A pilot tolerability and efficacy study of levetiracetam in patients with chronic myoclonus

Antiseizure Drugs and Movement Disorders

The relationship between antiseizure drugs and movement disorders is complex and not adequately reviewed so far. Antiseizure drugs as a treatment for tremor and other entities such as myoclonus and restless leg syndrome is the most common scenario, although the scientific evidence supporting their use is variable. However, antiseizure drugs also represent a potential cause of iatrogenic movement disorders, with parkinsonism and tremor the most common disorders. Many other antiseizure drug-induced movement disorders are possible and not always correctly identified. This review was conducted by searching for all the possible combinations between 15 movement disorders (excluding ataxia) and 24 antiseizure drugs. The main objective was to describe the movement disorders treated and worsened or induced by antiseizure drugs. We also summarized the proposed mechanisms and risk factors involved in the complex interaction between antiseizure drugs and movement disorders. Antiseizure drugs mainly used to treat movement disorders are clonazepam, gabapentin, lacosamide, levetiracetam, oxcarbazepine, perampanel, phenobarbital, pregabalin, primidone, topiramate, and zonisamide. Antiseizure drugs that worsen or induce movement disorders are cenobamate, ethosuximide, felbamate, lamotrigine, phenytoin, tiagabine, and vigabatrin. Antiseizure drugs with a variable effect on movement disorders are carbamazepine and valproate while no effect on movement disorders has been reported for brivaracetam, eslicarbazepine, lacosamide, and stiripentol. Although little information is available on the adverse effects or benefits on movement disorders of newer antiseizure drugs (such as brivaracetam, cenobamate, eslicarbazepine, lacosamide, and rufinamide), the evidence collected in this review should guide the choice of antiseizure drugs in patients with concomitant epilepsy and movement disorders. Finally, these notions can lead to a better understanding of the mechanisms involved in the pathophysiology and treatments of movement disorders.

Disorders of Movement due to Acquired and Traumatic Brain Injury

Purpose of Review

Both traumatic and acquired brain injury can result in diffuse multifocal injury affecting both the pyramidal and extrapyramidal tracts. Thus, these patients may exhibit signs of both upper motor neuron syndrome and movement disorder simultaneously which can further complicate diagnosis and management. We will be discussing movement disorders following acquired and traumatic brain injury.

Recent Findings

Multiple functions including speech, swallowing, posture, mobility, and activities of daily living can all be affected. Medical treatment and rehabilitation-based therapy can be especially challenging due to accompanying cognitive deficits and severity of the disorder which can involve multiple limbs in addition to muscles of the face and axial skeleton. Tremor and dystonia are the most reported movement disorders following traumatic brain injury. Dystonia and myoclonus are well documented following hypoxic ischemic brain injuries. Electrophysiological studies such as dynamic surface poly-electromyography can assist with identifying phenomenology, especially differentiating between jerk-like phenomenon and help guide further work up and management. Management with medications remains challenging due to potential adverse effects. Surgical interventions including stereotactic surgery, deep brain stimulation, and intrathecal baclofen pumps have been reported, but most of the evidence supporting them has been limited to primarily case reports except for post-traumatic tremor.

Summary

Brain injury can lead to motor disorders, movement disorders, visual (processing) deficits, and vestibular deficits which often coexist with cognitive deficits making it challenging to treat and rehabilitate these patients. Unfortunately, the evidence regarding the medical management and rehabilitation of brain injury patients with movement disorders is sparse and leaves much to be desired.

Assessment and Treatment of Myoclonus: A Review

Myoclonus is defined as sudden, brief, shock-like contractions of muscles, and it can be a challenging diagnosis for the clinician to face. The number of aetiologies can make it difficult to determine the appropriate diagnostic workup for each individual patient without ordering a broad array of diagnostic studies from the start. As with other neurological conditions, a comprehensive history and physical examination are paramount in generating and ordering the initial differential diagnosis. Neurophysiological classification of myoclonus, using both electroencephalogram and electromyography, can be very helpful in elucidating the underlying aetiology. Treatment of myoclonus is often symptomatic, unless a clear treatable underlying cause can be found. This article aims to help providers navigate the assessment and treatment of myoclonus, focusing on neurophysiological classification as a guide. By the end of this article, providers should have a good understanding of how to approach the workup and treatment of myoclonus of various aetiologies.

Myoclonus- A Review

Myoclonus is a hyperkinetic movement disorder characterized by a sudden, brief, involuntary jerk. Positive myoclonus is caused by abrupt muscle contractions, while negative myoclonus by sudden cessation of ongoing muscular contractions. Myoclonus can be classified in various ways according to body distribution, relation to activity, neurophysiology, and etiology. The neurophysiological classification of myoclonus by means of electrophysiological tests is helpful in guiding the best therapeutic strategy. Given the diverse etiologies of myoclonus, a thorough history and detailed physical examination are key to the evaluation of myoclonus. These along with basic laboratory testing and neurophysiological studies help in narrowing down the clinical possibilities. Though symptomatic treatment is required in the majority of cases, treatment of the underlying etiology should be the primary aim whenever possible. Symptomatic treatment is often not satisfactory, and a combination of different drugs is often required to control the myoclonus. This review addresses the etiology, classification, clinical approach, and management of myoclonus.

[A case of the successful treatment of severe myoclonus with Lance-Adams syndrome by add-on perampanel showing long term effects]

Perampanel is an α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor antagonist that has been marked as an antiepileptic drug for partial-onset and primary generalized tonic-clonic seizures. There have been some recent reports of perampanel being effective against cortical myoclonus by Lafora disease and Unverricht-Lundborg disease. We herein report a 49-year-old man who presented with myoclonus due to Lance-Adams syndrome (LAS) after cardiopulmonary arrest caused by a severe bronchial asthma attack. Perampanel was very effective against myoclonus induced by LAS even in the chronic state, over 10 years after the remote onset. Perampanel should be considered for the treatment of extremely refractory myoclonus due to LAS.

Myoclonus

PURPOSE OF REVIEW

This article offers clinicians a strategic approach for making sense of a symptom complex that contains myoclonus. The article presents an evaluation strategy that highly leverages the two major classification schemes of myoclonus. The goal of this article is to link evaluation strategy with diagnosis and treatment of myoclonus.

RECENT FINDINGS

The growth of medical literature has helped better define myoclonus etiologies. Physiologic study of myoclonus types and etiologies with electrophysiologic testing has provided greater clarity to the pathophysiology of the myoclonus in various diseases. Although studies have been limited, the role of newer treatment agents and methods has made progress.

SUMMARY

Myoclonus has hundreds of different etiologies. Classification is necessary to evaluate myoclonus efficiently and pragmatically. The classification of myoclonus etiology, which is grouped by different clinical presentations, helps determine the etiology and treatment of the myoclonus. The classification of myoclonus physiology using electrophysiologic test results helps determine the pathophysiology of the myoclonus and can be used to strategize symptomatic treatment approaches. Both basic ancillary testing (including EEG and imaging) and more comprehensive testing may be necessary. Treatment of the underlying etiology is the ideal approach. However, if such treatment is not possible or is delayed, symptomatic treatment guided by the myoclonus physiology should be considered. More controlled study of myoclonus treatment is needed. Further research on myoclonus generation mechanisms should shed light on future treatment possibilities.

Levetiracetam and brivaracetam: a review of evidence from clinical trials and clinical experience

Until the early 1990s, a limited number of antiepileptic drugs (AEDs) were available. Since then, a large variety of new AEDs have been developed and introduced, several of them offering new modes of action. One of these new AED families is described and reviewed in this article. Levetiracetam (LEV) and brivaracetam (BRV) are pyrrolidone derivate compounds binding at the presynaptic SV2A receptor site and are thus representative of AEDs with a unique mode of action. LEV was extensively investigated in randomized controlled trials and has a very promising efficacy both in focal and generalized epilepsies. Its pharmacokinetic profile is favorable and LEV does not undergo clinically relevant interactions. Adverse reactions comprise mainly asthenia, somnolence, and behavioral symptoms. It has now been established as a first-line antiepileptic drug. BRV has been recently introduced as an adjunct antiepileptic drug in focal epilepsy with a similarly promising pharmacokinetic profile and possibly increased tolerability concerning psychiatric adverse events. This review summarizes the essential preclinical and clinical data of LEV and BRV that is currently available and includes the experiences at a large tertiary referral epilepsy center.

Increasing Evidence for the Use of Sodium Oxybate in Multi-Drug-Resistant Lance-Adams Syndrome

Background

Treatment of posthypoxic myoclonus (PHM) can be a challenge in patients not responsive to first-line medications. PMH is a rare condition that has a dramatic impact on patients' quality of life. Refractory cases are not uncommon.

Case report

We report a patient with PHM non-responsive to conventional treatments who showed a dramatic improvement with sodium oxybate (SBX). Cases of PHM treated with SBX reported in the literature were reviewed.

Discussion

Resting and stimulus-induced myoclonus respond robustly to SBX, with significant improvement in patients' quality of life. SBX may be considered in patients with PHM resistant to first-line medications.

Update on Pharmacological Treatment of Progressive Myoclonus Epilepsies

BACKGROUND

Progressive myoclonus epilepsies (PMEs) are a group of rare inherited diseases featuring a combination of myoclonus, seizures and variable degree of cognitive impairment. Despite extensive investigations, a large number of PMEs remain undiagnosed. In this review, we focus on the current pharmacological approach to PMEs.

METHODS

References were mainly identified through PubMed search until February 2017 and backtracking of references in pertinent studies.

RESULTS

The majority of available data on the efficacy of antiepileptic medications in PMEs are primarily anecdotal or observational, based on individual responses in small series. Valproic acid is the drug of choice, except for PMEs due to mitochondrial diseases. Levetiracetam and clonazepam should be considered as the first add-on treatment. Zonisamide and perampanel represent promising alternatives. Phenobarbital and primidone should be reserved to patients with resistant disabling myoclonus or seizures. Lamotrigine should be used with caution due to its unpredictable effect on myoclonus. Avoidance of drugs known to aggravate myoclonus and seizures, such as carbamazepine and phenytoin, is paramount. Psychiatric (in particular depression) and other comorbidities need to be adequately managed. Although a 3- to 4-drug regimen is often necessary to control seizures and myoclonus, particular care should be paid to avoid excessive pharmacological load and neurotoxic side effects. Target therapy is possible only for a minority of PMEs.

CONCLUSIONS

Overall, the treatment of PMEs remains symptomatic (i.e. pharmacological treatment of seizures and myoclonus). Further dissection of the genetic background of the different PMEs might hopefully help in the future with individualised treatment options.

An Update on Myoclonus Management

INTRODUCTION

Myoclonus is a hyperkinetic movement disorder characterized by sudden, brief, lightning-like involuntary jerks. There are many possible causes of myoclonus and both the etiology and characteristics of the myoclonus are important in securing the diagnosis and treatment. Myoclonus may be challenging to treat, as it frequently requires multiple medications for acceptable results. Few randomized controlled trials investigating the optimal treatment for myoclonus are available, and expert experience and case series guide treatment. Areas Covered: In this article, the authors review the basics of myoclonus and its classification. The authors discuss the current management of myoclonus and then focus on recent updates in the literature, including both pharmacologic and surgical options. Expert opinion: Myoclonus remains a challenge to manage, and there is a paucity of rigorous clinical trials guiding treatment paradigms. Furthermore, due to the etiological heterogeneity of myoclonus, defining the appropriate scope for high-quality clinical trials is challenging. In order to advance the field, the myoclonus study group needs to be revived in the US and abroad so that interested investigators can collaborate on multicenter clinical trials for myoclonus treatments.

Improvement of Post-hypoxic Myoclonus with Bilateral Pallidal Deep Brain Stimulation: A Case Report and Review of the Literature

Background

Post-hypoxic myoclonus (PHM) is a syndrome that occurs when a patient has suffered hypoxic brain injury. The myoclonus is usually multifocal and generalized, often stemming from both cortical and subcortical origins. In severe cases, pharmacological treatments with antiepileptic medications may not satisfactorily control the myoclonus.

Methods

We present a case of a 23-year-old male with chronic medication refractory PHM following a cardiopulmonary arrest related to an asthmatic attack who improved with bilateral globus pallidus internus (GPi) deep brain stimulation (DBS). We review the clinical features of PHM, as well as the preoperative and postoperative Unified Myoclonus Rating Scale scores and DBS programming parameters in this patient and compare them with the three other published PHM-DBS cases in the literature.

Results

This patient experienced an alleviation of myoclonic jerks at rest and a 39% reduction in action myoclonus with improvement in both positive and negative myoclonus with bilateral GPi-DBS. High frequency stimulation (130 Hz) with amplitudes >2.5 V were needed for the therapeutic response.

Discussion

We demonstrate a robust improvement in a medication refractory PHM patient with bilateral GPi-DBS, and suggest that it is a viable therapeutic option for debilitating post-hypoxic myoclonus.

Levetiracetam in the management of feline audiogenic reflex seizures: a randomised, controlled, open-label study

Objectives

Currently, there are no published randomised, controlled veterinary trials evaluating the efficacy of antiepileptic medication in the treatment of myoclonic seizures. Myoclonic seizures are a hallmark of feline audiogenic seizures (FARS).

Methods

This prospective, randomised, open-label trial compared the efficacy and tolerability of levetiracetam (20–25 mg/kg q8h) with phenobarbital (3–5 mg/kg q12h) in cats with suspected FARS that experienced myoclonic seizures. Cats were included that had ⩾12 myoclonic seizure days during a prospective 12 week baseline period. This was followed by a 4 week titration phase (until a therapeutic serum concentration of phenobarbital was achieved) and a 12 week treatment phase.

Results

Fifty-seven cats completed the study: 28 in the levetiracetam group and 29 in the phenobarbital group. A reduction of ⩾50% in the number of myoclonic seizure days was seen in 100% of patients in the levetiracetam group and in 3% of patients in the phenobarbital group ( P <0.001) during the treatment period. Levetiracetam-treated cats had higher freedom from myoclonic seizures (50.0% vs 0%; P <0.001) during the treatment period. The most common adverse events were lethargy, inappetence and ataxia, with no difference in incidence between levetiracetam and phenobarbital. Adverse events were mild and transient with levetiracetam but persistent with phenobarbital.

Conclusions and relevance

These results suggest that levetiracetam is an effective and well tolerated treatment for cats with myoclonic seizures and is more effective than phenobarbital. Whether it will prevent the occurrence of generalised tonic–clonic seizures and other forebrain signs if used early in the course of FARS is not yet clear.

A randomized, controlled, double-blind, crossover trial of zonisamide in myoclonus-dystonia

OBJECTIVE

To evaluate the efficacy and safety of zonisamide in patients with myoclonus-dystonia.

METHODS

We conducted a randomized, double-blind, placebo-controlled crossover trial of zonisamide (300 mg/d) in 24 patients with myoclonus-dystonia. Each treatment period consisted of a 6-week titration phase followed by a 3-week fixed-dose phase. The periods were separated by a 5-week washout period. The co-primary outcomes were action myoclonus severity (section 4 of the Unified Myoclonus Rating Scale [UMRS 4]) and myoclonus-related functional disability (UMRS 5). Secondary outcomes included dystonia severity, assessed with the movement and disability subscales of the Burke-Fahn-Marsden-Dystonia Rating Scale (BFM), the Clinical Global Impression-Improvement scale (CGI), and safety measures. Wilcoxon signed-rank tests for paired data were used to analyze treatment effects.

RESULTS

Twenty-three patients (11 men, 12 women) were analyzed in the intention-to-treat analysis. Zonisamide significantly improved both action myoclonus (median improvement [95% confidence limits] -5 [-9.25 to -1.44], p = 0.003) and myoclonus-related functional disability (median improvement [95% confidence limits] -2 [-2.58 to -2.46], p = 0.007) compared to placebo. Zonisamide also significantly improved dystonia (BFM movement) compared to placebo (median improvement [95% confidence limits] -3 [-8.46 to 0.03], p = 0.009). No difference was found between zonisamide and placebo with respect to the CGI (median improvement [95% confidence limits] -1 [-1.31 to 0.09], p = 0.1). Zonisamide was well-tolerated.

CONCLUSIONS

Zonisamide is well-tolerated and effective on the motor symptoms of myoclonus-dystonia.

CLASSIFICATION OF EVIDENCE

This study provides Class I evidence that zonisamide improves myoclonus and related disability in patients with myoclonus-dystonia.

Network dysfunction in α-synuclein transgenic mice and human Lewy body dementia

Objective

Dementia with Lewy bodies (DLB) is associated with the accumulation of wild‐type human α‐synuclein (SYN) in neurons and with prominent slowing of brain oscillations on electroencephalography (EEG). However, it remains uncertain whether the EEG abnormalities are actually caused by SYN.

Methods

To determine whether SYN can cause neural network abnormalities, we performed EEG recordings and analyzed the expression of neuronal activity‐dependent gene products in SYN transgenic mice. We also carried out comparative analyses in humans with DLB.

Results

We demonstrate that neuronal expression of SYN in transgenic mice causes a left shift in spectral power that closely resembles the EEG slowing observed in DLB patients. Surprisingly, SYN mice also had seizures and showed molecular hippocampal alterations indicative of aberrant network excitability, including calbindin depletion in the dentate gyrus. In postmortem brain tissues from DLB patients, we found reduced levels of calbindin mRNA in the dentate gyrus. Furthermore, nearly one quarter of DLB patients showed myoclonus, a clinical sign of aberrant network excitability that was associated with an earlier age of onset of cognitive impairments. In SYN mice, partial suppression of epileptiform activity did not alter their shift in spectral power. Furthermore, epileptiform activity in human amyloid precursor protein transgenic mice was not associated with a left shift in spectral power.

Interpretation

We conclude that neuronal accumulation of SYN slows brain oscillations and, in parallel, causes aberrant network excitability that can escalate into seizure activity. The potential role of aberrant network excitability in DLB merits further investigation.

Progressive myoclonic epilepsy type 1: Report of an Emirati family and literature review

PURPOSE

Progressive myoclonic epilepsy type one is a neurodegenerative disorder characterized by action- and stimulus-sensitive myoclonus, tonic-clonic seizures, progressive cerebellar ataxia, preserved cognition, and poor outcome. The authors report clinical, neurophysiological, radiological, and genetic findings of an Emirati family with five affected siblings and review the literature.

METHODS

All data concerning familial and clinical history, neurologic examination, laboratory tests, electroencephalogram, brain imaging, and DNA analysis were examined.

RESULTS

Genetic testing confirmed the diagnosis of autosomal recessive progressive myoclonic epilepsy type 1 (EPM1) in two males and three females. The median age at onset was three years. Action- or stimulus-sensitive myoclonus and generalized seizures were recorded in 100% of our patients, at median age at onset of 3 and 4 years, respectively. Multisegmental myoclonus and generalized status myoclonicus were observed in 80% of our patients. Dysarthria and ataxia developed in 100% of our patients. Vitamin D deficiency and recurrent viral infections were noticed in 100% of our cohort. Cognitive, learning, and motor dysfunctions were involved in 100% of our patients. The sphincters were affected in 60% of our patients. Abnormal EEG was recorded in 100% of our cohort. Generalized brain atrophy progressively occurred in 60% of our patients. Phenytoin and carbamazepine were used in 60% of our patients with worsening effect. Valproate and levetiracetam were used in 100% of our patients with improving effect.

CONCLUSIONS

This is the first to report a family with EPM1 in UAE. Our study emphasized a particular phenotype expressed as earlier disease onset, severe myoclonus, and generalized seizures. Cognitive, cerebellar, motor, and autonomic dysfunctions and brain atrophy were also earlier at onset and more severe than previously reported. Recurrent viral infections are another unique feature. This constellation in tout à fait was not previously reported in the literature.

Treatment of myoclonus

Myoclonus creates significant disability for patients. This symptom or sign can have many different etiologies, presentations, and pathophysiological mechanisms. A thorough evaluation for the myoclonus etiology is critical for developing a treatment strategy. The best etiological classification scheme is a modified version from that proposed by Marsden et al. in 1982. Clinical neurophysiology, as assessed by electromyography and electroencephalography, can be used to classify the pathophysiology of the myoclonus using a neurophysiology classification scheme. If the etiology of the myoclonus cannot be reversed or treated, then symptomatic treatment of the myoclonus itself may be warranted. Unfortunately, there are few controlled studies for myoclonus treatments. The treatment strategy for the myoclonus is best derived from the neurophysiology classification scheme categories: 1) cortical, 2) cortical-subcortical, 3) subcortical-nonsegmental, 4) segmental, and 5) peripheral. A cortical physiology classification is most common. Levetiracetam is suggested as first-line treatment for cortical myoclonus, but valproic acid and clonazepam are commonly used. Cortical-subcortical myoclonus is the physiology demonstrated by myoclonic seizures, such as in primary epileptic myoclonus (e.g., juvenile myoclonic epilepsy). Valproic acid has demonstrated efficacy in such epileptic syndromes with other medications providing an adjunctive role. Clonazepam is used for subcortical-nonsegmental myoclonus, but other treatments, depending on the syndrome, have been used for this physiological type of myoclonus. Segmental myoclonus is difficult to treat, but clonazepam and botulinum toxin are used. Botulinum toxin is used for focal examples of peripheral myoclonus. Myoclonus treatment is commonly not effective and/or limited by side effects.

Postanoxic myoclonus: two case presentations and review of medical management

Postanoxic myoclonus is a rare manifestation after an anoxic event, with fewer than 150 cases reported in the literature. The condition is characterized by myoclonic jerks, which are worse on action than at rest, and postural lapses, ataxia, and dysarthria. The disability caused by postanoxic myoclonus can be profound, and treatment in the rehabilitation setting is exceptionally challenging. We present 2 patients who suffered from postanoxic myoclonus after an anoxic event, both of whom were successfully treated with a combination of levetiracetam, valproic acid, and clonazepam. These cases act as a framework for discussing the management of postanoxic myoclonus in the clinical setting.

Myoclonus

Myoclonus is a hyperkinetic movement disorder characterized by quick, involuntary jerks. It encompasses a vast range of etiologies and widespread anatomic locations. Treatment frequently requires multiple agents and is often only partially beneficial. These patients pose a considerable challenge for the clinician, further complicated by the fact that many of the treatment choices lack evidence-based support. In the past few years, publications regarding therapy have been largely observational case reports or series. Although the literature on treatment of cortical myoclonus appears to be growing, evidence regarding myoclonus of noncortical origin is less well established. Investigation of more satisfactory treatments is needed, as this condition can be disturbing, debilitating, and sometimes harmful for patients. Continuing investigations are using various animal models (mostly of posthypoxic myoclonus), electrophysiologic studies, new imaging techniques such as diffusion tensor imaging, and genetic studies. Meanwhile, the clinical approach to diagnosing and classifying myoclonus remains largely unchanged. This review updates readers on current investigations and suggests guidelines for diagnosing and treating myoclonus.

Lance-adams syndrome

It is not common for a patient who survives cardiac arrest to experience significant neurologic impairment such as acute and chronic post-hypoxic myoclonus, known as Lance-Adams syndrome. This syndrome is predominantly characterized by myoclonus that starts days to weeks after cardiopulmonary resuscitation in patients who regained consciousness. Although several cases of LAS were reported, the decisive treatment method has not been established. We report a 43 year old man with Lance-Adams syndrome who showed long-term improvement through treatment with anti-myoclonic agents and participation in a rehabilitation program.

Simultaneous quantification of levetiracetam and gabapentin in plasma by ultra-pressure liquid chromatography coupled with tandem mass spectrometry detection

INTRODUCTION

Gabapentin (Neurontin) and levetiracetam (Keppra) are anticonvulsants with novel structures and suggested therapeutic ranges of 2-10 mg/L and 6-20 mg/L, respectively. Gabapentin is also used extensively to manage neuropathic pain, and for this indication, wherein higher doses are prescribed, plasma concentrations of 15-30 mg/L are typical.

OBJECTIVE

Here, we describe a simple rapid assay to support therapeutic drug monitoring of gabapentin and levetiracetam in plasma by ultra-pressure liquid chromatography couples to tandem mass spectrometry (UPLC-MS/MS) detection.

METHODS

After the addition of internal standard and protein precipitation of patient plasma with methanol:acetonitrile in a 50:50 ratio, 1 μL of supernatant sample is injected onto an Acquity UPLC HSS T3, 1.8 μm, 2.1 × 50 mm (Waters) column. Elution occurs using a linear gradient of acetonitrile and water, each having 0.1% formic acid added. The column is eluted into a Waters Acquity UPLC TQD, operating in a positive mode to detect gabapentin at transition 172.18 > 154.11, levetiracetam at 171.11 > 126, and internal standard (3-amino-2-naphthoic acid) at 188.06 > 170. Secondary transitions for each analyte are also monitored for gabapentin at 172.18 > 137.06, levetiracetam at 171.11 > 154, and internal standard at 188.06 > 115. Runtime is 1.5 minutes per injection with baseline resolved chromatographic separation.

RESULTS

The analytical measurement ranges were 1-150 mg/L for gabapentin and for levetiracetam. Intra-assay imprecision by the coefficient of variance (CV) was less than 8% and interassay CV was less than 5% for both analytes, at 4 different concentrations. Results obtained from patient samples were compared with results generated by established high-performance liquid chromatography-UV methods with the following regression statistics: y = 1.12x - 0.77, r = 0.996, Sy, x = 0.89, and n = 29 for gabapentin and y = 0.991x + 0.70, r = 0.997, Sy, x = 2.24, and n = 30 for levetiracetam. No analytical interferences were identified.

CONCLUSION

: In summary, a simple reliable UPLC-MS/MS method was developed and validated for routine clinical monitoring of gabapentin and levetiracetam.

Myoclonus

Myoclonus can be classified as physiologic, essential, epileptic, and symptomatic. Animal models of myoclonus include DDT and posthypoxic myoclonus in the rat. 5-Hydrotryptophan, clonazepam, and valproic acid suppress myoclonus induced by posthypoxia. The diagnostic evaluation of myoclonus is complex and involves an extensive work-up including basic electrolytes, glucose, renal and hepatic function tests, paraneoplastic antibodies, drug and toxicology screens, thyroid antibody and function studies, neurophysiology testing, imaging, and tests for malabsorption disorders, assays for enzyme deficiencies, tissue biopsy, copper studies, alpha-fetoprotein, cytogenetic analysis, radiosensitivity DNA synthesis, genetic testing for inherited disorders, and mitochondrial function studies. Treatment of myoclonus is targeted to the underlying disorder. If myoclonus physiology cannot be demonstrated, treatment should be aimed at the common pattern of symptoms. If the diagnosis is not known, treatment could be directed empirically at cortical myoclonus as the most common physiology. In cortical myoclonus, the most effective drugs are sodium valproic acid, clonazepam, levetiracetam, and piracetam. For cortical-subcortical myoclonus, valproic acid is the drug of choice. Here, lamotrigine can be used either alone or in combination with valproic acid. Ethosuximide, levetiracetam, or zonisamide can also be used as adjunct therapy with valproic acid. A ketogenic diet can be considered if everything else fails. Subcortical-nonsegmental myoclonus may respond to clonazepam and deep-brain stimulation. Rituximab, adrenocorticotropic hormone, high-dose dexamethasone pulse, or plasmapheresis have been reported to improve opsoclonus myoclonus syndrome. Reticular reflex myoclonus can be treated with clonazepam, diazepam and 5-hydrotryptophan. For palatal myoclonus, a variety of drugs have been used.

Management of patients with myoclonus: available therapies and the need for an evidence-based approach

Myoclonus is a hyperkinetic movement disorder characterised by quick and involuntary jerks. Therapy should focus on cure of an underlying disorder; however, symptomatic treatment is often needed when treatment of an underlying cause is impossible or ineffective. The appropriate treatment for a specific type of myoclonus is based on the classification of the anatomical origin of the myoclonus: cortical, subcortical, spinal, or peripheral. We outline criteria for classification and present an overview of the available therapeutic options for the different types of myoclonus. Because of a generally low level of evidence, therapeutic options mainly rely on small observational studies and expert opinion. For an evidence-based approach in the future, randomised controlled trials of symptomatic therapies for myoclonus in homogeneous patient groups are needed.

Levetiracetam for managing neurologic and psychiatric disorders

PURPOSE

The role of levetiracetam in different epileptic, nonepileptic, neurologic, and psychiatric disorders is discussed.

SUMMARY

Levetiracetam, an antiepileptic drug (AED), was first approved as an adjunctive therapy for the treatment of partial epilepsy in adults. It is currently being used in the treatment of multiple seizure disorders, including generalized tonic-clonic; absence; myoclonic, especially juvenile myoclonic; Lennox-Gastaut syndrome; and refractory epilepsy in children and adults. Data are emerging on possible uses of levetiracetam outside the realm of epilepsy because of its unique mechanisms of action. There is preliminary evidence about the efficacy of levetiracetam in the treatment of different psychiatric disorders, including anxiety, panic, stress, mood and bipolar, autism, and Tourette's syndrome. The most serious adverse effects associated with levetiracetam use are behavioral in nature and might be more common in patients with a history of psychiatric and neurobehavioral problems.

CONCLUSION

Levetiracetam is an effective AED with potential benefits in other neurologic and psychiatric disorders. The benefit-risk ratio in an individual patient with a specific condition should be used to determine its optimal use. Levetiracetam's use in nonepileptic conditions is not recommended until more data become available from larger trials.

Pharmacodynamic and pharmacokinetic interaction profiles of levetiracetam in combination with gabapentin, tiagabine and vigabatrin in the mouse pentylenetetrazole-induced seizure model: an isobolographic analysis

To characterize the interactions between levetiracetam and the antiepileptic drugs gabapentin, tiagabine, and vigabatrin in suppressing pentylenetetrazole-induced clonic seizures in mice, type II isobolographic analysis was used. Clonic seizures were evoked in Albino Swiss mice by subcutaneous injection of pentylenetetrazole at its CD(97)(98 mg/kg). Adverse-effect profiles with respect to motor performance, long-term memory and skeletal muscular strength were measured along with total brain antiepileptic drug concentrations. The combination of gabapentin with levetiracetam at the fixed-ratios of 2:1, 1:1, 1:2, and 1:4 were supra-additive (synergistic) in terms of seizure suppression whilst the combination at the fixed-ratio of 4:1 was additive. Tiagabine with levetiracetam and vigabatrin with levetiracetam at the fixed-ratios of 1:25, 1:50, 1:100, 1:200, and 1:400 and at 2:1, 3:1, 4:1, 6:1, 8:1, and 16:1 were additive, respectively. No acute adverse effects were observed. Measurement of total brain antiepileptic drug concentrations revealed that levetiracetam in combination with gabapentin at the fixed-ratio of 1:4 significantly elevated (21%) total brain gabapentin concentrations. In contrast, levetiracetam was without affect on tiagabine or vigabatrin concentrations and co-administration with gabapentin, tiagabine or vigabatrin had no effect on levetiracetam brain concentrations, indicating the pharmacodynamic nature of interaction between these antiepileptic drugs in the mouse pentylenetetrazole model. The combination of gabapentin with levetiracetam at the fixed-ratios of 2:1, 1:1, 1:2, and 1:4 appears to be particularly favorable combination exerting supra-additive interaction in suppressing pentylenetetrazole-induced seizures, although there is a pharmacokinetic contribution to the interaction between levetiracetam and gabapentin at the fixed-ratio of 1:4. Levetiracetam in combination with tiagabine and vigabatrin appear to be neutral combinations producing only additivity in the mouse pentylenetetrazole model.

Levetiracetam for stiff-person syndrome: report of 2 patients

We report 2 patients with stiff-person syndrome whose spasms were greatly relieved by levetiracetam (Keppra).

Activity, tolerability and efficacy of levetiracetam on cerebellar symptoms in multiple sclerosis patients: a pilot kinematic study

BACKGROUND AND PURPOSE

The aim of this study was to evaluate the activity measured by kinematic analysis, tolerability and efficacy of levetiracetam (LEV) in multiple sclerosis (MS) patients affected by cerebellar symptoms, in a randomized single-blind, placebo-controlled cross-over study.

METHODS

Eight MS subjects with cerebellar signs (five female and three male; mean EDSS: 4.77; mean disease duration 9.2) performed a reaching task on a digitizing tablet and their trajectories went through a kinematic analysis. The subjects were assessed at baseline, after 21 days of treatment, after wash-out period (day 35) and after 21 days of treatment (day 56). LEV was used at the maximum dosage of 1500 mg daily. The primary outcome was the modification on smoothness (JERK) whilst aiming error (AAI) and centripetal acceleration (CA) were considered as secondary outcomes.

RESULTS

Two subjects were excluded from the final analysis. Primary outcome (i.e. JERK) was significantly affected by the administration of LEV overtime (nine arms in active treatment versus three arms in placebo decreased the mean values of their JERK). Regarding secondary outcomes CA was significantly affected by the administration of LEV. No statistical significant results were found comparing clinical scales during the four assessments.

DISCUSSION

The results indicate that LEV was able to modify kinematic parameter so the medication was active but no improvement in clinical scales was observed. LEV needs to be tested in a larger group of subjects designed to verify treatment efficacy using higher dosage of the medication.

Levetiracetam in the treatment of epilepsy

Epilepsy is a common chronic disorder that requires long-term antiepileptic drug therapy. Approximately one half of patients fail the initial antiepileptic drug and about 35% are refractory to medical therapy, highlighting the continued need for more effective and better tolerated drugs. Levetiracetam is an antiepileptic drug marketed since 2000. Its novel mechanism of action is modulation of synaptic neurotransmitter release through binding to the synaptic vesicle protein SV2A in the brain. Its pharmacokinetic advantages include rapid and almost complete absorption, minimal insignificant binding to plasma protein, absence of enzyme induction, absence of interactions with other drugs, and partial metabolism outside the liver. The availability of an intravenous preparation is yet another advantage. It has been demonstrated effective as adjunctive therapy for refractory partial-onset seizures, primary generalized tonic-clonic seizures, and myoclonic seizures of juvenile myoclonic epilepsy. In addition, it was found equivalent to controlled release carbamazepine as first-line therapy for partial-onset seizures, both in efficacy and tolerability. Its main adverse effects in randomized adjunctive trials in adults have been somnolence, asthenia, infection, and dizziness. In children, the behavioral adverse effects of hostility and nervousness were also noted. Levetiracetam is an important addition to the treatment of epilepsy.

Clinical picture of EPM1-Unverricht-Lundborg disease

Unverricht-Lundborg disease (ULD), progressive myoclonic epilepsy type 1 (EPM1, OMIM254800), is an autosomal recessively inherited neurodegenerative disorder characterized by age of onset from 6 to 16 years, stimulus-sensitive myoclonus, and tonic-clonic epileptic seizures. Some years after the onset ataxia, incoordination, intentional tremor, and dysarthria develop. Individuals with EPM1 are mentally alert but show emotional lability, depression, and mild decline in intellectual performance over time. The diagnosis of EPM1 can be confirmed by identifying disease-causing mutations in a cysteine protease inhibitor cystatin B (CSTB) gene. Symptomatic pharmacologic and rehabilitative management, including psychosocial support, are the mainstay of EPM1 patients' care. Valproic acid, the first drug of choice, diminishes myoclonus and the frequency of generalized seizures. Clonazepam and high-dose piracetam are used to treat myoclonus, whereas levetiracetam seems to be effective for both myoclonus and generalized seizures. There are a number of agents that aggravate clinical course of EPM1 such as phenytoin aggravating the associated neurologic symptoms or even accelerating cerebellar degeneration. Sodium channel blockers (carbamazepine, oxcarbazepine) and GABAergic drugs (tiagabine, vigabatrin) as well as gabapentin and pregabalin may aggravate myoclonus and myoclonic seizures. EPM1 patients need lifelong clinical follow-up, including evaluation of the drug-treatment and comprehensive rehabilitation.

Levetiracetam in juvenile myoclonic epilepsy: long-term efficacy in newly diagnosed adolescents

The aim of this study was to evaluate the efficacy and tolerability of levetiracetam (LEV) monotherapy in juvenile myoclonic epilepsy (JME). The study group consisted of 32 patients with epilepsy (20 males, 12 females) with a mean age of 13 years 3 months (SD 7y 11mo) at seizure onset. LEV was administered as the first drug; all patients were followed up at 6 and 12 months. The dose that achieved seizure control ranged from 1000 to 2500mg/daily. At 6-month evaluation: 15 patients were seizure free; 14 patients were responders (>50% reduction in seizures); and three patients had marginal effects (<50% reduction of seizures). At 12-month evaluation: 29 patients were seizure free; three patients were responders. No patients reported adverse events. These data provide preliminary evidence that LEV may be effective for treating patients with newly diagnosed JME.

Lance-Adams syndrome: a report of two cases

Chronic post-hypoxic myoclonus, also known as Lance-Adams syndrome (LAS), is a rare complication of successful cardiopulmanry resuscitation often accompanied by action myoclonus and cerebellar ataxia. It is seen in patients who have undergone a cardiorespiratory arrest, regained consciousness afterwards, and then developed myoclonus days or weeks after the event. Worldwide, 122 cases have been reported in the literature so far, including 1 case of Chinese. Here we report 2 Chinese LAS patients with detailed neuroimagings. Cranial single photon emission computed tomography (SPECT) of patient 1, a 52-year-old woman, showed a mild hypoperfusion in her left temporal lobe, whereas patient 2, a 54-year-old woman, manifested a mild bilateral decrease of glucose metabolism in the frontal lobes and a mild to moderate decrease of the N-acetyl aspartate (NAA) peak in the bilateral hippocampi by cranial [(18)F]-fluorodeoxyglucose positron emission tomographic (PET) scan and cranial magnetic resonance spectroscopy (MRS), respectively. We also review the literature on the neuroimaging, pathogenesis, and treatment of LAS.

Influence of levetiracetam on the anticonvulsant efficacy of conventional antiepileptic drugs against audiogenic seizures in DBA/2 mice

Levetiracetam (LEV, [S]-alpha-ethyl-2-oxo-1-pyrrolidine acetamide) is a new antiepileptic that has been used as adjunctive therapy to treat patients with intractable epilepsy. Systemic administration of levetiracetam (2.5-30 mg/kg, intraperitoneally (i.p.)) was able to produce a dose-dependent decrease in DBA/2 audiogenic seizure severity score. In combination with conventional antiepileptic drugs, levetiracetam, 5mg/kg, i.p., which per se did not significantly affect the occurrence of audiogenic seizures in DBA/2 mice, potentiated the anticonvulsant activity of some antiepileptic drugs studied against sound-induced seizures in DBA/2 mice. The degree of potentiation induced by levetiracetam was greater, approximately twice, for carbamazepine, diazepam, felbamate, topiramate, gabapentin, and valproate, less for lamotrigine, phenobarbital and phenytoin. This increase was associated with a comparable impairment in motor activity; however, the therapeutic index of combined treatment of antiepileptic drugs with levetiracetam was more favourable than the combination with saline with the exception of lamotrigine, phenytoin and phenobarbital. Since levetiracetam did not significantly influence the total and free plasma and the brain levels of antiepileptics studied. In addition, levetiracetam did not significantly affect the hypothermic effects of the anticonvulsants tested. In conclusion, levetiracetam showed an additive anticonvulsant effect when administered in combination with some classical anticonvulsants, most notably carbamazepine, diazepam, felbamate, gabapentin, topiramate and valproate, implicating a possible therapeutic relevance of such drug combinations.

The safety of levetiracetam

Levetiracetam is an antiepileptic drug approved for use as an adjunct agent in partial-onset seizures in adults and children aged > or = 4 years. It was also approved as adjunctive therapy in the treatment of adults and adolescents aged > or = 12 years with juvenile myoclonic epilepsy. A parenteral intravenous formulation has recently become available allowing for its use when oral administration is temporarily not feasible. Available literature has demonstrated and supported that levetiracetam has an acceptable safety profile and this review discusses the safety profile of levetiracetam, with attention to special populations. The most common adverse effects are somnolence, asthenia and dizziness, which usually appear early after initiation of levetiracetam therapy and generally resolve without medication withdrawal. The most serious adverse effects are behavioral in nature and are more common in children and in patients with a prior history of behavioral problems.

Potential of levetiracetam in mood disorders: a preliminary review

Levetiracetam is a newer antiepileptic agent that was first approved by the US FDA in 1999 as an adjunctive therapy for the treatment of refractory partial epilepsy in adults. Since then, it has been approved for a wider patient population, i.e. as adjunctive therapy for partial seizures in patients >4 years of age (worldwide) and as first-line monotherapy for partial seizures in patients >16 years of age (in Europe); and as adjunctive therapy for juvenile myoclonic seizures (in Europe and the US). It has a favourable pharmacokinetic profile and appears to act at a specific site in the CNS. Pharmacodynamic evidence indicates that levetiracetam indirectly facilitates GABAergic function, and an increasing body of evidence suggests an important role for GABA in the pathophysiology of mood disorders. Preclinical studies using animal models of depression, anxiety and mania provide evidence for levetiracetam as a mood stabiliser. Preliminary clinical evidence from case reports and open-label pilot studies indicates that the drug, both as add-on therapy and as monotherapy, has efficacy in a wide range of bipolar spectrum disorders. Most recently, a 31% remission rate was reported in patients with bipolar disorder who were in the depressed phase at baseline and who received levetiracetam as add-on therapy for 8 weeks in an open-label trial. While these results are encouraging, placebo-controlled data are needed to further clarify the role of levetiracetam in the treatment of mood disorders.

Levetiracetam and felbamate interact both pharmacodynamically and pharmacokinetically: an isobolographic analysis in the mouse maximal electroshock model

PURPOSE

Polytherapy with two or more antiepileptic drugs (AEDs) is generally required for approximately 30% of patients with epilepsy, who do not respond satisfactorily to monotherapy. The potential usefulness of AED combinations, producing synergistic anticonvulsant efficacy and minimal adverse effects, is therefore of significant importance. The present study sought to ascertain the potential usefulness of levetiracetam (LEV) and felbamate (FBM) in combination in the mouse maximal electroshock (MES)-induced seizure model.

METHODS

The anticonvulsant interaction profile between LEV and FBM in the mouse MES-induced seizure model was determined using type II isobolographic analysis. Acute adverse effects (motor performance) were ascertained by use of the chimney test. LEV and FBM brain concentrations were measured by HPLC in order to determine any pharmacokinetic contribution to the observed antiseizure effect.

RESULTS

LEV in combination with FBM, at the fixed ratios of 1:2, 1:1, 2:1, and 4:1, were supraadditive, whereas at the fixed ratio of 1:4, additivity was observed in the mouse MES model. Furthermore, none of the investigated combinations altered motor performance in the chimney test. Brain FBM concentrations were unaffected by concomitant LEV administration. In contrast, FBM significantly increased LEV brain concentrations.

CONCLUSIONS

LEV in combination with FBM was associated with pharmacodynamic supraadditivity in the MES test. However, this anticonvulsant supraadditivity was associated with a concurrent increase in brain LEV concentrations indicating a pharmacokinetic contribution to the observed pharmacodynamic interaction between LEV and FBM.

Post-anoxic myoclonus: a case presentation and review of management in the rehabilitation setting

Post-anoxic myoclonus is a rare movement disorder manifested by diffuse action-triggered jerking movements that may result in significant disability. The incidence of this disorder is not clearly established, but over 122 cases have so far been reported in the literature. The pathogenesis is not entirely known, although it has been hypothesized that particular susceptibility of the Purkinje cells of cerebellum to anoxic injury may play a key role. A case is presented of an independently living 60-year-old woman admitted to the rehabilitation unit with diffuse myoclonus after sustaining a cardio-pulmonary arrest. She presented with severe jerking movements in all extremities with startle to noise and exacerbations upon attempting any purposeful actions. The patient's myoclonus was controlled by a variety of anti-epileptic medications. The patient initially responded to a combination of divalproex sodium and zonisamide, but relapsed in several weeks, requiring addition of levetriacetam and clonazepam. At a 1-year follow-up she demonstrated a significant improvement in ambulation and self-care activities. This case illustrates that, although patients with post-anoxic myoclonus cannot be fully cured, their quality of life can be significantly improved by rehabilitation interventions.

Levetiracetam: past, present and future

Levetiracetam is an antiepileptic drug approved for use as an adjunctive agent in partial-onset seizures in adults. This approval was recently extended to children over 4 years of age. Among the currently approved antiepileptic drugs, levetiracetam is unique in its mechanism of action. Its CNS binding site, the synaptic vesicle protein SV2A, was discovered recently. Binding at this site may be important for the antiseizure activity of levetiracetam and the role of this binding site and its modulation by levetiracetam is an area of active research in epilepsy. Levetiracetam is generally safe, has near to ideal pharmacokinetics and does not interact with other medications. The most serious adverse events are behavioral in nature. Recent studies suggest that levetiracetam may be effective in generalized epilepsies, status epilepticus, pain and selected movement disorders. Intriguing studies using the kindling model of epilepsy suggest that levetiracetam may protect against the development of kindling and chronic epilepsy. A parenteral formulation of levetiracetam may soon become available and may lead to larger studies of levetiracetam in status epilepticus.

Movement disorders after resuscitation from cardiac arrest

It is difficult to predict precisely the final neurologic outcome from cardiac arrest and accompanying cerebral hypoxia. Although rare, several movement disorders may arise as a consequence of hypoxic injury, including myoclonus, dystonia, akinetic-rigid syndromes, tremor, and chorea. Dys-function of various portions of the central nervous system, including the basal ganglia, thalamus, midbrain, and cerebellum, is implicated in the pathogenesis of these posthypoxic movement disorders. The development of animal models of posthypoxic movement disorders and of newer imaging techniques applied to human patients who have movement disorders after hypoxic episodes has improved understanding of the pathophysiology of posthypoxic movement disorders and has suggested newer treatments. Many outstanding questions remain, however. What factors promote susceptibility to the development of posthypoxic movement disorders? Why do patients who have similar clinical hypoxic insults develop markedly dis-similar movement disorders? Why are the basal ganglia especially vulnerable to cerebral hypoxia? Why do some movement disorders occur in delayed fashion and progress for years after the hypoxic insult? Is the pathogenesis of progressive posthypoxic movement disorders related to that of neurodegenerative diseases? What are the most effective medications for the various posthypoxic movement disorders? Is there a role for deep brain stimulation in the treatment of posthypoxic movement disorders? We anticipate that current and future research in the area of posthypoxic movement disorders will reveal answers to some of these important questions.

Clinical analysis in familial cortical myoclonic tremor allows differential diagnosis with essential tremor

Familial cortical myoclonic tremor (FCMT) is a rare disorder often leading to a wrong clinical diagnosis of essential tremor. Electrophysiological data are usually considered to allow a correct diagnosis. We describe a FCMT French family with previously unreported clinical features such as sensitivity to glucose deprivation, vibration, repetitive visual patterns, and intense visual or auditory stimulation and contrasts. Electrophysiological studies of the propositus confirm the cortical reflex myoclonus elicited by photic stimulation and the absence of epileptic electroencephalographic discharges. We emphasize that a precise clinical analysis can lead to a correct diagnosis before electrophysiological confirmation. This is also the first-ever report of efficacy of levetiracetam in FCMT.

Benefits and risks of pharmacological and surgical treatments for essential tremor: disease mechanisms and current management

Essential tremor (ET) is a neurological disease (and possibly a family of diseases) whose most recognisable feature is an action tremor of the hands and occasionally of the voice and head. Current data support the view that CNS gamma-amino-butyric acid (GABA)-ergic mechanisms may underlie ET and that the tremor may be further modulated by peripheral (muscle) adrenoreceptors. Potential pharmacotherapeutic options, targeted to influence the activity of the neurotransmitter GABA within the CNS and the peripheral adrenergic receptors, are part of the current armamentarium to treat ET. As such, primidone and propranolol remain the mainstays of the therapy for ET. Intramuscular injections of botulinum toxin A may play a role in the treatment of voice and head tremor. Surgical options, which are reserved for patients with severe, medically-refractory tremor, provide adequate tremor control in the majority of patients. As with other progressive neurological disorders of late life, the ability to use neuroprotective medications to intervene in the developing disease to either slow or halt the progression of the pathological process, would involve an understanding of underlying disease mechanisms. The understanding of these mechanisms in ET is limited and further study of these mechanisms is critical for the development of such therapies.

Levetiracetam in patients with generalised epilepsy and myoclonic seizures: an open label study

PURPOSE

To evaluate the efficacy and tolerability of levetiracetam (LEV) as either 'de novo' (monotherapy) or 'add-on' therapy in patients with different generalised epilepsies characterised by myoclonic seizures from an observational study.

METHODS

We evaluated 35 patients (21 female, mean age 24.7 years) with different types of generalised epilepsies (juvenile myoclonic epilepsy (JME), severe myoclonic epilepsy of infancy (SMEI), Lennox-Gastaut syndrome (LGS), myoclonic-astatic epilepsy (MAE), myoclonic absences (MA), benign myoclonic epilepsy in infancy (BMEI) and 4 patients had unspecified epileptic syndromes). Patients received LEV as de novo monotherapy or add-on therapy. Seizure frequency changes and adverse events were observed. Follow-up was conducted for a period of 12 months after treatment.

RESULTS

Patients received LEV 2000-3000 mg/day as de novo (n = 8) and as add-on therapy. In total, 29 (82%) of the 35 patients achieved > or = 50% seizure frequency reduction, 15 (42%) patients achieved seizure freedom while a further 14 (40%) patients achieved > or = 50-99% seizure frequency reduction. Six (17%) patients discontinued LEV due to inefficacy or seizure worsening. Not even a single patient discontinued due to adverse effects.

CONCLUSIONS

Our results confirm that LEV as de novo (monotherapy) and add-on therapy at doses between 2000 and 3000 mg/day effectively reduces myoclonic seizure frequency in patients with generalised epilepsy. LEV was also well-tolerated.

Pharmacodynamic and Pharmacokinetic Characterization of Interactions between Levetiracetam and Numerous Antiepileptic Drugs in the Mouse Maximal Electroshock Seizure Model: An Isobolographic Analysis

PURPOSE

Approximately 30% of patients with epilepsy do not experience satisfactory seizure control with antiepileptic drug (AED) monotherapy and often require polytherapy. The potential usefulness of AED combinations, in terms of efficacy and adverse effects, is therefore of major importance. The present study sought to identify potentially useful AED combinations with levetiracetam (LEV) METHODS: With isobolographic analysis, the mouse maximal electroshock (MES)-induced seizure model was investigated with regard to the anticonvulsant effects of carbamazepine (CBZ), phenytoin, phenobarbital (PB), valproate, lamotrigine, topiramate (TPM), and oxcarbazepine (OXC), administered singly and in combination with LEV. Acute adverse effects were ascertained by use of the chimney test evaluating motor performance and the step-through passive-avoidance task assessing long-term memory. Brain AED concentrations were determined to ascertain any pharmacokinetic contribution to the observed antiseizure effect.

RESULTS

LEV in combination with TPM, at the fixed ratios of 1:2, 1:1, 2:1, and 4:1, was supraadditive (synergistic) in the MES test. Likewise, the combination of LEV with CBZ (at the fixed ratio of 16:1) and LEV with OXC (8:1 and 16:1) were supraadditive. In contrast, all other LEV/AED combinations displayed additivity. Furthermore, none of the investigated LEV/AED combinations altered motor performance and long-term memory. LEV brain concentrations were unaffected by concomitant AED administration, and LEV had no significant effect on brain concentrations of concomitant AEDs.

CONCLUSIONS

These preclinical data would suggest that LEV in combination with TPM is associated with beneficial anticonvulsant pharmacodynamic interactions. Similar, but less profound effects were seen with OXC and CBZ.