A double-blind, placebo-controlled study of topiramate in adult patients with refractory partial epilepsy

Efficacy and safety of add-on antiseizure medications for focal epilepsy: A network meta-analysis

OBJECTIVE

Several antiseizure medications (ASMs) have been approved for the treatment of focal epilepsy. However, there is a paucity of evidence on direct comparison of ASMs. We evaluated the comparative efficacy and safety of all approved add-on ASMs for the treatment of focal epilepsy using network meta-analysis.

METHODS

Data through extensive literature search was retrieved from PubMed, Embase, Cochrane, and ClinicalTrial.gov databases using predefined search terms from inception through March 2023. PRISMA reporting guidelines (CRD42023403450) were followed in this study. Efficacy outcomes assessed were ≥50%, ≥75%, and 100% responder rates. Patient retention rate and safety outcomes such as overall treatment-emergent adverse events (TEAEs) and individual TEAEs were assessed. "Gemtc" 4.0.4 package was used to perform Bayesian analysis. Outcomes are reported as relative risks (RRs) and 95% confidence interval (CI).

RESULTS

Literature search retrieved 5807 studies of which, 75 studies were included in the analysis. All ASMs showed significantly higher ≥50% responder rate compared with placebo. Except the ≥75% seizure frequency reduction for zonisamide (2.23; 95% CI: 1.00-5.70) and 100% for rufinamide (2.03; 95% CI: 0.54-11.00), all other interventions showed significantly higher ≥75% and 100% responder rates compared with placebo. Among treatments, significantly higher 100% responder rate was observed with cenobamate compared to eslicarbazepine (10.71; 95% CI: 1.56-323.9) and zonisamide (10.63; 95% CI: 1.37-261.2). All ASMs showed a lower patient retention rate compared to placebo, with the least significant value observed for oxcarbazepine (0.77; 95% CI: 0.7-0.84). Levetiracetam showed a lower risk of incidence (1.0; 95%CI: 0.94-1.1; SUCRA: 0.885067) for overall TEAE compared with other medications.

SIGNIFICANCE

All approved ASMs were effective as add-on treatment for focal epilepsy. Of the ASMs included, cenobamate had the greatest likelihood of allowing patients to attain seizure freedom.

PLAIN LANGUAGE SUMMARY

This article compares the efficacy and safety of antiseizure medications (ASMs) currently available to neurologists in the treatment of epileptic patients. Several newer generation ASMs that have been developed may be as effective or better than the older medications. We included 75 studies in the analysis. In comparison, all drugs improved ≥50%, ≥75% and 100% responder rates compared to control, except for Zonisamide and Rufinamide in the ≥75% and 100% responder rate categories. Retention of patients undergoing treatment was lower in drugs than placebo. All drugs were tolerated, the levetiracetam showed the best tolerability. Cenobamate more likely help completely to reduce seizures.

Efficacy and Safety of Five Broad-Spectrum Antiseizure Medications for Adjunctive Treatment of Refractory Epilepsy: A Systematic Review and Network Meta-analysis

BACKGROUND

Overall, up to one-third of epilepsy patients have drug-resistant epilepsy. However, there was previously no meta-analysis to support the guidelines for broad-spectrum antiseizure medication selection for the adjunctive treatment of refractory epilepsy. In the present meta-analysis, we assessed the efficacy and safety of three second-generation broad-spectrum antiseizure medications, lamotrigine (LTG), levetiracetam (LEV), and topiramate (TPM), and two third-generation broad-spectrum antiseizure medications, perampanel (PER) and lacosamide (LCM), for the adjunctive treatment of refractory epilepsy.

METHODS

We systematically searched PubMed, Embase, and CENTRAL from inception to July 15, 2022. The studies included in the meta-analysis were required to meet the following criteria: (1) be randomized, double-blind clinical trials; (2) include patients aged >2 years with a clinical diagnosis of drug-resistant epilepsy; (3) have at least 8 weeks for the treatment period excluding the titration phase; and (4) report the outcomes of seizure response, seizure freedom and the withdrawal rate due to treatment-emergent adverse effects. Data were extracted, and the risk of bias for each study was assessed by two authors independently using RoB2 tools. We performed the network meta-analysis for each outcome through a group of programs in the mvmeta and network packages in Stata. Relative odds ratios with 95% confidence intervals were calculated as the result of the analyses. The surface under the cumulative ranking curve (SUCRA) and mean ranks were used to rank these treatments.

RESULTS

Forty-two randomized controlled trials (RCTs) (LTG-placebo: n = 6, LEV-placebo: n = 13, TPM-placebo: n = 9, PER-placebo: n = 6, LCM-placebo: n = 7, LEV-TPM: n = 1) with 10257 participants (LTG = 569, LEV = 1626, TPM = 701, PER = 1734, LCM = 1908, placebo = 3719) were included. Levetiracetam had subequal efficacy in 50 % seizure frequency reduction to TPM [odds ratio (OR) 1.00, 95% confidence interval (CI) 0.73-1.38], and LEV had a higher rate of ≥ 50% seizure frequency reduction than LCM (OR 1.49, 95% CI 1.11-2.01) and PER (OR 1.68, 95% CI 1.24-2.29). Levetiracetam was also related to a higher proportion of seizure freedom participants than TPM (OR 1.87, 95% CI 1.20-2.89), PER (OR 2.23, 95% CI 1.12-4.43), and LCM (OR 2.97, 95% CI 1.46-6.05). In addition, LEV was associated with a lower risk of experiencing at least one treatment-emergent adverse event (TEAE) than PER (OR 0.63, 95% CI 0.46-0.85) and TPM (OR 0.51, 95 % CI 0.36-0.72) and a lower proportion of patients experiencing TEAEs leading to discontinuation than PER (OR 0.51, 95% CI 0.27-0.97) and TPM (OR 0.50, 95 % CI 0.27-0.93).

CONCLUSIONS

Third-generation drugs (PER and LCM) had no advantages in terms of efficacy and safety for adjunctive treatment of refractory epilepsy compared with several second-generation drugs (LEV and LTG). Levetiracetam was the priority choice for adjunctive treatment of refractory epilepsy. Perampanel and LCM had no advantages in terms of efficacy and safety among the five drugs.

REGISTRATION

PROSPERO registration number, CRD42022344153; last edited on December 23, 2022.

Effectiveness of dose-escalated topiramate monotherapy and add-on therapy in neurosurgery-related epilepsy: A prospective study

BACKGROUND

Lesional and symptomatic causes of epilepsy are the most common neurological disorders of the brain. Topiramate effectively controls newly diagnosed epilepsy and refractory focal seizures, but high-dose topiramate does not improve seizure control. This study aimed to evaluate the clinical efficacy and safety of dose-escalated topiramate as first-line monotherapy and add-on therapy in patients with neurosurgery-related epilepsy.

MATERIAL AND METHODS

A total of 55 neurosurgical patients with epilepsy were divided into monotherapy and add-on therapy groups and both groups received topiramate via the dose-escalation method. The primary efficacy outcomes were seizure-free rate and seizure response rate. Adverse events and seizure frequency were recorded.

RESULTS

The seizure response rate in the first month of monotherapy was significantly better than that of add-on therapy (89% vs 65%, P < .05), but no significant differences were found in seizure response rates between the 2 groups after 2 months of treatment. Both monotherapy and add-on therapy were effective in controlling seizures, with mean seizure frequency of 0.725 vs 0.536 and seizure-free rate of 88% vs 78.6%. Both treatments showed good improvement of seizure frequency in patients without tumor. The efficacy of monotherapy was better than that of add-on therapy (80% vs 29.2%) in patients with body mass index (BMI) ≤24. However, add-on therapy was better than monotherapy (76.7% vs 21.4%) in patients with BMI > 24. Dizziness (25.5%) and headache (16.4%) were the most common adverse events. No severe adverse event such as cognitive impairment was observed.

CONCLUSIONS

Dose-escalated topiramate monotherapy and add-on therapy demonstrate good efficacy and safety, with fewer adverse events in seizure control in neurosurgical patients.

Efficacy, safety, and tolerability of perampanel in Asian and non-Asian patients with epilepsy

People of different ethnic or racial backgrounds may experience variations in pharmacokinetic and pharmacodynamic responses to drug therapies. Our post hoc analysis evaluated the efficacy, safety, and tolerability of perampanel in Asian and non-Asian populations with refractory focal seizures with or without focal to bilateral tonic-clonic (FBTC) seizures. This analysis pooled data from 4 randomized, placebo-controlled, phase-3 studies involving patients aged ≥12 years who have focal seizures with or without FBTC seizures. Patients were receiving 2, 4, 8, or 12 mg perampanel (or placebo) by the end of a 6-week titration period and for a further 13 weeks during the maintenance phase. Efficacy endpoints included median percent change in seizure frequency per 28 days, and 50% and seizure-freedom responder rates relative to baseline. The median percent change in seizure frequency per 28 days from baseline was significantly greater than placebo for perampanel 8 and 12 mg (-31.1% and -38.1% change, respectively; each P < 0.0001) in the Asian population, and for perampanel 4, 8, and 12 mg (-21.1% [P = 0.0001], -26.3% [P < 0.0001], and -27.7% [P = 0.0001] change, respectively) in the non-Asian population. The 50% responder rate relative to baseline was significantly greater than placebo for perampanel 8 and 12 mg (40.1% and 43.8%, respectively; each P < 0.0001) in the Asian population, and for perampanel 4, 8, and 12 mg (29.4% [P = 0.0002], 32.8% [P < 0.0001] and 34.5% [P = 0.0001]), respectively, in the non-Asian population. Seizure-freedom rate among all patients was 4.9%-11.7% for perampanel 2, 4, 8, and 12 mg. The most frequently reported treatment-emergent adverse events (TEAEs) across both populations were dizziness, somnolence, irritability, headache, and fatigue. The most common psychiatric TEAEs were aggression and irritability. Perampanel demonstrated a favorable and similar risk-benefit profile in both Asian and non-Asian populations with refractory focal seizures.

Topiramate add-on therapy for drug-resistant focal epilepsy

BACKGROUND

The majority of people with epilepsy have a good prognosis and their seizures are controlled by a single antiepileptic drug. However, up to 20% of patients from population-based studies, and up to 30% from clinical series (not population-based), develop drug-resistant epilepsy, especially those with focal-onset seizures. In this review, we summarise the current evidence regarding topiramate, an antiepileptic drug first marketed in 1996, when used as an add-on treatment for drug-resistant focal epilepsy.This is an update of a Cochrane Review first published in 1999, and last updated in 2014.

OBJECTIVES

To evaluate the efficacy and tolerability of topiramate when used as an add-on treatment for people with drug-resistant focal epilepsy.

SEARCH METHODS

For the latest update of this review we searched the following databases on 2 July 2018: Cochrane Register of Studies (CRS Web), which includes the Cochrane Epilepsy Group Specialized Register and the Cochrane Central Register of Controlled Trials (CENTRAL); MEDLINE (Ovid, 1946- ); ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform (ICTRP). We imposed no language restrictions. We also contacted the manufacturers of topiramate and researchers in the field to identify any ongoing or unpublished studies.

SELECTION CRITERIA

Randomised, placebo-controlled add-on trials of topiramate, recruiting people with drug-resistant focal epilepsy.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials for inclusion and extracted the relevant data. We assessed the following outcomes: (1) 50% or greater reduction in seizure frequency; (2) seizure freedom; (3) treatment withdrawal (any reason); (4) adverse effects. Primary analyses were intention-to-treat (ITT), and summary risk ratios (RRs) with 95% confidence intervals (95% CIs) are presented. We evaluated dose-response in regression models. We carried out a 'Risk of bias' assessment for each included study using the Cochrane 'Risk of bias' tool and assessed the overall certainty of evidence using the GRADE approach.

MAIN RESULTS

We included 12 trials, representing 1650 participants. Baseline phases ranged from four to 12 weeks and double-blind phases ranged from 11 to 19 weeks. The RR for a 50% or greater reduction in seizure frequency with add-on topiramate compared to placebo was 2.71 (95% CI 2.05 to 3.59; 12 studies; high-certainty evidence). Dose regression analysis showed increasing effect with increasing topiramate dose demonstrated by an odds ratio (OR) of 1.45 (95% CI 1.28 to 1.64; P < 0.001) per 200 mg/d increase in topiramate dosage. The proportion of participants achieving seizure freedom was also significantly increased with add-on topiramate compared to placebo (RR 3.67, 95% CI 1.79 to 7.54; 8 studies; moderate-certainty evidence). Treatment withdrawal was significantly higher for add-on topiramate compared to placebo (RR 2.37, 95% CI 1.66 to 3.37; 12 studies; high-certainty evidence). The RRs for the following adverse effects indicate that they are significantly more prevalent with topiramate, compared to placebo: ataxia 2.29 (99% CI 1.10 to 4.77; 4 studies); concentration difficulties 7.81 (99% CI 2.08 to 29.29; 6 studies; moderate-certainty evidence); dizziness 1.52 (99% CI 1.07 to 2.16; 8 studies); fatigue 2.08 (99% CI 1.37 to 3.15; 10 studies); paraesthesia 3.65 (99% CI 1.58 to 8.39; 7 studies; moderate-certainty evidence); somnolence 2.44 (99% CI 1.61 to 3.68; 9 studies); 'thinking abnormally' 5.70 (99% CI 2.26 to 14.38; 4 studies; high-certainty evidence); and weight loss 3.99 (99% CI 1.82 to 8.72; 9 studies; low-certainty evidence). Evidence of publication bias for the primary outcome was found (Egger test, P = 0.001). We rated all studies included in the review as having either low or unclear risk of bias. Overall, we assessed the evidence as moderate to high certainty due to the evidence of publication bias, statistical heterogeneity and imprecision, which was partially compensated for by large effect sizes.

AUTHORS' CONCLUSIONS

Topiramate has efficacy as an add-on treatment for drug-resistant focal epilepsy as it is almost three times more effective compared to a placebo in reducing seizures. The trials reviewed were of relatively short duration and provided no evidence for the long-term efficacy of topiramate. Short-term use of add-on topiramate was shown to be associated with several adverse events. The results of this review should only be applied to adult populations as only one study included children. Future research should consider further examining the effect of dose.

Comparative effectiveness of add-on therapy with newer-generation antiepileptic drugs in Bulgarian patients with refractory epilepsy

OBJECTIVES

The objective of this study is to perform an open, prospective study on various aspects of comparative effectiveness of newer-generation antiepileptic drugs as add-on therapy in Bulgarian patients with drug-resistant epilepsy.

METHODS

The study was performed with the participation of 1259 patients with epilepsy who attended the Clinic of Neurology at the University Hospital in Plovdiv, Bulgaria for regular visits and completed diaries about seizure frequency, severity, and adverse events.

RESULTS

Oxcarbazepine was used in 82 patients, topiramate in 120 patients, lamotrigine in 73 patients, levetiracetam in 135 patients, pregabalin in 47 patients, tiagabine in 43 patients, gabapentin in 18 patients, lacosamide in 12 patients, and retigabine in 6 patients. During the first 24 months of study, improvement of seizure severity and frequency was most frequent in patients on treatment with pregabalin and levetiracetam and rarest in those on treatment with oxcarbazepine. The retention rate of patients on pregabalin and tiagabine was significantly lower compared to the retention rate of patients on most of the other antiepileptic drugs. The frequency of adverse events was higher in patients on treatment with tiagabine and pregabalin.

CONCLUSION

Despite some similar characteristics of newer-generation antiepileptic drugs' effectiveness, levetiracetam stands out with better dynamic improvement of seizure severity and frequency and satisfactory tolerability; typical for pregabalin is a very good dynamic improvement of seizure severity and frequency mainly in patients with focal seizures, but a lower tolerability, and the main advantage of oxcarbazepine is a good tolerability, efficacy, however, is less satisfactory.

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

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

Assessing the Cost-Effectiveness of New Pharmaceuticals in Epilepsy in Adults: The Results of a Probabilistic Decision Model

Epilepsy currently affects more than 400,000 people in the United Kingdom and 2.3 million in the United States. Drug therapy is the mainstay of treatment for patients with epilepsy, but therapies vary widely in their mechanism of action and acquisition cost. This article describes a decision model developed for the National Institute for Clinical Excellence in the United Kingdom. It compares the long-term cost-effectiveness of drugs licensed in adults for use in 3 situations: monotherapy for newly diagnosed patients, monotherapy for refractory patients, and combination therapy for refractory patients. The analysis separately considers the treatment of partial and generalized seizures. The full range of pharmaceutical therapies feasibly used in the UK health system was included in the analysis. The analysis showed that, on the basis of existing evidence, for newly diagnosed patients with partial seizures, carbamazepine and valproate are likely to be the most cost-effective mono-therapies. Carbamazepine is likely to be the most cost-effective 2nd-line monotherapy for refractory patients, and oxcarbazepine would probably be the most cost-effective adjunctive therapy for refractory patients if the willingness to pay for additional health benefits is greater than £18,000 per quality-adjusted life year (QALY). For patients with generalized seizures, valproate is most likely to be cost-effective for newly diagnosed patients. For refractory patients, adjunctive topiramate is more cost-effective than monotherapy alone if the willingness to pay for additional health benefits is greater than £35,000 per QALY. There is, however, considerable uncertainty regarding these results. Some of the methodological features of the study will be of value in designing cost-effectiveness analyses of other therapies for chronic conditions. These include the methods used to deal with the absence of head-to-head trial data and the need to reflect time dependency in Markov transition probabilities.

Topiramate add-on for drug-resistant partial epilepsy

BACKGROUND

The majority of people with epilepsy have a good prognosis and their seizures are controlled by a single antiepileptic drug. However, up to 20% of patients from population-based studies and up to 30% from clinical series (not population-based) develop drug-resistant epilepsy, especially those with partial onset seizures. In this review we summarise the current evidence regarding topiramate, an antiepileptic drug first marketed in 1996, when used as an add-on treatment for drug-resistant partial epilepsy. This is an updated version of the original Cochrane review published in Issue 3, 1999.

OBJECTIVES

To evaluate the efficacy and safety of topiramate when used as an add-on treatment for people with drug-resistant partial epilepsy.

SEARCH METHODS

We searched the Cochrane Epilepsy Group Specialised Register (June 2013); the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2013, Issue 5); MEDLINE (1946 to 2013); SCOPUS (1823 to 2013); ClinicalTrials.gov and ICTRP. We imposed no language restrictions. We also contacted the manufacturers of topiramate and researchers in the field to identify any ongoing or unpublished studies.

SELECTION CRITERIA

Randomised, placebo-controlled or active drug controlled add-on trials of topiramate, recruiting people with drug-resistant partial epilepsy.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials for inclusion and extracted the relevant data. We assessed the following outcomes: (a) 50% or greater reduction in seizure frequency; (b) seizure freedom; (c) treatment withdrawal (any reason); (d) side effects. Primary analyses were intention-to-treat and summary risk ratios (RR) with 95% confidence intervals (95% CI) are presented. We evaluated dose response in regression models. We carried out a 'Risk of bias' assessment for each included study using the Cochrane 'Risk of bias' tool and assessed the overall quality of evidence using the GRADE approach, which we presented in a 'Summary of findings' table.

MAIN RESULTS

Eleven trials were included, representing 1401 randomised participants. Baseline phases ranged from 4 to 12 weeks and double-blind phases from 11 to 19 weeks. The RR for a 50% or greater reduction in seizure frequency compared to placebo was 2.97 (95% CI 2.38 to 3.72). Dose regression analysis shows increasing effect with increasing dose, but found no advantage for doses over 300 or 400 mg per day. The RR for seizure freedom (95% CI) compared to placebo was 3.41 (95% CI 1.37 to 8.51). The RR for treatment withdrawal compared to placebo was 2.44 (95% CI 1.64 to 3.62). The RRs for the following side effects indicate that they are significantly associated with topiramate: ataxia 2.29 (99% CI 1.10 to 4.77); concentration difficulties 7.81 (2.08 to 29.29); dizziness 1.54 (99% CI 1.07 to 2.22); fatigue 2.19 (99% CI 1.42 to 3.40); paraesthesia 3.91 (1.51 to 10.12); somnolence 2.29 (99% CI 1.49 to 3.51); 'thinking abnormally' 5.70 (99% CI 2.26 to 14.38) and weight loss 3.47 (1.55 to 7.79). Evidence of publication bias was found (P-value from the Egger test was P=0.003). We rated all studies included in the review as having either low or unclear risk of bias. Overall, we assessed the evidence as moderate quality due to the evidence of publication bias.

AUTHORS' CONCLUSIONS

Topiramate has efficacy as an add-on treatment for drug-resistant partial epilepsy in that it is three times more effective compared to a placebo in reducing seizures. However, the trials reviewed were of relatively short duration and provide no evidence for the long-term efficacy of topiramate. In the short term topiramate as an add-on has been shown to be associated with several adverse events. The results of this review cannot be extrapolated to monotherapy or treatment of other epilepsy types and future research should consider examining the effect of dose.

Comparative efficacy and tolerability of anti-epileptic drugs for refractory focal epilepsy: systematic review and network meta-analysis reveals the need for long term comparator trials

AIMS

To evaluate the comparative efficacy (50% reduction in seizure frequency) and tolerability (premature withdrawal due to adverse events) of anti-epileptic drugs (AEDs) for refractory epilepsy.

METHODS

We searched Cochrane Central Register of Controlled Trials (Cochrane Library 2009, issue 2) including Epilepsy Group's specialized register, MEDLINE (1950 to March 2009), EMBASE (1980 to March 2009), and Current Contents Connect (1998 to March 2009) to conduct a systematic review of published studies, developed a treatment network and undertook a network meta-analysis.

RESULTS

Forty-three eligible trials with 6346 patients and 12 interventions, including placebo, contributed to the analysis. Only three direct drug comparator trials were identified, the remaining 40 trials being placebo-controlled. Conventional random-effects meta-analysis indicated all drugs were superior in efficacy to placebo (overall odds ratio (OR] 3.78, 95% CI 3.14, 4.55) but did not permit firm distinction between drugs on the basis of the efficacy or tolerability. A Bayesian network meta-analysis prioritized oxcarbazepine, topiramate and pregabalin on the basis of short term efficacy. However, sodium valproate, levetiracetam, gabapentin and vigabatrin were prioritized on the basis of short-term efficacy and tolerability, with the caveat that vigabatrin is recognized as being associated with serious visual disturbance with chronic use.

CONCLUSION

Of the wide range of AEDs licensed for the treatment of refractory epilepsy, sodium valproate, levetiracetam and gabapentin demonstrated the best balance of efficacy and tolerability. Until regulators mandate greater use of active comparator trials with longer term follow-up, network meta-analysis provides the only available means to quantify these clinically important parameters.

Investigation of influencing factors on higher placebo response in East Asian versus Western clinical trials for partial epilepsy: a meta-analysis

BACKGROUND

Placebo response in clinical trials for anti-epileptic drugs (AEDs) has been examined and a recent meta-analysis revealed that East Asian trials showed unexpectedly higher placebo response. As multi-national trials have become common, it is important to understand placebo response in different settings, including regions/countries for future clinical trials.

OBJECTIVE

The present meta-analysis aims to investigate the potential factors that contribute to higher placebo response in clinical trials for add-on therapy to adult patients with refractory partial epilepsy in East Asian and Western populations.

METHODS

A database was established based on published clinical trials conducted in East Asian and Western countries. The relationship between the degree of placebo response and potential influencing factors was examined by logistic regression analyses.

RESULTS

The database included 33 trials from five AEDs: gabapentin, topiramate, levetiracetam, pregabalin, and zonisamide. Placebo response was associated with patient characteristics such as disease duration, percentage of patients with complex partial seizure (CPS) at baseline, percentage of patients treated with two AEDs, protocol-required seizure frequency at baseline, and year of publication. Logistic regression analysis demonstrated that the placebo response in East Asian trials was statistically higher than that in Western trials.

CONCLUSION

Patient characteristics such as longer disease duration and CPS at baseline contribute to a reduction in placebo response in clinical trials of AEDs for partial epilepsy. While the reasons for the geographical difference in placebo response are not clear, these and other patient characteristics contributing to placebo response should be carefully considered in the design of future clinical trials of AEDs for partial epilepsy.

Topiramate attenuates cerebral ischemia/reperfusion injury in gerbils via activating GABAergic signaling and inhibiting astrogliosis

Impaired GABAergic inhibitory synaptic transmission plays an essential role in the pathogenesis of selective neuronal cell death following transient global ischemia. GABA(A) receptor (GABA(A)R), K⁺-Cl⁻ co-transporter 2 (KCC2), Na⁺-K⁺-Cl⁻ co-transporter 1 (NKCC1) and astrocytes are of particular importance to GABAergic transmission. The present study was designed to explore whether the neuroprotective effect of topiramate (TPM) was linked with the alterations of GABAergic signaling and astrocytes. The bilateral carotid arteries were occluded, and TPM (80 mg/kg/day (divided twice daily), i.p.) was injected into gerbils. At day 1, 3 and 7 post-ischemia, neurological deficit was scored and changes in hippocampal neuronal cell death were evaluated by Nissl staining. The apoptosis-related regulatory proteins (procaspase-3, caspase-3, Bax and Bcl-2) and GABAergic signal molecules (GABA(A)R α1, GABA(A)R γ2, KCC2 and NKCC1) were also detected using western blot assay. In addition, the fluorescent intensity and protein level of glial fibrillary acidic protein (GFAP), a major component of astrocyte, were examined by confocal and immunoblot analysis. Our results showed that TPM treatment significantly decreased neurological deficit scores, attenuated the ischemia-induced neuronal loss and remarkably decreased the expression levels of procaspase-3, caspase-3 as well as the ratio of Bax/Bcl-2. Besides, treatment with TPM also resulted in the increased protein expressions of GABA(A)R α1, GABA(A)R γ2 and KCC2 together with the decreased protein level of NKCC1 in gerbils hippocampus. Furthermore, fluorescent intensity and protein level of GFAP were evidently reduced in TPM-treated gerbils. These findings suggest that the therapeutic effect of TPM on global ischemia/reperfusion injury appears to be associated with the enhancement of GABAergic signaling and the inhibition of astrogliosis in gerbils.

Topiramate as an adjunctive treatment for refractory partial epilepsy in the elderly

This double-blind, placebo-controlled study investigated the efficacy and tolerability of adjunctive topiramate in 86 elderly Chinese patients with refractory partial epilepsy. Patients who had at least four seizures per 4 weeks during an 8-week baseline period, despite medication with up to three standard antiepileptic drugs (AEDs), were randomly assigned to receive topiramate (n = 46) or placebo (n = 40). Topiramate dosages were titrated (target dose 200 mg/day orally) for 8 weeks and maintained at stable levels for another 12 weeks; concomitant AEDs continued at original dosages. All patients completed the study: 47.8% in the topiramate group and 7.5% on placebo reached ≥ 50% reduction in complex partial seizures. In the topiramate group, the most common adverse events were dizziness, somnolence, fatigue, headache and difficulty with memory; most events were transient and mild or moderate in severity. It was concluded that 200 mg/day topiramate was effective and well-tolerated in elderly patients with refractory partial epilepsy.

Efficacy and safety of adjunctive zonisamide in adult patients with refractory partial-onset epilepsy: a randomized, double-blind, placebo-controlled trial

BACKGROUND AND OBJECTIVE

Clinical studies have reported that zonisamide is effective for a wide range of seizure types, including refractory partial-onset seizures. However, there have been no reported studies of the efficacy of zonisamide in the Chinese population to date. The aim of the present study was to evaluate the efficacy and safety of zonisamide in the treatment of adult Chinese patients with refractory partial-onset epilepsy.

METHODS

This was a randomized, double-blind, placebo-controlled trial conducted over a 16-week period. 104 patients with refractory partial-onset epilepsy were enrolled. Participants were randomly assigned to receive add-on zonisamide or placebo. Zonisamide was titrated to a target dosage of 300 or 400 mg/day. Seizure frequency and adverse effects were documented.

RESULTS

102 patients completed the trial. Zonisamide showed significantly greater efficacy compared with placebo (responder rate 55.8% vs 36.0%, p<0.05), including 55.2% (16 of 29 patients) in the zonisamide 300 mg/day arm and 56.5% (13 of 23 patients) in the zonisamide 400 mg/day arm. Zonisamide 300 and 400 mg/day showed similar efficacy (p>0.05). Moreover, similar efficacy of zonisamide was found in the control of complex partial seizures, simple partial seizures and secondary generalized seizures. There was no difference in the incidence of adverse effects between zonisamide and placebo. Reported adverse effects in the zonisamide group involved the digestive system (32.5% of total adverse effects in the group) [including transient increases in liver enzymes (27.8%)], weight changes (30.2%), the haematological system (15.1%), neurological/psychiatric effects (10.3%), the urinary system (7.9%) and the cardiovascular system (4.0%). Only digestive system adverse effects constituted a significantly higher proportion of adverse effects in the zonisamide group than in the placebo group (32.5% vs 30.2%, p<0.05).

CONCLUSION

Zonisamide 300-400 mg/day is effective and well tolerated as an adjunctive drug in adult Chinese patients with refractory partial-onset epilepsy.

Factors determining response to antiepileptic drugs in randomized controlled trials. A systematic review and meta-analysis

PURPOSE

Because of the lack of head-to-head adjunctive-therapy trials of antiepileptic drugs (AEDs) in refractory partial epilepsy, meta-analyses of placebo-controlled randomized controlled trials (RCTs) represent a potentially important source of evidence to guide treatment decisions. However, such indirect comparisons raise various methodologic issues that may hamper their relevance.

METHODS

All RCTs in adult refractory partial epilepsy were analyzed to assess whether efficacy outcomes are influenced by: characteristics of patients and trials ; use of last observation carried forward (LOCF) analysis; evaluation period (entire period versus maintenance period); and year of publication. A meta-analysis of these AEDs was then performed taking these factors into consideration.

KEY FINDINGS

Sixty-three RCTs evaluating 20 AEDs were included. The following variables influenced efficacy estimates: (1) responder rates correlated positively with duration of the entire treatment period (p = 0.038); (2) response to placebo was significantly greater in the maintenance period than in the entire treatment period (p = 0.005); (3) responder rates increased over the years both for AEDs (p < 0.001) and for placebo (p = 0.001); (4) LOCF analysis overestimated responder rates for AEDs (p < 0.001) and for placebo (p = 0.001) compared with completer-based analysis, and the overestimation correlated positively with withdrawal rates (p < 0.001). A meta-analysis of available data showed large differences in efficacy ranking in relation to dose selection and type of analysis, but these were mostly nonsignificant due to statistical power limitations.

SIGNIFICANCE

Several methodologic issues hamper the relevance of indirect comparisons of AEDs in the adjunctive-therapy of refractory partial epilepsy. Some of these issues could be overcome by improved standardization in the reporting of efficacy outcomes.

Placebo responses in randomized trials of antiepileptic drugs

This meta-analysis of published, randomized, controlled trials (RCTs) of antiepileptic drugs in adults with focal drug-resistant epilepsy was performed to estimate a mean placebo effect, to evaluate variability in placebo response rates, to investigate associations between placebo effect rates and study characteristics, and to determine whether there were changes in placebo response rates over recent years in RCTs (so-called "placebo drift"). One hundred ninety-eight potentially appropriate studies were identified after MEDLINE search and carefully reviewed. Twenty-seven RCTs (with 5662 randomized patients, including 1887 patients in placebo arms) were included in the meta-analysis. A random effects meta-analytic model estimated the pooled placebo response at 12.5% (95% CI: 10.03-14.94%). A statistically significant correlation between baseline median seizure frequency and placebo response rates was not observed. "Placebo drift" was not considered statistically significant.

Placebo-corrected efficacy of modern antiepileptic drugs for refractory epilepsy: systematic review and meta-analysis

Although adjunctive treatment with modern antiepileptic drugs (AEDs) is standard care in refractory epilepsy, it is unclear how much of the effect can be attributed directly to the AEDs and how much to the beneficial changes seen with placebo. Therefore, we performed a systematic review and meta-analysis of the evidence to determine the placebo-corrected net efficacy of adjunctive treatment with modern AEDs on the market for refractory epilepsy. Of 317 potentially eligible articles reviewed in full text, 124 (39%) fulfilled eligibility criteria. After excluding 69 publications, 55 publications of 54 studies in 11,106 adults and children with refractory epilepsy form the basis of evidence. The overall weighted pooled-risk difference in favor of AEDs over placebo for seizure-freedom in the total sample of adults and children was 6% [95% confidence interval (CI) 4-8, z = 6.47, p < 0.001] and 21% (95% CI 19-24, z = 17.13, p < 0.001) for 50% seizure reduction. Although the presence of moderate heterogeneity may reduce the validity of the results and limit generalizations from the findings, we conclude that the placebo-corrected efficacy of adjunctive treatment with modern AEDs is disappointingly small and suggest that better strategies of finding drugs are needed for refractory epilepsy, which is a major public health problem.

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.

Greater response to placebo in children than in adults: a systematic review and meta-analysis in drug-resistant partial epilepsy

BACKGROUND

Despite guidelines establishing the need to perform comprehensive paediatric drug development programs, pivotal trials in children with epilepsy have been completed mostly in Phase IV as a postapproval replication of adult data. However, it has been shown that the treatment response in children can differ from that in adults. It has not been investigated whether differences in drug effect between adults and children might occur in the treatment of drug-resistant partial epilepsy, although such differences may have a substantial impact on the design and results of paediatric randomised controlled trials (RCTs).

METHODS AND FINDINGS

Three electronic databases were searched for RCTs investigating any antiepileptic drug (AED) in the add-on treatment of drug-resistant partial epilepsy in both children and adults. The treatment effect was compared between the two age groups using the ratio of the relative risk (RR) of the 50% responder rate between active AEDs treatment and placebo groups, as well as meta-regression. Differences in the response to placebo and to active treatment were searched using logistic regression. A comparable approach was used for analysing secondary endpoints, including seizure-free rate, total and adverse events-related withdrawal rates, and withdrawal rate for seizure aggravation. Five AEDs were evaluated in both adults and children with drug-resistant partial epilepsy in 32 RCTs. The treatment effect was significantly lower in children than in adults (RR ratio: 0.67 [95% confidence interval (CI) 0.51-0.89]; p = 0.02 by meta-regression). This difference was related to an age-dependent variation in the response to placebo, with a higher rate in children than in adults (19% versus 9.9%, p < 0.001), whereas no significant difference was observed in the response to active treatment (37.2% versus 30.4%, p = 0.364). The relative risk of the total withdrawal rate was also significantly lower in children than in adults (RR ratio: 0.65 [95% CI 0.43-0.98], p = 0.004 by metaregression), due to higher withdrawal rate for seizure aggravation in children (5.6%) than in adults (0.7%) receiving placebo (p < 0.001). Finally, there was no significant difference in the seizure-free rate between adult and paediatric studies.

CONCLUSIONS

Children with drug-resistant partial epilepsy receiving placebo in double-blind RCTs demonstrated significantly greater 50% responder rate than adults, probably reflecting increased placebo and regression to the mean effects. Paediatric clinical trial designs should account for these age-dependent variations of the response to placebo to reduce the risk of an underestimated sample size that could result in falsely negative trials.

Topiramate add-on for drug-resistant partial epilepsy

BACKGROUND

The majority of people with epilepsy have a good prognosis and their seizures are controlled by a single antiepileptic drug. However, up to 20% of patients from population-based studies and up to 30% from clinical series (not population-based) develop drug-resistant epilepsy, especially those with partial onset seizures. In this review we summarize the current evidence regarding a new antiepileptic drug, topiramate, when used as an add-on treatment for drug-resistant partial epilepsy.

OBJECTIVES

To evaluate the efficacy and safety of topiramate when used as an add-on treatment for drug-resistant partial epilepsy.

SEARCH STRATEGY

We searched the Cochrane Epilepsy Group Specialized Register (10 May 2007); the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 3, 2007). No language restrictions were imposed. We also contacted the manufacturers of topiramate and researchers in the field to see any ongoing or published studies.

SELECTION CRITERIA

Randomized placebo controlled add-on trials of topiramate recruiting people with drug-resistant partial epilepsy.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials for inclusion and extracted the relevant data. The following outcomes were assessed: (a) 50% or greater reduction in seizure frequency; (b) treatment withdrawal (any reason); (c) side effects. Primary analyses were intention-to-treat. Summary relative risks (RR) with 95% confidence intervals (95% CI) are presented. Dose response was evaluated in regression models.

MAIN RESULTS

Ten trials were included representing 1312 randomized participants. Baseline phases ranged from 4-12 weeks and double-blind phases from 11-19 weeks. The RR for a 50% or greater reduction in seizure frequency compared to placebo was 2.85 (95% CI 2.27 to 3.59). Dose regression analysis shows increasing effect with increasing dose, but found no advantage for doses over 300 or 400 mg per day. The RR for treatment withdrawal compared to placebo was 2.26 (95% CI 1.55 to 3.31). The RR for the following side effects indicate that they are significantly associated with topiramate: ataxia 1.95 (99% CI 1.04 to 3.65); dizziness 1.55 (99% CI 1.08 to 2.22); fatigue 2.19 (99% CI 1.43 to 3.35); nausea 2.35 (99% CI 1.28 to 4.29); somnolence 2.18 (99% CI 1.47 to 3.21) and 'thinking abnormally' 5.77 (99% CI 2.50 to 13.35).

AUTHORS' CONCLUSIONS

Topiramate has efficacy as an add-on treatment for drug-resistant partial epilepsy. However, trials reviewed were of relatively short duration, and provide no evidence for the long-term efficacy of topiramate. Results cannot be extrapolated to monotherapy or treating other epilepsy types.

Topiramate prescribing patterns among medicaid patients: Diagnosis, comorbidities, and dosing

BACKGROUND

Routine clinical practice data are useful for payers and formulary decision makers to make sound decisions regarding coverage policy. Based on a literature search, there has been scant research into topiramate prescribing patterns among Medicaid patients.

OBJECTIVE

The aim of this study was to describe diagnoses, demographic characteristics, additional co-existing diagnoses, and dosing among Medicaid patients prescribed topiramate.

METHODS

This descriptive, retrospective database analysis used data from South Carolina (SC) and Texas (TX) ambulatory Medicaid claims dated October 1, 2003, to December 31, 2004. Patients whose data were eligible for inclusion in the study were enrolled in Medicaid during the study period, had >or=2 topiramate prescriptions, were aged <65 years, and had evidence of a topiramate treatment-related diagnosis (possible diagnoses were identified through literature search and drug compendiums). Four cohorts were defined: (1) epilepsy only; (2) migraine only; (3) epilepsy and migraine; and (4) nonepilepsy/nonmigraine. Demographic characteristics, diagnoses, comorbidities, and daily dose of topiramate were summarized using descriptive statistics. The initial study analysis (period 1) was a 180-day window comprising the 90 days before and after the first available topiramate prescription claim was filed. A second, 360-day analysis (period 2) was completed comprising the 180 days before and after the index topiramate prescription date.

RESULTS

In the 180-day analysis, 2216 SC and 4766 TX Medicaid patients met the selection criteria. Cohort classification percentages were 32.3% and 39.6% (epilepsy only), 29.7% and 16.4% (migraine only), 10.7% and 9.2% (epilepsy and migraine), and 27.3% and 34.9% (nonepilepsy/nonmigraine) for SC and TX, respectively. Mean (SD) ages were 29.9 (15.9) (SC) and 27.1 (16.1) (TX) years. In the nonepilepsy/nonmigraine cohort, the most common diagnoses were bipolar disorder and depression. The median daily doses in the epilepsy-only cohort were 175 mg/d in the SC group and 200 mg/d in the TX group. In the migraine-only cohort, the median daily dose was 100 mg/d in SC and TX. Results for the 360-day analysis were similar.

CONCLUSIONS

In this descriptive study using data from 2 Medicaid populations, the majority of patients using topiramate had a diagnosis of epilepsy and/or migraine. Median dosages ranged from 175 to 200 mg/d in patients with epilepsy and 100 mg/d in those with migraine. Depression was a common comorbidity in the migraine cohort and the nonepilepsy/nonmigraine cohort.

Second-generation antiepileptic drugs' impact on balance: a meta-analysis

OBJECTIVE

To systematically review available evidence regarding whether second-generation antiepileptic drugs (AEDs) contribute to the risk of balance disorders.

METHODS

We systematically evaluated data from randomized controlled trials that compared adjunctive therapy with a second-generation AED (gabapentin, lamotrigine, levetiracetam, oxcarbazepine, pregabalin, tiagabine, topIramate, or zonisamide) vs placebo for partial epilepsy and that reported dose-specific rates of ataxia or Imbalance for each group. Random-effects meta-analysis was used to pool ratios (risk ratio [RR]) and associated 95% confidence Intervals to determine whether there was evidence of an overall AED class effect or a dose-response effect and whether there were differences between Individual AEDs.

RESULTS

Sixteen studies met inclusion criteria, representing 4279 individuals randomized to a second-generation AED and 1830 patients to placebo. Pooled analyses of all AEDs demonstrated that they Increase imbalance risk at any dose (RR, 2.73; 95% confidence interval, 2.07-3.61) and at lowest dose (RR, 1.76; 95% confidence interval, 1.26-2.46). The highest dose analysis showed heterogeneity; evaluation of individual AEDs revealed that oxcarbamazepine and topiramate increased imbalance risk at all doses, whereas gabapentin and levetiracetam did not increase imbalance risk at any dose. A dose-response effect was observed for most AEDs.

CONCLUSION

Second-generation AEDs at standard dosages, except for gabapentin and levetiracetam, increase the imbalance risk, and evidence exists for a dose-response effect. The mechanisms, risk factors, and consequences of this risk for individual AEDs warrant further study.

Tolerability and Safety of Topiramate in Chinese Patients with Epilepsy

OBJECTIVES

This study focused on (i) evaluating the long-term tolerability and safety of topiramate in Chinese patients with epilepsy, and (ii) comparing the tolerability and safety of topiramate monotherapy versus polytherapy in the same population.

METHODS

This was a prospective, open-label, long-term (36 months) clinical trial. 320 patients (275 adults and 45 children) with epilepsy were recruited into the study; of these, 156 patients had generalised seizures, 151 patients had partial seizures and 13 patients had unclassifiable seizures. All patients received topiramate approximately 200 mg/day either as monotherapy or as adjunctive therapy. At each visit, a physical examination and routine laboratory analysis were performed, and the adverse event (AE) profile was obtained by face-to-face interview.

RESULTS

268 patients received topiramate <or=100 mg/day and 52 patients received topiramate 100-200 mg/day. Topiramate-associated AEs occurred in 98 patients (30.6%). The most common AEs were weight loss in 18 patients (8.4%), paraesthesias in 17 (7.2%), poor memory in ten (3.8%), and dizziness in six (2.8%). Most AEs were mild to moderate and transitory; discontinuation of topiramate was observed in 13 patients (4.1%) as a result of AEs such as impaired memory (seven patients [54%]), paraesthesias (four patients [31%]), and weight loss and cutaneous reaction (each one patient [7.5% each]). The rate of AEs was significantly higher with use of topiramate as monotherapy than as adjunctive therapy (68 patients vs 30 patients [47.8% vs 16.4%], respectively).

CONCLUSION

Topiramate is well tolerated in Chinese patients with epilepsy in clinical practice. Compared with its use as adjunctive therapy, topiramate monotherapy is associated with a significantly higher frequency of adverse events.

The combination of topiramate and diazepam is partially neuroprotective in the hippocampus but not antiepileptogenic in the lithium-pilocarpine model of temporal lobe epilepsy

Lithium-pilocarpine induces status epilepticus (SE), leading to extensive damage and spontaneous recurrent seizures (SRS). Neuroprotective and antiepileptogenic effects of topiramate (TPM) associated with diazepam (DZP) were investigated in this model. SE was induced by LiCl and pilocarpine. TPM (10, 30 or 60 mg/kg) was injected at the onset of SE and 10h later and DZP (2.5 and 1.25mg/kg) at 2 and 10h after SE. TPM treatment was continued twice daily for 6 days. Other rats received two injections of DZP on the day of SE. Cell counting was performed on thionine-stained sections 14 days after SE and after 2 months of epilepsy. Occurrence and frequency of SRS were video-recorded. The MRI T2-weighted signal was quantified in hippocampus and ventral cortices. DZP-TPM treatment induced partial neuroprotection in CA1 and hilus, and tended to increase the percentage of rats with protected neurons in layer III/IV of the ventral entorhinal cortex. The latency to and frequency of SRS were not modified by DZP-TPM. T2-weighted signal was decreased in hippocampus 3 days after SE at all TPM doses and in ventral hippocampus after epilepsy onset. In conclusion, although DZP-TPM treatment was able to partially protect two areas critical for epileptogenesis, the hippocampus and ventral entorhinal cortex, it was not sufficient to prevent epileptogenesis.

Topiramate and its clinical applications in epilepsy

Topiramate, a derivative of the monosaccharide d-fructose, has shown a wide spectrum of antiepileptic efficacy in both animal models and clinical trials. Multiple putative mechanisms of action include voltage-sensitive sodium channel blockade, calcium channel inhibition, increase of potassium conductance, GABA-mediated chloride current increment, glutamate-mediated neurotransmission inhibition and carbonic anhydrase isoenzyme inhibition. In general, the clinical response is maintained in the long-term. The most common side effects include somnolence, fatigue, headache, psychomotor slowing, confusion, difficulty with memory, impaired concentration and attention, speech and language problems and weight loss. If slowly titrated and used at a low-to-medium dosage, it is well tolerated and offers a valid therapeutic option, the relevance of which is comparable to that of the most widely used 'old' antiepileptic drugs. As it is not yet wholly clear which specific epilepsy syndromes may benefit most from topiramate with respect to other drugs, more accurate indications for initial monotherapy would require syndrome-oriented trials and more clinical experience.

Time Course of Adverse Events in Patients with Localization-related Epilepsy Receiving Topiramate Added to Carbamazepine

PURPOSE

To explore the time course of treatment-emergent adverse events (AEs) during topiramate (TPM) adjunctive therapy.

METHODS

Post hoc analyses were performed by using data from a large (264 subjects) multicenter, double-blind, placebo-controlled trial in which 200 mg/day TPM was added to carbamazepine (CBZ) with or without another antiepileptic drug (AED) in adults with treatment-resistant partial-onset seizures. The daily incidence and mean duration of the most common (> or =5% incidence) AEs were calculated for patients completing the 12-week study.

RESULTS

The daily incidence of somnolence, headache, loss of appetite, nervousness, fatigue, dizziness, upper respiratory tract infection, and vertigo peaked during titration and declined to rates similar to that of placebo after the target TPM dose had been reached. In contrast, the daily incidence of paresthesia increased during titration and was maintained for the study duration. Relatively few patients had cognitive symptoms (9% with TPM, 5% with placebo), but these were the most common AEs associated with treatment discontinuation. Patient/investigator reports of weight loss increased gradually over the course of the trial, corresponding with the pattern of change in weight measured at study visits.

CONCLUSIONS

This study demonstrates that most of the more common AEs with TPM adjunctive therapy are transient. Patients can be counseled that most AEs emerging when TPM is initially added to CBZ can be expected to diminish with continued therapy.

Ketter's hypothesis of the mood effects of antiepileptic drugs coupled to the mechanism of action of topiramate and levetiracetam

Mood-modulating profiles of antiepileptic drugs (AEDs) have been classified by Ketter, Post, and Theodore [Neurology 1999; 53 (5, Suppl. 2) S53-76] into two classes: the first class is assumed to have deactivating effects related to GABA potentiation, and the second class is assumed to have activating effects that are associated with glutamate attenuation. We tested this hypothesis by reviewing the multiple mechanisms of action of topiramate (TPM) and levetiracetam (LEV) together with clinical behavioral side effects of patients who had been treated with TPM and LEV in a tertiary referral center for epilepsy. We found LEV to manifest activating and deactivating side effects equally and TPM to act as a deactivating AED, with tiredness/sleepiness side effects being predominant. TPM, in comparison to LEV, was found to be associated with a high incidence of side effects. Testing the hypothesis of Ketter et al. (1999) the deactivating effects of TPM may be coupled to a predominance of potentiation of GABA, but the oversimplified basis of the model needs to be acknowledged.

Topiramate in long-term treatment of epilepsy in the intellectually disabled

BACKGROUND

To study the effectiveness of topiramate (TPM) in refractory epilepsy in patients who have intellectual disability (ID).

METHODS

A representative population sample of 57 patients with ID (age range 2-61, mean 32.8) was administered add-on TPM for drug-refractory epilepsy.

RESULTS

Seizure freedom for at least for 6 months was attained by 10 (17%), and seizure reduction of > or = 50% by further 26 (46%). Less than 50% decrease in seizure frequency was found in 16 (29%). TPM was more efficacious in localisation-related than in generalised epilepsies (81% vs. 50%, P=0.019). An at least 50% decrease in seizure frequency was achieved by patients with temporal lobe epilepsy in 100%, continuous spike-waves during sleep syndrome in 75%, Lennox-Gastaut syndrome in 52%, and those with infantile spasms in 25% of cases. As great decrease in seizure frequency was found in most patients with cortical dysplasia (83%), acquired encephalopathy with mesial temporal sclerosis (MTS) (75%), and genetic disease associated with MTS (66%). Adverse effects occurred in 10% including two (3%) with seizure aggravation and three (5%) necessitating discontinuation.

CONCLUSION

TPM is an effective antiepileptic drug which is of value in treating people with seizures that are resistant to other antiepileptic medication. As a broad-spectrum drug it may substitute for polypharmacy and, at the same time decrease adverse effects and costs of therapy.

A new approach in anti-epileptic drug evaluation

Presurgical trials with video-electroencephalogram (EEG) monitoring for a couple of days provide the possibility to objectively and quantitatively analyze seizure activity during different drug treatments. Patients are provided with the optimal medical care and safety precautions when hospitalized. Hereby a method used in the antiepileptic drug (AED) trials called therapeutic intensive seizure analysis (TISA) has been recently introduced, by which AED efficacy on seizure activity can be objectively quantified by using continuous video-EEG monitoring. This could be used not only as a supplement to the traditional evaluation of AEDs' efficacy by treatment failure designs in large groups, but also can provide early individual information on the changes of seizure activity of each patient during the therapy. Data from TISA studies suggest that secondarily generalized tonic-clonic seizures (SGTCs) mostly occur in patients with a SGTC history after withdrawal of AED. The first 3 days of titration of a newly introduced AED was important for efficacy assessment; with a low risk of SGTCs. By using the TISA method an early recognition of first effects of a new AED on seizure activity and neuropsychological changes is possible, which can be correlated to serum concentration levels in a small sample size. The essentials of the proposed modification to the conventional presurgical trial are: (1) a complete withdrawal of AEDs should be avoided, if possible and (2) a titration phase limited to 3 days is suggested, using a condensed evaluation setting including the TISA method, serum concentration and neuropsychological monitoring. In addition long-term effects can be evaluated by repeated video-EEG monitoring.

Efficacy and tolerability of the new antiepileptic drugs, II: Treatment of refractory epilepsy: report of the TTA and QSS Subcommittees of the American Academy of Neurology and the American Epilepsy Society

PURPOSE

To assess the evidence demonstrating efficacy, tolerability, and safety of seven new antiepileptic drugs (AEDs) [gabapentin (GBP), lamotrigine (LTG), topiramate (TPM), tiagabine (TGB), oxcarbazepine (OXC), levetiracetam (LEV), and zonisamide (ZNS)] in the treatment of children and adults with refractory partial and generalized epilepsies.

METHODS

A 23-member committee, including general neurologists, pediatric neurologists, epileptologists, and doctors in pharmacy, evaluated the available evidence based on a structured literature review including MEDLINE, Current Contents, and Cochrane Library for relevant articles from 1987 to March 2003.

RESULTS

All of the new AEDs were found to be appropriate for adjunctive treatment of refractory partial seizures in adults. GBP can be effective for the treatment of mixed seizure disorders, and GBP, LTG, OXC, and TPM for the treatment of refractory partial seizures in children. Limited evidence suggests that LTG and TPM also are effective for adjunctive treatment of idiopathic generalized epilepsy in adults and children, as well as treatment of the Lennox-Gastaut syndrome.

CONCLUSIONS

The choice of AED depends on seizure and/or syndrome type, patient age, concomitant medications, and AED tolerability, safety, and efficacy. The results of this evidence-based assessment provide guidelines for the prescription of AEDs for patients with refractory epilepsy and identify those seizure types and syndromes for which more evidence is necessary.

Daytime Sleepiness in Epilepsy Patients Receiving Topiramate Monotherapy

PURPOSE

Limited research has focused to date on objective neurophysiological evaluation of daytime sleepiness in patients treated with newer antiepileptic drugs (AEDs), especially when used as monotherapy. This study was aimed at assessing occurrence of daytime sleepiness in newly diagnosed, drug-naïve patients with partial epilepsy receiving initial topiramate (TPM) monotherapy.

METHODS

Daytime vigilance was assessed in 14 consecutive, newly diagnosed and never medicated adult patients with focal epilepsy, receiving monotherapy with TPM. At baseline and 2 months after slowly titrated therapy with TPM, 200 mg/day, patients underwent the Multiple Sleep Latency Test (MSLT), visual simple and choice reaction times (VRT), and self-rated their own degree of sleepiness with the Epworth Sleepiness Scale. A group of 14 age- and gender-matched healthy volunteers served as controls.

RESULTS

At baseline, mean daytime sleep latencies on the MSLT were comparable in patients and in controls. Two months after TPM monotherapy, MSLT scores did not significantly change in patients as compared with pretreatment values. Accordingly, subjective daytime sleepiness and VRTs, which were comparable in controls and in untreated patients at baseline, did not change in patients after TPM monotherapy.

CONCLUSIONS

Study results suggest that an initial short-course monotherapy with TPM, 200 mg/day, does not impair daytime vigilance in newly diagnosed adult patients with partial seizures.

Health-related quality of life in senior adults with epilepsy: what we know from randomized clinical trials and suggestions for future research

OBJECTIVE

The goal of this work was to review the randomized controlled trial (RCT) literature on antiepileptic medication effects on health-related quality of life in seniors with epilepsy.

METHODS

Studies published from 1998 to June 2002 were identified by searching through Medline and the Cochrane Clinical Trials Register. Pre-1998 RCTs identified by Baker et al. [Epilepsia 41 (2003) 1357] were also examined for relevance to the present review. Studies were reviewed if they included a RCT design and included epilepsy patients over the age of 60.

RESULTS

A total of 85 clinical trials were reviewed. Of the 85 studies reviewed only 37 RCT studies included patients over the age of 60. However, formal quality-of-life outcome assessment was not performed in any of the RCTs that included senior adults, and only six studies provided formal quantitative analyses of AED effects in the form of adverse events incidence and participant withdrawal rates. For the most part, early study withdrawal rates were substantial for seniors and adverse events were very common. Two studies reporting on the cognitive and behavioral effects of study AEDs indicated only modest impact when AED monotherapy was kept at therapeutic levels.

CONCLUSIONS

Despite growing appreciation for quality-of-life, issues in the management of epilepsy little current empirical guidance is available for elderly with epilepsy. There exists virtually no information on elderly patient preferences and goals for epilepsy treatment outcomes, and available data primarily concerns younger adults. Despite some encouraging preliminary evidence from this review suggesting that conservative AED treatment may have a more favorable quality of life-related outcome, more conclusive statements await further systematic investigation.

Neuroprotective properties of topiramate in the lithium-pilocarpine model of epilepsy

The lithium-pilocarpine model reproduces the main characteristics of human temporal lobe epilepsy. After status epilepticus (SE), rats exhibit a latent seizure-free phase characterized by development of extensive damage in limbic areas and occurrence of spontaneous recurrent seizures. Neuroprotective and antiepileptogenic effects of topiramate were investigated in this model. SE was induced in adult male rats by LiCl (3 mEq/kg) followed 20 h later by pilocarpine (25 mg/kg). Topiramate (10, 30, or 60 mg/kg) was injected at 1 and 10 h of SE. Injections were repeated twice a day for six additional days. Another group received two injections of diazepam on the day of SE and of vehicle for 6 days. Neuronal damage was assessed at 14 days after SE by cell counting on thionin-stained sections. Occurrence of spontaneous recurrent seizures (SRS) was videorecorded for 10 h per day in other groups of rats. In diazepam-treated rats, the number of neurons was dramatically reduced after SE in all subregions of hippocampus and layers II-IV of ventral cortices. At all doses, topiramate induced a 24 to 30% neuroprotection in layer CA1 of hippocampus (p < 0.05). In CA3b, the 30-mg/kg dose prevented neuronal death. All rats subjected to SE became epileptic. The latency (14-17 days) to and frequency of SRS were similar in topiramate- and diazepam-treated rats. The high mortality in the 30 mg/kg topiramate group (84%) was possibly the result of interaction between lithium and topiramate. In conclusion, topiramate displayed neuroprotective properties only in CA1 and CA3 that were not sufficient to prevent epileptogenesis.

Low-dose topiramate in adults with treatment-resistant partial-onset seizures

OBJECTIVES

Based on dose predictions from animal and human volunteer studies, most patients enrolled in initial randomized controlled trials of topiramate as adjunctive therapy in adults with partial-onset seizures were randomized to >or= 600 mg/day topiramate. Subsequent experience suggests that dosage needs were overestimated. This double-blind, placebo-controlled study evaluated 200 mg/day topiramate in adults with treatment-resistant partial-onset seizures receiving a concurrent enzyme-inducing antiepileptic agent (carbamazepine).

MATERIALS AND METHODS

After a 4-week baseline, 263 adults receiving carbamazepine who had at least three partial-onset seizures during the baseline period were randomized to placebo or one of two topiramate 200 mg/day treatment arms: topiramate escalated weekly 25 mg/day(8-week escalation) or 50 mg/day(4-week escalation). Therapy was then maintained for the remainder of the 12-week double-blind study.

RESULTS

Median percent reduction in seizure frequency from baseline to study end was 44% with topiramate and 20% with placebo (P <or= 0.001). A significant therapeutic effect was present at 2 weeks with a dose of 100 mg/day. The most common adverse events (>or=10% incidence in topiramate-treated patients) were somnolence, fatigue, paresthesia, nervousness and anorexia; 8% of topiramate-treated patients and 2% of placebo-treated patients discontinued because of adverse events. As a result of the low incidence of adverse events, differences between titration rates in terms of tolerability were not detected.

CONCLUSION

Topiramate 200 mg/day is an appropriate target dose as adjunctive therapy in adults with treatment-resistant partial-onset seizures, even when receiving an enzyme-inducing agent; 100 mg/day also appears to be effective. A significant therapeutic effect may be seen in the second week of treatment with a dose of 100 mg/day.

Topiramate and weight loss in patients with neurodevelopmental disabilities

STUDY OBJECTIVE

To characterize weight changes in patients with neurodevelopmental disabilities who received topiramate.

DESIGN

Retrospective, observational study.

SETTING

State-supported developmental center.

PATIENTS

Fifteen patients with neurodevelopmental disabilities who received topiramate therapy

MEASUREMENTS AND MAIN RESULTS

Monthly weights for 1 year after the start of topiramate therapy were recorded. Mean body weight at drug initiation differed significantly compared with the nadir weight during the next 12 months (52.2+/-7.5 vs 49.9+/-7.2 kg, p<0.02). Twelve patients who were receiving ad libitum oral diets demonstrated a significant decrease in body weight (52.1+/-7.5 vs 49.0+/-7.3 kg, p<0.01), whereas the three patients who received enteral nutrition through enterostomy did not experience significant weight loss.

CONCLUSION

Weight loss is common in patients with neurodevelopmental disabilities who receive topiramate. Since patients who received oral diets lost weight whereas those receiving enteral nutrition did not, decreased nutrient intake is the likely cause of weight loss.

Low dose and slow titration of topiramate as adjunctive therapy in refractory partial epilepsies: a multicentre open clinical trial

PURPOSE

A multicentre open clinical trial was conducted to evaluate the clinical usefulness of a slower titration of topiramate (TPM) to 300 mg /day as adjunctive therapy for medically intractable partial epilepsies.

METHODS

Nineteen centres participated in the trial. Study patients had to have had two or more seizures per 4 weeks whilst taking maximum tolerated doses of one but not more than two anti-epileptic drugs. The starting dose of TPM was 25 mg /day and the dose was increased weekly by 25 mg /day until 100 mg /day was reached. Thereafter TPM was increased by 50 mg /day weekly up to the target dose of 300 mg /day, which was followed by an 8 week maintenance phase. Seizure outcomes were measured by intention-to-treat analysis (ITTA).

RESULTS

Two hundred and thirteen patients entered the study. Median seizure frequency reduction rate was 44.8%, responder rate was 47.6%, and seizure free rate was 9.0%. These results were comparable to that of TPM 600 mg /day in our previous controlled trial. In subgroup analysis, seizure free rate was higher in those patients with a lower baseline seizure frequency rate. Seventeen patients (8.0%) were prematurely withdrawn from the study due to adverse events (AE) or lack of effect. One or more AEs were reported in 22% of patients, with dizziness being the most frequent AE. Other AEs occurred in less than 5% of patients.

CONCLUSION

TPM 300 mg /day was effective and in conjunction with a slower dose-titration, markedly reduced the incidence of AEs, compared with previous study.

Adolescent issues in epilepsy

Approximately one third of new cases of epilepsy have their onset before age 20 years. Many children will enter adolescence with epilepsy or have an onset of seizures during adolescence. Adolescence is a time of dramatic change in growth, hormonal, psychologic, and social situations. Seizure frequency, teenage pregnancy, driving, and alcohol and drug use often become major issues during the adolescent years. Furthermore, adolescents often have difficulty accepting the chronicity of epilepsy and complying with medications, which can result in physical injury and perceived or real obstacles to employment, thereby contributing to low morale. Both pediatricians and neurologists should be aware of adolescent issues in epilepsy.

Topiramate add-on for drug-resistant partial epilepsy

BACKGROUND

The majority of people with epilepsy have a good prognosis and their seizures are controlled by a single antiepileptic drug. However, up to 30 per cent develop drug-resistant epilepsy, especially those with partial onset seizures. In this review we summarize the current evidence regarding a new antiepileptic drug, topiramate, when used as an add-on treatment for drug resistant partial epilepsy.

OBJECTIVES

To evaluate the effects of topiramate when used as an add-on treatment for drug-resistant partial epilepsy.

SEARCH STRATEGY

We searched the Cochrane Epilepsy Group's specialized register (28 March 2002); the Cochrane Controlled Trials Register (Cochrane Library Issue 1, 2002). In addition, we contacted Johnson and Johnson (makers of topiramate) and experts in the field to seek any ongoing or unpublished studies.

SELECTION CRITERIA

Randomized placebo controlled add-on trials of topiramate recruiting people with drug-resistant partial epilepsy.

DATA COLLECTION AND ANALYSIS

Two reviewers independently selected trials for inclusion and extracted the relevant data. The following outcomes were assessed: (a) 50 per cent or greater reduction in seizure frequency; (b) treatment withdrawal (any reason); (c) side effects. Primary analyses were intention-to-treat. Summary relative risks (RR) with 95% confidence intervals (95% CI) are presented. Dose response was evaluated in regression models.

MAIN RESULTS

Nine trials were included representing 1049 randomized participants. The RR for a 50 per cent or greater reduction in seizure frequency compared to placebo was 3.32(95% CI 2.52 to 4.39). Dose regression analysis shows increasing effect with increasing dose, but found no advantage for doses over 300 mg per day. The RR for treatment withdrawal compared to placebo was 2.06(95% CI 1.38 to 3.08). The RR for the following side effects indicate that they are significantly associated with topiramate: 1.95(99% CI 1.04 to 3.65), dizziness 1.55(99% CI 1.07 to 2.24); fatigue 2.21(99% CI 1.42 to 3.45); nausea 2.75(99% CI 1.36 to 5.57); somnolence 2.26(99% CI 1.48 to 3.46) and 'thinking abnormally' 5.54(99% CI 2.34 to 13.12).

REVIEWER'S CONCLUSIONS

Topiramate has efficacy as an add-on treatment for drug-resistant partial epilepsy. However, trials reviewed were of relatively short duration, and provide no evidence for the long term efficacy of topiramate. Results cannot be extrapolated to monotherapy or treating other epilepsy types.

New antiepileptic drugs

Finding a niche for each antiepileptic drug has become challenging as more new agents are approved. In this article, the most recent information regarding these drugs is reported, with emphasis on the agents approved in the past 10 years. The evidence clearly shows that, despite limited Food and Drug Administration indications, all drugs are useful in monotherapy, and many have broader spectrums of action. Adverse effects can also help distinguish between agents. Familiarity with this latest information will help clinicians make the best choice for each of their patients with epilepsy.