use when administered as only add-on treatment to a current AED monotherapy in adult patients with partial-onset seizures.

METHODS

This multicenter observational study was performed in 4 European countries and comprised three visits: baseline, and after 3 and 6 months. Data on patients' retention, reported efficacy, tolerability and safety, and quality of life was collected. Of 100 included patients, 93 could be evaluated.

RESULTS

After 6 months, the retention rate of zonisamide add-on therapy was 82.8%. At this time, a reduction of seizure frequency of at least 50% was observed in 79.7% of patients, with 43.6% reporting seizure freedom over the last 3 months of the study period. Adverse events were reported by 19.4% of patients, with fatigue, agitation, dizziness, and headache being most frequent. Approximately 25% of patients were older than 60 years, many of whom suffered from late-onset epilepsy. Compared to younger patients, these patients showed considerable differences with regard to their antiepileptic drug regimen at baseline, and slightly higher responder and retention rates at 6 months.

CONCLUSIONS

Despite limitations due to the non-interventional open-label design and the low sample size, the results show that zonisamide as only add-on therapy is well retained, indicating effectiveness in the majority of patients under real-life conditions.

Multi-target pharmacology: possibilities and limitations of the "skeleton key approach" from a medicinal chemist perspective

Multi-target drugs have raised considerable interest in the last decade owing to their advantages in the treatment of complex diseases and health conditions linked to drug resistance issues. Prospective drug repositioning to treat comorbid conditions is an additional, overlooked application of multi-target ligands. While medicinal chemists usually rely on some version of the lock and key paradigm to design novel therapeutics, modern pharmacology recognizes that the mid- and long-term effects of a given drug on a biological system may depend not only on the specific ligand-target recognition events but also on the influence of the repeated administration of a drug on the cell gene signature. The design of multi-target agents usually imposes challenging restrictions on the topology or flexibility of the candidate drugs, which are briefly discussed in the present article. Finally, computational strategies to approach the identification of novel multi-target agents are overviewed.

Use of Antiepileptic Drugs in Patients with Chronic Kidney Disease and End Stage Renal Disease

Epilepsy is a disorder with an approximate worldwide prevalence of 1%. Due to complexities of metabolism, protein-binding, renal elimination, and other pharmacokinetic parameters, the dosing of antiepileptic drugs (AEDs) in patients with chronic kidney disease (CKD) or end stage renal disease (ESRD) deserves special attention. This is a review of the most commonly prescribed AEDs with special focus on their indication, pharmacokinetics, and unique considerations for use in patients with CKD and ESRD. A review of their renal toxicities is also included.

Epilepsy: new advances

Epilepsy affects 65 million people worldwide and entails a major burden in seizure-related disability, mortality, comorbidities, stigma, and costs. In the past decade, important advances have been made in the understanding of the pathophysiological mechanisms of the disease and factors affecting its prognosis. These advances have translated into new conceptual and operational definitions of epilepsy in addition to revised criteria and terminology for its diagnosis and classification. Although the number of available antiepileptic drugs has increased substantially during the past 20 years, about a third of patients remain resistant to medical treatment. Despite improved effectiveness of surgical procedures, with more than half of operated patients achieving long-term freedom from seizures, epilepsy surgery is still done in a small subset of drug-resistant patients. The lives of most people with epilepsy continue to be adversely affected by gaps in knowledge, diagnosis, treatment, advocacy, education, legislation, and research. Concerted actions to address these challenges are urgently needed.

Eslicarbazepine acetate for the treatment of focal epilepsy: an update on its proposed mechanisms of action

Eslicarbazepine acetate (ESL) is a once daily antiepileptic drug (AED) approved by the European Medicines Agency (EMA), the Food and Drug Administration (FDA) and Health Canada as an adjunctive therapy in adults with partial-onset seizures (POS). In humans and in relevant animal laboratory species, ESL undergoes extensive first pass hydrolysis to its major active metabolite eslicarbazepine that represents ∼95% of circulating active moieties. ESL and eslicarbazepine showed anticonvulsant activity in animal models. ESL may not only suppress seizure activity but may also inhibit the generation of a hyperexcitable network. Data reviewed here suggest that ESL and eslicarbazepine demonstrated the following in animal models: (1) the selectivity of interaction with the inactive state of the voltage-gated sodium channel (VGSC), (2) reduction in VGSC availability through enhancement of slow inactivation, instead of alteration of fast inactivation of VGSC, (3) the failure to cause a paradoxical upregulation of persistent Na(+) current (I NaP), and (4) the reduction in firing frequencies of excitatory neurons in dissociated hippocampal cells from patients with epilepsy who were pharmacoresistant to carbamazepine (CBZ). In addition, eslicarbazepine effectively inhibited high- and low-affinity hCaV3.2 inward currents with greater affinity than CBZ. These preclinical findings may suggest the potential for antiepileptogenic effects; furthermore, the lack of effect upon KV7.2 outward currents may translate into a reduced potential for eslicarbazepine to facilitate repetitive firing.

Failure of a first regimen of monotherapy to control the newly diagnosed epilepsies. What to do next?

Background. Monotherapy is the choice regimen to treat newly diagnosed epilepsies. However, if it fails, several strategies may be followed.

Aim. To discuss the treatment options when an initial monotherapy regimen fails.

Methods. We reviewed the relevant literature on the topic by using PubMed.

Review and Discussion. Approximately 64% of people with epilepsy (PWE) de novo are free of seizures with the first appropriate antiepileptic drug (AED) in monotherapy. The type (first versus second generation) of the first AED to use depends on the physician's personal choice provided that it is a first-line AED. There is a tendency to prefer a substitution rather than a combination of a failed first AED when it was produced associated with an idiosyncratic reaction, was poorly tolerated at a moderate dose, or produced no improvement in seizure control. In contrast, there is some evidence to prefer secondary polytherapy whenever the PWE tolerate its first AED but with a suboptimal response. In this case, and particularly mainly if a first generation AED was used as a first-line treatment, I prefer to choose a new generation AED given their more favourable pharmacokinetic and pharmacodynamic profiles. A very often used strategy is transitional polytherapy between two regimens of monotherapy.

Conclusion. Any therapeutic decision should take into account factors such as seizure type or syndrome, possibility of drug side effects, comorbidities, comedications, age, teratogenic potential, and compliance. Whatever the option to be taken, the PWE, his family or the caregivers should take part in the decision making.

Eslicarbazepine and the enhancement of slow inactivation of voltage-gated sodium channels: a comparison with carbamazepine, oxcarbazepine and lacosamide

This study aimed at evaluating the effects of eslicarbazepine, carbamazepine (CBZ), oxcarbazepine (OXC) and lacosamide (LCM) on the fast and slow inactivated states of voltage-gated sodium channels (VGSC). The anti-epileptiform activity was evaluated in mouse isolated hippocampal slices. The anticonvulsant effects were evaluated in MES and the 6-Hz psychomotor tests. The whole-cell patch-clamp technique was used to investigate the effects of eslicarbazepine, CBZ, OXC and LCM on sodium channels endogenously expressed in N1E-115 mouse neuroblastoma cells. CBZ and eslicarbazepine exhibit similar concentration dependent suppression of epileptiform activity in hippocampal slices. In N1E-115 mouse neuroblastoma cells, at a concentration of 250 μM, the voltage dependence of the fast inactivation was not influenced by eslicarbazepine, whereas LCM, CBZ and OXC shifted the V0.5 value (mV) by -4.8, -12.0 and -16.6, respectively. Eslicarbazepine- and LCM-treated fast-inactivated channels recovered similarly to control conditions, whereas CBZ- and OXC-treated channels required longer pulses to recover. CBZ, eslicarbazepine and LCM shifted the voltage dependence of the slow inactivation (V0.5, mV) by -4.6, -31.2 and -53.3, respectively. For eslicarbazepine, LCM, CBZ and OXC, the affinity to the slow inactivated state was 5.9, 10.4, 1.7 and 1.8 times higher than to the channels in the resting state, respectively. In conclusion, eslicarbazepine did not share with CBZ and OXC the ability to alter fast inactivation of VGSC. Both eslicarbazepine and LCM reduce VGSC availability through enhancement of slow inactivation, but LCM demonstrated higher interaction with VGSC in the resting state and with fast inactivation gating.

Treatment of epilepsy in China: Formal or informal

Antiepileptic drugs are the preferred treatment approach for epileptic patients. However, informal treatment is important for intractable epilepsy. In this study, 500 epileptic patients were recruited from the General Hospital of Beijing Military Area Command of Chinese PLA during the period of October 2009 to January 2012. These involved patients that had been medically treated for at least 1 year. Information on the initial treatment and changes to treatment regimens for each patient was collected through questionnaires. The survey results showed that 52.3% of the epileptic patients searched for treatment after the first seizure, and the mean numbers of seizures was 12.8; 59.8% of the epileptic patients were diagnosed at the first visit, and the mean onset time was 17 months after the first seizure. After diagnosis, patients were treated for an average of 20 days, and the median time was 1 day. Formal anti-epileptic drugs were selected as the first treatment regimen by 67.8% of patients, and 77.5% of these drugs were monotherapies. The mean and median numbers of seizure were respectively 36.9 and 3.0 times before the first regimen was changed. The regimen was changed within the first 6 months by 46.6% of patients, and after the first and second years of treatment, the proportions increased to 54.0% and 71.8%, respectively. In total, 78.5% of the regimens were changed to informal treatments. The informal treatment of epilepsy in China is common, being initiated by either patients or physicians. Enhancing epileptic treatment services in hospital, improving physicians’ professional quality, and strengthening health propaganda may promote the normalization of drug treatment of epilepsy in China.

Drug-resistant epilepsy: definition and treatment alternatives

INTRODUCTION

Drug-resistant epilepsy affects 25% of all epileptic patients, and quality of life decreases in these patients due to their seizures. Early detection is crucial in order to establish potential treatment alternatives and determine if the patient is a surgical candidate.

DEVELOPMENT

PubMed search for articles, recommendations published by major medical societies, and clinical practice guidelines for drug-resistant epilepsy and its medical and surgical treatment options. Evidence and recommendations are classified according to the criteria of the Oxford Centre for Evidence-Based Medicine (2001) and the European Federation of Neurological Societies (2004) for therapeutic actions.

CONCLUSIONS

Identifying patients with drug-resistant epilepsy is important for optimising drug therapy. Experts recommend rational polytherapy with antiepileptic drugs to find more effective combinations with fewer adverse effects. When adequate seizure control is not achieved, a presurgical evaluation in an epilepsy referral centre is recommended. These evaluations explore how to resect the epileptogenic zone without causing functional deficits in cases in which this is feasible. If resective surgery is not achievable, palliative surgery or neurostimulation systems (including vagus nerve, trigeminal nerve, or deep brain stimulation) may be an option. Other treatment alternatives such as ketogenic diet may also be considered in selected patients.

Effect of minocycline on pentylenetetrazol-induced chemical kindled seizures in mice

Inflammation is one of the mechanisms involved in seizure induction. In this study, the effect of minocycline, an anti-inflammatory drug, was investigated on kindling acquisition. Chemical kindling was induced by injection of a subthreshold dose of pentylenetetrazol (PTZ; 37.5 mg/kg) in mice on every other day. Two groups of animals received minocycline (25 mg/kg) at 1 h before or 1 h after PTZ injection. Following the last PTZ injection, the changes in gene expression of TNF-α receptor, γ2 subunit of GABAA receptor and NR2A subunit of NMDA receptor were assessed in the hippocampus and piriform cortex. Injection of minocycline before PTZ increased the latency to stage 4 seizure, and decreased the duration of stages 4 and 5 seizure. It also prevented the increase in the mRNA of NR2A subunit of NMDA receptor in the hippocampus and removed the PTZ-induced increase in mRNA of γ2 subunit of GABAA receptor in piriform cortex of PTZ kindled mice. Minocycline also prevented the increase in TNF-α receptor gene expression in both hippocampus and piriform cortex. Injection of minocycline after PTZ had no significant effect on measured parameters. Therefore, it can be concluded that minocycline may exert an anticonvulsant effect through preventing the increase in GABAA and NMDA receptor subunits. These effects are accompanied by a reduction in an important inflammation index, TNF-α receptor.

Development of lacosamide for the treatment of partial-onset seizures

Lacosamide is an antiepileptic drug (AED) available in multiple formulations that was first approved in 2008 as adjunctive therapy for partial-onset seizures (POS) in adults. Unlike traditional sodium channel blockers affecting fast inactivation, lacosamide selectively enhances sodium channel slow inactivation. This mechanism of action results in stabilization of hyperexcitable neuronal membranes, inhibition of neuronal firing, and reduction in long-term channel availability without affecting physiological function. Lacosamide has a well-characterized and favorable pharmacokinetic profile, including a fast absorption rate, minimal or no interaction with cytochrome P-450 izoenzymes, and a low potential for drug-drug interactions. Lacosamide clinical development included three placebo-controlled, double-blind, randomized trials conducted in more than 1300 patients, each demonstrating safety and efficacy of lacosamide compared to placebo as adjunctive therapy for adults with POS. The clinical use of lacosamide may broaden, pending results of trials evaluating its use as monotherapy for POS in adults, as treatment for epilepsy in pediatric subjects, and as adjunctive treatment for uncontrolled primary generalized tonic-clonic seizures in those with idiopathic generalized epilepsy.

When one plus one makes three: the quest for rational antiepileptic polytherapy with supraadditive anticonvulsant efficacy

The experimental and clinical evidence in support of "rational polytherapy" is sparse, and to date, no clear evidence-based indications can be made to help physicians in their choice of a specific drug combination against specific forms of epilepsy. This article briefly reviews the data available in the literature and obtained from studies conducted in humans to evaluate which main AED combinations might possess supraadditive, synergistic effects in terms of efficacy, with infraadditive toxicity. By far, the most documented association resulting in supraadditive anticonvulsant effects against focal seizures is that of VPA and LTG. There are some indications that combinations of drugs with different primary mechanisms of action may be more effective than combining drugs with the same mechanisms of action. However, further animal and human research studies that focus both on toxicity and anticonvulsant effects of various combinations of AEDs are required.

Lack of effect of lacosamide on the pharmacokinetic and pharmacodynamic profiles of warfarin

PURPOSE

The aim of this study was to evaluate the effect of the antiepileptic drug lacosamide on the pharmacokinetics and pharmacodynamics of the anticoagulant warfarin.

METHODS

In this open-label, two-treatment crossover study, 16 healthy adult male volunteers were randomized to receive a single 25-mg dose of warfarin alone in one period and lacosamide 200 mg twice daily on days 1-9 with a single 25 mg dose of warfarin coadministered on day 3 in the other period. There was a 2-week washout between treatments. Pharmacokinetic end points were area under the plasma concentration-time curve (AUC(0,last) and AUC(0,∞) ) and maximum plasma concentration (Cmax ) for S- and R-warfarin. Pharmacodynamic end points were area under the international normalized ratio (INR)-time curve (AUCINR ), maximum INR (INRmax ), maximum prothrombin time (PTmax ) and area under the PT-time curve (AUCPT ).

KEY FINDINGS

Following warfarin and lacosamide coadministration, Cmax and AUC of S- and R-warfarin, as well as peak value and AUC of PT and INR, were equivalent to those after warfarin alone. In particular, the AUC(0,∞) ratio (90% confidence interval) for coadministration of warfarin and lacosamide versus warfarin alone was 0.97 (0.94-1.00) for S-warfarin and 1.05 (1.02-1.09) for R-warfarin, and the AUCINR ratio was 1.04 (1.01-1.06). All participants completed the study.

SIGNIFICANCE

Coadministration of lacosamide 400 mg/day did not alter the pharmacokinetics of warfarin 25 mg or the anticoagulation level. These results suggest that there is no need for dose adjustment of warfarin when coadministered with lacosamide.

Utilization patterns of antiepileptic drugs among adult epileptic patients at a tertiary hospital in Oman

Objectives

To describe utilization patterns of antiepileptic drugs (AEDs) among adult epileptic patients at a tertiary hospital in Oman.

Methods

Data were collected retrospectively from January 2006 to December 2009. The study included all adult (&gt;18 years) epileptic patients on AEDs and followed up at a neurology clinic at Sultan Qaboos University Hospital in Oman. All reported therapeutic drug monitoring (TDM) requests for serum AED concentrations were also collected. Institutional ethical approval was sought and obtained.

Key findings

The study included a total of 372 patients with a mean age of 34 ± 15 years. Monotherapy AEDs accounted for 53% of the prescriptions, whereas polytherapy with two or three AED combinations accounted for 27% and 20% respectively. The most frequently prescribed AED was sodium valproate (27%) followed by carbamazepine (23%). The commonly prescribed AED combinations were sodium valproate with clonazepam (12%) followed by sodium valproate with lamotrigine (12%). Evaluation of 574 TDM requests for three AEDs showed that 57% of carbamazepine, 78% of phenytoin and 54% of valproic acid requests were either above or below the recommended therapeutic threshold. Most of these requests were ordered from the hospital's emergency department for suspected insufficient serum concentrations.

Conclusions

Antiepileptic drug monotherapy is still the most frequently employed therapeutic strategy in adult patients with epilepsy in keeping with the standard therapeutic guidelines. Sodium valproate is commonly used for different types of seizures reflecting its wide spectrum of anticonvulsant potential. Newer AED utilizations are becoming increasingly popular in our subjects particularly as add-on with other standard AEDs.

Antiepileptic drug monotherapy versus polytherapy: pursuing seizure freedom and tolerability in adults

PURPOSE OF REVIEW

Despite the availability of many new antiepileptic drugs (AEDs), only around 50% of people with epilepsy will become seizure free on their first drug. This article explores treatment options and issues influencing whether AEDs should be substituted or combined in the remainder of the patient population.

RECENT FINDINGS

Prior to the introduction of novel AEDs, it was generally opined that combining traditional agents did not necessarily lead to an improvement in seizure control and might increase the propensity for side effects. Newer AEDs, many with different mechanisms of action, have increased the potential for polytherapy regimens, although robust data to support or refute this therapeutic strategy are sparse. It seems sensible to substitute rather than combine when the first AED produces an idiosyncratic reaction, is poorly tolerated at a low/moderate dose or shows no efficacy. Polytherapy may be preferred if the patient tolerates their first or second AED well, but with a suboptimal response, particularly when there is an identifiable anatomical substrate for the seizures. AED selection requires consideration of many factors some of which are discussed in this study.

SUMMARY

There are no definitive answers on whether to combine or substitute AEDs. Different strategies are required for different scenarios in different patients.

Patterns of treatment response in newly diagnosed epilepsy

OBJECTIVE

To delineate the temporal patterns of outcome and to determine the probability of seizure freedom with successive antiepileptic drug regimens in newly diagnosed epilepsy.

METHODS

Patients in whom epilepsy was diagnosed and the first antiepileptic drug prescribed between July 1, 1982, and April 1, 2006, were followed up until March 31, 2008. Outcomes were categorized into 4 patterns: (A) early and sustained seizure freedom; (B) delayed but sustained seizure freedom; (C) fluctuation between periods of seizure freedom and relapse; and (D) seizure freedom never attained. Probability of seizure freedom with successive drug regimens was compared. Seizure freedom was defined as no seizures for ≥1 year.

RESULTS

A total of 1,098 patients were included (median age 32 years, range 9-93). At the last clinic visit, 749 (68%) patients were seizure-free, 678 (62%) on monotherapy. Outcome pattern A was observed in 408 (37%), pattern B in 246 (22%), pattern C in 172 (16%), and pattern D in 272 (25%) patients. There was a higher probability of seizure freedom in patients receiving 1 compared to 2 drug regimens, and 2 compared to 3 regimens (p < 0.001). The difference was greater among patients with symptomatic or cryptogenic than with idiopathic epilepsy. Less than 2% of patients became seizure-free on subsequent regimens but a few did so on their sixth or seventh regimen.

CONCLUSIONS

Most patients with newly diagnosed epilepsy had a constant course which could usually be predicted early. The chance of seizure freedom declined with successive drug regimens, most markedly from the first to the third and among patients with localization-related epilepsies.

No pharmacokinetic interaction between lacosamide and valproic acid in healthy volunteers

Two open-label, randomized, multiple-dose clinical studies evaluated the potential for pharmacokinetic interaction between the antiepileptic drugs lacosamide and valproic acid. The influence of lacosamide on valproic acid pharmacokinetics (trial A) and valproic acid on lacosamide pharmacokinetics (trial B) was investigated in 32 healthy male volunteers, 16 in each trial. Volunteers in trial A received valproic acid (300 mg bid) with randomization to either early or late addition of lacosamide (200 mg bid). Those in trial B received lacosamide (200 mg bid) with randomization to either early or late addition of valproic acid (300 mg bid). Area under the concentration-time curve during a 12-hour dosing interval at steady state (AUC(τ,ss)) and maximum steady-state plasma drug concentration (C(max,ss)) were measured for each drug alone and together and tested for equivalence. The point estimates (90% confidence intervals) for AUC(τ,ss) and C(max,ss) were 104% (99%-109%) and 101% (97%-107%), respectively, for valproic acid and 100% (98%-103%) and 101% (96%-107%), respectively, for lacosamide, which were within the generally accepted equivalence range of 80% to 125%. No changes in the rate or extent of absorption, terminal half-life, or time to maximum concentration were observed. These results suggest that lacosamide and valproic acid have no relevant pharmacokinetic drug-drug interaction.

Intractable childhood epilepsy: choosing between the treatments

Intractable epilepsy is a significant problem affecting approximately 1 in 10 children with seizures. This is traditionally defined as a failure to respond to at least 2 anticonvulsant drugs tried at reasonable doses for several weeks. Although involving a minority of those with epilepsy, these children typically have significant morbidity, detrimental effects on quality of life, and often require hours of time from a child neurologist in their care. In this review and special issue, a practical approach to management options for children who have refractory epilepsy will be presented from experts in the field.

Antiepileptic drug therapy: does mechanism of action matter?

This article represents a synthesis of presentations made by the authors during a scientific meeting held in London on 7 June 2010 and organized by GlaxoSmithKline. Each speaker produced a short précis of his lecture to answer a specific question, resulting in an overview of what we know about the relevance of the mechanisms of action of antiepileptic drugs in determining appropriate combination therapies for the treatment of drug-resistant epilepsy.

Experimental re-evaluation of flunarizine as add-on antiepileptic therapy

Background:

Experimental studies have found several calcium channel blockers with anticonvulsant property. Flunarizine is one of the most potent calcium channel blockers, which has shown anticonvulsant effect against pentylenetetrazole (PTZ) and maximal electroshock (MES)-induced seizures. However, further experimental and clinical trials have shown varied results. We conducted a PTZ model experimental study to re-evaluate the potential of flunarizine for add-on therapy in the management of refractory epilepsy.

Materials and Methods:

Experiments were conducted in PTZ model involving Swiss strain mice. Doses producing seizures in 50% and 99% mice, i.e. CD₅₀ and CD₉₉ values of PTZ were obtained from the dose-response study. Animals received graded, single dose of sodium valproate (100–300 mg/kg), lamotrigine (3–12 mg/kg) and flunarizine (5–20 mg/kg), and then each group of mice was injected with CD₉₉ dose of PTZ (65mg/kg i.p.). Another group of mice received single ED₅₀ dose (dose producing seizure protection in 50% mice) of sodium valproate and flunarizine separately in left and right side of abdomen. Results were analysed by Kruskal–Wallis ANOVA on Ranks test.

Results:

As compared to control, sodium valproate at 250 mg/kg and 300 mg/kg produced statistical significant seizure protection. At none of the pre-treatment dose levels of lamotrigine, the seizure score with PTZ differed significantly from that observed in the vehicle-treated group. Pre-treatment with flunarizine demonstrated dose-dependent decrease in the seizure score to PTZ administration. As compared to control group, flunarizine at 20 mg/kg produced statistical significant seizure protection.

Conclusion:

As combined use of sodium valproate and flunarizine has shown significant seizure protection in PTZ model, flunarizine has a potential for add-on therapy in refractory cases of partial seizures. It is therefore, we conclude that further experimental studies and multicenter clinical trials involving large sample size are needed to establish flunarizine as add-on therapy in refractory epilepsy.

Capsaicin prevents kainic acid-induced epileptogenesis in mice

Epilepsy is a neurodegenerative disease with periodic occurrences of spontaneous seizures as the main symptom. The aim of this study was to investigate the neuroprotective effects of capsaicin, the major ingredient of hot peppers, in a kainic acid (KA)-induced status epilepticus model. After intraperitoneal injections of KA (30mg/kg) in 8-week-old male ICR mice, the animals were treated subcutaneously with capsaicin (0.33mg/kg or 1mg/kg) and then examined for any anti-ictogenic, hypothermic, antioxidative, anti-inflammatory, and anti-apoptotic effects of the capsaicin treatment 3 days after KA treatment. KA injections significantly enhanced neurodegenerative conditions but co-injection with capsaicin reduced the detrimental effects of KA in a dose-dependent manner in mice. The co-administered group that received KA and 1mg/kg of capsaicin showed significantly decreased behavioral seizure activity and body temperature for 3h and also remarkably blocked intense and high-frequency seizure discharges in the parietal cortex for 3 days compared with those that received KA alone. Capsaicin treatment significantly diminished the levels of oxidant activity and malondialdehyde concentration and increased the antioxidant activity in the blood and brain of KA-treated mice. In addition, capsaicin significantly lowered the KA-induced increase in the concentration of the cytokines IL-1β and TNF-α in the brain. Furthermore, co-treatment of KA and capsaicin (1mg/kg) resulted in considerably decreased apoptotic cell death in the cornu ammonis sections of the hippocampus compared with that seen in the KA-alone group. These findings indicate that capsaicin is preventative for the epileptogenesis induced by KA in mice.

Combining antiepileptic drugs--rational polytherapy?

The global introduction of 14 new antiepileptic drugs (AEDs) over the past 20 years as adjunctive treatment in refractory epilepsy has triggered an increased interest in optimising combination therapy. With a widening range of available mechanisms of AED action, much activity has been focused on the defining and refining "rational polytherapy" with AEDs that have differing pharmacological properties. This paper reviews the available animal and human data exploring this issue. The experimental and clinical evidence in support of "rational polytherapy" is sparse, with only the combination of sodium valproate with lamotrigine demonstrating synergism. Robust evidence to guide clinicians on how and when to combine AEDs is lacking and current practice recommendations are largely empirical. Practical guidance for the clinician is summarised and discussed in this review. In particular, care should be taken to avoid excessive drug load, which can be associated with decreased tolerability and, therefore, reduced likelihood of seizure freedom. A palliative strategy should be defined early for the more than 30% of patients with refractory epilepsy. Nevertheless, the availability of an increasing number of pharmacologically distinct AEDs has produced a modest improvement in prognosis with combination therapy, which will encourage the clinician to persevere with continued pharmacological manipulation when other therapeutic options have been tried or are not appropriate.

A pooled analysis of lacosamide clinical trial data grouped by mechanism of action of concomitant antiepileptic drugs

BACKGROUND

Lacosamide, a new antiepileptic drug (AED) with a different pharmacological action that enhances sodium channel slow inactivation, is approved for the adjunctive treatment of partial-onset seizures in adults. Previous analyses of pooled phase II/III trials have demonstrated that lacosamide provides additional efficacy when added to a broad range of AEDs.

OBJECTIVE

To further evaluate the efficacy and safety of lacosamide by grouping patients based upon the sodium channel-blocking properties of their concomitant AEDs.

STUDY DESIGN

Post hoc exploratory analyses were performed on pooled data in which patients were grouped based upon inclusion or non-inclusion of at least one 'traditional' sodium channel-blocking AED (defined as carbamazepine, lamotrigine, oxcarbazepine and phenytoin derivatives) as part of their concomitant AED regimen.

SETTING

Data pooled from previously conducted phase II/III clinical trials of lacosamide.

PATIENTS

Adult patients with partial-onset seizures with or without secondary generalization (N = 1308).

INTERVENTION

Four- to six-week Titration Phase followed by 12-week maintenance treatment with adjunctive lacosamide (Vimpat®) [200, 400 or 600 mg/day] or placebo.

MAIN OUTCOME MEASURE

Efficacy variables included change in seizure frequency per 28 days and the proportion of patients experiencing a ≥50% reduction in seizure frequency (50% responder rate) from Baseline to the Maintenance Phase. The proportion of patients experiencing a ≥75% reduction in seizure frequency from Baseline to the Maintenance Phase (75% responder rate) was also assessed. Safety parameters assessed were treatment-emergent adverse events (TEAEs) and discontinuation due to TEAEs. Additional safety assessments were changes in ECG and laboratory parameters as well as vital signs (including bodyweight).

RESULTS

Of 1308 patients in the pooled phase II/III population, the majority (82%) were using at least one 'traditional' sodium channel-blocking concomitant AED. In this subgroup of patients, adjunctive lacosamide showed significant reductions in seizure frequency (p < 0.01, all dosages) and significantly greater 50% and 75% responder rates (p < 0.01 for 400 mg/day; p < 0.01 [50% responder rate] and p < 0.05 [75% responder rate] for 600 mg/day) compared with placebo; these effects were similar to the results seen in the pooled phase II/III population. TEAEs and discontinuations due to TEAEs in this subgroup were dose related and similar to the pooled phase II/III population. In the remaining subgroup of patients, i.e. those not taking 'traditional' sodium channel-blocking AEDs as part of their concomitant AED regimen (n = 231; 18%), a pronounced, dose-related seizure reduction was observed with lacosamide (p < 0.01, 400 and 600 mg/day for median percent seizure reduction and 50% or 75% responder rates). Also in this group, incidences of TEAEs were low, and discontinuations due to TEAEs did not appear to increase with dose. Analyses of ECG, laboratory and vital signs (including bodyweight) assessments did not identify abnormalities in either subgroup that were outside of the known safety profile of lacosamide observed in the pooled phase II/III population.

CONCLUSION

In this post hoc exploratory analysis, adjunctive lacosamide demonstrated significant seizure reduction over placebo regardless of the inclusion of 'traditional' sodium channel blockers in the concomitant AED regimen. Future prospective studies evaluating single AED combinations (e.g. lacosamide plus one other drug) are needed to better evaluate the potential for additive or synergistic effects of lacosamide in combination with AEDs not considered 'traditional' sodium channel blockers.

Update on treatment of partial onset epilepsy: role of eslicarbazepine

Partial epilepsy comprises simple partial seizures, complex partial seizures, and secondarily generalized seizures, and covers more than 60% of patients with epilepsy. Antiepileptic drugs are generally considered to be the major therapeutic intervention for epilepsy but, despite a broad range of commonly used antiepileptic drugs, approximately 30% of adult patients and approximately 25% of children with epilepsy have inadequate seizure control. Eslicarbazepine acetate (ESL) is a novel voltage-gated sodium channel-blocking agent with presumed good safety and efficacy for adjunctive treatment of patients with drug-resistant partial epilepsy. ESL is a prodrug of eslicarbazepine (the active entity responsible for pharmacologic effects), and is rapidly and extensively hydrolyzed during first pass by liver esterases after oral administration. The half-life of eslicarbazepine at steady-state plasma concentrations is 20-24 hours, compatible with once-daily administration. ESL 800 mg and 1200 mg significantly reduces seizure frequency and shows a favorable safety profile in adult patients with drug-resistant partial-onset seizures, as demonstrated in previous Phase II and III trials. In children, ESL showed a clear dose-dependent decrease in seizure frequency with good tolerability. The most commonly reported adverse events associated with ESL are dizziness, somnolence, nausea, diplopia, headache, vomiting, blurred vision, vertigo, and fatigue. In conclusion, these characteristics suggest that ESL might be a valid and well tolerated treatment option for patients with drug-resistant partial-onset epilepsy. The convenience of once-daily dosing and a short, simple titration regimen would be of special interest for children, although conclusive published data are lacking to date. Hence, there is an urgent need to establish the therapeutic value of ESL in this special population in the near future.

Rational Polytherapy with Antiepileptic Drugs

Approximately 30-40% of patients do not achieve seizure control with a single antiepileptic drug (AED). With the advent of multiple AEDs in the past 15 years, rational polytherapy, the goal of finding combinations of AEDs that have favorable characteristics, has become of greater importance. We review the theoretical considerations based on AED mechanism of action, animal models, human studies in this field, and the challenges in finding such optimal combinations. Several case scenarios are presented, illustrating examples of rational polytherapy.