Current Pharmaceutical Design - Volume 23, Issue 37, 2017

Background: Emerging evidence suggests that epigenetic mechanisms are involved in different brain functions such as the development of the nervous system and normal neuronal function. At the same time, it has been proposed that several neurological diseases are in part, caused by aberrant epigenetic modifications. Nevertheless, the mechanisms underlying pathological alterations in the brain genome are not completely understood. Methods and Results: Post-transcriptional histone acetylation is a major mechanism of chromatin remodeling, contributing to epigenetic regulation of gene transcription. Histone deacetylases (HDACs) are a family of proteins involved in both physiological and pathological conditions by regulating the status of chromatin histone acetylation. It is now becoming clear that epigenetic regulatory mechanisms may also play a major role in epilepsy; modulation of chromatin structure through histone modifications has emerged as an important regulator of gene transcription in the brain and altered histone acetylation seems to contribute to changes in gene expression associated with epilepsy and the epileptogenic process. Histone modification is crucial for regulating neurobiological processes such as neural network function, synaptic plasticity, and synaptogenesis which also contribute to the pathophysiology of epilepsy. Conclusions: The role of epigenetics in epilepsy development is a new and emerging research area; the present article reviews the recent findings on the role played by HDACs and the possible function of different histone modifications in epilepsy and epileptogenesis. Inhibitors of HDACs (HDACIs) have been tested in different experimental models of epilepsy with some success. We also review the results from these studies, which indicate HDACIs as potential new therapeutic agents for the treatment of human epilepsy.

Background: A variety of evidence suggested that an imbalance in excitatory and inhibitory neurotransmission could be one of the pathophysiological mechanisms underlying the occurrence and progression of seizures. Understanding the causes of this imbalance may provide essential insight into the basic mechanisms of epilepsy and may uncover novel targets for future drug therapies. Accordingly, GABA is the most important inhibitory neurotransmitter in the CNS and its receptors (e.g., GABAARs) can still be relevant targets of new antiepileptic drugs (AEDs). Methods: Up to now, a variety of modulating agents that directly or indirectly act at GABAARs have been proposed for restoring the physiological balance of excitation and inhibition in the epileptogenic brain. While benzodiazepine, barbiturates and allosteric modulators of GABAARs are well-known for their anticonvulsant effect, new compounds as modulators of chloride homeostasis or phytocannabinoids are not completely unraveled and their antiepileptic action is still matter of debate. In addition, several inflammatory mediators as cytokines and chemokines play an important role in the modulation of GABAAR function, even if further research is needed to translate these new findings from the bench to the bedside. Finally yet importantly, a new frontier in epilepsy research is represented by the observation that specific small noncoding RNAs, namely miRNAs, may regulate GABAAR function paving the road to therapeutic approaches based on the modulation of gene expression. Conclusion: Here, we review key physiological, neuropathological and functional studies that altogether strengthen the role of modulation of GABAARs function as therapeutic target. The discovery of the novel molecular mechanisms underlying the GABAergic transmission in epilepsy represents another heavy piece in the “epileptic puzzle”. Even if GABAAR is an old story in the pharmacology of the epilepsy, the reviewed findings suggest that new players in the scenario need to be considered.

Background: The lack of treatments which can prevent epilepsy development or improve disease prognosis represents an unmet and urgent clinical need. The development of such drugs requires a deep understanding of the mechanisms underlying disease pathogenesis. In the last decade, preclinical studies in models of acute seizures and of chronic epilepsy highlighted that neuroinflammation arising in brain areas of seizure onset and generalization is a key contributor to neuronal hyper-excitability underlying seizure generation. Microglia and astrocytes are pivotal cells involved in both the induction and perpetuation of the inflammatory response to epileptogenic injuries or seizures; other cell contributors are neurons, cell components of the blood brain barrier and leukocytes. Methods: From the clinical standpoint, neuroinflammation is now considered an hallmark of epileptogenic foci in various forms of focal onset pharmacoresistant epilepsies. Moreover, pharmacological studies in animal model with drugs targeting specific inflammatory molecules, and changes in intrinsic seizure susceptibility of transgenic mice with perturbed neuroinflammatory mechanisms, have demonstrated that neuroinflammation is not a bystander phenomenon but has a pathogenic role in seizures, cell loss and neurological co-morbidities. Understanding the role of neuroinflammation in seizure pathogenesis is instrumental for a mechanism-based discovery of selective therapies targeting the epilepsy causes rather than its symptoms, thereby allowing the development of novel disease-modifying treatments. Notably, clinical translation of laboratory findings may take advantage of anti-inflammatory drugs already in medical use for peripheral autoinflammatory or autoimmune disorders. Conclusion: This review reports key preclinical and clinical findings supporting a role for brain inflammation in the pathogenesis of seizures. It also highlights the emerging proof-of-concept studies showing signs of clinical efficacy of target-specific anti-inflammatory interventions in epilepsies of differing etiologies. We will discuss the need for biomarkers and novel clinical trial designs for anti-inflammatory therapies that have a mechanism of action very different than standard antiepileptic drugs.

Background: The benign character of absence epilepsy compared to other genetic generalized epilepsy syndromes has often hampered the search for new treatment options. Absence epilepsy is most often treated with ethosuximide or valproic acid. However, both drugs are not always well tolerated or fail, and seizure freedom for a larger proportion of patients remains to be achieved. The availability of genuine animal models of epilepsy does allow to search for new treatment options not only for absence epilepsy per se but also for other genetic - previously called idiopathic - forms of epilepsy. The recent discovery of a highly excitable cortical zone in these models is considered as a new therapeutic target area. Methods: Here, we provide an overview regarding the search for new therapeutical options as has been investigated in the genetic rodent models (mainly WAG/Rij and GAERS) including drugs and whether antiepileptogenesis can be achieved, various types of electrical and optogenetical invasive stimulations, different types of noninvasive stimulation and finally whether absence seizures can be predicted and prevented. Results: Many factors determine either the cortical and or thalamic excitability or the interaction between cortex and thalamus and offer new possibilities for new anti-absence drugs, among others metabotropic glutamatergic positive and negative allosteric modulators. The inhibition of epileptogenesis by various drugs with its widespread consequences seems feasible, although its mechanisms remain obscure and seems different from the antiabsence action. Surgical intervention on the cortical zone initiating seizures, either with radiosurgery using synchrotron- generated microbeams, or ablation techniques might reduce spike-and-wave discharges in the rodent models. High frequency electrical subcortical or cortical stimulation might be a good way to abort ongoing spikeand- wave discharges. In addition, possibilities for prevention with real-time EEG analyses in combination with electrical stimulation could also be a way to fully control these seizures. Conclusion: Although it is obvious that some of these treatment possibilities will not be used for absence epilepsy and/or need to be further developed, all can be considered as proof of principle and provide clear directives for further developments.

Background: Animal models when carefully selected, designed and conducted, are important parts of any translational drug development strategy. However, research of new compounds for patients with drugresistant epilepsies is still based on animal experiments, mostly in rodents, which are far from being a model of chronic human epilepsy and have failed to differentiate the efficacy of new compounds versus standard drug treatment. Objective: The objective was identification and description of compounds in clinical development in 2016. Method: Search was conducted from the website of the U.S. National Institutes of Health and from literature. Results: Identified compounds have been divided in two groups: 1) compounds initially developed for the treatment of diseases other than epilepsy: biperiden, bumetanide, everolimus, fenfluramine, melatonin, minocycline, verapamil. 2) Compounds specifically developed for the treatment of epilepsy: allopregnanolone, cannabidiol, cannabidivarin, ganaxolone, nalutozan, PF-06372865, UCB0942, and cenobamate. Everolimus, and perhaps, fenfluramine are effective in specific epileptic diseases and may be considered as true disease modifying antiepileptic drugs. These are tuberous sclerosis complex for everolimus and Dravet syndrome for fenfluramine. With the exception of a few other compounds such as cannabinidiol, cannabidivarin and minocycline, the vast majority of other compounds had mechanisms of action which are similar to the mechanism of action of the anti-seizure drugs already in the market. Conclusion: Substantial improvements in the efficacy, specifically as pharmacological treatment of drug-resistant epilepsy is regarded, are not expected. New drugs should be developed to specifically target the biochemical alteration which characterizes the underlying disease and also include targets that contribute to epileptogenesis in relevant epilepsy models.

Background: Despite the introduction of new antiepileptic drugs (AEDs), the quality of life and therapeutic response for patients with epilepsy remain unsatisfactory. In addition, whilst several antiepileptic drugs (AEDs) have been approved and consequently marketed in recent years, little is known about their long-term safety and tolerability. Availability of the newest AEDs, characterized by improved pharmacokinetic profiles, has positively impacted the treatment approach for patients with partial seizures in clinical practice. However, the main cause of treatment failure is still poor patient compliance due to the occurrence of adverse drug reactions (ADRs) that lead to treatment withdrawal in about 25% of cases before achieving maximal efficacy, and is associated with increasing health care costs. Methods: In this Review, we conducted an online database search using Medline, PubMed, Embase, and the Cochrane Online Library to review the available studies highlighting the clinical relevance of side effects, pharmacological interactions, safety and tolerability of the newest AEDs: Brivaracetam (BRV), Cannabidiol (CBD), Eslicarbazepine acetate (ESL), Lacosamide (LCM), and Perampanel (PER). Results: The principal benefit of the newest AEDs, in addition to reduced frequency and seizure severity, is the low number and severity of ADRs reported compared to more historic drugs. Conclusion: Early detection of ADRs could lead to an improvement in patients' quality of life, therefore it is important to monitor ADRs and to adequately perform post marketing surveillance in the clinical practice setting.

Background: Prior articles paid little attention to pharmacodynamic drug interactions (DIs) between antiepileptic drugs (AEDs) and the most important psychotropic medications (antidepressants, antipsychotics, benzodiazepines and lithium) which have potential to be clinically relevant. Objective: This article aims to provide an updated review of the potentially clinically relevant pharmacodynamic DIs between AEDs and psychotropic medications. Pharmacodynamic DIs take place directly at the site of action of a drug or indirectly by interfering with another physiological mechanism. From the clinical perspective, these DIs are classified as having 1) beneficial effects (increased efficacy and/or safety) or 2) harmful effects (decreased efficacy and/or safety). Method: Articles, including animal studies, were obtained from a PubMed search with no time limit. This search went beyond the articles previously found and listed in the authors' published literature reviews and DI studies. Results: Using knowledge of pharmacodynamic mechanisms, the potentially beneficial and dangerous pharmacodynamic DIs between AEDs and psychotropic drugs with psychotropic medications are summarized for clinicians in practical tables. The possible pharmacodynamic DIs of AEDs include 20 with antidepressants, 17 with antipsychotics, 4 with benzodiazepines and 5 with lithium. Conclusion: The pharmacodynamic DIs between AEDs and psychotropic drugs have not been systematically investigated or even described in the literature. Clinicians need to become more aware of the potential for dangerous combinations of the increasingly frequent co-prescription of AEDs and psychotropic agents. Likewise, researchers need to consider these DIs in their studies, and clinicians facing cases with adverse drug reactions secondary to these pharmacodynamic DIs need to publish them.

Background: Patient features, apart from the type of seizures/epilepsy, affect markedly antiepileptic drug (AED) choice and dosage. The present review focuses on gender, age and psychiatric comorbidities which play a leading role in influencing antiepileptic treatment. Methods: Reviews with large population of patients, controlled clinical trials, observational investigations, experimental studies and experimental reviews of experimental data, where appropriated, were analysed and illustrated to produce the most homogeneous indications possible. Different and also contradictory observations have been highlighted to stimulate a critical approach to specific aspects. Results: Women of childbearing age should avoid valproic (VPA), acid, since this drug doubles the risk of major malformations and causes in the exposed offspring reduced intellectual development and disorders of autistic spectrum. The drug is also associated with hormonal disorders, polycystic ovary and reduced fertility. Children treated with valproic acid or phenobarbital can exhibit hyperactivity, nervousness and attention disorders. As a consequence of increased drug elimination, younger children require higher doses as compared to adults and older patients. Elderly patients treated with phenobarbital may face the risk of cognitive disorders and/or falls resulting in bone fractures. Fractures are also facilitated by carbamazepine-induced osteoporosis. Psychiatric disorders are frequently associated with epilepsy and evidence has been gained that common pathological steps underlie these conditions. Depressed patients should avoid drugs like phenobarbital, topiramate, levetiracetam, zonisamide and perampanel since these drugs can induce mood disorders. Although not conclusive, literature data indicate that topiramate and levetiracetam and also tiagabine and vigabatrin, are associated with suicidal thought/behaviour. Conversely, lamotrigine, carbamazepine, VPA and oxcarbazepine exert beneficial effects on mood. Bupropion, clomipramine, amoxapine and maprotyline among antidepressants, and clozapine, olanzapine and quietapine among antipsychotics have been observed to lower seizure threshold. Serum AED concentration monitoring is of help in dosage adjustments, especially in very young children, in patients with cognitive decline and in patients with psychiatric comorbidities. Conclusions: A careful evaluation of the patient variables analysed in the present review is useful to personalize and optimize AED therapy.

Background: Sexual dysfunction is very common in patients with epilepsy. Objective: We sought to review the published literature around sexual dysfunction in epilepsy, and particularly the role played by anticonvulsant drugs. Method: We searched all related articles on PubMed using the search terms sexual dysfunction, various AEDs and epilepsy, and restricted the search to English language articles. Results: The most common manifestations of sexual dysfunction in patients with epilepsy are hyposexuality and erectile dysfunction. The cause of this dysfunction is multifactorial and overlapping, and includes changes in the levels of sex hormones, anti-convulsants, the epilepsy itself and psychosocial factors. Traditional anti-convulsants which induce the cytochrome P450 enzyme system have the highest rates of sexual dysfunction, which is primarily mediated by changes in sex hormone levels. Sexual dysfunction associated with newer anti-convulsants is likely to occur through different mechanisms. Some anti-convulsants such as oxcarbazepine and lamotrigine may improve sexual function, but can also rarely be associated with sexual dysfunction. Conclusion: Management of sexual dysfunction thought to be caused by anti-convulsants should include the cessation of the offending drug, and consideration of switching to alternative anti-convulsants that have been reported to improve sexual function such as oxcarbazepine, and lamotrigine.

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.

Background: Epileptic encephalopathies represent the most severe epilepsies, with onset in infancy and childhood and seizures continuing in adulthood in most cases. New genetic causes are being identified at a rapid rate. Treatment is challenging and the overall outcome remains poor. Available targeted treatments, based on the precision medicine approach, are currently few. Objective: To provide an overview of the treatment of epileptic encephalopathies with known genetic determinants, including established treatment, anecdotal reports of specific treatment, and potential tailored precision medicine strategies. Method: Genes known to be associated to epileptic encephalopathy were selected. Genes where the association was uncertain or with no reports of details on treatment, were not included. Although some of the genes included are associated with multiple epilepsy phenotypes or other organ involvement, we have mainly focused on the epileptic encephalopathies and their antiepileptic treatments. Results: Most epileptic encephalopathies show genotypic and phenotypic heterogeneity. The treatment of seizures is difficult in most cases. The available evidence may provide some guidance for treatment: for example, ACTH seems to be effective in controlling infantile spams in a number of genetic epileptic encephalopathies. There are potentially effective tailored precision medicine strategies available for some of the encephalopathies, and therapies with currently unexplained effectiveness in others. Conclusions: Understanding the effect of the mutation is crucial for targeted treatment. There is a broad range of disease mechanisms underlying epileptic encephalopathies, and this makes the application of targeted treatments challenging. However, there is evidence that tailored treatment could significantly improve epilepsy treatment and prognosis.

Background: Although a larger number of antiepileptic drugs became available in the last decades, epilepsy remains drug-resistant in approximately a third of patients. Ketogenic diet (KD), first proposed at the beginning of the last century, is complex and has anticonvulsant effects, yet not completely understood. Over the last decades, different types of ketogenic diets (KDs) have been developed, namely classical KD and modified Atkins diet (MAD). They offer an effective alternative for children and adults with drug-resistant epilepsies. Methods: We review several papers on KDs as an adjunctive treatment of refractory epilepsy of children and adults, discussing its efficacy and adverse events. Because of the heterogenous, uncontrolled nature of the studies, we analyzed all studies individually, without a meta-analysis. Results: KDs may be considered first choice treatment in some specific metabolic conditions, such as glucosetransporter type 1 and pyruvate dehydrogenase deficiencies, and mitochondrial complex I defects. Preliminary findings indicate that KDs may be specifically effective in some epileptic syndromes, such as West syndrome, severe myoclonic epilepsy of infancy, myoclonic-astatic epilepsy, febrile infection related epileptic syndrome, and drug-resistant idiopathic generalized epilepsies or refractory status epilepticus. Short term adverse events are usually mild in both children and adults, including gastrointestinal symptoms, hyperlipidemia, and hypercalciuria; potential long term adverse effects include nephrolitiasis, decreased bone density, and liver steatosis. Possible atherosclerotic effects remain a concern. Patients on KDs should be carefully monitored in specialized centers during initiation, maintenance and withdrawal periods, in order to minimize such adverse events, and to improve compliance. Although the majority of KD trials on children and adults with drug-resistant epilepsies are openlabel, uncontrolled studies based on small samples, an increasing number of randomized controlled trials have provided better quality evidence on its efficacy in recent years. Conclusion: There is a need for future randomized clinical trials aimed to confirm the efficacy of KDs in specific epileptic syndromes, and to provide further information about some practical unsolved problems, i.e. for how long KD treatment should be continued.

Background: An increasing amount of evidence suggests an association between epilepsy and multiple somatic and psychiatric conditions, which is more significant than in the general population. Furthermore, a bidirectional association has been established between epilepsy and several conditions, notably depression and suicide, cerebrovascular disease, stroke, dementia and migraine, which is best explained by the presence of common underlying mechanisms and risk factors. Gaining knowledge about these common mechanisms can provide insight into new therapeutic targets, screening and preventive measures. Methods: This review discusses several of the more significant somatic and psychiatric comorbidities of epilepsy, the mechanisms and direction of their association, as well as the implications of these comorbidities for treatment. Results: Somatic and psychiatric comorbidity in epilepsy have been investigated in several population-based studies using medical records databases and different survey methods. All show a significantly higher prevalence for a number of medical conditions in people with epilepsy (PWE) compared to the general population. Conclusion: The coexistence of different medical conditions with epilepsy carries important implications for the assessment of the burden of the disease and the outcome and management of these patients, as they often require long-term antiepileptic drug intake.

Background: Approximately one third of patients with epilepsy are refractory to medical treatment. Adverse effects associated with Anti-Epileptic Drugs (AEDs) are considered to affect quality of life often more than seizures themselves. Neuroimaging techniques, particularly Magnetic Resonance Imaging (MRI), have proven instrumental in clinical decision making in relation to epilepsy surgery, but may also provide further insights into the mechanisms underlying treatment response and side effects associated with AEDs. Objective and Method: We searched PubMed and Scopus databases for original articles and reviews published in the last two decades, which addressed the effects of AEDs on structural MRI, functional MRI and Magnetic Resonance Spectroscopy (MRS) measures. Results: The majority of investigations implemented task-based fMRI, and probed the influence of widely used anti-epileptic drugs on tasks assessing language, executive functions and emotion recognition. Collectively, MRI allows detecting reproducible AED-related effects on regions and networks relevant to disease pathomechanisms, thus elucidating the anatomo-functional substrates of cognitive side effects. MRS analyses shed light on the molecular correlates of AED action, and may provide indicators of treatment response. Conclusion: MRI techniques have considerably improved our understanding of the effects of AEDs at a regional and network level, and provide biomarkers with potential to improve routine clinical decision making in epilepsy.

Background: Epilepsy affects about 70 million people worldwide, nearly 90% of whom live in developing countries. Epilepsy is surrounded by myths and stigma in these countries. Discrimination and social stigmatization are difficult obstacles for patients to overcome. Knowledge, attitudes and practices towards epilepsy are often inadequate, even sometimes totally false and then dangerous. Methods: The goal was to present the situation and analyse the determinants of using antiepileptic drugs in developing countries. Results: The treatment gap exceeds 75% in most low-income countries, and could be even higher in rural areas. Reasons for that are low accessibility, availability, and/or affordability, lack of trained medical personnel and the associated beliefs and stigma. The interactions between drugs or due to other factors, such as malnutrition, are frequent. A long-lasting treatment is not usual for populations in developing countries due to cultural beliefs. The traditional healers are the first ones consulted in such a context, then delaying the entry in the “modern” medical care system. Conclusion: Information and education campaigns are mandatory among the general population and among the medical and paramedical staff to make progress on the management of epilepsy in developing countries.

Background: Although epilepsy surgery is a recognized treatment option for drug-resistant epilepsies since several decades, the management of antiepileptic drugs (AEDs) after successful surgery still remains one of the most difficult and unsolved therapeutic challenges. Indeed, no systematic controlled trials have been specifically conducted so far and no consensus or standardized guidelines regarding postsurgical drug discontinuation policy and procedures are available. Methods: In this paper, we aim to provide an updated overview on the present knowledge on this topic, which is based mainly on retrospective studies reporting practices used in individual centers. Results: Currently available data suggest that: 1) rate of seizure recurrence appears to be higher in patients undergoing early (before 6 months or 9 months according to different studies) AED withdrawal; 2) seizures that recur during AED tapering are easier to control than unprovoked postoperative seizure relapses; 3) there is no evidence to support negative long-term implications on seizure outcomes in patients who attempted AED withdrawal. In the pediatric age group, shorter intervals from surgery to AED reduction and to complete AED discontinuation predict seizure relapse during or after AED reduction/withdrawal. However, this does not correlate with the chances of regaining seizure freedom after drug reintroduction. Conclusion: Carefully conducted prospective longitudinal studies and randomized controlled trials are warranted to establish the correct post-surgical pharmacologic treatment and to identify the best candidates for AEDs discontinuation.

Background. Growing evidence indicates that pharmacogenomics will positively impact treatment for patients with epilepsy in the near future, leading to the implementation of a precision-based use of antiepileptic drug (AED) therapy, thereby providing a cornerstone for precision medicine. Objective: In this review, we briefly summarize the studies of pharmacogenomics in epilepsy, recent advances, and how it may progress in the future. Methods: We subdivided the review into two main sections: genetic variants that may modulate response to AEDs through pharmacokinetics or pharmacodynamics mechanisms; and gene variants that may affect tolerability and safety of AEDs. Results: Results from most studies have been contradictory, due to several flaws, including small sample sizes, inaccurate phenotyping, and genotyping strategies. However, even with these limitations, very recent developments indicate that the goal of incorporating genetic data into clinical practice may be attainable in the near future. In addition, recent pharmacogenomic studies of hypersensitivity reactions to AEDs have also made important strides, as its prevention appears attainable with the identification of HLA-A genotypes for patients at high risk of carbamazepine hypersensitivity. Conclusion: To better clarify the relationship between genetic factors and AEDs, future studies will require more precise epilepsy phenotypes, larger sample sizes, and astute use of new genotyping strategies. Reasonably, this will lead to novel therapeutic approaches in drug targeting and antiepileptogenesis.