Designing clinical trials to assess antiepileptic drugs as monotherapy : difficulties and solutions

N-of-1 trials in epilepsy: A systematic review and lessons paving the way forward

OBJECTIVE

Defined as prospective single-patient crossover studies with repeated paired cycles of active and control intervention, N-of-1 trials have gained attention as an option to obtain high-quality evidence of efficacy, particularly for patients with rare epilepsies in whom conduction of well-powered randomized controlled trials can be challenging. The objective of this systematic review is to provide an appraisal of the literature on N-of-1 trials in individuals with epilepsy.

METHODS

We searched PubMed and Embase on January 12, 2024, for studies meeting the following criteria: prospectively planned, within-patient, multiple-crossover design in individuals with epilepsy and outcomes related to comorbidities. Information on design, outcome measurements, intervention, and analyses was retrieved. Risk of bias assessment was performed using the Risk of Bias in N-of-1 Trials (RoBiNT) scale. We highlighted methodological aspects of the N-of-1 trials identified and discuss future recommendations.

RESULTS

Five studies met our inclusion criteria. An additional multiple-crossover trial that evaluated treatment effects exclusively at group level was also included because of its relevance to N-of-1 study methodology. The studies enrolled individuals with focal seizures, absences or cognitive impairement and electrographic discharges. Treatments included established or investigational antiseizure medications, off-label medications, neurostimulation or lifestyle intervention. Three of the five N-of-1 trials reported on individual cases. The studies' strengths were the use of individualized treatment dosages and symptom-specific patient-reported outcomes. Limitations were related to minimal reporting of baseline characteristics and seizure burden.

SIGNIFICANCE

The trials identified by our search exemplify how the N-of-1 design can be applied to assess interventions in individuals with epilepsy-related disorders. Future N-of-1 trials of antiseizure interventions should take into account baseline seizure frequency, should apply statistical models suited to capture seizure frequency changes reliably and make predefined interim assessments. Non-seizure outcome measures evaluable over short periods should be considered. Tailored N-of-1 methodology could pave the way to evidence-based, treatment selection for patients with rare epilepsies.

Treatment guidelines for rare, early-onset conditions associated with epileptic seizures: a literature review on Rett syndrome and tuberous sclerosis complex

BACKGROUND

Rett syndrome (RTT) and tuberous sclerosis complex (TSC) are two rare disorders presenting with a range of different epileptic seizures. Seizure management requires careful therapy selection, thereby necessitating development of high-quality treatment guidelines. This targeted literature review (TLR) aimed to characterise country-specific and international treatment guidelines available for pharmacological management of seizures in RTT and TSC.

METHODS

A TLR was performed between 25-Jan and 11-Mar 2021. Manual searches of online rare disease and guideline databases, and websites of national heath technology assessment bodies were conducted for the following countries: Australia, Canada, France, Germany, Israel, Italy, Japan, Spain, Switzerland, UK, and US as defined by pre-specified eligibility criteria. Search terms were developed for each condition and translated into local languages where appropriate. Eligible publications were defined as guidelines/guidance reporting pharmacological management of seizures in patients with RTT and TSC. Guideline development methodology, geographical focus, author information and treatment recommendations were extracted from guidelines. An author map was generated using R version 3.5.1 to visualise extent of collaboration between authors.

RESULTS

24 total guidelines were included, of which three and six contained only recommendations for RTT and TSC, respectively (some provided recommendations for ≥ 1 condition). Guideline development processes were poorly described (50% [12 guidelines] had unclear/absent literature review methodologies); reported methodologies were variable, including systematic literature reviews (SLRs)/TLRs and varying levels of expert consultation. Most (83% [20/24]) were country-specific, with guideline authors predominantly publishing in contained national groups; four guidelines were classified as 'International,' linking author groups in the US, UK, Italy and France. High levels of heterogeneity were observed in the availability of treatment recommendations across indications, with 13 and 67 recommendations found for RTT and TSC, respectively. For RTT, all treatment recommendations were positive and sodium valproate had the highest number of positive recommendations (Khwaja, Sahin (2011) Curr Opin Pediatr 23(6):633-9). All TSC treatments (21 medications) received either exclusively negative (National Organization for Rare Disorders (2019)) or positive (Chu-Shore et al. (2010) Epilepsia 51(7):1236-41) recommendations; vigabatrin received the highest number of positive recommendations (Kaur, Christodoulou (2019)).

CONCLUSIONS

This review highlights the need for the development of international high-quality and comprehensive consensus-based guidance for the management of seizures with pharmacological therapy in RTT and TSC.

TRIAL REGISTRATION

Not applicable.

Efficacy and tolerability of brivaracetam monotherapy in childhood and juvenile absence epilepsy: An innovative adaptive trial design

OBJECTIVE

Despite introduction of several antiseizure medications over the past two decades, treatment options for childhood absence epilepsy (CAE) and juvenile absence epilepsy (JAE) remain limited. We report the innovative adaptive design of an ongoing phase 2/3 trial to evaluate efficacy, safety, and tolerability of brivaracetam (BRV) monotherapy in patients 2-25 years of age with CAE or JAE.

METHODS

N01269 (ClinicalTrials.gov: NCT04666610; start: July 2021; expected completion: 2024) is a randomized, dose-finding and confirmatory, double-blind, placebo-controlled, parallel-group, multicenter trial. The trial consists of a dose-selection and assessment for futility stage, followed by an optimal-dose stage after interim analysis. Both stages include an up to 2-week screening period, a 2-week placebo-controlled period, and an 11-week active treatment period (10 weeks of initial treatment followed by a 24-hour electroencephalogram [EEG] and an additional week of active treatment for 24-hour EEG assessment). Patients who are absence seizure-free will enter an up to 4-week randomized withdrawal period. Efficacy assessments will be based on 24-hour EEG and seizure diaries.

SIGNIFICANCE

This two-stage adaptive trial design allows investigation of two potentially efficacious BRV doses, where one dose is dropped in favor of the other dose with a better benefit-risk profile. This allows for a combined phase 2 dose-finding and phase 3 confirmatory efficacy trial, which reduces the number of patients needed to be recruited and reduces trial duration. A randomized withdrawal period is included to evaluate sustainability of treatment effect over time and to allow for placebo control while minimizing placebo exposure. Use of EEG capture in addition to seizure diaries offers a robust mechanism of detecting seizure activity and measuring treatment effect. Positive efficacy and safety/tolerability data may support the use of BRV as monotherapy for CAE or JAE, providing another treatment option and representing long-delayed progress in the treatment of absence seizures in these populations.

Induced Pluripotent Stem Cell-Based Systems for Personalising Epilepsy Treatment: Research Ethics Challenges and New Insights for the Ethics of Personalised Medicine

ABSTRACTThis paper examines potential ethical and legal issues arising during the research, development and clinical use of a proposed strategy in personalized medicine (PM): using human induced pluripotent stem cell (iPSC)-derived tissue cultures as predictive models of individual patients to inform treatment decisions. We focus on epilepsy treatment as a likely early application of this strategy, for which early-stage stage research is underway. In relation to the research process, we examine issues associated with biological samples; data; health; vulnerable populations; neural organoids; and what level of accuracy justifies using the iPSC-derived neural tissue system. In relation to clinical use, we examine potential uses in pre-natal screening, and effects on clinical decision-making. Although our focus is providing recommendations for researchers developing work in this area, we identify the novel issue of deciding on an acceptable accuracy level for the system. We also emphasize an issue thus far neglected in the ethics of PM: PM tends to represent treatment decisions as though they should be directed solely by biomedical information, but this in itself could be detrimental to best personalizing treatment decisions in the clinic.

Long-term safety and efficacy following conversion to eslicarbazepine acetate monotherapy in adults with focal seizures

OBJECTIVE

To assess the long-term safety and efficacy of eslicarbazepine acetate (ESL) monotherapy in adults with focal seizures (FS).

METHODS

Study 050 was a long-term, multicenter, open-label (OL) safety extension of two conversion-to-ESL monotherapy studies in adults with refractory FS. After participating in Study 045 or 046, patients started on ESL 1600 mg once daily (QD) (or 1200 mg if they previously had a dose reduction), and could adjust the dose 400 mg/week to a dose between 800-2400 mg QD. Patients could add up to two additional antiepileptic drugs (AEDs). This post-hoc analysis focuses on the actual monotherapy subgroup, which included patients in Studies 045/046/050 who did not add additional AEDs. Study endpoints included treatment retention time, time on ESL monotherapy, change in standardized seizure frequency (SSF), change in quality of life (QoL) in epilepsy (QOLIE-31) and Montgomery-Åsberg Depression Rating Scale (MADRS) scores, and incidence of treatment-emergent adverse events (TEAEs); serious adverse events (SAEs), TEAEs leading to discontinuation, and TEAEs related to allergic reaction, hyponatremia and thyroid function were also evaluated.

RESULTS

There were 274 patients in the Study 050 full intent-to-treat (ITT) population and 140 patients in the actual monotherapy subgroup. Median treatment retention time and time on ESL monotherapy were both >5 years. Median reduction in SSF from baseline was 66.4% in the full ITT population and 78.3% in the actual monotherapy subgroup; responder (≥50% reduction in SSF) rates were 62.4% and 74.3%, respectively. QOLIE-31 scores increased from baseline in the full ITT population and the actual monotherapy subgroup (4.1- and 7.5-point increases, respectively). MADRS scores decreased from baseline in both the full ITT population and the actual monotherapy subgroup (0.7- and 2.9-point decreases, respectively). TEAEs occurred in 85.4% of patients in the full ITT population and 81.4% of patients in the actual monotherapy subgroup. Incidences of SAEs and TEAEs leading to discontinuation, as well as dizziness, depression, fall, partial seizures with secondary generalization, and complex partial seizures, were higher in the full ITT population than in the actual monotherapy subgroup. Allergic reactions, hyponatremia, and hypothyroidism were infrequent, particularly in the actual monotherapy subgroup.

CONCLUSIONS

The results of this post-hoc analysis suggest that long-term treatment with ESL was effective and well tolerated, both as a monotherapy and in combination with other AEDs for FS. QoL and tolerability appeared to be better, and incidence of depression lower, in the patient population taking ESL as a monotherapy, compared with the population that included patients taking ESL as an adjunctive therapy.

From clinical trials of antiepileptic drugs to treatment

Rational prescribing should be based on the assessment of high-quality evidence about the benefits and risks of available treatment options. Because clinical trials, particularly randomized controlled trials (RCTs), provide the best source of evidence, their design and results need to be carefully scrutinized. The majority of RCTs of antiepileptic drugs (AEDs) have been designed to address regulatory requirements, and generally they involve restrictive eligibility criteria, rigid dosing schemes, short duration of follow-up, and comparison with placebo rather than standard treatments. Although these studies have high internal validity, they are conducted in a setting that is distant from routine clinical practice and therefore their usefulness in guiding treatment decisions is limited. Information more directly applicable to clinical practice can be derived from a relatively small number of comparative effectiveness monotherapy RCTs, although the design of some of these studies was probably biased in favor of the sponsor's product. Alarmingly, there is a paucity of well-designed trials in epilepsy syndromes other than focal epilepsies, and no RCTs at all in most of the less common epileptic syndromes of infancy and childhood. In the light of these shortcomings, there is scope for re-assessing regulatory requirements to facilitate generation of data more directly applicable to the routine clinical setting. Likewise, research-funding organizations should be sensitized about the lack of adequate evidence to guide therapeutic practice in epilepsy, and the need to promote high-quality comparative effectiveness trials. Future prospective pragmatic trials may benefit from the increasingly widespread availability of electronic health records.

Methodological issues associated with clinical trials in epilepsy

INTRODUCTION

despite methodological advances in epilepsy clinical trials, the proportion of patients reaching seizure-freedom has not substantially changed over the years. We review the main methodological limitations of current trials, the possible strategies to overcome these limits, and the issues that need to be addressed in next future. Area covered: references were identified by PubMed search until March 2017 and unpublished literature was searched on ClinicalTrials.gov. Add-on trials mainly involve refractory epilepsy subjects, reducing overall response to the investigational drug. The inclusion of subjects with earlier disease from less developed countries has partially allowed overcoming this limitation, but has introduced more random variability of results. Monotherapy trials rise methodological, economical, and ethical concerns with different regulatory requirements in European Union and in the United States of America. Newer trial designs, such as futility trials or 'time-to-event' design, have been implemented. Moreover, both add-on and monotherapy trials results might be affected by patient's ability to recognize and record seizures, and by randomness of seizures occurrence over time. Possible strategies to achieve more reliable outcomes are detailed. Expert commentary: clinical trial methodology needs to be optimized to better address regulatory agencies requirements and to encounter both patients' and clinicians' needs.

Not all that glitters is gold: A guide to the critical interpretation of drug trials in epilepsy

Clinical trials represent the best source of evidence on which to base treatment decisions. For such evidence to be utilized meaningfully, however, it is essential that results are interpreted correctly. This requires a good understanding of strengths and weaknesses of the adopted design, the clinical relevance of the outcome measures, and the many factors that could affect such outcomes. As a general rule, uncontrolled studies tend to provide misleading evidence as a result of the impact of confounders such as regression to the mean, patient‐related bias, and observer bias. On the other hand, although randomized controlled trials (RCTs) are qualitatively superior, aspects of their execution may still decrease their validity. Bias and decreased validity in RCTs may occur by chance alone (for example, treatment groups may not necessarily be balanced for important variables despite randomization) or because of specific features of the trial design. In the case of industry‐driven studies, bias often influences the outcome in favor of the sponsor's product. Factors that need to be carefully scrutinized include (1) the purpose for which the trial is conducted; (2) potential bias due to unblinding or lack of blinding; (3) the appropriateness of the control group; (4) the power of the study in detecting clinically relevant differences; (5) the extent to which eligibility criteria could affect outcomes and be representative of routine clinical practice; (6) whether the treatments being compared are used optimally in terms of dosing, duration of treatment, and other variables; (7) the appropriateness of the statistical comparisons; (8) the clinical relevance of the outcome measures and whether all key outcome information is reported (for example, responder rates in completers); and (9) potential bias in the way results are presented and discussed. This article discusses each of these aspects and illustrates the discussion with examples taken from published antiepileptic drug trials.

Pharmacotherapy in pediatric epilepsy: from trial and error to rational drug and dose selection - a long way to go

INTRODUCTION

Whereas ongoing efforts in epilepsy research focus on the underlying disease processes, the lack of a physiologically based rationale for drug and dose selection contributes to inadequate treatment response in children. In fact, limited information on the interindividual variation in pharmacokinetics and pharmacodynamics of anti-epileptic drugs (AEDs) in children drive prescription practice, which relies primarily on dose regimens according to a mg/kg basis. Such practice has evolved despite advancements in pediatric pharmacology showing that growth and maturation processes do not correlate linearly with changes in body size.

AREAS COVERED

In this review we aim to provide 1) a comprehensive overview of the sources of variability in the response to AEDs, 2) insight into novel methodologies to characterise such variation and 3) recommendations for treatment personalisation.

EXPERT OPINION

The use of pharmacokinetic-pharmacodynamic principles in clinical practice is hindered by the lack of biomarkers and by practical constraints in the evaluation of polytherapy. The identification of biomarkers and their validation as tools for drug development and therapeutics will require some time. Meanwhile, one should not miss the opportunity to integrate the available pharmacokinetic data with modeling and simulation concepts to prevent further delays in the development of personalised treatments for pediatric patients.

Conversion to eslicarbazepine acetate monotherapy: A pooled analysis of 2 phase III studies

Objective:

To assess the efficacy and safety of eslicarbazepine acetate (ESL) monotherapy.

Methods:

This post hoc pooled analysis of 2 randomized double-blind studies (093-045 and -046) included adults with partial-onset seizures medically uncontrolled by 1 or 2 antiepileptic drugs (AEDs). Following the baseline period (8 weeks), eligible patients were randomized 2:1 to receive ESL 1,600 mg or 1,200 mg once daily for 18 weeks; the primary endpoint was study exit by meeting predefined exit criteria (signifying worsening seizure control). In each study, treatment was considered effective if the upper 95% confidence limit for exit rate was lower than the historical control threshold (65.3%).

Results:

Pooled exit rates were as follows: ESL 1,600 mg = 20.6% (95% confidence interval: 15.6%–26.8%); ESL 1,200 mg = 30.8% (23.0%–40.5%). Use of 2 baseline AEDs or rescue medication, US location, epilepsy duration ≥20 years, and higher maximum baseline seizure frequency were associated with higher exit risks. Median percent reductions in standardized seizure frequency between baseline and the 18-week double-blind period were as follows: ESL 1,600 mg = 43.2%; ESL 1,200 mg = 35.7%; baseline carbamazepine use was associated with smaller reductions. Safety profiles were similar between ESL doses.

Conclusions:

Exit rates for ESL monotherapy (1,600 mg and 1,200 mg once daily) were lower than the historical control threshold, irrespective of baseline AED use and region, with no additional safety concerns identified. Clinical factors and location clearly influence treatment responses in conversion-to-monotherapy trials.

Classification of evidence:

This pooled analysis provides Class IV evidence that for adults with medically uncontrolled partial-onset seizures, ESL monotherapy is well tolerated and effective.

Efficacy and safety of conversion to monotherapy with eslicarbazepine acetate in adults with uncontrolled partial-onset seizures: a historical-control phase III study

Background

Eslicarbazepine acetate (ESL, Aptiom®) is a once-daily (QD) anticonvulsant, approved as adjunctive treatment of partial-onset seizures (POS). It is extensively converted after oral administration to eslicarbazepine, and is believed to exert its effect through inhibition of voltage-gated sodium channels. The possible role of ESL as monotherapy to treat POS has not yet been established.

Methods

This study was an 18-week, multicenter, randomized double-blind trial of gradual conversion to ESL monotherapy in adults with POS not well controlled by 1–2 antiepileptic drugs (AEDs), using historical data as the control. The study comprised an 8-week baseline period, a 2-week titration period, a 6-week AED conversion period, a 10-week monotherapy period, and either a 1-week taper period or optional entry to an open-label extension study. The primary endpoint compared the Kaplan–Meier (KM)-estimated 112-day exit rate with a threshold value calculated from the historical controls.

Results

There were 172 randomized patients; 154 (90%) entered the AED conversion period and 121 (70%) completed the study. The KM-estimated exit rates [confidence interval (CI)] were 15.6% [8.1–28.7%] for ESL 1200 mg, and 12.8% [7.5–21.5%] for ESL 1600 mg. The upper limits of the 95% CI KM-estimates were below the pre-specified threshold for historical control of 65.3%, indicating that ESL was efficacious in reducing seizure-related exits, compared with historical control. During the 18-week double-blind treatment period, median reductions in standardized seizure frequency occurred with ESL 1200 mg (36.1%) and ESL 1600 mg (47.5%). The responder rates (a 50% or greater reduction in seizure frequency from baseline) during the 18-week double-blind period and the monotherapy period, respectively, were 35.2% and 38.9% for ESL 1200 mg, and 46.0% and 46.0% for ESL 1600 mg. The overall adverse event profile was consistent with the known safety profile of ESL.

Conclusions

These findings indicate that ESL monotherapy (1200 and 1600 mg QD) was efficacious and well tolerated in this study.

Trial registration

NCT01091662; EudraCT No. 2010-018684-42.

Electronic supplementary material

The online version of this article (doi:10.1186/s12883-015-0305-5) contains supplementary material, which is available to authorized users.

Efficacy and safety of conversion to monotherapy with eslicarbazepine acetate in adults with uncontrolled partial-onset seizures: a randomized historical-control phase III study based in North America

Objective

To assess the efficacy and safety of eslicarbazepine acetate (ESL) as monotherapy in North American patients with partial‐onset seizures (POS).

Methods

This multicenter, randomized, double‐blind “withdrawal to monotherapy” study used historical control data as the comparator. Adults with POS medically uncontrolled by one to two antiepileptic drugs gradually converted to ESL monotherapy. Following an 8‐week baseline period, patients were randomized 2:1 to receive ESL 1,600 mg (n = 128) or 1,200 mg QD (n = 65) for 18 weeks. The primary end point was the proportion of patients meeting predefined exit criteria (signifying worsening seizure control). Treatment was considered effective if the 95% upper confidence limit (UCL) for the Kaplan‐Meier estimated exit rate was lower than the exit rate threshold calculated from the historical control (65.3%).

Results

Kaplan‐Meier estimated exit rates were: ESL 1,600 mg, 28.7% (95% CI 21.2–38.1%) and 1,200 mg, 44.4% (32.5–58.3%). The difference between doses was not significant (p = 0.07). For both doses, the 95% UCLs for the exit rate were ˂65.3%; ESL monotherapy was considered superior to the historical control. There was no statistically significant increase in the risk of study exit related to carbamazepine use. Nine (7.6%) and five patients (8.3%) remained seizure‐free during the 10‐week monotherapy period, while taking ESL 1,600 and 1,200 mg, respectively. The reductions in median standardized seizure frequency (seizures per 28 days) between baseline and the 18‐week treatment period were: ESL 1,600 mg, 42% and 1,200 mg, 31%. Treatment‐emergent adverse events (TEAEs) occurring in ≥10% of patients were dizziness, headache, fatigue, somnolence, nausea, and nasopharyngitis. The TEAE most frequently leading to discontinuation was hyponatremia (2.1%).

Significance

ESL was efficacious and well tolerated as monotherapy in North American patients, and led to a reduction in seizure frequency. Exit rates for ESL 1,600 and 1,200 mg QD were superior to the historical control; the difference in exit rates between doses was not statistically significant.

Off-label prescribing of antiepileptic drugs in pharmacoresistant epilepsy: a cross-sectional drug utilization study of tertiary care centers in Italy

PURPOSE

To assess the extent of off-label prescribing of antiepileptic drugs (AEDs) and associated variables in a large population of patients with pharmacoresistant epilepsy.

METHODS

Descriptive analysis of data recorded from consecutively enrolled patients with pharmacoresistant epilepsy attending 11 tertiary referral centers in Italy. Off-label use was stratified by therapeutic indication, dose, and age. Multivariate logistic regression was used to identify variables associated with off-label prescription.

RESULTS

Of a total of 1,124 patients enrolled between November 2006 and August 2007, 53 % (101/191) of children and 31 % (287/933) of adults were receiving at least one off-label AED prescription. Among adults, off-label use was related primarily to indication and was highest for clobazam (100 %) and ethosuximide (40 %), followed by lamotrigine (25 %), and vigabatrin (25 %). In children, clobazam (100 %), lamotrigine (79 %), vigabatrin (55 %), ethosuximide (46 %), and levetiracetam (43 %) were most frequently used off-label, with indication or age being the main causes depending on the specific AED. Logistic regression analysis indicated that higher rates of off-label use were associated with a polytherapy regimen (odds ratio [OR] 2.50, 95 % confidence interval [95 % CI], 1.55-4.03), pediatric age (2.49, 1.66-3.76), having failed ≥3 AEDs (2.16, 1.04-4.48), a diagnosis of generalized epilepsy with structural/metabolic or unknown etiology (2.97, 1.25-7.04), and increasing seizure frequency (1.07, 1.01-1.14).

CONCLUSIONS

Off-label prescribing of AEDs is common among patients with pharmacoresistant epilepsy and is influenced by demographic and disease-related characteristics. Studies are needed to improve the quality of evidence guiding epilepsy treatment, and to evaluate the risks and benefits of off-label prescribing in epilepsy.

Pregabalin monotherapy in patients with partial-onset seizures: a historical-controlled trial

OBJECTIVE

To assess pregabalin monotherapy for partial-onset seizures using a historical-controlled conversion-to-monotherapy design.

METHODS

Adults with inadequately controlled partial-onset seizures while receiving 1 or 2 antiepileptic drugs during an 8-week prospective baseline were randomized to double-blind monotherapy with pregabalin 600 or 150 mg/d (4:1) for 20 weeks (8-week conversion and 12-week monotherapy period). The primary endpoint was the seizure-related exit rate for pregabalin 600 mg/d, based on discontinuations due to predefined criteria. Efficacy was declared if the upper limit of the 95% confidence interval for the exit rate was below a historical-control threshold of 74%, with stepwise evaluation using a threshold of 68%.

RESULTS

The trial was stopped early for positive efficacy after an interim analysis in 125 patients. The full study population included 161 patients, with 148 evaluable for efficacy. The mean time since epilepsy diagnosis was 14 years. Overall, 54.3% (600 mg/d) and 46.9% (150 mg/d) of patients completed 20 weeks of double-blind treatment. Seizure-related exit rate in the 600 mg/d group (27.5%; 95% confidence interval, 17.8%-37.2%) was significantly below the 74% and 68% thresholds (p < 0.001 for both). Eight patients on 600 mg/d and 2 on 150 mg/d were seizure-free throughout pregabalin monotherapy. Pregabalin's overall safety profile was consistent with prior trials.

CONCLUSIONS

Pregabalin monotherapy was safe and efficacious for patients with inadequately controlled partial-onset seizures.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that patients with inadequately controlled partial-onset seizures switched to pregabalin monotherapy have fewer seizure-related exit events compared with historical controls switched to pseudo-placebo monotherapy.

Probable levetiracetam-related serum alkaline phosphatase elevation

Background

Levetiracetam (LEV) is an antiepileptic drug with a favorable tolerability and safety profile with little or no effect on liver function.

Case presentation

Here, we reported an epileptic pediatric patient who developed a significant elevation in serum alkaline phosphatase level (ALP) during LEV monotherapy. Moreover, the serum ALP level was surprisingly decreased to normal after LEV discontinuation. The Naranjo Adverse Drug Reaction Probability Scale score was 6, indicating firstly LEV was a probable cause for the increased serum ALP.

Conclusions

Cautious usage and concerns of the LEV-associated potential ALP elevation should be considered when levetiracetam is prescribed to epilepsy patients, especially pediatric patients.

Lamotrigine XR conversion to monotherapy: first study using a historical control group

The efficacy and safety of lamotrigine extended-release tablets (LTG XR) as monotherapy for partial seizures were evaluated using the conversion-to-monotherapy design, and historical data as the control. This methodology was recently approved by the United States Food and Drug Administration, and this study is the first historical control design in epilepsy to complete enrollment. Patients ≥13 years old with uncontrolled partial epilepsy receiving monotherapy with valproate or a noninducing antiepileptic drug were converted to once-daily LTG XR (250 mg or 300 mg) as monotherapy and were followed up for 12 additional weeks. Efficacy was measured by the proportion of patients meeting predefined escape criteria for seizure worsening compared with aggregated pseudoplacebo control data from 8 previously conducted conversion-to-monotherapy trials. Nonoverlap of the 95% confidence limit for LTG XR and the 95% prediction interval of the historical control denotes efficacy. Of 226 randomized patients, 174 (93 in 300 mg/day group and 81 in 250 mg/day group) started withdrawal of the background AED and were evaluated for escape. In the historical control analysis population, the lower 95% prediction interval of the historical control (65.3%) was not overlapped by the upper 95% confidence limit of either LTG XR (300 mg/day; 37.2%) or LTG XR (250 mg/day; 43.4%). Adverse events were reported in 53% and 61% of patients receiving LTG XR (300 mg/day and 250 mg/day, respectively). LTG XR (250 mg or 300 mg once daily) is effective for conversion-to-monotherapy treatment of partial seizures in patients ≥13 years old.

Adverse antiepileptic drug effects in new-onset seizures: a case-control study

OBJECTIVE

Adverse effects (AEs) are a major concern when starting antiepileptic drug (AED) treatment. This study quantified the extent to which AE reporting in people with new-onset seizures started on AEDs is attributable to the medication per se, and investigated variables contributing to AE reporting.

METHODS

We pooled data from 2 large prospective studies, the Multicenter Study of Early Epilepsy and Single Seizures and the Northern Manhattan Study of incident unprovoked seizures, and compared adverse event profile (AEP) total and factor scores between adult cases prescribed AEDs for new-onset seizures and untreated controls, adjusting for several demographic and clinical variables. Differences in AEP scores were also tested across different AED monotherapies and controls, and between cases and controls grouped by number of seizures.

RESULTS

A total of 212 cases and 206 controls were identified. Most cases (94.2%) were taking low AED doses. AEP scores did not differ significantly between the 2 groups. Depression, female gender, symptomatic etiology, younger seizure onset age, ≥2 seizures, and history of febrile seizures were associated with higher AEP scores. There were no significant differences in AEP scores across different monotherapies and controls. AEP scores increased in both cases and controls with increasing number of seizures, the increment being more pronounced in cases.

CONCLUSIONS

When AED treatment is started at low doses following new-onset seizures, AE reporting does not differ from untreated individuals. Targeting specific factors affecting AE reporting could lead to improved tolerability of epilepsy treatment.

Pregabalin for the management of partial epilepsy

Pregabalin is one of the latest antiepileptic drugs introduced for the treatment of partial epilepsy. Its efficacy and safety as adjunctive therapy in refractory partial epilepsy have been established in four double-blind placebo-controlled trials (n = 1396) and 4 long-term open-label studies (n = 1480). In 3 fixed-dose trials, the proportion of patients with a >/=50% reduction in seizure frequency across the effective dose-range (150-600 mg/day) ranged between 14% and 51%, with a clear dose-response relationship. Suppression of seizure activity could be demonstrated as early as day 2. The most frequently reported CNS-related adverse events included dizziness, somnolence, ataxia and fatigue, were usually mild or moderate, and tended to be dose related. In long-term studies, weight gain was reported as an adverse event by 24% of patients. When pregabalin dose was individualized to according to response within the 150 to 600 mg/day dose range, tolerability was considerably improved compared with use of a high-dose, fixed-dose regimen (600 mg/day) without titration. In long-term studies up to 4 years, no evidence of loss efficacy was identified. During the last year on pregabalin, 3.7% of patients were seizure-free. Pregabalin appears to be a useful addition to the therapeutic armamentariun for the management of refractory partial epilepsy.