The long-term use of gabapentin, lamotrigine, and vigabatrin in patients with chronic epilepsy

Gabapentin monotherapy for epilepsy: A review

BACKGROUND

Epilepsy is one of the most common chronic neurological disorders, affecting more than 50 million people globally. In this review we summarised the evidence from randomised controlled trials of gabapentin used as monotherapy for the treatment of focal epilepsy, both newly diagnosed and drug-resistant, with or without secondary generalisation.

OBJECTIVE

To assess the effects of gabapentin monotherapy for people with epileptic focal seizures with and without secondary generalisation.

METHODS

We searched the Cochrane Register of Studies (CRS Web) and MEDLINE (Ovid, 1946 to 24 February 2020) on 25 February 2020. CRS Web includes randomised or quasi-randomised controlled trials from PubMed, Embase, ClinicalTrials.gov, the World Health Organization International Clinical Trials Registry Platform, the Cochrane Central Register of Controlled Trials (CENTRA), and the specialised registers of Cochrane Review Groups including the Cochrane Epilepsy Group. We also searched several Russian databases, reference lists of relevant studies, ongoing trials registers, conference proceedings, and we contacted trial authors.

RESULTS

We found five randomised controlled trials (3167 participants) comparing gabapentin to other antiepileptic drugs (AEDs) and differing doses of gabapentin as monotherapy for newly diagnosed focal epilepsy and drug- resistant focal epilepsy with or without secondary generalisation. Two review authors independently applied the inclusion criteria, assessed trial quality, risk of bias, and extracted data. We used the GRADE approach to assess the certainty of evidence and present seven patient-important outcomes in the "Summary of findings" tables. The quality of evidence was very low to moderate due to poor reporting quality, poor trial design, and other risks of bias, such as selective presentation of findings and potential heavy industry input. Better quality research may change our certainty in the effect estimates. None of the included trials reported on the number of people with 50% or greater reduction in seizures and time to withdrawal (retention time) in an extractable way. Gabapentin-treated participants were more likely to withdraw from treatment for any cause (285/539) than those treated with lamotrigine, oxcarbazepine, or topiramate pooled together (695/1317) (RR 1.13, 95% CI 1.02 to 1.25; 3 studies, 1856 participants; moderate-certainty evidence), but not carbamazepine. Fewer people treated with gabapentin withdrew from treatment owing to adverse events (190/525) than those treated with carbamazepine, oxcarbazepine, or topiramate (479/1238), (RR 0.79, 95% CI 0.69 to 0.91; 1763 participants, 3 studies; moderate-certainty evidence), but not lamotrigine.

CONCLUSION

Gabapentin as monotherapy probably controlled seizures no better and no worse than comparator AEDs (lamotrigine, carbamazepine, oxcarbazepine, and topiramate). Compared to carbamazepine, gabapentin was probably better in retaining people in studies and preventing withdrawals due to adverse events. The most common side effects associated with gabapentin were ataxia (poor co-ordination and unsteady gait), dizziness, fatigue, and drowsiness.

Retention of brivaracetam in adults with drug-resistant epilepsy at a single tertiary care center

INTRODUCTION

Brivaracetam (BRV) is licensed as an adjunctive treatment for focal epilepsy. We describe our clinical experience with BRV at a large UK tertiary center.

METHODS

Adults initiated on BRV between July 2015 and July 2020 were followed up until they discontinued BRV or September 2021. Data on epilepsy syndrome, duration, seizure types, concomitant and previous antiseizure medication (ASM) use, BRV dosing, efficacy, and side effects were recorded. Efficacy was categorized as temporary (minimum three months) or ongoing (at last follow-up) seizure freedom, ≥50% seizure reduction, or other benefits (e.g., no convulsions or daytime seizures). Brivaracetam retention was estimated using Kaplan-Meier survival analysis.

RESULTS

Two-hundred people were treated with BRV, of whom 81% had focal epilepsy. The mean (interquartile range [IQR]) follow-up time was 707 (688) days, and the dose range was 50-600 mg daily. The mean (IQR) of the previous number of used ASMs was 6.9 (6.0), and concomitant use was 2.2 (1.0). One-hundred and eighty-eight people (94%) had previously discontinued levetiracetam (LEV), mainly due to side effects. 13/200 (6.5%) were seizure free for a minimum of six months during treatment, and 46/200 (23%) had a ≥50% reduction in seizure frequency for six months or more. Retention rates were 83% at six months, 71% at 12 months, and 57% at 36 months. Brivaracetam was mostly discontinued due to side effects (38/75, 51%) or lack of efficacy (28/75, 37%). Concomitant use of carbamazepine significantly increased the hazard ratio of discontinuing BRV due to side effects (p = 0.006). The most commonly reported side effects were low mood (20.5%), fatigue (18%) and aggressive behavior (8.5%). These side effects were less prevalent than when the same individuals took LEV (low mood, 59%; aggressive behavior, 43%). Intellectual disability was a risk factor for behavioral side effects (p = 0.004), and a pre-existing mood disorder significantly increased the likelihood of further episodes of low mood (p = 0.019).

CONCLUSIONS

Brivaracetam was effective at a broad range of doses in managing drug-resistant epilepsy across various phenotypes, but less effective than LEV in those who switched due to poor tolerability on LEV. There were no new tolerability issues, but 77% of the individuals experiencing side effects on BRV also experienced similar side effects on LEV.

Prevalence, Safety and Long-Term Retention Rates of Biologics in Hong Kong from 2001 to 2015

BACKGROUND

Biologic agents were initially introduced as treatment for rheumatoid arthritis (RA) but have since been used for other medical conditions. As new biologics become increasingly widespread in treatment regimens, it is important to understand their safety and utilization in the post-marketing context.

PURPOSE

The aim of this study was to investigate long-term prescribing patterns and the safety of biologics in real clinical settings in Hong Kong.

METHODS

This was a population-based drug utilization study in Hong Kong using a territory-wide electronic medical database Clinical Data Analysis and Reporting System (CDARS). Patients who received biologic treatments from 2001 to 2015 were identified and their corresponding demographic and clinical details retrieved from CDARS. The annual prevalence of biologic prescriptions, the long-term retention rates and incidence rates of infections associated with biologic treatments were evaluated.

RESULTS

A total of 30,298 patients (male: 44%) prescribed biologic treatments were identified from CDARS from 2001 to 2015. The annual prevalence of biologic prescriptions increased from 0.1 to 16.1 per 100 persons for both sexes. Infliximab had the highest first-year retention rate of 95.6% among all biologics and continuously attained the highest retention rate from second to fifth year. The overall incidence rate of serious infections was less than five per 100 person-years. Specifically, the incidence rates of tuberculosis, upper and lower respiratory infections and herpes zoster were 0.52, 3.24, 4.99 and 1.01 per 100 person-years, respectively.

CONCLUSION

This population-based study revealed an increasing prevalence of biologic prescribing. Results from the study described the long-term retention rates and incidence rates of serious infections of biologic treatments for all indications, and confirmed the safety of biologic treatments. Since this study provides an overview of all biologic utilization, further studies on cost effectiveness, safety and compliance of treatment in different patient groups are still warranted.

Variability in expression of the human MDR1 drug efflux transporter and genetic variation of the ABCB1 gene: implications for drug-resistant epilepsy

Among individuals diagnosed with epilepsy, as many as one in three develop resistance to antiepileptic drugs (AEDs) thus rendering their seizures refractory to treatment. Despite current antiepileptic drugs (AEDs) having a variety of modes of action, seizures in drug-resistant individuals often persist even after treatment with two or more drugs. The underlying cause of this broad resistance is currently under debate, but two dominant theories have emerged and have been widely studied. Here we discuss current literature investigating the "transporter theory", the idea that individuals present with drug resistance due to genetic variability in the ABCB1 gene encoding the efflux transporter multidrug resistance protein 1 (MDR1). Results of in vitro and in vivo studies suggest that variability in the expression of the MDR1 transporter may be closely tied to drug resistance. While there is much support for this hypothesis from molecular and mechanistic studies, population-based studies of ABCB1 polymorphisms are divergent in their conclusions, and there is need for additional investigations.

Is Mossy Fiber Sprouting a Potential Therapeutic Target for Epilepsy?

Mesial temporal lobe epilepsy (MTLE) caused by hippocampal sclerosis is one of the most frequent focal epilepsies in adults. It is characterized by focal seizures that begin in the hippocampus, sometimes spread to the insulo-perisylvian regions and may progress to secondary generalized seizures. Morphological alterations in hippocampal sclerosis are well defined. Among them, hippocampal sclerosis is characterized by prominent cell loss in the hilus and CA1, and abnormal mossy fiber sprouting (granular cell axons) into the dentate gyrus inner molecular layer. In this review, we highlight the role of mossy fiber sprouting in seizure generation and hippocampal excitability and discuss the response of alternative treatment strategies in terms of MFS and spontaneous recurrent seizures in models of TLE (temporal lobe epilepsy).

Vagus nerve stimulation for refractory epilepsy: experience from Saudi Arabia

BACKGROUND

Vagus nerve stimulation (VNS) has been approved for the treatment of refractory partial epilepsy in adults and children over 12 years of age. Later on, its application expanded to include younger children and other types of epilepsy. We report our experience with this treatment modality for refractory epilepsy in Saudi Arabia.

DESIGN AND SETTINGS

Open-label, uncontrolled, retrospective study of patients with refractory epilepsy, who were treated with VNS in a tertiary care hospital from January 2010 to June 2013.

PATIENTS AND METHODS

Collected data included 26 patients' demographics, epilepsy characteristics, seizure frequency, and treatment history. Patients with a follow-up duration of minimum 12 months were included in the analysis. The examined outcome measures were seizure reduction rates, antiepileptic drugs (AEDs) burden, and impact on patients' quality of life (QOL).

RESULTS

Onset of seizures was from birth to 30 years. Patients' ages at VNS implantation ranged from 4 to 38 years (18.9 [8.7] years). Epilepsy was classified as focal in 8 patients (30%), multifocal in 9 patients (35%), and generalized in 9 patients (35%). The average number of AEDs failed before VNS was 4.2 (1.4). Greater than 50% seizure reduction was achieved in 50% of patients at 3 months, 67% at 6 months, 73% at 12 months, and 78% at 24 months. There was no significant reduction in AEDs burden during the same period. Subjective QOL improvement was reported by 72% of patients at 3 months, 83% at 6 months, 78% at 12 months, and 73% at 24 months after VNS. Minor adverse effects were reported in 27% of patients. One patient had the device replaced due to malfunction.

CONCLUSION

The experience with VNS in a single center in Saudi Arabia confirms that it is a safe and effective adjunctive therapy for refractory epilepsy in adult and pediatric patients.

Pregabalin is increasingly prescribed for neuropathic pain, generalised anxiety disorder and epilepsy but many patients discontinue treatment

AIM

To assess prescribing patterns, sociodemographic characteristics and previous disease history in patients receiving pregabalin.

METHODS

An observational study using register data on dispensed drugs and recorded diagnoses for all patients in Stockholm, Sweden, who filled at least one prescription of pregabalin between July 2005 and December 2009. Analyses focused on prevalence, incidence, diagnosis patterns, prior dispensing of other analgesics/psychotropics and persistence to treatment over time.

RESULT

A total of 18,626 patients (mean age 55 years, 63% women) were initiated on treatment between July 2006 and December 2009. Approved indications were recorded in hospital and/or primary care within 1 year prior to the first dispensing for 40% of the patients (epilepsy 1.3%, neuropathic pain 35.5% and generalised anxiety disorder (GAD) 3.6%). Antidepressants were used by 55%, opioids by 49% and sedatives by 48% prior to initiation of pregabalin. One-third (34%) only purchased one prescription and the proportion purchasing pregabalin 1 year after initiation was 42.1% for epilepsy, 36.3% for GAD, 21.5% for neuropathic pain and 25.6% for those without any of the included diagnoses.

CONCLUSION

Pregabalin was mainly used as a second-line drug for the treatment of GAD or neuropathic pain and to a lesser extent as add-on therapy in epilepsy. However, a large proportion of all patients only purchased one prescription and the persistence declined rapidly over time. The issue of potential off-label prescribing or poor registration of diagnoses should also be noted as a high proportion had been prescribed the drug without a record of any of the approved indications.

Systematic review and meta-analysis of the efficacy and safety of perampanel in the treatment of partial-onset epilepsy

INTRODUCTION

Perampanel is a first-in-class antiepileptic drug approved for adjunctive treatment of partial-onset seizure in patients aged 12 years or older. Published randomised controlled trials (RCTs) had small sample sizes, and meta-analyses have included too few studies to draw conclusive results for the assessment of tolerability, efficacy and safety of perampanel. There is a need to conduct a meta-analysis with a larger dataset and an appropriate study design.

OBJECTIVE

The aim of this study was to systematically review the efficacy and safety of perampanel in the treatment of partial-onset epilepsy.

METHODS

Electronic and clinical trials databases were searched for RCTs of perampanel published up to March 2013. Outcomes of interest were 50 % responder rates, seizure freedom, treatment-emergent adverse events (TEAEs) and incidence of withdrawal. Meta-analysis was performed to investigate the outcomes of interest.

RESULTS

Five RCTs with a total of 1,678 subjects were included. The 50 % responder rates were significantly greater in patients receiving 4, 8 and 12 mg perampanel versus placebo, with risk ratios of 1.54 (95 % CI 1.11-2.13), 1.80 (95 % CI 1.38-2.35) and 1.72 (95 % CI 1.17-2.52), respectively. There was no statistical evidence of a difference in seizure freedom between 8 or 12 mg perampanel and placebo. Of the five commonly reported TEAEs included, both dizziness and somnolence were statistically associated with 8 mg perampanel, whilst dizziness was statistically associated with 12 mg perampanel. Incidences of withdrawal due to adverse events were significantly higher in the 8 mg and 12 mg perampanel groups versus placebo.

CONCLUSION

The use of perampanel resulted in a statistically significant reduction of seizure frequency with respect to the 50 % responder rate in patients with partial-onset epilepsy. Perampanel is well tolerated at 4 mg and reasonably tolerated at 8 and 12 mg. Further clinical and pharmacovigilance studies are required to investigate the long-term efficacy and safety of perampanel in the management of other types of epilepsy.

Safety and efficacy of ezogabine (retigabine) in adults with refractory partial-onset seizures: Interim results from two ongoing open-label studies

Interim results of two open-label extension studies assessed ezogabine/retigabine safety and tolerability for partial-onset seizures. At data cutoff, 336 (60%) patients received ≥ 12 months' open-label ezogabine/retigabine. The most common TEAEs included dizziness (22%), somnolence (19%), headache (14%), and fatigue (10%). Change in seizure frequency from baseline (median reduction, 53%) and responder rate (52.5%) was maintained in patients remaining on ezogabine/retigabine. Continuous 6-month and 12-month seizure-free rates for ezogabine/retigabine exposures ≥ 12 months were 13.1% and 7.1%, respectively.

Vagal nerve stimulation for the treatment of medically refractory epilepsy: a review of the current literature

Object

The authors conducted a study to evaluate the published results of vagal nerve stimulation (VNS) for medically refractory seizures according to evidence-based criteria.

Methods

The authors performed a review of available literature published between 1980 and 2010. Inclusion criteria for articles included more than 10 patients evaluated, average follow-up of 1 or more years, inclusion of medically refractory epilepsy, and consistent preoperative surgical evaluation. Articles were divided into 4 classes of evidence according to criteria established by the American Academy of Neurology.

Results

A total of 70 publications were reviewed, of which 20 were selected for review based on inclusion and exclusion criteria. There were 2 articles that provided Class I evidence, 7 that met criteria for Class II evidence, and 11 that provided Class III evidence.

The majority of evidence supports VNS usage in partial epilepsy with a seizure reduction of 50% or more in the majority of cases and freedom from seizure in 6%–27% of patients who responded to stimulation. High stimulation with a gradual increase in VNS stimulation over the first 6 weeks to 3 months postoperatively is well supported by Class I and II data. Predictors of positive response included absence of bilateral interictal epileptiform activity and cortical malformations.

Conclusions

Vagal nerve stimulation is a safe and effective alternative for adult and pediatric populations with epilepsy refractory to medical and other surgical management.

Clinical comparability of the new antiepileptic drugs in refractory partial epilepsy: a systematic review and meta-analysis

PURPOSE

Evaluate the clinical comparability of new antiepileptic drugs (AEDs) in partial refractory epilepsy.

METHODS

Systematic review of randomized trials (RCTs) comparing a new AED (add-on treatment) with placebo or another AED.

PRIMARY OUTCOMES

responder (≥50% seizure reduction) and withdrawal (tolerability) rates. Pooled estimates of odds ratios (ORs) and number needed treat/harm (NNT/NNH) taking into account baseline risk were derived by random-effects meta-analysis. Adjusted frequentist indirect comparisons between AEDs were estimated.

KEY FINDINGS

Sixty-two placebo-controlled (12,902 patients) and eight head-to-head RCTs (1,370 patients) were included. Pooled ORs for responder and withdrawal rates (vs. placebo) were 3.00 [95% confidence interval (CI) 2.63-3.41] and 1.48 (1.30-1.68), respectively. Indirect comparisons of responder rate based on relative measurements of treatment effect (ORs) favored topiramate (1.52; 1.06-2.20) in comparison to all other AEDs, whereas gabapentin (0.67; 0.46-0.97) and lacosamide (0.66; 0.48-0.92) were less efficacious, without significant heterogeneity. When analyses were based on absolute estimates (NNTs), topiramate and levetiracetam were more efficacious, whereas gabapentin and tiagabine were less efficacious. Withdrawal rate was higher with oxcarbazepine (OR 1.60; 1.12-2.29) and topiramate (OR 1.68; 1.07-2.63), and lower with gabapentin (OR 0.65; 0.42-1.00) and levetiracetam (OR 0.62; 0.43-0.89).

SIGNIFICANCE

The differences found are of relatively small magnitude to allow a definitive conclusion about which new AED(s) has superior effectiveness. This uncertainty probably reflects the limitations of conclusions based on indirect evidence. The process of pharmacologic clinical decision making in partial refractory epilepsy probably depends more on other aspects, such as individual patient characteristics and pharmacoeconomics, than on available controlled randomized evidence.

Comparison of antiepileptic drug prescribing in children in three European countries

PURPOSE

Antiepileptic drug (AED) use in young people is increasing. However, evidence of its use at a multinational level is limited. This study aims to characterize AED prescribing in the young in three European countries and to assess the capacity of drug safety surveillance.

METHODS

A retrospective cohort study was conducted in 2001-2005 using primary care databases: PEDIANET (Italy, 0-11 years), IPCI (The Netherlands, 0-18 years), and IMS Disease Analyzer (United Kingdom, 0-18 years). Prescribing prevalence was calculated by country, patient age, and drug type.

RESULTS

In 2005, AED prevalence in children (0-11 years) was highest in Italy [3.9 subjects/1,000 person-years (PY)] followed by the United Kingdom (3.0 subjects/1,000 PY) and The Netherlands (2.2 subjects/1,000 PY). Over the study period, prescribing prevalence in 0-11 year olds was stable in all countries. In contrast, a steady rise of AED prevalence was observed in adolescents (12-18 years) in the United Kingdom (p = 0.0003) but not in The Netherlands (p = 0.88). All countries showed a slight increase in prevalence for newer AEDs. Simultaneously, the prevalence of conventional AEDs decreased in The Netherlands and Italy, but not in the United Kingdom. In 2005, lamotrigine use was highest in The Netherlands and the United Kingdom, whereas topiramate was favored in Italy.

DISCUSSION

In Europe, conventional AEDs are still the main treatment choice for children with epilepsy, and the use of newer AEDs remains low. Our study highlights a lack of research capacity to conduct multinational AED safety studies in children. Further work should explore large databases and other health care settings to meet these research needs.

Retention rates of new antiepileptic drugs in localization-related epilepsy: a single-center study

OBJECTIVES

We evaluated long-term retention rates of newer antiepileptic drugs (AED) in adults with localization-related epilepsy retrospectively.

METHODS

We estimated retention rates by Kaplan-Meier method in all 222 patients (age > or = 16) with localization-related epilepsy exposed to new AED at the Tampere University Hospital.

RESULTS

There were 141 patients exposed to lamotrigine, 78 to levetiracetam, 97 to topiramate, 68 to gabapentin, and 69 to tiagabine. Three-year retention rate for lamotrigine was 73.5%, levetiracetam 65.4%, topiramate 64.2%, gabapentin 41.7%, and tiagabine 38.2%. The most common cause for withdrawal of these AED was lack of efficacy.

CONCLUSIONS

Our study suggests that there are clinically significant differences among gabapentin, lamotrigine, levetiracetam, tiagabine, and topiramate as treatment for focal epilepsy in everyday practice. Gabapentin and tiagabine seem to be less useful than the other three AED. Furthermore, our study supports the value of retention rate studies in assessing outcome of the drugs in clinical practice.

Lamotrigine in clinical practice: long-term experience in patients with refractory epilepsy referred to a tertiary epilepsy center

Lamotrigine (LTG, Lamictal), one of the newer antiepileptic drugs, was admitted to the Dutch market in 1996. It was first used as adjunctive therapy and later as a monotherapy in partial and generalized epilepsy. All patients who started on LTG in 1996 or 1997 in the Epilepsy Centre Kempenhaeghe (n=314) were enrolled in this study and followed for 48 months. The data indicate that the retention rates for LTG after 1, 2, 3, and 4 years are respectively 74.4, 69.3, 63.1, and 55.6%. Patients with normal cognitive function were more likely to continue than patients with mental retardation. The main reason for discontinuing LTG therapy was lack of efficacy (19.1%). Four patients (1.4%) were seizure-free for the total follow-up period of 48 months. The most frequently reported negative side effects were dizziness and headache, both in patients who continued and in those who discontinued therapy. A large percentage of patients also reported positive side effects like "feeling/being more active" and "feeling more clear/more responsive." For the whole patient group, the plasma level of LTG was measured 277 times. Plasma levels of LTG were influenced by the patients' comedications. Plasma levels of LTG in groups taking LTG in monotherapy, LTG plus an inducer, and LTG plus valproate were 8.7, 4.8, and 8.7 mg/L, respectively. The correlation between measured plasma level and dose confirm the manufacturer's dose recommendations. The manufacturer recommends half the dosage of lamotrigine monotherapy when the patient also uses valproate. When the patient uses an inducer, the dosage of LTG must be two times the dose used in monotherapy.

The cost-effectiveness of newer drugs as add-on therapy for children with focal epilepsies

PURPOSE

Epilepsies in children are complex diseases. Guidelines are needed on the appropriate use of newer versus older anti-epileptic drugs (AEDs). This paper presents an individual patient-sampling model to assess the cost-effectiveness of using newer AEDs as add-on therapy in line with UK prescribing guidance.

METHODS

Identification of the relevant parameters and treatment pathways for the model were achieved by a systematic review of the literature and discussions with clinical experts. Data were obtained from the literature and supplemented with data elicited from paediatric neurologists. The model considered paediatric patients over the period of childhood from the age of diagnosis to 18 years.

RESULTS

The results suggest that the older and newer AEDs are similar in terms of drug retention rates and the average time in 'good' treatment outcomes. In terms of cost, the results indicate a consistent increase in cost (compared to older AEDs) when all of the newer AEDs are considered. The decision analysis results indicate that there are no important health benefits from the use of newer AEDs when used as add-on therapy. However, the analysis also reveals that the uncertainties in the model are greater than the differences between the drug strategies.

CONCLUSIONS

To develop guidelines on the appropriate use of newer AEDs, better information is required from randomised controlled trials as there is insufficient data available in the public domain to accurately estimate the nature of the trade off between older versus newer AEDs.

Lamotrigine in idiopathic epilepsy - increased risk of cardiac death?

OBJECTIVES

Lamotrigine (LTG) has recently been shown to inhibit the cardiac rapid delayed rectifier potassium ion current (Ikr). Ikr-blocking drugs may increase the risk of cardiac arrhythmia and sudden unexpected death. With this background, it may be of importance that in our outpatient clinic between August 1, 1995 and August 1, 2005 we registered four consecutive cases of sudden unexpected death in epilepsy (SUDEP) in non-hospitalized patients that were all being treated with LTG in monotherapy. Here we describe and discuss these cases, the relevant literature, and the reasons to question whether these events were as a result of coincidence alone.

METHODS

All the cases were collected consecutively at the outpatient clinic, Department of Neurology, Stavanger University Hospital, Norway. Clinical and pathological data were obtained and the relevant literature reviewed.

RESULTS

All were females with idiopathic epilepsy.

CONCLUSIONS

A systematic study is needed to reveal whether LTG may increase the risk of SUDEP in certain groups of patients.

Long-term retention rates of new antiepileptic drugs in adults with chronic epilepsy and learning disability

We compared the long-term retention rates of several newly licensed antiepileptic drugs (AEDs) in a residential community of adults with chronic epilepsy and learning disability. Data relating to duration of therapy, maximum dose, and tolerability of six new AEDs-gabapentin (GBP), lamotrigine (LTG), levetiracetam (LEV), oxcarbazepine (OXC), tiagabine (TIA), and topiramate (TPM)-were collected. Drug retention at 2 years was 85% (OXC), 57% (LTG), 56% (LEV), 45% (TPM), 24% (TIA) and 15% (GBP). OXC was used mainly as a substitute for carbamazepine. LTG, LEV, and TPM were all associated with retention rates higher than those of GBP or TIA. TPM had the highest rate of adverse event development at the maximum tried dose (60%), whereas LEV had the lowest (16%). Experience from this single epilepsy community study indicated limited impact for GBP or TIA but higher retention of OXC, LEV, LTG, and TPM in patients with chronic epilepsy and learning disability.

Comparison of the efficacy and tolerability of new antiepileptic drugs: what can we learn from long-term studies?

OBJECTIVE

A review of long-term open-label studies was performed with the aim of detecting differences in efficacy and/or tolerability of new antiepileptic drugs (AEDs).

METHODS

From more than 500 open studies conducted to evaluate the efficacy and tolerability of gabapentin (GBP), lamotrigine (LTG), levetiracetam (LEV), oxcarbazepine (OXC), pregabalin (PGB), tiagabine (TGB), topiramate (TPM) or zonisamide (ZNS), we selected all studies that reported or allowed us to calculate the number of patients who achieved seizure freedom for 6 months and/or the number of patients withdrawing for adverse effects and/or the number or percentage of patients continuing treatment after 1 year.

RESULTS

No studies were found in which this information was available for OXC, PGB, TGB or ZNS. The number of patients who achieved seizure freedom for 6 months was reported in four studies each for GBP and TPM, five studies for LTG, and eight studies for LEV. The best efficacy profile using this end point was found for LEV, followed by TPM, LTG, and GBP. Twenty-two studies reported the number of patients withdrawing due to adverse effects. LEV was the best-tolerated AED, a little ahead of LTG, and significantly better than GBP or TPM . TPM was by far the least well-tolerated drug. Information concerning patients continuing treatment after 1 year was reported in two GBP studies, two TPM studies, six LEV studies and five LTG studies. GBP had a very low retention rate (between 20% and 25% of patients continued the drug), while TPM and LTG had a retention rate of 40-60% and LEV had a retention rate of 60-75%.

CONCLUSION

One limitation of these rankings is that their statistical value is limited because of the indirect nature of the comparisons. Anyhow, this review covers the main studies published thus far on this subject and provides full updated information on the current literature about these drugs.

Levetiracetam: a long-term follow-up study of efficacy and safety

OBJECTIVES

To evaluate the efficacy and safety of long-term add-on treatment with levetiracetam 1,000-4,000 mg/day.

PATIENTS AND METHODS

In this multicenter, open-label follow-up study, 505 patients, from 10 European countries, who had benefited from previous add-on treatment with levetiracetam in a clinical trial or compassionate-use program were enrolled; 274 (54.3%) stayed to the end. Most then continued levetiracetam by prescription or in a named patient program, where it was not yet commercially available. Mean treatment duration was 1,045 days (range: 24 days to >7 years). Median daily dosage was 3,000 mg/day (range: 250-6,000 mg/day), with 250 (49.5%) patients receiving levetiracetam for >3 years.

RESULTS

Median total and partial seizure frequency per week over the evaluation period were 0.8 and 0.7; seizure frequency per week was generally stable over time and remained low. There was a probability of 6.6% of remaining seizure-free for the first 3 years, and of 18.9% of having a seizure-free period of at least 3 years at any time. Most adverse events were mild or moderate and unrelated to study drug. Levetiracetam was well tolerated, and provided stable seizure control during long-term treatment.

New antiepileptic drugs in practice--how do they perform in the real world?

Most large-scale clinical trials of antiepileptic drugs (AEDs) are undertaken for regulatory purposes and generate basic data supporting the efficacy and safety of a new treatment. They do not, however, provide all the information required for physicians to know how well the drug will work in clinical practice. One valuable approach to generating more clinically meaningful information is to assess AED treatment retention rates, which reflect the combination of efficacy and tolerability in the real world, and have historically been low. Long-term retention rate data are available for levetiracetam (LEV), topiramate, gabapentin, and lamotrigine, and these data suggest that LEV is more likely to retain patients than other new AEDs. In a recent tertiary care study involving mainly refractory patients, 11% of participants became seizure-free on LEV and nearly two-thirds were retained on long-term treatment. High seizure freedom rates and good tolerability reported with LEV in clinical trials thus appear to translate into improved treatment retention rates in clinical practice.

When Do Children Convert from Liquid Antiretroviral to Solid Formulations?

BACKGROUND

Liquid formulations are usually regarded as the gold standard in paediatric formulation; but sometimes, liquid formulations have stability and taste problems as well as being inconvenient for travelling. Therefore, for the management of long-term illness, some older children, parents and clinicians would prefer to use solid formulations. However, there is a lack of studies to investigate the age at which children are converted from liquid to solid formulations.

OBJECTIVES

(1) To investigate the age range at which children convert from liquid antiretroviral drug formulations to solid formulations, the formulations are abacavir, didanosine, lamivudine, stavudine, and zidovudine. (2) To calculate how long children stay on each of five UK liquid formulations (retention time) and factors affecting the retention times of the above liquid formulations.

METHOD

This was a retrospective medical records survey at Great Ormond Street Hospital for Children, London, United Kingdom. Patients' treatment details were entered into SPSS for Windows v. 11.0 and the retention times for the above liquid formulations were calculated i.e., from initiation of the liquid treatment to conversion to solid preparation. The retention times of different preparations were then compared using Cox regression analysis.

RESULTS

A total of 92 patients are included in the analysis. The overall average age at conversion was 7.3 years (95% CI 6.3-8.2). Patients on stavudine were more likely to switch to the corresponding solid dose form than the other four medicines (P < 0.001); more than 50% of patients on stavudine switched to solid formulation after nine months of treatment, however, less than 25% of patients on other formulations switched during the same period.

CONCLUSION

Children taking antiretroviral liquid preparations change to solid dose forms at approximately seven years of age. However, for stavudine, children are more likely to take the solid form at an earlier age.

Effectiveness of lamotrigine in clinical practice: Results of a retrospective population-based study

OBJECTIVE

Evaluation of the effectiveness of lamotrigine in a population-based cohort of epilepsy patients.

METHODS

Medical charts of 360 patients treated in 37 centres in The Netherlands were reviewed. Effectiveness of lamotrigine therapy was assessed during the first year of use, with patients serving as their own controls. Effectiveness was measured by reduction in seizure frequency and retention time.

RESULTS

Effectiveness could only be assessed in 165 patients; assessment in remaining patients was not possible due to various reasons, such as insufficient medical chart information. Lamotrigine was effective in 40% of patients who had been prescribed lamotrigine because of insufficient seizure control (n=112), and 14% of these 112 patients became seizure free. Duration of epilepsy, baseline seizure frequency, valproate use, drug load and number of antiepileptic drugs (AED) used were related to effectiveness of lamotrigine. In this group, 36% continued lamotrigine (LTG) throughout the first year without experiencing a >50% seizure reduction. Lamotrigine was effective in 63% of patients who received the drug because of poor tolerability of other antiepileptic drugs (n=53).

DISCUSSION

Lamotrigine is an effective drug in clinical practice. Use of retention time measures only may not correctly reflect the efficacy of antiepileptic drugs.

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.

Gonadal morphology and sex hormones in male and female Wistar rats after long-term lamotrigine treatment

Drug-induced disturbances in reproductive hormones and gonadal morphology have been observed both in patients with epilepsy and in non-epileptic animals. Less is known about the influence of newer antiepileptic drugs including lamotrigine on reproduction. Lamotrigine is now increasingly used both in epilepsy and psychiatric disorders. Sixty-five Wistar rats were fed by gastric tube either 5 mg kg(-1) lamotrigine solution (males=15, females=20) or 0 (vehicle control, males=15, females=15) twice daily for 90 days. In males, no significant differences were found in body or testicular weight. Testicular atrophy was observed in one control animal and in two of the rats receiving lamotrigine. No morphological changes were seen in the other organs investigated (liver, kidney, pancreas, brain, lymphatic tissue, heart). None of the animals showed over-expression of p53. No significant differences were observed between the control rats and the male rats receiving lamotrigine regarding testosterone, FSH and LH. In females, no changes in ovarian morphology or alterations in other tissues were observed. Serum testosterone, FSH, LH, insulin and progesterone remained unchanged in the lamotrigine treated animals, while serum estrogen was significantly reduced.

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.

Selection criteria for the clinical use of the newer antiepileptic drugs

In recent years, several new antiepileptic drugs (AEDs) have been licensed: felbamate, gabapentin, lamotrigine, levetiracetam, oxcarbazepine, tiagabine, topiramate, vigabatrin and zonisamide. These drugs have proven efficacy as add-on therapy in patients with difficult-to-treat partial epilepsy, as 20-50% of patients treated in add-on trials experienced a seizure reduction of >or=50%. Relatively few trials have been conducted to evaluate these drugs as monotherapy for patients with newly diagnosed epilepsy. In the monotherapy trials that have been conducted, the newer drugs were often as efficacious as conventional drugs, and their tolerability was often better. However, the methodology of these trials can be criticised. Because of the relative lack of robust data for the newer agents, the conventional drugs have thus far maintained their status as first-line monotherapy. However, when first-line monotherapy fails, an alternative drug has to be chosen from the available conventional and newer drugs. This article aims to give detailed background information on the newer AEDs in order to enable physicians to make a rational choice from the available drugs for individual patients. Data are provided for the different newer AEDs on mechanisms of action; efficacy in refractory partial epilepsy, newly diagnosed epilepsy in adults and generalised seizure types; adverse effects; pharmacokinetics; and use in special patient categories.

Pros and cons for the development of new antiepileptic drugs

There continues to be an escalation in the number of new antiepileptic drugs, with many recently marketed drugs and many more entering clinical trials. This growth begs the question as to whether we need additional antiepileptic drugs. We consider the answer to this question from the medical perspective and also from the viewpoint of the pharmaceutical industry, health providers and from a more global, international perspective. There is undoubtedly a medical need for new antiepileptic drugs, and despite growing competition, the antiepileptic drug market remains profitable. However, in health services with limited resources, it is important that this expense is not offset by failure to research more appropriate use of existing antiepileptic drugs that may have a greater impact on healthcare. This is especially true for developing countries where resources would be much better spent on prevention and closing the treatment gap (the difference between those who can be treated and those who are treated).

The clinical impact of new antiepileptic drugs after a decade of use in epilepsy

The introduction of numerous effective, well tolerated and safe new antiepileptic drugs (AEDs) in the last decade of the 20th century has widened the choice of treatment options in epilepsy and improved the tolerability and the ease of use of treating patients with epilepsy. Nevertheless, significant safety and efficacy deficits continue to exist. Severe idiosyncratic reactions and organ toxicity have hampered the wide use of some of the newer AEDs. As a decade before, about one third of patients with chronic epilepsy is resistant to current pharmacotherapy. Even in patients in whom pharmacotherapy is efficacious, current AED do not seem to affect the progression or the underlying natural history of epilepsy. In addition, there is currently no drug available which prevents the development of epilepsy, e.g. after head trauma. Thus, there is an unmet need for safer and more effective drugs, especially for chronic, drug-resistant epilepsy. To stimulate the development of even better compounds, the demonstrated benefits and risks of current new AEDs are reviewed.

Long-term use of gabapentin for treatment of pain after traumatic spinal cord injury

OBJECTIVE

To determine the long-term efficacy of gabapentin as a treatment of pain after spinal cord injury.

DESIGN

All patients with traumatic-onset spinal cord injury treated with gabapentin were identified and followed up using a longitudinal observational design with two contact points (6 and 36 months after the trial) using a semi-structured interview. The first follow-up interview attempted to capture all 31 patients placed on therapeutic trial. The second follow-up interview attempted to capture those reporting a favorable response (n = 14) to the therapeutic trial at the first follow-up.

RESULTS

Of the 27 patients contacted at the first follow-up (87% response rate), 6 (22%) discontinued the trial secondary to intolerable side effects; therefore, the pain analgesic effects of gabapentin in these patients could not be determined. Of the remaining 21 patients, 14 (67%) reported a favorable response (i.e., a 2 or greater point reduction on a 0-10 pain-rating scale). The second follow-up interview captured 11 (79% response rate) of the 14 patients reporting a favorable response at the first interview, and 91% (10 of 11 patients) continued to report that gabapentin was an effective analgesic. There was no evidence to suggest dosing difficulties due to tolerance over the 3-year period. Sedation, dizziness, and forgetfulness were the most common side effects.

CONCLUSIONS

Gabapentin may be an effective treatment of pain after spinal cord injury among those able to tolerate initial and long-term side effects.

The promise of new antiepileptic drugs

Epilepsy is the most common serious disorder of the brain and comprises a wide range of different conditions with varying aetiologies. The long-established antiepileptic drugs (AEDs) control seizures in 50% of patients developing partial seizures, and 60-70% of those developing generalized seizures. Several AEDs were made available in the 1990s. These drugs have efficacy, but have had only a modest impact on those with refractory epilepsies. A 50% seizure reduction, which is commonly used as an endpoint in clinical trials, confers little benefit to a patient. Of the newer AEDs, lamotrigine and oxcarbazepine are now licensed for use as monotherapy and vigabatrin has a monotherapy licence for infantile spasms. Careful and prolonged postmarketing surveillance is essential to detect adverse effects, which may not be evident in premarketing clinical trials. At this time, there are 10 AEDs currently in varying stages of clinical development. Current strategies for selecting an AED for a particular patient are crude. Magnetic resonance spectroscopic measures of cerebral neuro-transmitters and genetic analysis may allow better prediction of which drug is most likely to be efficacious and to have low risk of adverse effects. Present AEDs suppress the occurrence of seizures. Agents that prevent the development of epilepsy and which protect the brain from the consequences of seizures would be of great value, but it will be difficult to prove their effectiveness. At present AEDs are given continually and systemically. Local drug delivery is feasible and could avoid the adverse effects of AEDs. The combination of local drug delivery with prediction of seizure occurrence could revolutionize the treatment of currently refractory epilepsies.

Direct medical costs of refractory epilepsy incurred by three different treatment modalities: a prospective assessment

PURPOSE

More than 20% of epilepsy patients have refractory seizures. Treatment options for these patients include continued polytherapy with/without novel antiepileptic drugs (AEDs), epilepsy surgery (ES), or vagus nerve stimulation (VNS). The purpose of this study was prospectively to compare epilepsy-related direct medical costs (ERDMCs) incurred by these different treatment modalities.

METHODS

Eighty-four patients underwent a complete presurgical evaluation protocol at our institution. As a result, 24 (29%) patients were treated with continued AED polytherapy only; 35 (40%) underwent ES; and 25 (30%) had VNS. In each patient, annual costs in the 2 years preceding the therapeutic decision (ERDMC-pre) and during the follow-up afterward (ERDMC-post) were prospectively calculated. Furthermore, frequency of complex partial seizures with/without secondary generalization (CPS+/-SG), dosage and number of AEDs, number of hospital admission days, clinic visits, and laboratory tests before and after the therapeutic decision also were prospectively assessed. ERDMC-pre and ERDMC-post were compared in and among the three treatment groups.

RESULTS

In patients conservatively treated with AEDs, mean frequency of CPSs decreased from 12 per month to nine per month, whereas mean ERDMCs decreased from $2,525 U.S. to $2,421 U.S. In surgical patients, mean seizure frequency decreased from six to fewer than one per month; mean ERDMCs per year decreased from $1,465 U.S. preoperatively to $1,186 U.S. postoperatively. In the VNS group, mean seizure frequency decreased from 21 per month to seven per month. ERDMCs in this subgroup decreased from $4,826 U.S. to $2,496 U.S. Mean seizure frequency changes were significant when conservatively treated patients were compared with surgically treated and VNS patient groups (chi2 test, p<0.001 and p=0.0019, respectively). ERDMC changes in conservatively treated patients also were statistically significant when compared with surgically treated and VNS patients (chi2 test, p=0.0007 and p=0.0036, respectively). No statistically significant differences were found in ERDMC changes between the surgical and VNS groups (chi2 test, p=0.387).

CONCLUSIONS

Ongoing daily treatment of patients who underwent resective surgery costs significantly less than conservative treatment. For patients in whom resective surgery is not an option, ERDMC show a significant decrease in VNS-treated patients compared with conservatively treated patients.

Levetiracetam: a novel antiepileptic drug

Levetiracetam is a new antiepileptic drug, structurally and mechanistically dissimilar to other marketed antiepileptic drugs. It is effective in reducing partial seizures in patients with epilepsy, both as adjunctive treatment and as monotherapy. Levetiracetam has many therapeutic advantages for patients with epilepsy. It has favorable pharmacokinetic characteristics (good bioavailability, linear pharmacokinetics, insignificant protein binding, lack of hepatic metabolism, and rapid achievement of steady-state concentrations) and a low potential for drug interactions. Recommended starting dosages are considered to be clinically effective; therefore, patients can have some protection from seizures soon after they begin levetiracetam. The most common adverse effects observed with levetiracetam are mild and include somnolence, asthenia, and dizziness. Clinical experience and data from meta-analyses indicate that levetiracetam is well tolerated, with efficacy comparable or slightly better than that observed with other new antiepileptic drugs. Levetiracetam may be particularly useful in patients who are unresponsive to other antiepileptic drugs, patients receiving drugs with increased potential for drug interactions, or those with hepatic impairment.

A pharmacoepidemiologic study of factors influencing the outcome of treatment with lamotrigine in chronic epilepsy

PURPOSE

To identify prognostic factors for freedom from seizures and long-term retention of treatment in patients receiving lamotrigine (LTG).

METHODS

A multicenter, retrospective, case record study of 1,050 patients with chronic epilepsy was carried out. Logistic regression and Cox regression analyses were used to identify clinical features associated with freedom from seizures and retention of treatment, respectively. Long-term retention rates of LTG therapy were estimated using Kaplan-Meier survival analysis.

RESULTS

The 1,050 patients with chronic epilepsy were included in the study. Patients with generalized epilepsy (p = 0.01), who were not receiving carbamazepine (CBZ; p = 0.02) were more likely to become seizure-free. Sixty percent of patients continued on LTG therapy >1 year and estimated retention at 8 years was 38%. Patients with generalized epilepsy (p = 0.002), patients receiving concurrent sodium valproate (VPA; p < 0.0001), those not previously exposed to gabapentin and vigabatrin (p < 0.0001), and those in whom the starting dose was lower (p < 0.0012), were more likely to remain on long-term treatment with LTG. The relationships with exposure to other antiepileptic drugs remained significant in patients with focal and with generalized epilepsy when considered separately.

CONCLUSIONS

The best results from LTG treatment in terms of freedom from seizures and long-term retention of treatment were obtained in patients with generalized epilepsy. Retention of treatment was enhanced by VPA not only in generalized but also in focal epilepsy. The importance of a low starting dose of LTG was again confirmed. The apparent negative effect of CBZ in patients taking LTG merits further investigation.

Vagus nerve stimulation for refractory epilepsy

Vagus nerve stimulation (VNS) is a neurophysiological treatment for patients with medically or surgically refractory epilepsy. Since the first human implant in 1989, more than 10 000 patients have been treated with VNS. Two randomized controlled studies have shown a statistically significant decrease in seizure frequency during a 12-week treatment period versus a baseline period when 'high stimulation' mode was compared with 'low stimulation' mode. The efficacy appears to increase over time. In general, one third of the patients show a >50% reduction of seizure frequency; one third show a 30-50% seizure reduction, and one third of patients show no response. Few patients become seizure-free. Side effects during stimulation are mainly voice alteration, coughing, throat paraesthesia and discomfort. When studied on a long-term basis, VNS is an efficacious, safe and cost-effective treatment not only in adults but also in children and the elderly. The precise mechanism of action remains to be elucidated. In recent years much progress has been made through neurophysiological, neuroanatomical, neurochemical and cerebral blood flow studies in animals and patients treated with VNS. Further elucidation of the mechanism of action of VNS may increase its clinical efficacy and our general understanding of some physiopathological aspects of epilepsy. Finally, VNS may become an alternative treatment for other conditions such as depression and pain.

Efficacy of clobazam as add-on therapy in patients with refractory partial epilepsy

PURPOSE

Clobazam (CLB) has an important antiepileptic effect and is less expensive than the new antiepileptic drugs (AEDs), but still has not been considered as first-line drug in the treatment of epilepsy. We evaluated the efficacy of CLB as add-on therapy in patients with refractory partial epilepsy.

METHODS

This was an open, retrospective study, conducted at the epilepsy clinic of our university hospital. All patients had chronic epilepsy and were being evaluated for epilepsy surgery. CLB was introduced as add-on therapy (starting with 10 mg/ day) in patients with previous failure of at least two AEDs. Information was obtained from clinical notes and follow-up visits.

RESULTS

We evaluated 97 patients, 37 men and 60 women. Ages ranged from 15 to 70 years (mean, 35.8 years). Etiology of epilepsy was hippocampal atrophy in 67 (69%), cortical dysgenesis in nine (9.3%), and other etiologies in nine (9.3%). In 12 (12.3%) patients, the etiology of epilepsy was not identified despite clinical and neurologic investigation. Patients used CLB for a period ranging from 1 month to 7 years and 9 months (mean, 16.7 months) with doses ranging from 10 to 60 mg/day (mean, 29.7 mg/day). Seven (7.2%) patients were seizure free, 48 (49.4%) had > or =50% of improvement in seizure control, 39 (40.2%) had <50% of improvement in seizure control, and in three (3.1%), no data were available.

CONCLUSIONS

We conclude that CLB may have efficacy equivalent to that of the new AEDs when used as add-on therapy in patients with refractory epilepsy. CLB should be considered an economic alternative in the treatment of patients with refractory epilepsy.

Adverse reactions to new anticonvulsant drugs

A lack of systematic pharmacoepidemiological studies investigating adverse drug reactions (ADRs) to anticonvulsants makes it difficult to assess accurately the incidence of anticonvulsant-related ADRs. Most of the available information in this regard stems from clinical trial experience, case reports and postmarketing surveillance, sources that are not, by any means, structured to provide precise data on adverse event epidemiology. For various ethical, statistical and logistical reasons, the organisation of structured clinical trials that are likely to provide substantial data on ADRs is extremely difficult. This review concentrates on current literature concerning serious and life-threatening ADRs. As with the older anticonvulsants, the majority of ADRs to newer anticonvulsants are CNS-related, although there are several that are apparently unique to some of these new drugs. Gabapentin has been reported to cause aggravation of seizures, movement disorders and psychiatric disturbances. Felbamate should only be prescribed under close medical supervision because of aplastic anaemia and hepatotoxicity. Lamotrigine causes hypersensitivity reactions that range from simple morbilliform rashes to multi-organ failure. Psychiatric ADRs and deterioration of seizure control have also been reported with lamotrigine treatment. Oxcarbazepine has a safety profile similar to that of carbamazepine. Hyponatraemia associated with oxcarbazepine is also a problem; however, it is less likely to cause rash than carbamazepine. Nonconvulsive status epilepticus has been reported frequently with tiagabine, although there are insufficient data at present to identify risk factors for this ADR. Topiramate frequently causes cognitive ADRs and, in addition, also appears to cause word-finding difficulties, renal calculi and bodyweight loss. Vigabatrin has been reported to cause seizure aggravation, especially in myoclonic seizures. There have been rare reports of other neurological ADRs to vigabatrin, such as encephalopathy, aphasia and motor disturbances. Vigabatrin-induced visual field constriction is the latest and most worrying ADR. Many questions regarding the nature of this potentially serious ADR remain unanswered, as no prospective controlled study examining the phenomenon has been published. Rare cases of behavioural ADRs and IgA and IgG2 deficiency associated with the use of zonisamide have been reported. However, relatively few patients so far have been exposed to this drug, and therefore more postmarketing information is required. The relatively late establishment of aplastic anaemia and hepatic failure as potentially fatal ADRs of felbamate, and of visual field constriction with vigabatrin, should serve as ample reminders that ADRs can appear at any time.

A comparison of four new antiepileptic medications

In order to select a new medication for a patient with epilepsy, it would be helpful to have an idea of which drug might have the greatest overall chance for success. Since epilepsy is a chronic disorder, the long-term effectiveness and tolerability of the medications are very important. Here, we compared gabapentin, lamotrigine, topiramate and vigabatrin using Kaplan-Meier survival analysis to see how long patients chose to stay on each drug and if they stopped, why they stopped. The results seem to suggest the type of responses to be expected in a hospital seizure clinic.