Vigabatrin vs carbamazepine monotherapy in patients with newly diagnosed epilepsy. A randomized, controlled study

Anti-seizure medication exposure and the risk of dementia: A meta-analysis of observational studies

Objective

There is growing evidence of a relationship between anti-seizure medication (ASM) use and the risk of dementia. This study examined this association using a meta-analysis approach.

Methods

PubMed, EMBASE, and Cochrane Library were systematically searched for peer-reviewed observational studies published up to February 2023. Study quality was evaluated using the Newcastle-Ottawa Scale, and an overall odds ratio (OR) was pooled using fixed or random-effects models.

Results

The analysis included 9 publications with 10 studies. The results showed that overall ASM exposure was associated with an increased risk of dementia [OR: 1.09, 95% confidence interval (CI): 1.03-1.15; P = 0.003] in general population. However, this association disappeared (OR: 1.02, 95% CI: 0.97-1.07; P = 0.361) when the study data adjusted for drug indications were pooled. Subgroup analysis based on individual drugs found only a positive association among those exposed to valproate, carbamazepine, and clonazepam. Furthermore, an increased risk was found in patients with bipolar disorder exposed to ASMs (OR: 1.43, 95% CI: 1.07-1.92; P = 0.015).

Conclusions

The statistically significant association between ASM and dementia in general population may be driven by unmeasured confounding or several individual first-generation ASMs. However, a higher risk of dementia was observed among bipolar disorder patients treated with ASMs. Given the few included studies and evidence of high heterogeneity, further larger, prospective studies that control for important confounders are needed to verify our findings.

Impact of Antiseizure Medications on Appetite and Weight in Children

There are numerous potential factors that may affect growth in children with epilepsy, and these must be evaluated in any child with appetite and weight concerns. Antiseizure medications (ASMs) have potential adverse effects, and many may affect appetite, thus impacting normal growth and weight gain. The aim of this review is to focus on the impact of both epilepsy and ASMs on appetite and weight in children. We systematically reviewed studies using Medline assessing the impact of ASMs on appetite and weight in children. Eligible studies included randomized controlled trials and open-label studies (open-label extension and interventional) that targeted or included the pediatric population (0-18 years of age). Each study was classified using the American Academy of Neurology (AAN) Classification of Evidence for Therapeutic Studies, and the level of evidence for impact on appetite and weight in children was graded. ASMs associated with decreased appetite and/or weight loss include fenfluramine, topiramate, zonisamide, felbamate, rufinamide, stiripentol, cannabidiol, brivaracetam and ethosuximide; ASMs with minimal impact on weight and appetite in children include oxcarbazepine, eslicarbazepine, lamotrigine, levetiracetam, lacosamide, carbamazepine, vigabatrin and clobazam. The ASM most robustly associated with increased appetite and/or weight gain is valproic acid; however, both pregabalin and perampanel may also lead to modest weight gain or increased appetite in children. Certain ASMs may impact both appetite and weight, which may lead to increased morbidity of the underlying disease and impaired adherence to the treatment regimen.

The Discordance between Network Excitability and Cognitive Performance Following Vigabatrin Treatment during Epileptogenesis

Vigabatrin (VGB), a potent selective γ-aminobutyric acid transaminase (GABA-T) inhibitor, is an approved non-traditional anti-seizure drug for patients with intractable epilepsy. Nevertheless, its effect on epileptogenesis, and whether this effect is correlated with post-epileptogenic cognitive function remain unclear. Based on lithium-pilocarpine-induced seizure modeling, we evaluated the effect of VGB on epileptogenesis and neuronal damage following status epilepticus in Sprague-Dawley rats. Cognitive evaluations were performed with the aid of inhibitory avoidance testing. We found that VGB could interrupt epileptogenesis by reducing spontaneous recurrent seizures, hippocampal neuronal damage, and chronic mossy fiber sprouting. Nevertheless, VGB did not help with the retention of cognitive performance. Our findings suggest that further research into the role of VGB in epileptogenesis and the treatment of epilepsy in clinical practice is warranted.

Efficacy and tolerability of antiseizure drugs

Drug-resistant epilepsy occurs in 25-30% of patients. Furthermore, treatment with a first-generation antiseizure drug (ASD) fails in 30-40% of individuals because of their intolerable adverse effects. Over the past three decades, 20 newer- (second- and third-)generation ASDs with unique mechanisms of action and pharmacokinetic profiles have been introduced into clinical practice. This advent has expanded the therapeutic armamentarium of epilepsy and broadens the choices of ASDs to match the individual patient's characteristics. In recent years, research has been focused on defining the ASD of choice for different seizure types. In 2017, the International League Against Epilepsy published a new classification for seizure types and epilepsy syndrome. This classification has been of paramount importance to accurately classify the patient's seizure type(s) and prescribe the ASD that is appropriate. A year later, the American Academy of Neurology published a new guideline for ASD selection in adult and pediatric patients with new-onset and treatment-resistant epilepsy. The guideline primarily relied on studies that compare the first-generation and second-generation ASDs, with limited data for the efficacy of third-generation drugs. While researchers have been called for investigating those drugs in future research, epilepsy specialists may wish to share their personal experiences to support the treatment guidelines. Given the rapid advances in the development of ASDs in recent years and the continuous updates in definitions, classifications, and treatment guidelines for seizure types and epilepsy syndromes, this review aims to present a complete overview of the current state of the literature about the efficacy and tolerability of ASDs and provide guidance to clinicians about selecting appropriate ASDs for initial treatment of epilepsy according to different seizure types and epilepsy syndromes based on the current literature and recent US and UK practical guidelines.

Neuropharmacology of Antiseizure Drugs

BACKGROUND

Antiseizure drugs (ASDs) are the primary therapy for epilepsy, with more than 20 drugs introduced into clinical practice to date. These drugs are typically grouped by their mechanisms of action and therapeutic spectrum. This article aims to educate non-neurologists and medical students about the new frontiers in the pharmacology of ASDs and presents the current state of the literature on the efficacy and tolerability of these agents.

METHODS

Randomized controlled trials, observational studies, and evidence-based meta-analyses of ASD efficacy and tolerability as initial monotherapy for epileptic seizures and syndromes were identified in PubMed, EMBASE, the Cochrane Library, and Elsevier Clinical Pharmacology.

RESULTS

The choice of ASD varies primarily according to the seizure type. Practical guidelines for ASD selection in patients with new-onset and drug-resistant epilepsy were recently published. The guidelines have shown that the newer-generation drugs, which have unique mechanistic and pharmacokinetic properties, are better tolerated but have similar efficacy compared with the older drugs. Several ASDs are effective as first-line monotherapy in focal seizures, including lamotrigine, carbamazepine, phenytoin, levetiracetam, and zonisamide. Valproate remains the first-line drug for many patients with generalized and unclassified epilepsies. However, valproate should be avoided, if possible, in women of childbearing potential because of teratogenicity. Toxicity profile precludes several drugs from use as first-line treatment, for example, vigabatrin, felbamate, and rufinamide.

CONCLUSIONS

Antiseizure drugs have different pharmacologic profiles that should be considered when selecting and prescribing these agents for epilepsy. These include pharmacokinetic properties, propensity for drug-drug interactions, and adverse effects.

Practice guideline update summary: Efficacy and tolerability of the new antiepileptic drugs I: Treatment of new-onset epilepsy: Report of the American Epilepsy Society and the Guideline Development, Dissemination, and Implementation Subcommittee of the American Academy of Neurology

Objective: To update the 2004 American Academy of Neurology (AAN) guideline for treating new-onset focal or generalized epilepsy (GE) with second- and third-generation antiepileptic drugs (AEDs). Methods: The 2004 AAN criteria was used to systematically review literature (January 2003 to November 2015), classify pertinent studies according to the therapeutic rating scheme, and link recommendations to evidence strength. Results: Several second-generation AEDs are effective for new-onset focal epilepsy. Data are lacking on efficacy in new-onset generalized tonic-clonic seizures, juvenile myoclonic epilepsy, or juvenile absence epilepsy, and on efficacy of third-generation AEDs in new-onset epilepsy. Recommendations: Lamotrigine (LTG) should (Level B) and levetiracetam (LEV) and zonisamide (ZNS) may (Level C) be considered in decreasing seizure frequency in adults with new-onset focal epilepsy. LTG should (Level B) and gabapentin (GBP) may (Level C) be considered in decreasing seizure frequency in patients ≥60 years with new-onset focal epilepsy. Unless there are compelling adverse-effect-related concerns, ethosuximide (ETS) or valproic acid (VPA) should be considered before LTG to decrease seizure frequency in treating absence seizures in childhood absence epilepsy (Level B). No high-quality studies suggest clobazam, eslicarbazepine, ezogabine, felbamate, GBP, lacosamide, LEV, LTG, oxcarbazepine, perampanel, pregabalin, rufinamide, tiagabine, topiramate, vigabatrin, or ZNS is effective in treating new-onset epilepsy because no high-quality studies exist in adults of various ages. A recent FDA strategy allows extrapolation of efficacy across populations; therefore, for focal epilepsy, eslicarbazepine and lacosamide (oral only for pediatric use) as add-on or monotherapy in persons ≥4 years old and perampanel as monotherapy received FDA approval.

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

Objective

To update the 2004 American Academy of Neurology (AAN) guideline for treating new-onset focal or generalized epilepsy with second- and third-generation antiepileptic drugs (AEDs).

Methods

The 2004 AAN criteria were used to systematically review literature (January 2003–November 2015), classify pertinent studies according to the therapeutic rating scheme, and link recommendations to evidence strength.

Results

Several second-generation AEDs are effective for new-onset focal epilepsy. Data are lacking on efficacy in new-onset generalized tonic-clonic seizures, juvenile myoclonic epilepsy, or juvenile absence epilepsy, and on efficacy of third-generation AEDs in new-onset epilepsy.

Recommendations

Lamotrigine (LTG) should (Level B) and levetiracetam (LEV) and zonisamide (ZNS) may (Level C) be considered in decreasing seizure frequency in adults with new-onset focal epilepsy. LTG should (Level B) and gabapentin (GBP) may (Level C) be considered in decreasing seizure frequency in patients ≥60 years of age with new-onset focal epilepsy. Unless there are compelling adverse effect–related concerns, ethosuximide or valproic acid should be considered before LTG to decrease seizure frequency in treating absence seizures in childhood absence epilepsy (level B). No high-quality studies suggest clobazam, eslicarbazepine, ezogabine, felbamate, GBP, lacosamide, LEV, LTG, oxcarbazepine, perampanel, pregabalin, rufinamide, tiagabine, topiramate, vigabatrin, or ZNS is effective in treating new-onset epilepsy because no high-quality studies exist in adults of various ages. A recent Food and Drug Administration (FDA) strategy allows extrapolation of efficacy across populations; therefore, for focal epilepsy, eslicarbazepine and lacosamide (oral only for pediatric use) as add-on or monotherapy in persons ≥4 years old and perampanel as monotherapy received FDA approval.

Detecting Retinal Vigabatrin Toxicity in Patients with Partial Symptomatic or Cryptogenic Epilepsy

Purpose.

Detecting retinal vigabatrin toxicity in patients with partial symptomatic or cryptogenic epilepsy can be challenging because of preexisting visual field defects secondary to a structural abnormality in the brain or lack of collaboration. The aim of this study was to measure the retinal nerve fiber layer thickness (RNFLT) with optic coherence tomography (OCT), as well as contrast sensitivity, color vision, and perimetry, in patients with partial symptomatic or cryptogenic epilepsy on vigabatrin, and to determine the efficacy of these tests as markers of vigabatrin-related retinal damage in these subgroups of epileptic patients.

Methods.

The study involved 38 patients with either partial symptomatic or cryptogenic epilepsy and 16 healthy individuals comprising the control group. At the time of the study, 14 of the patients were using vigabatrin, 10 were receiving sodium valproate monotherapy, and 14 were on carbamazepine monotherapy. All the participants underwent RNFLT imaging with OCT, contrast sensitivity, color discrimination assessment, and perimetry.

Results.

The average 360° RNFLT of the vigabatrin group was significantly lower when compared to the other groups. The average RNFLT of all quadrants except the temporal one in the vigabatrin group was also significantly reduced. There was no difference in the mean deviation, contrast sensitivity, and color discrimination between the study groups, but they were all significantly lower than the control group.

Conclusions.

RNFLT measurement with OCT can efficiently identify vigabatrin toxicity in patients with partial symptomatic and cryptogenic epilepsy. Perimetry, contrast sensitivity, and color discrimination assessment might be inconclusive in these particular subgroups of epileptic patients.

Bipolar Disorder and Cognitive Dysfunction: A Complex Link

The aim of this article was to describe the current evidence regarding phenomenon of cognitive functioning and dementia in bipolar disorder (BD). Cochrane Library and PubMed searches were conducted for relevant articles, chapters, and books published before 2016. Search terms used included "bipolar disorder," "cognitive dysfunction," and "dementia." At the end of the selection process, 159 studies were included in our qualitative synthesis. As result, cognitive impairments in BD have been previously considered as infrequent and limited to the affective episodes. Nowadays, there is evidence of stable and lasting cognitive dysfunctions in all phases of BD, including remission phase, particularly in the following domains: attention, memory, and executive functions. The cause of cognitive impairment in BD raises the question if it subtends a neurodevelopmental or a neurodegenerative process. Impaired cognitive functioning associated with BD may contribute significantly to functional disability, in addition to the distorted affective component usually emphasized.

Efficacy and Tolerability of Antiepileptic Drugs in Patients with Focal Epilepsy: Systematic Review and Network Meta-analyses

Several newer antiepileptic drugs (AEDs) have been introduced into clinical practice, offering choices for individualizing the treatment of epilepsy since AEDs have different efficacy and tolerability profiles. In particular, questions exist regarding which AEDs are the best options for the monotherapy of focal epilepsy. Is carbamazepine (CBZ), which is considered the standard treatment for focal epilepsy, still the best option for monotherapy of focal epilepsy, despite the emergence of new AEDs? In this systematic review, we compared the relative tolerability of all available AEDs for monotherapy of all types of epilepsy as well as their efficacy in the monotherapy of focal epilepsy. In addition, we compared CBZ with other AEDs for the monotherapy of focal epilepsy. We performed a search of the MEDLINE/PubMed, Scopus, Web of Science, and Cochrane Central Register of Controlled Trials (CENTRAL) databases for randomized controlled clinical trials. To compare the relative efficacy and tolerability of the AEDs, we performed network meta-analyses using a Bayesian random-effects model. Sensitivity analyses were conducted to determine the robustness of the results. A total of 65 studies were included in this review, composing 16,025 patients. Clobazam, levetiracetam, lamotrigine, oxcarbazepine, sulthiame, topiramate, and valproate had the best efficacy profiles and demonstrated no evidence of superiority or inferiority compared with CBZ. However, CBZ showed the greatest risk of patient discontinuation due to intolerable adverse reactions, whereas lamotrigine had the best safety profile and an 81% probability of being the best for the tolerability outcome of patient withdrawals from the study due to intolerable adverse reactions, followed by sulthiame (60%) and clobazam (51%). The newer AEDs-levetiracetam, lamotrigine, oxcarbazepine, sulthiame, and topiramate-should be considered for monotherapy of focal epilepsy because they were demonstrated to be as effective as the older ones (CBZ, clobazam, and valproate) for the treatment of focal epilepsy and were more tolerable. Lamotrigine was the AED with the best tolerability profile, suggesting that it may be the best option for the treatment of focal epilepsy in children and adults.

Reduction of retinal nerve fiber layer thickness in vigabatrin-exposed patients: A meta-analysis

OBJECTIVE

Vigabatrin (VGB) is currently served as an effective adjunctive therapy for patients with partial epilepsy worldwide. In this study, meta-analysis was conducted to comprehensively evaluate the changes in peripapillary retinal nerve fiber layer (RNFL) thickness assessed by optical coherence tomography (OCT) in epilepsy patients who were treated by VGB.

MATERIAL AND METHODS

Publications on PubMed, Wiley Online Library and the Elsevier Science databases were searched by September 2016. The statistical analysis was performed by RevMan 5.3 software.

RESULTS

Four studies were identified, and 202 eyes in VGB-exposed patients (VGB group) as well as 162 eyes in patients who never received VGB treatment (NON-VGB group) were included. The studies demonstrated that the total RNFL thickness is attenuated in VGB treated patients (weighted mean differences in μm, WMD=-15.96, 95% CI: -23.69 to -8.23, P<0.0001). RNFL thickness in 3 quadrants were significantly reduced in VGB group: superior (WMD=-18.15, 95% CI: -23.31 to -12.98, P<0.00001), inferior (WMD=-23.19, 95% CI: -32.23 to -14.15, P<0.00001) and nasal (WMD=-19.29, 95% CI: -35.57 to -3.02, P=0.02). However, the temporal RNFL thickness in these two groups showed no significant difference: temporal (WMD=-2.41, 95% CI: -6.67 to 1.85, P=0.27).

CONCLUSION

Based on the meta-analysis, RNFL thickness appears to reduce in epilepsy patients who received VGB treatment, and OCT could be a useful tool to help clinicians assessing its retinal toxicity and guiding its dosage.

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.

Cutaneous Adverse Effects of Neurologic Medications

Life-threatening and benign drug reactions occur frequently in the skin, affecting 8 % of the general population and 2-3 % of all hospitalized patients, emphasizing the need for physicians to effectively recognize and manage patients with drug-induced eruptions. Neurologic medications represent a vast array of drug classes with cutaneous side effects. Approximately 7 % of the United States (US) adult population is affected by adult-onset neurological disorders, reflecting a large number of patients on neurologic drug therapies. This review elucidates the cutaneous reactions associated with medications approved by the US Food and Drug Administration (FDA) to treat the following neurologic pathologies: Alzheimer disease, amyotrophic lateral sclerosis, epilepsy, Huntington disease, migraine, multiple sclerosis, Parkinson disease, and pseudobulbar affect. A search of the literature was performed using the specific FDA-approved drug or drug classes in combination with the terms 'dermatologic,' 'cutaneous,' 'skin,' or 'rash.' Both PubMed and the Cochrane Database of Systematic Reviews were utilized, with side effects ranging from those cited in randomized controlled trials to case reports. It behooves neurologists, dermatologists, and primary care physicians to be aware of the recorded cutaneous adverse reactions and their severity for proper management and potential need to withdraw the offending medication.

Vigabatrin versus carbamazepine monotherapy for epilepsy

BACKGROUND

This is an update of a Cochrane review first published in 2012 (Cochrane Database of Systematic Reviews 2012, Issue 1).The efficacy and safety of vigabatrin (VGB) as an add-on therapy for refractory epilepsy have been well established. However, this information needs to be weighed against the risk of development of visual field defects. Whether VGB monotherapy is an effective and safe treatment compared with the standard antiepileptic drug carbamazepine (CBZ) as monotherapy for epilepsy has not been systematically reviewed.

OBJECTIVES

To investigate the efficacy and safety of VGB versus CBZ monotherapy for epilepsy in children and adults.

SEARCH METHODS

For the latest update, we searched the Cochrane Central Register of Controlled Trials (CENTRAL; 2015, Issue 3 of 4), MEDLINE (1948 to July 2015), EMBASE (1974 to July 2015) and the Chinese Biomedical Database (CBM) (1979 to July 2015). We searched trial registers and contacted the manufacturer of VGB and authors of included studies for additional information. We applied no language restrictions.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing VGB versus CBZ monotherapy for epilepsy.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality and extracted data. The primary outcome was time to treatment withdrawal. Secondary outcomes were time to achieve six-month and 12-month remission after randomisation, time to first seizure after randomisation and adverse events. We presented results as hazard ratios (HRs) with 95% confidence intervals (CIs) (time to event data) or as risk ratios (RRs) with 95% CIs (adverse events).

MAIN RESULTS

Five studies involving a total of 734 participants were eligible for inclusion. We assessed only one study as good quality and the other four as poor quality. However, it was difficult to perform a meta-analysis by extracting aggregate data to synthesise the results as originally planned, mainly because not all studies reported the same outcomes as those chosen for this review. No significant differences favoured VGB or CBZ in terms of time to treatment withdrawal and time to achieve six-month remission after dose stabilisation from randomisation, but results did show a disadvantage for VGB on time to first seizure after randomisation. Compared with CBZ, VGB was associated with more occurrences of weight gain and fewer occurrences of skin rash and drowsiness. No differences in visual field defects and visual disturbances were noted.

AUTHORS' CONCLUSIONS

Data are currently insufficient to address the risk-benefit balance of VGB versus CBZ monotherapy for epilepsy. Given the high prevalence of visual field defects reported in an existing systematic review of observational studies (Maguire 2010), VGB monotherapy should be prescribed with caution for epilepsy and should not be considered a first-line choice. If necessary, the visual field should be frequently assessed. Future research should focus on investigating the reasons for visual field defects and exploring potential prevention strategies. Moreover, future monotherapy studies of epilepsy should report results according to the recommendations of the International League Against Epilepsy (ILAE) Commission, and methodological quality should be improved.

Antiepileptic drug treatment: new drugs and new strategies

PURPOSE OF REVIEW

Selection of the ideal antiepileptic drug (AED) for an individual patient can be a daunting process. Choice of treatment should be based on several factors, including but not limited to epilepsy classification, AED mechanism of action, AED side-effect profile, and drug interactions. Special consideration must be given to populations such as women, older adults, patients with other medical comorbidities, and patients who are newly diagnosed.

RECENT FINDINGS

Head-to-head trials between AEDs in newly diagnosed patients rarely demonstrate that one AED is more or less effective. The second-generation drugs, lamotrigine, topiramate, oxcarbazepine, zonisamide, and levetiracetam, have undergone head-to-head trials confirming similar efficacy and equal or better tolerability than standard drugs in focal epilepsy.

SUMMARY

A thoughtful approach to the AED selection process must factor in data from clinical AED trials as well as a variety of patient characteristics and confounding factors. When neurologists apply an individualized approach to AED drug selection for their patients, they can find an effective and well-tolerated drug for most patients.

Updated ILAE evidence review of antiepileptic drug efficacy and effectiveness as initial monotherapy for epileptic seizures and syndromes

The purpose of this report was to update the 2006 International League Against Epilepsy (ILAE) report and identify the level of evidence for long-term efficacy or effectiveness for antiepileptic drugs (AEDs) as initial monotherapy for patients with newly diagnosed or untreated epilepsy. All applicable articles from July 2005 until March 2012 were identified, evaluated, and combined with the previous analysis (Glauser et al., 2006) to provide a comprehensive update. The prior analysis methodology was utilized with three modifications: (1) the detectable noninferiority boundary approach was dropped and both failed superiority studies and prespecified noninferiority studies were analyzed using a noninferiority approach, (2) the definition of an adequate comparator was clarified and now includes an absolute minimum point estimate for efficacy/effectiveness, and (3) the relationship table between clinical trial ratings, level of evidence, and conclusions no longer includes a recommendation column to reinforce that this review of efficacy/evidence for specific seizure types does not imply treatment recommendations. This evidence review contains one clarification: The commission has determined that class I superiority studies can be designed to detect up to a 20% absolute (rather than relative) difference in the point estimate of efficacy/effectiveness between study treatment and comparator using an intent-to-treat analysis. Since July, 2005, three class I randomized controlled trials (RCT) and 11 class III RCTs have been published. The combined analysis (1940-2012) now includes a total of 64 RCTs (7 with class I evidence, 2 with class II evidence) and 11 meta-analyses. New efficacy/effectiveness findings include the following: levetiracetam and zonisamide have level A evidence in adults with partial onset seizures and both ethosuximide and valproic acid have level A evidence in children with childhood absence epilepsy. There are no major changes in the level of evidence for any other subgroup. Levetiracetam and zonisamide join carbamazepine and phenytoin with level A efficacy/effectiveness evidence as initial monotherapy for adults with partial onset seizures. Although ethosuximide and valproic acid now have level A efficacy/effectiveness evidence as initial monotherapy for children with absence seizures, there continues to be an alarming lack of well designed, properly conducted epilepsy RCTs for patients with generalized seizures/epilepsies and in children in general. These findings reinforce the need for multicenter, multinational efforts to design, conduct, and analyze future clinically relevant adequately designed RCTs. When selecting a patient's AED, all relevant variables and not just efficacy and effectiveness should be considered.

The cognitive impact of antiepileptic drugs

Effective treatment of epilepsy depends on medication compliance across a lifetime, and studies indicate that drug tolerability is a significant limiting factor in medication maintenance. Available antiepileptic drugs (AEDs) have the potential to exert detrimental effects on cognitive function and therefore compromise patient wellbeing. On the other hand, some agents may serve to enhance cognitive function. In this review paper, we highlight the range of effects on cognition linked to a variety of newer and older AEDs, encompassing key alterations in both specific executive abilities and broader neuropsychological functions. Importantly, the data reviewed suggest that the effects exerted by an AED could vary depending on both patient characteristics and drug-related variables. However, there are considerable difficulties in evaluating the available evidence. Many studies have failed to investigate the influence of patient and treatment variables on cognitive functioning. Other difficulties include variation across studies in relation to design, treatment group and assessment tools, poor reporting of methodology and poor specification of the cognitive abilities assessed. Focused and rigorous experimental designs including a range of cognitive measures assessing more precisely defined abilities are needed to fill the gaps in our knowledge and follow up reported patterns in the literature. Longitudinal studies are needed to improve our understanding of the influence of factors such as age, tolerance and the stability of cognitive effects. Future trials comparing the effects of commonly prescribed agents across patient subgroups will offer critical insight into the role of patient characteristics in determining the cognitive impact of particular AEDs.

Non-vision adverse events with vigabatrin therapy

Vigabatrin is an effective antiepileptic drug (AED) for the treatment of refractory complex partial seizures (rCPS) and infantile spasms (IS). In clinical trials, vigabatrin was generally well-tolerated with an adverse event profile similar to that of other AEDs. The most common treatment-related adverse events were central nervous system effects, including drowsiness, dizziness, headache, and fatigue, with adjunctive vigabatrin in adults with rCPS, and sedation, somnolence, and irritability with vigabatrin monotherapy in infants with IS. Vigabatrin had little effect on cognitive function, mood, or behavior in a battery of neuropsychologic tests for rCPS. In placebo-controlled clinical trials, the incidence of depression and psychosis, but not other psychiatric adverse events, was greater with vigabatrin than placebo. Intramyelinic edema (IME) was initially identified in rats and dogs and led to a temporary suspension of clinical trials in the United States. IME was subsequently correlated with delays in evoked potential (EP) and increased T(2) -weighted signals on magnetic resonance imaging (MRI). Clinical trials of vigabatrin were allowed to resume after IME was not detected by neuropathologic assessments of autopsy and neurosurgical specimens or by serial EP or MRI assessments in older children and adults receiving vigabatrin. Subsequently, MRI abnormalities characterized by increased T(2) intensity and restricted diffusion were identified in infants treated with vigabatrin for IS. These abnormalities generally resolved with discontinuation of vigabatrin and, in some cases, during continued therapy. The benefit of improved seizure control must be balanced against the potential risks associated with vigabatrin, including abnormal MRI changes and other vigabatrin-related safety issues.

Vigabatrin versus carbamazepine monotherapy for epilepsy

BACKGROUND

The efficacy and safety of vigabatrin (VGB) as an add-on therapy for refractory epilepsy has been well established. However, this needs to be weighed against the risk of the development of visual field defects. Whether VGB monotherapy is an effective and safe treatment compared with the standard antiepileptic drug carbamazepine (CBZ) monotherapy for epilepsy has not been systematically reviewed.

OBJECTIVES

To investigate the efficacy and safety of VGB versus CBZ monotherapy for epilepsy.

SEARCH METHODS

We searched the Cochrane Epilepsy Group Specialized Register (10 October 2011), the Cochrane Central Register of Controlled Trials (CENTRAL Issue 4 of 4, The Cochrane Library 2011) and MEDLINE (1948 to week 4, September 2011), EMBASE (1974 to January 2011) and the Chinese Biomedical Database (CBM) (1979 to January 2011). We searched trials registers and contacted the manufacturer of VGB and authors of included studies for additional information. There were no language restrictions.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing VGB with CBZ monotherapy for epilepsy.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality and extracted data. The primary outcome was time to treatment withdrawal. The secondary outcomes were time to achieve six- and 12-month remission after randomisation, time to first seizure after randomisation and adverse events. Results were presented as hazard ratio (HR) with 95% confidence intervals (CI) (time to event data) or risk ratio (RR) with 95%CI (adverse events).

MAIN RESULTS

Five studies involving a total of 734 participants were eligible for inclusion. We assessed only one study as having good quality while the other four were of poor quality. However, it was difficult to perform a meta-analysis by extracting aggregate data to synthesise the results as originally planned, mainly because not all the studies reported the same outcomes as those chosen for this review. There was no significant difference favouring either VGB or CBZ in terms of time to treatment withdrawal and time to achieve six-month remission after dose stabilisation from randomisation, but results did show a disadvantage for VGB on time to first seizure after randomisation. Compared with CBZ, taking VGB was associated with more occurrences of weight gain and less occurrences of skin rash and drowsiness. There were no differences in visual field defects and visual disturbances.

AUTHORS' CONCLUSIONS

There is currently insufficient data to address the risk-benefit balance of using VGB versus CBZ monotherapy for epilepsy. Considering the high prevalence of visual field defects, reported in an existing systematic review of observational studies (Maguire 2010), the prescribing of VGB monotherapy for epilepsy should be used with caution and not considered as a first-line choice. If necessary, a frequent assessment of visual field is needed. Future research should focus on investigating the reasons for visual field defects and exploring the potential prevention strategies. Moreover, future monotherapy studies of epilepsy should report results according to the recommendation of International League Against Epilepsy (ILAE) Commission, and methodological quality should be improved.

Selection of antiepileptic drugs in adults

Epilepsy affects approximately 50 million people worldwide, with an annual incidence of 50 to 70 cases per 100,000 population. The condition can strike at any time of life, with an immediate impact on everyday activities and routine. Key to optimal management is swift referral to an epilepsy specialist, appropriate investigation, and timely institution of antiepileptic drug therapy. In the past 20 years, the explosion of 13 new agents into the marketplace has greatly increased the potential for therapeutic intervention. This article explores the rationale for treatment selection in adults with epilepsy.

Visual impairment at large eccentricity in participants treated by vigabatrin: visual, attentional or recognition deficit?

A relationship between peripheral visual field loss and vigabatrin (VGB) has been reported in several studies but with inconsistent results. We investigated the level of visual processing at which the impairment occurs: attentional or cognitive (recognition) deficit. A simple reaction time task was used as a baseline condition. A spatial attention task measured the benefit and cost for the detection of a target appearing at a cued or at an uncued location. A rapid categorization task assessed object recognition. Performance was tested at eccentricities varying from 30 degrees to 60 degrees on a panoramic screen covering 180 degrees. Participants were patients with epilepsy treated with VGB, patients treated with other drugs and healthy controls. In the VGB group 9 patients exhibited a mild visual field constriction. We observed a general slowing down of response times in participants treated by VGB, especially at 60 degrees eccentricity but their performance remained above chance at large eccentricity in the most complex categorization task. The slowing down of visual processing at large eccentricity for flashed stimuli suggests that VGB treated patients might be impaired at detecting moving objects in the periphery and this may have consequences in behavioural tasks like driving.

Antiepileptic drug-induced cognitive adverse effects: potential mechanisms and contributing factors

Cognitive dysfunction is frequently observed in patients with epilepsy and represents an important challenge in the management of patients with this disorder. In this respect, the relative contribution of antiepileptic drugs (AEDs) is of relevance. The fact that a considerable number of patients require AED therapy for many years, or perhaps even a lifetime, emphasizes the need to focus on the long-term adverse effects of these drugs on cognition. The most prevalent of the CNS adverse effects observed during AED therapy are sedation, somnolence, distractibility, insomnia and dizziness. Sedation, in particular, is associated with most of the commonly used AED therapies. Nevertheless, cognitive function in individuals with epilepsy may also be influenced by several factors, of which AEDs constitute only one of many putative causes. In general terms, most studies agree that some differences exist among the older AEDs with regard to the effects on cognition, and some newer generation molecules may have a better cognitive profile than older AEDs. The mechanisms of action are an obvious determinant; however, there is still a lack of evidence for differentiation between available drugs with regard to cognitive effects. Some authors have suggested that there may be different cognitive effects associated with individual drugs; however, the question as to whether there are more specific deficits related to the action of individual drugs remains unsolved. There seems to be agreement that polytherapy and high-dose treatment can produce cognitive adverse effects and when high dosages or adjunctive polytherapy is needed, the balance between benefits and disadvantages may be negatively biased against drug treatment. Thus, drug treatment requires careful balancing in the attempt to reach maximal seizure control while avoiding neurotoxic adverse effects. Finally, the mood status of the patient and clinical relevance of the information obtained by neuropsychological testing represent important variables that need to be taken into account when discussing cognitive adverse effects of AEDs.

Drug treatment of epilepsy in the century of the ILAE: the second 50 years, 1959-2009

The drug therapy of epilepsy evolved enormously in this 50 year period. Advances in therapeutics included the incorporation of pharmacokinetics into clinical practice, enormous advances in neurochemistry, a trend to antiepileptic drug monotherapy, better drug assessment, better understanding of therapeutic outcomes, and the recognition of the large epilepsy treatment gap in many countries. An unprecedented range of new drugs was introduced in this period. Before 1989, these included carbamazepine, valproate, ethosuximide, and the benzodiazepines. Since 1989, 13 more new drugs have been licensed and marketed and there are others in the pipeline. The International League Against Epilepsy and its leading figures have played an important role in these developments. In this period, too, there has been a rapid expansion in research and development within the pharmaceutical industry and a rise in the value of the antiepileptic drug market. In parallel, governmental regulation of pharmaceuticals has greatly increased. To what extent the overall prognosis of epilepsy has improved as a result of these activities is an interesting and perplexing question.

Long-term efficacy and cognitive effects of vigabatrin

Vigabatrin is effective as add-on therapy in about 50% of patients with partial epilepsy refractory to drugs. Furthermore, at least half of the original responders maintain the response over several years. As monotherapy, both vigabatrin and carbamazepine seem to be successful in a similar proportion of newly diagnosed patients with epilepsy, but carbamazepine monotherapy fails more often due to side-effects and vigabatrin more often due to lack of efficacy. However, vigabatrin monotherapy seems to be extremely well tolerated, particularly in relation to cognitive function.

Treatment of refractory complex partial seizures: role of vigabatrin

Vigabatrin (VGB) is an antiepileptic drug that was designed to inhibit GABA-transaminase, and increase levels of gamma-amino-butyric acid (GABA), a major inhibitory neurotransmitter in the brain. VGB has demonstrated efficacy as an adjunctive antiepileptic drug for refractory complex partial seizures (CPS) and for infantile spasms (IS). This review focuses on its use for complex partial seizures. Although VGB is well tolerated, there have been significant safety concerns about intramyelinic edema and visual field defects. VGB is associated with a risk of developing bilateral concentric visual field defects. Therefore, the use of VGB for complex partial seizures should be limited to those patients with seizures refractory to other treatments. Patients must have baseline and follow-up monitoring of visual fields, early assessment of its efficacy, and ongoing evaluation of the benefits and risks of VGB therapy.

Patient-reported cognitive side effects of antiepileptic drugs: predictors and comparison of all commonly used antiepileptic drugs

Subjective cognitive side effects (CSEs) are common in patients taking antiepileptic drugs (AEDs). The objective of this study was to predict which patients are at risk for CSEs, and compare the CSE profiles of all commonly used AEDs. In this nonrandomized retrospective study, medical records of 1694 adult outpatients with epilepsy seen at our center over a 5-year period who had taken one or more AEDs were examined. Non-AED predictors of CSEs were investigated, and rates of AED-related CSEs were compared in 1189 patients (546 on monotherapy) newly started on an AED at our center. The average rate of AED-related intolerable CSEs (leading to dosage change or discontinuation) was 12.8%. On multivariate analysis, no significant non-AED predictors of CSEs were found. Significantly more intolerable CSEs were attributed to topiramate (21.5% of 130 patients) than to most other AEDs, including carbamazepine (9.9%), gabapentin (7.3%), levetiracetam (10.4%), lamotrigine (8.9%), oxcarbazepine (11.6%), and valproate (8.3%). CSE rates with zonisamide (14.9%) were significantly higher than those for gabapentin and lamotrigine. After exclusion of CSEs during the first 8 weeks of therapy, rates of CSEs were lower, but relative differences remained unchanged. In monotherapy, significantly more intolerable CSEs occurred with topiramate (11.1% of 18 patients) than with carbamazepine or valproate, and both phenytoin and zonisamide were associated with more CSEs than valproate. From this study, it can be concluded that intolerable patient-reported CSEs are most common with topiramate, followed by zonisamide, phenytoin, and oxcarbazepine. They are least likely to be reported with gabapentin, valproate, lamotrigine, carbamazepine, and levetiracetam.

CNS adverse events associated with antiepileptic drugs

A variety of newer antiepileptic drugs (AEDs) are now available for treating patients with epilepsy in addition to the 'conventional' drugs that have been available throughout a large part of the last century. Since these drugs act to suppress the pathological neuronal hyperexcitability that constitutes the final substrate in many seizure disorders, it is not surprising that they are prone to causing adverse reactions that affect the CNS.Information on adverse effects of the older AEDs has been mainly observational. Equally, whilst the newer drugs have been more systematically studied, their long-term adverse effects are not clearly known. This is illustrated by the relatively late emergence of the knowledge of visual field constriction in the case of vigabatrin, which only became known after several hundred thousand patient-years of use. However, older drugs continue to be studied and there has been more recent comment on the possible effect of valproate (valproic acid) on cognition following exposure to this drug in utero.With most AEDs, there are mainly dose-related adverse effects that could be considered generic, such as sedation, drowsiness, incoordination, nausea and fatigue. Careful dose titration with small initial doses can reduce the likelihood of these adverse effects occurring. Adverse effects such as paraesthesiae are more commonly reported with drugs such as topiramate and zonisamide that have carbonic anhydrase activity. Weight loss and anorexia can also be peculiar to these drugs. Neuropsychiatric adverse effects are reported with a variety of AEDs and may not be dose related. Some drugs, such as carbamazepine when used to treat primary generalized epilepsy, can exacerbate certain seizure types. Rare adverse effects such as hyperammonaemia with valproate are drug specific. There are relatively very few head-to-head comparisons of AEDs and limited information is available in this regard.In this review, we discuss the available literature and provide a comprehensive summary of adverse drug reactions of AEDs affecting the CNS.

Cognitive effects of antiepileptic drugs

Antiepileptic drugs (AEDs) can adversely affect cognitive function by suppressing neuronal excitability or enhancing inhibitory neurotransmission. The main cognitive effects of AEDs are impaired attention, vigilance, and psychomotor speed, but secondary effects can manifest on other cognitive functions. Although the long-term use of AEDs can obviously elicit cognitive dysfunction in epilepsy patients, their cognitive effects over short periods of up to a year are inconclusive due to methodological problems. In general, the effects on cognition are worse for older AEDs (e.g., phenobarbital) than for placebo, nondrug condition, and newer AEDs. However, topiramate is the newer AED that has the greatest risk cognitive impairment irrespective of the comparator group. Since the cognitive impact of AEDs can be serious, clinicians should be alert to adverse events by evaluating cognitive function using screening tests. Adverse cognitive events of AEDs can be avoided by slow titration to the lowest effective dosage and by avoiding polytherapy.

Vigabatrin and Epilepsy: Lessons Learned

PURPOSE

The risk factors for visual field loss attributable to vigabatrin (VAVFL) are equivocal. This multinational, prospective, observational study aimed to clarify the principal/major factors for VAVFL.

METHODS

Interim analysis of three groups with refractory partial epilepsy, stratified by age (8-12 years; >12 years) and exposure to vigabatrin (VGB). Group I comprised participants treated with VGB for >or=6 months, Group II participants previously treated with VGB for >or=6 months who had discontinued the drug for >or=6 months and Group III those never treated with VGB. Perimetry was undertaken at least every six months, for up to 36 months; results were evaluated masked to drug exposure.

RESULTS

Based upon 563 participants in the locked data set, 432 yielded one or more Conclusive visual field examinations. For Group I, the frequency of VAVFL at the last Conclusive examination was 10/32 (31.2%) for those aged 8-12 years and 52/125 (41.6%) for those aged >12 years. For Group II, the proportions were 4/39 (10.3%) and 31/129 (24.0%). No cases resembling VAVFL manifested in Group III. VAVFL was associated with duration of VGB therapy (Odds ratio [OR] 14.2; 95% CI 5.0 to 40.5); mean dose of VGB (OR 8.5; 95% CI 2.2 to 33.2); and male gender (OR 2.1; 95% CI 1.2 to 3.7). VAVFL was more common with static than kinetic perimetry (OR 2.3, 95% CI 1.3 to 4.2).

CONCLUSIONS

The therapeutic benefit of VGB is counteracted by the progressive accrual of the risk of VAVFL with continued exposure and with increase in mean dose.

A cost-effectiveness decision model for antiepileptic drug treatment in newly diagnosed epilepsy patients

OBJECTIVE

To establish cost-effectiveness of antiepileptic drug (AED) treatment strategies of newly diagnosed patients with epilepsy.

METHODS

A decision analysis was carried out comparing effectiveness and treatment cost of six treatment strategies comprising carbamazepine (CBZ), lamotrigine (LTG), and valproate (VPA) as first-line and second-line drugs. Three outcome groups were defined: complete success, partial success, and failure. Data on seizure control and failure due to adverse effects were derived from the literature. Data on resource use and costs were collected for each outcome group by means of a patient survey.

RESULTS

Cost data were obtained from 71 patients. Cost increased from complete success to failure outcome groups. The probability of obtaining complete success varied from 64% (VPA-CBZ strategy) to 74% (LTG-VPA strategy). The strategy LTG-VPA was more effective than the least expensive strategy CBZ-VPA, but at higher costs per additional effectively treated patient. Probabilistic sensitivity analysis confirmed these findings to be robust. Subsequent analysis showed that changing inclusion criteria used in the selection of the studies from the literature had a major effect on cost-effectiveness ratios of the various strategies. The probability that LTG first-line therapy is the most cost-effective option remains small, even defining a high cost-effectiveness threshold. Nevertheless, LTG second-line strategies can be cost-effective depending on the willingness to pay for patient improvement.

CONCLUSIONS

Only a few studies satisfied our inclusion criteria for employment in our decision model. Our model supports the use of conventional AEDs as first-line options for patients with newly diagnosed epilepsy. LTG second-line therapy is likely to be the most cost-effective option in case society is willing to pay more than Euro 6000 for an additional successfully treated patient. This study also illustrates that, with the data presently available, the outcome of decision analysis for AED treatment choice depends on the inclusion criteria used to select trials. Prospective real-life studies are needed in which first- and second-line treatment strategies are compared with respect to both effectiveness and costs.

The SANAD study of effectiveness of carbamazepine, gabapentin, lamotrigine, oxcarbazepine, or topiramate for treatment of partial epilepsy: an unblinded randomised controlled trial

BACKGROUND

Carbamazepine is widely accepted as a drug of first choice for patients with partial onset seizures. Several newer drugs possess efficacy against these seizure types but previous randomised controlled trials have failed to inform a choice between these drugs. We aimed to assess efficacy with regards to longer-term outcomes, quality of life, and health economic outcomes.

METHODS

SANAD was an unblinded randomised controlled trial in hospital-based outpatient clinics in the UK. Arm A recruited 1721 patients for whom carbamazepine was deemed to be standard treatment, and they were randomly assigned to receive carbamazepine, gabapentin, lamotrigine, oxcarbazepine, or topiramate. Primary outcomes were time to treatment failure, and time to 12-months remission, and assessment was by both intention to treat and per protocol. This study is registered as an International Standard Randomised Controlled Trial, number ISRCTN38354748.

FINDINGS

For time to treatment failure, lamotrigine was significantly better than carbamazepine (hazard ratio [HR] 0.78 [95% CI 0.63-0.97]), gabapentin (0.65 [0.52-0.80]), and topiramate (0.64 [0.52-0.79]), and had a non-significant advantage compared with oxcarbazepine (1.15 [0.86-1.54]). For time to 12-month remission carbamazepine was significantly better than gabapentin (0.75 [0.63-0.90]), and estimates suggest a non-significant advantage for carbamazepine against lamotrigine (0.91 [0.77-1.09]), topiramate (0.86 [0.72-1.03]), and oxcarbazepine (0.92 [0.73-1.18]). In a per-protocol analysis, at 2 and 4 years the difference (95% CI) in the proportion achieving a 12-month remission (lamotrigine-carbamazepine) is 0 (-8 to 7) and 5 (-3 to 12), suggesting non-inferiority of lamotrigine compared with carbamazepine.

INTERPRETATION

Lamotrigine is clinically better than carbamazepine, the standard drug treatment, for time to treatment failure outcomes and is therefore a cost-effective alternative for patients diagnosed with partial onset seizures.

Effect of antiepileptic drugs on spontaneous seizures in epileptic rats

The present study investigated whether spontaneously seizing animals are a valid model for evaluating antiepileptic compounds in the treatment of human epilepsy. We examined whether clinically effective antiepileptic drugs (AEDs), including carbamazepine (CBZ), valproic acid (VPA), ethosuximide (ESM), lamotrigine (LTG), or vigabatrin (VGB) suppress spontaneous seizures in a rat model of human temporal lobe epilepsy, in which epilepsy is triggered by status epilepticus induced by electrical stimulation of the amygdala. Eight adult male rats with newly diagnosed epilepsy and focal onset seizures were included in the study. Baseline seizure frequency was determined by continuous video-electroencephalography (EEG) monitoring during a 7 days baseline period. This was followed by a 2-3 days titration period, a 5-7 days treatment period, and a 2-3 days wash-out period. During the 5-7 days treatment period, animals were treated successively with CBZ (120 mg/kg/day), VPA (600 mg/kg/day), ESM (400 mg/kg/day), LTG (20 mg/kg/day), and VGB (250 mg/kg/day). VPA, LTG, and VGB were the most efficient of the compounds investigated, decreasing the mean seizure frequency by 83, 84, and 60%, respectively. In the VPA group, the percentage of rats with a greater than 50% decrease in seizure frequency was 100%, in the LTG group 88%, in the VGB group 83%, in the CBZ group 29%, and in the ESM group 38%. During the 7 day treatment period, 20% of the VPA-treated animals and 14% of the CBZ-treated animals became seizure-free. These findings indicate that rats with focal onset spontaneous seizures respond to the same AEDs as patients with focal onset seizures. Like in humans, the response to AEDs can vary substantially between animals. These observations support the idea that spontaneously seizing animals are a useful tool for testing novel compounds for the treatment of human epilepsy.

ILAE treatment guidelines: evidence-based analysis of antiepileptic drug efficacy and effectiveness as initial monotherapy for epileptic seizures and syndromes

PURPOSE

To assess which antiepileptic medications (AEDs) have the best evidence for long-term efficacy or effectiveness as initial monotherapy for patients with newly diagnosed or untreated epilepsy.

METHODS

A 10-member subcommission of the Commission on Therapeutic Strategies of The International League Against Epilepsy (ILAE), including adult and pediatric epileptologists, clinical pharmacologists, clinical trialists, and a statistician evaluated available evidence found through a structured literature review including MEDLINE, Current Contents and the Cochrane Library for all applicable articles from 1940 until July 2005. Articles dealing with different seizure types (for different age groups) and two epilepsy syndromes were assessed for quality of evidence (four classes) based on predefined criteria. Criteria for class I classification were a double-blind randomized controlled trial (RCT) design, >or=48-week treatment duration without forced exit criteria, information on >or=24-week seizure freedom data (efficacy) or >or=48-week retention data (effectiveness), demonstration of superiority or 80% power to detect a <or=20% relative difference in efficacy/effectiveness versus an adequate comparator, and appropriate statistical analysis. Class II studies met all class I criteria except for having either treatment duration of 24 to 47 weeks or, for noninferiority analysis, a power to only exclude a 21-30% relative difference. Class III studies included other randomized double-blind and open-label trials, and class IV included other forms of evidence (e.g., expert opinion, case reports). Quality of clinical trial evidence was used to determine the strength of the level of recommendation.

RESULTS

A total of 50 RCTs and seven meta-analyses contributed to the analysis. Only four RCTs had class I evidence, whereas two had class II evidence; the remainder were evaluated as class III evidence. Three seizure types had AEDs with level A or level B efficacy and effectiveness evidence as initial monotherapy: adults with partial-onset seizures (level A, carbamazepine and phenytoin; level B, valproic acid), children with partial-onset seizures (level A, oxcarbazepine; level B, None), and elderly adults with partial-onset seizures (level A, gabapentin and lamotrigine; level B, None). One adult seizure type [adults with generalized-onset tonic-clonic (GTC) seizures], two pediatric seizure types (GTC seizures and absence seizures), and two epilepsy syndromes (benign epilepsy with centrotemporal spikes and juvenile myoclonic epilepsy) had no AEDs with level A or level B efficacy and effectiveness evidence as initial monotherapy.

CONCLUSIONS

This evidence-based guideline focused on AED efficacy or effectiveness as initial monotherapy for patients with newly diagnosed or untreated epilepsy. The absence of rigorous comprehensive adverse effects data makes it impossible to develop an evidence-based guideline aimed at identifying the overall optimal recommended initial-monotherapy AED. There is an especially alarming lack of well-designed, properly conducted RCTs for patients with generalized seizures/epilepsies and for children in general. The majority of relevant existing RCTs have significant methodologic problems that limit their applicability to this guideline's clinically relevant main question. Multicenter, multinational efforts are needed to design, conduct and analyze future clinically relevant RCTs that can answer the many outstanding questions identified in this guideline. The ultimate choice of an AED for any individual patient with newly diagnosed or untreated epilepsy should include consideration of the strength of the efficacy and effectiveness evidence for each AED along with other variables such as the AED safety and tolerability profile, pharmacokinetic properties, formulations, and expense. When selecting a patient's AED, physicians and patients should consider all relevant variables and not just efficacy and effectiveness.

Comparison of the Cognitive Effects of Tiagabine and Carbamazepine as Monotherapy in Newly Diagnosed Adult Patients with Partial Epilepsy: Pooled Analysis of Two Long-term, Randomized, Follow-up Studies

PURPOSE

Patients with epilepsy are at greater risk for cognitive impairment than are age- and education-matched controls. Cognitive decline is a significant adverse event associated with many first-generation anticonvulsant drugs (AEDs); however, the past decade has seen the introduction of several new AEDs with more-favorable cognitive profiles. Tiagabine (TGB) is indicated as adjunctive therapy for the treatment of partial seizures. The cognitive effects of TGB and carbamazepine (CBZ) monotherapy were evaluated in adult epilepsy patients with partial seizures.

METHODS

This analysis pooled data from two randomized studies with similar populations, dosing, and cognitive assessments. TGB was titrated to 20-30 mg/day and CBZ to 400-800 mg/day over a 6-week period. A control or no-drug group of untreated patients with a single epileptic seizure was included for comparison. Cognitive function was assessed at baseline and 52 weeks.

RESULTS

Of the 105 epilepsy patients enrolled, 79 completed the 52 weeks of monotherapy (TGB, 74%; CBZ, 77%). Altogether, 19 untreated patients composed the no-drug group. During the 52-week follow-up, only one statistically significant difference was found between the treatment groups and the no-drug group [verbal fluency task: F(2, 92) = 3.16; p = 0.047]. On further analysis, it was determined that this statistical difference was solely based on the patients receiving CBZ performing worse than the control group (p = 0.048). Statistically significant improvements (p < 0.05) were found on six (26%) of 23 variables with TGB and CBZ, as well as the no-drug group, although the variables differed between the groups. Significant worsening in the test scores was not seen in any of the study groups.

CONCLUSIONS

The results of this 52-week, follow-up study show that successful TGB monotherapy with 20-30 mg/day has a cognitive profile similar to that of successful long-term CBZ monotherapy with 400-800 mg/day in newly diagnosed patients with epilepsy and to that of untreated patients with a single seizure. We observed no significant decline in cognitive scores associated with TGB monotherapy.

Long-term effects of tiagabine monotherapy on cognition and mood in adult patients with chronic partial epilepsy

The long-term effects of tiagabine monotherapy on cognition and mood were evaluated in adult patients with chronic partial epilepsy in a 48-week, open-label extension period that followed an 8-week, double-blind, titration study. Cognitive function was evaluated using neuropsychological evaluations that measured learning and memory, general intellectual ability, attention and mental speed, and reaction speed. Mood was assessed using a Finnish modification of the Profile of Mood States. Of the 34 patients who entered the open-label extension period, 18 successfully continued long-term monotherapy and underwent neuropsychological evaluation at 48 weeks of tiagabine monotherapy. The mean daily dose of tiagabine monotherapy at the end of open-label treatment was 19.7 mg/day (range, 5-35 mg/day). Tiagabine monotherapy did not adversely affect cognitive function. No significant changes in mood were observed. The median number of seizures was 2 (range, 0-71), and 8 patients (44%) were seizure-free during the 48 weeks of open-label tiagabine treatment. The results of this small open-label extension study indicate that patients with chronic partial epilepsy who were successfully converted to long-term tiagabine monotherapy demonstrated no adverse effects on cognitive function or mood.

Cognitive side effects of antiepileptic drugs

Antiepileptic drugs produce global changes in the excitation levels in the central nervous system and often lead to cognitive and behavioral deficits. These deficits vary and must be considered independently in every patient. A number of consistent risk factors have been established. Polypharmacy and high blood levels of an antiepileptic drug (AED) increase the risk of cognitive side effects. Different effects have been demonstrated for some AEDs, but comparative data are incomplete across all of them. Other factors such as patient age and type/frequency of seizures may also be important contributors to the patient's cognitive state. AEDs can have positive or negative effects on mood, providing another consideration in choosing the course of treatment.

Translating monotherapy trials into clinical practice: a look into the abyss

To be approved for monotherapy by regulatory authorities, new antiepileptic drugs (AEDs) must first be tested in well-controlled studies in refractory patients (conversion to monotherapy trials) or in patients with newly diagnosed epilepsy. However, the applicability of the information obtained in these trials to day-to-day clinical practice is limited. Clinical trials in newly diagnosed patients, particularly those allowing dose flexibility, offer more useful information, but a close scrutiny of methodological details is required to avoid misinterpretation of the findings. In many instances, the neurologist has a drug with a label, but lacks critical information on optimal titration rates, optimal target and maintenance dosages, response rates in populations with different epilepsy syndromes, different age ranges and comorbidities, and long-term safety data. Such information becomes available only through general clinical experience, well-designed phase IV studies, and postmarketing surveillance.

Tiagabine synergistically interacts with gabapentin in the electroconvulsive threshold test in mice

Polytherapy, based on the rational combining of antiepileptic drugs (AEDs), is required for patients with drug-resistant epilepsy. In such cases, the combinations of AEDs usually offer a significant enhancement of their protective effects against seizures. There has appeared a hypothesis that combining two AEDs, influencing the same neurotransmitter system, results in the potentialization of their anticonvulsant effects. For corroborating this hypothesis, a pharmacological character of interaction between tiagabine (TGB) and gabapentin (GBP)-two novel AEDs affecting the GABA-ergic system, in the maximal electroshock seizure threshold (MEST)-test in mice was evaluated. TGB at the dose of 4 mg/kg and GBP at 75 mg/kg significantly raised the electroconvulsive threshold. Further, using the isobolographic calculations, TGB was coadministered with GBP at three fixed-ratios (1 : 3, 1 : 1, and 3 : 1) of their respective protective drug doses. All examined combinations of TGB with GBP exerted supra-additive (synergistic) interactions against MEST-induced seizures in mice. The interaction index, describing the strength and magnitude of interaction, ranged between 0.25 and 0.50 indicating supra-additivity. Adverse (neurotoxic) effects were evaluated in the chimney (motor performance) and the step-through, light-dark passive avoidance (long-term memory) tests in mice. The examined combinations of TGB with GBP did not affect the motor coordination, except for the fixed-ratio of 1 : 1, at which significant impairment of motor performance was observed. Moreover, all combinations selectively impaired the acquisition of the task in the passive avoidance test, having no impact on consolidation and retrieval in the long-term memory test. The pain threshold test revealed that the observed disturbances in the passive avoidance testing resulted presumably from the antinociceptive activity of these AEDs in combinations. After lengthening the exposing time to the direct current stimulus in the passive avoidance test from 2 to 6 s, the acquisition of the task, in animals receiving the combinations of TGB and GBP was not impaired. Neither the plasma, nor brain concentrations of GBP were affected by TGB application, so pharmacokinetic events that might negatively influence the observed effects are not probable. Results of this study clearly indicate that the activation of the same neurotransmitter system (GABA-ergic) leads to a synergistic interaction. The pain threshold test is a very good paradigm for screening the antinociceptive properties of AEDs, which may disturb the long-term memory testing in animals. Combinations of TGB with GBP (very promising from a preclinical point of view) should be clinically verified for elaborating the most effective treatment regimen in patients with intractable seizures.

Epilepsy: from consensus to daily practice

Most clinicians would accept that epilepsy treatment should begin with monotherapy, and in the majority of cases this is the preferred drug maintenance option. The clinical choice of one antiepileptic drug (AED) over another should be based on firm evidence of efficacy and tolerability as evaluated in comparative monotherapy studies and pharmacokinetics. This paper presents the findings of evidence-based reviews of AED monotherapy in patients newly diagnosed with epilepsy. The main study was conducted in the United Kingdom and investigated the clinical evidence supporting AEDs used as first-line monotherapy. In this paper the general treatment recommendations will focus on valproate, one of the mainstay drugs used in the fight against epilepsy. Finally, with these recommendations in mind, the principles behind AED drug selection in clinical practice will be discussed. Factors for consideration that impact on AED decision-making include: seizure and syndrome diagnosis, AED tolerability profiles, patient characteristics and pharmacokinetic/pharmacodynamic AED interactions.

Levetiracetam monotherapy for newly diagnosed epilepsy patients

We retrospectively reviewed the charts of all of our patients with a history of partial seizures, with and without secondarily generalisation, who received levetiracetam (LEV; Keppra) for treatment of their seizures during the years 2000-2002. Forty-five patients were identified, 13 of whom began LEV as first line therapy. Eleven patients continued on LEV for at least 6 months; six of whom became seizure free and five had >50% reduction in their seizures. The remaining two patients discontinued LEV because of adverse effects. LEV monotherapy can be effective and well tolerated in adults with new onset seizures. A prospective, large, double-blind monotherapy study for newly diagnosed patients is needed to confirm this finding.

Carbamazepine-provoked hepatotoxicity and possible aetiopathological role of glutathione in the events. Retrospective review of old data and call for new investigation

The antiepileptic drug (AED) carbamazepine is widely used in the treatment of different kinds of seizures as well as affective and behavioural disorders. This paper presents an epidemiological study of carbamazepine-induced hepatic injuries and death, and describes the possible mechanisms of its toxicity. A retrospective analysis of clinical data revealed that the likelihood of hepatic death was comparatively higher in children, particularly when they were receiving medication with multiple AEDs, whereas reversible hepatic injuries were more likely to be seen in elderly patients. As suggested in this paper, the development of carbamazepine hepatotoxicity is rare, and unpredictable with the present state of knowledge, but it is somehow related to disturbance of glutathione metabolism, although data in this regard are imperfect. There appear to be two types of carbamazepine-initiated idiosyncratic liver injury, hypersensitivity and toxin-induced. It is feasible that both are due to the accumulation of toxic metabolite(s), and arene oxides may probably be considered as damaging derivatives of carbamazepine metabolism. Despite the lack of clear-cut underlying clinical and experimental findings in those patients in whom an inherited weakness of drug eliminating capacity is present, those conditions that may deteriorate glutathione balance, may increase the possibility of the emergence of toxic events during carbamazepine therapy. Finally, some recommendations for carbamazepine therapy are presented.

Topiramate, carbamazepine and valproate monotherapy: double-blind comparison in newly diagnosed epilepsy

OBJECTIVES

To compare topiramate (TPM) with investigator's choice of carbamazepine (CBZ) or valproate (VPA) for initial treatment in patients with newly diagnosed epilepsy.

MATERIAL AND METHODS

In patients with epilepsy diagnosed within previous 3 months, investigators selected CBZ (600 mg/day) or VPA (1250 mg/day) as preferred therapy based on the patient's clinical presentation. Based on investigators' treatment choice, patients (n=613) were assigned to the CBZ or VPA treatment branch. Within each branch, patients were randomized to double-blind treatment with the traditional antiepileptic drugs (CBZ or VPA), TPM 100 mg/day, or TPM 200 mg/day. Patients continued double-blind treatment until exiting the study or until 6 months after last patient randomized.

RESULTS

No statistically significant differences between fixed doses of TPM and CBZ or VPA were observed in efficacy measures: time to exit, time to first seizure, and the proportion of patients seizure-free during the last 6 months of treatment. TPM 100 mg/day was associated with the fewest discontinuations due to adverse events.

CONCLUSION

In patients with newly diagnosed epilepsy, an initial target dose of TPM 100 mg/day is at least as effective as therapeutic doses of CBZ and VPA.