Catalyst-free decarboxylative cross-coupling of N-hydroxyphthalimide esters with tert-butyl 2-(trifluoromethyl)acrylate and its application

Here, we demonstrate a practical method toward the facile synthesis of CF3-containing amino acids through visible light promoted decarboxylative cross-coupling of a redox-active ester with tert-butyl 2-(trifluoromethyl)acrylate. The reaction was driven by the photochemical activity of electron donor-acceptor (EDA) complexes that were formed by the non-covalent interaction between a Hantzsch ester and a redox-active ester. The advantages of this protocol are its synthetic simplicity, rich functional group tolerance, and a cost-effective reaction system.

Anticonvulsant Classes and Possible Mechanism of Actions

Epilepsy is considered one of the most common neurological disorders worldwide; it needs long-term or life-long treatment. Despite the presence of several novel antiepileptic drugs, approximately 30% patients still suffer from drug-resistant epilepsy. Subsequently, searching for new anticonvulsants with lower toxicity and better efficacy is still in paramount demand. Using target-based studies in the discovery of novel antiepileptics is uncommon owing to the insufficient information on the molecular pathway of epilepsy and complex mode of action for most of known antiepileptic drugs. In this review, we investigated the properties of anticonvulsants, types of epileptic seizures, and mechanism of action for anticonvulsants.

Efficacy and safety of vigabatrin in patients with tuberous sclerosis complex and infantile epileptic spasm syndrome: a systematic review

INTRODUCTION

Tuberous sclerosis complex (TSC) is a common genetic cause of epilepsy. Infantile epileptic spasm syndrome (IESS) is often the presenting neurologic feature, progressively evolving into refractory epilepsy. Vigabatrin (VGB) is often used in clinical practice as a first-line therapy in TSC with IESS. This systematic review aims to collect and analyze the efficacy data about VGB in TSC cases with IESS, in order to evaluate the strength of evidence in the literature.

METHODS

A systematic search of trials, observational studies, and case series involving patients with TSC and IESS treated with VGB was performed using MEDLINE, CENTRAL, and the US NIH Clinical Trials Registry. Single case studies, animal and non-English language studies were excluded. Seventeen studies were selected, of which 3 were RCTs and 14 were observational studies.

RESULTS

An overall response rate of 67% (231/343 responders) resulted from the analysis, with a spasm-free rate restricted to RCTs of 88% (29/33 subjects).

CONCLUSIONS

Although all the studies analyzed reported beneficial effects of VGB in TSC patients with IESS, with higher response rates in comparison to non-TSC subjects with IESS, a low level of evidence and high heterogeneity do not guarantee sufficient strength for therapeutic recommendations.

Epilepsy and Cognitive Impairment in Childhood and Adolescence: A Mini-Review

Managing epilepsy in people with an intellectual disability remains a therapeutic challenge and must take into account additional issues such as diagnostic difficulties and frequent drug resistance. Advances in genomic technologies improved our understanding of epilepsy and raised the possibility to develop patients-tailored treatments acting on the key molecular mechanisms involved in the development of the disease. In addition to conventional antiseizure medications (ASMs), ketogenic diet, hormone therapy and epilepsy surgery play an important role, especially in cases of drugresistance. This review aims to provide a comprehensive overview of the mainfactors influencing cognition in children and adolescents with epilepsy and the main therapeutic options available for the epilepsies associated with intellectual disability.

Vigabatrin-associated brain abnormalities on MRI in tuberous sclerosis complex patients with infantile spasms: are they preventable?

Background

Vigabatrin (VGB) is currently the most widely prescribed first-line medication for individuals with infantile spasms (IS) and especially for those with tuberous sclerosis complex (TSC), with demonstrated efficacy. Meanwhile, its adverse events, such as vigabatrin-associated brain abnormalities on magnetic resonance imaging (MRI; VABAM), have also been widely reported.

Objectives

The objectives of this study were to observe the occurrences of VABAM in patients with IS caused by TSC (IST) and further explore the associated risk factors.

Methods

Children with IS receiving VGB were recruited from our institution; clinical, imaging, and medication data were collected. Cerebral MRI was reviewed to determine the occurrence of VABAM. Group comparisons (IS caused by TSC and other etiologies) were performed; subgroup analyses on IST were also performed. Next, a retrospective cohort study of children taking VGB was conducted to explore risk/protective factors associated with VABAM.

Results

The study enrolled 172 children with IS who received VGB. VABAM was observed in 38 patients (22.1%) with a peak dosage of 103.5 ± 26.7 mg/kg/day. Subsequent analysis found the incidence of VABAM was significantly lower in the 80 patients with IST than in the 92 patients with IS caused by other etiologies (10% versus 32.6%, p-value < 0.001). In subgroup analyses within the IST cohort, VABAM was significantly lower in children who received concomitant rapamycin therapy. Univariate and multivariate logistic regression analysis of the 172 IS children showed that treatment with rapamycin was the independent factor associated with a lower risk of VABAM; similar results were observed in the survival analysis.

Conclusion

The incidence of VABAM was significantly lower in IST patients. Further research is needed to examine the mechanisms that underlie this phenomenon and to determine if treatment with rapamycin may reduce the risk of VABAM.

Role of Taurine Transporter in the Retinal Uptake of Vigabatrin

Vigabatrin (VGB) is a first-line drug used for treatment of infantile spasms. On therapeutic dose, VGB accumulates in the retina causing permanent peripheral visual field constriction. The mechanism involved in retinal accumulation of VGB is ambiguous. In the present study, mechanism of VGB transport into retina was evaluated. VGB uptake into retina was studied in vitro using human adult retinal pigment epithelial (ARPE-19) cells as a model for outer blood retinal barrier. The VGB cell uptake studies demonstrated saturation kinetics with K_m value of 13.1 mM and uptake was significantly increased at pH 7.4 and hyperosmolar conditions indicating involvement of carrier-mediated Na⁺-Cl^--dependent transporter. In the presence of taurine transporter (TauT) substrates (taurine and GABA) and inhibitor guanidinoethyl sulfonate (GES), the uptake of VGB decreased significantly demonstrating contribution of TauT. The VGB retinal levels in rats were decreased by 1.5- and 1.3-folds on chronic administration of GES and taurine, respectively. In conclusion, this study demonstrated the TauT involvement in VGB uptake and accumulation in retina.

West Syndrome: A Review and Guide for Paediatricians

West syndrome (WS), also known as infantile spasms, occurs in infancy with a peak between 4 and 7 months. Spasms, neurodevelopmental regression and hypsarrhythmia on electroencephalogram (EEG) basically define WS. The International League Against Epilepsy commission classifies the aetiologies of WS into genetic, structural, metabolic and unknown. Early diagnosis and a shorter lag time to treatment are essential for the overall outcome of WS patients. These goals are feasible with the addition of brain magnetic resonance imaging (MRI) and genetic and metabolic testing. The present work analysed the medical literature on WS and reports the principal therapeutic protocols of its management. Adrenocorticotropic hormone (ACTH), vigabatrin (VGB) and corticosteroids are the first-line treatments for WS. There is no unique therapeutic protocol for ACTH, but most of the evidence suggests that low doses are as effective as high doses for short-term treatment, which is generally 2 weeks followed by dose tapering. VGB is generally administered at doses from 50 to 150 mg/kg/day, but its related retinal toxicity, which occurs in 21-34% of infants, is most frequently observed when treatment periods last longer than 6 months. Among corticosteroids, a treatment of 14 days of oral prednisolone (40-60 mg/day) has been considered effective and well tolerated. Considering that an early diagnosis and a shorter lag time to treatment are essential for successful outcomes in these patients, further studies on efficacy of the different therapeutic approaches with evaluation of final outcome after cessation of therapy are needed.

A case report on the efficacy of vigabatrin analogue (1S, 3S)-3-amino-4-difluoromethylenyl-1-cyclopentanoic acid (CPP-115) in a patient with infantile spasms

West Syndrome is characterized by infantile spasms, a hypsarrhythmic electroencephalogram (EEG) pattern, and a poor neurodevelopmental prognosis. First-line treatments include adrenocorticotrophic hormone (ACTH) and vigabatrin, but adverse effects often limit their use. CPP-115 is a high-affinity vigabatrin analogue developed to increase therapeutic potency and to limit retinal toxicity. Here, we present a child treated with CPP-115 through an investigational new drug protocol who experienced a marked reduction of seizures with no evidence of retinal dysfunction. Given the potential consequences of ongoing infantile spasms and the limitations of available treatments, further assessment of CPP-115 is warranted.

Management of infantile spasms

West syndrome, or infantile spasms syndrome is a frequently catastrophic infantile epileptic encephalopathy with a variety of etiologies. Despite the heterogeneous nature of causes of infantile spasms, a careful diagnostic evaluation can lead to diagnosis in many patients and may guide treatment choices. Magnetic resonance imaging (MRI) brain remains the highest yield initial study in determining the etiology in infantile spasms. Treatment of infantile spasms has little class I data, but adrenocorticotropic hormone (ACTH), prednisolone and vigabatrin have the best evidence as first-line medications. Other therapies including the ketogenic diet and other anti-epileptics medications may also prove useful in the treatment of infantile spasms. In general, more studies are needed to determine the best treatment regimen for this condition. Prognosis is generally poor, with the majority of patients having some or profound neurocognitive delays. Patients without delays at diagnosis and without an identifiable etiology, if treated appropriately, have the greatest likelihood of a normal outcome.

Drug utilization in pediatric neurology outpatient department: A prospective study at a tertiary care teaching hospital

Background:

Neurological disorders are a significant cause of morbidity, mortality and adversely affect quality of life among pediatric patients. In India, more than 30% population is under 20 years of age, many of whom present late during the course of illness. Several drugs prescribed to pediatric population suffering from neurological disorders may be off label or unlicensed.

Aims and Objectives:

To study drug use pattern, identify off-label/unlicensed drug use and to check potential for drug-drug interactions in patients attending outpatient department of pediatric neurology at a tertiary care teaching hospital.

Methodology:

Prescriptions of patients attending pediatric neurology outpatient department were collected prospectively for 8 weeks. They were analyzed for prescribing pattern, WHO core prescribing indicators, off-label/unlicensed drug use and potential for drug-drug interactions.

Result:

A total of 140 prescriptions were collected, male female ratio being 2:1. Epilepsy was the most common diagnosis (73.57%) followed by breath holding spells, migraine and developmental disorders. Partial seizure was the most common type of epilepsy (52.42%). Average number of drugs prescribed per patient was 1.56. Most commonly prescribed drug was sodium valproate (25.11%) followed by phenytoin (11.41%). About 16% of the prescriptions contained newer antiepileptic drugs. More than 60% of the drugs were prescribed from WHO essential drug list. In 8.57% of cases drugs were prescribed in off-label/unlicensed manner. Twenty-six percent prescriptions showed potential for drug interactions.

Conclusion:

Epilepsy is the most common neurological disease among children and adolescents. Sodium valproate is the most commonly prescribed drug. A few prescriptions contained off-label/unlicensed drugs.

Low vision due to cerebral visual impairment: differentiating between acquired and genetic causes

Background

To gain more insight into genetic causes of cerebral visual impairment (CVI) in children and to compare ophthalmological findings between genetic and acquired forms of CVI.

Methods

The clinical data of 309 individuals (mainly children) with CVI, and a visual acuity ≤0.3 were analyzed for etiology and ocular variables. A differentiation was made between acquired and genetic causes. However, in persons with West syndrome or hydrocephalus, it might be impossible to unravel whether CVI is caused by the seizure disorder or increased intracranial pressure or by the underlying disorder (that in itself can be acquired or genetic). In two subgroups, individuals with ‘purely’ acquired CVI and with ‘purely’ genetic CVI, the ocular variables (such as strabismus, pale optic disc and visual field defects) were compared.

Results

It was possible to identify a putative cause for CVI in 60% (184/309) of the cohort. In the remaining 40% the etiology could not be determined. A ‘purely’ acquired cause was identified in 80 of the patients (26%). West syndrome and/or hydrocephalus was identified in 21 patients (7%), and in 17 patients (6%) both an acquired cause and West and/or hydrocephalus was present. In 66 patients (21%) a genetic diagnosis was obtained, of which 38 (12%) had other possible risk factor (acquired, preterm birth, West syndrome or hydrocephalus), making differentiation between acquired and genetic not possible. In the remaining 28 patients (9%) a ‘purely’ genetic cause was identified.

CVI was identified for the first time in several genetic syndromes, such as ATR-X, Mowat-Wilson, and Pitt Hopkins syndrome. In the subgroup with ‘purely’ acquired causes (N = 80) strabismus (88% versus 64%), pale optic discs (65% versus 27%) and visual field defects (72% versus 30%) could be observed more frequent than in the subgroup with ‘purely’ genetic disorders (N = 28).

Conclusions

We conclude that CVI can be part of a genetic syndrome and that abnormal ocular findings are present more frequently in acquired forms of CVI.

Antiepileptic drug treatment: new drugs and new strategies

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

SUMMARY

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

Epilepsy in four genetically determined syndromes of intellectual disability

BACKGROUND

Epilepsy occurs with increased frequency in people with an intellectual disability (ID) compared to the rest of the population. A variety of research has in recent years shed light on genetic and biochemical aetiologies of epilepsy and, often in a different literature, on syndromes of ID. The aims of this annotation are to review developments in understanding of the pathophysiology of several ID syndromes in which epilepsy is a frequent co-occurrence and to relate these observations to recent advances in understanding of how these pathophysiological disturbances may lead to epilepsy.

METHOD

The ID syndromes selected for review were fragile X (FXS), Rett (RTT) and Angelman syndromes (AS) and tuberous sclerosis complex (TSC). Epilepsy is a significant aspect of these syndromes and relevant research into the genetic and biochemical pathophysiology of these four ID syndromes may be informative in establishing the association between epilepsy and ID. Employing a structured approach the authors initially searched the PubMed database for large case series describing the characteristics of epilepsy as manifested in these ID syndromes. The criteria for inclusion of the case series in the review were a sample size of greater than 50 and the description of several of the characteristic features of epilepsy, namely prevalence of seizures, age of seizure onset, seizure frequency, seizure semiology, severity and treatment. Following this, studies of the genetic and biochemical pathophysiology of these four ID syndromes were reviewed and the potential relevance of this research in understanding the association with epilepsy highlighted. Findings were considered in a focused manner in terms of effects on excitatory and inhibitory neurotransmitter systems and on glial function.

RESULTS

Diverse genetic pathologies underlying several ID syndromes can lead to alterations in the functioning of the glutamatergic and GABAergic neurotransmitter systems. The mechanisms involved include transcriptional regulation in RTT, translational regulation in FXS and TSC, and UBE3A-mediated proteolysis in AS. Expression or functioning of receptor subunits, uptake sites and enzymes involved in neurotransmitter metabolism are often affected by these changes, and may lead to modifications in network excitability and neuronal plasticity that may contribute to epileptogenesis and ID. Dysfunction in astrocytes may also contribute to epileptogenesis and ID in FXS, RTT and TSC with potential mechanisms including failure of astrocytic support functions, glial inflammation and homeostatic disturbances that affect the excitability and architecture of neuronal networks.

CONCLUSIONS

The annotation highlights research describing disturbances in excitatory and inhibitory neurotransmitter systems, neuronal ion channel and glial functions that provide possible explanations for the co-occurrence of seizures within several ID syndromes, in some cases suggesting possible avenues for research into novel therapeutic targets. Phenotypic overlaps between syndromes may also relate to roles for the implicated genes in different disturbances in linked biochemical pathways.

Infantile spasms (West syndrome) in children with inborn errors of metabolism: a review of the literature

West syndrome (infantile spasms) is an epileptic encephalopathy that includes psychomotor deterioration. In rare cases, it is due to an inherited, progressive metabolic disease. More than 25 inborn errors of metabolism have been considered etiologic or predisposing factors for infantile spasms. This is a review of the literature on reported cases of children diagnosed with a metabolic disease who developed infantile spasms. This article presents in brief the most frequent inborn errors of metabolism that have been associated with West syndrome and also illustrates the importance of screening for inborn errors of metabolism in infantile spasms.

The safety and tolerability of newer antiepileptic drugs in children and adolescents

Childhood epilepsy continues to be intractable in more than 25% of patients diagnosed with epilepsy. The introduction of new anti-epileptic drugs (AEDs) provides more options for treatment of children with epilepsy. We review the safety and tolerability of seven new AEDs (levetiracetam, lamotrigine, oxcarbazepine, rufinamide, topiramate, vigabatrin and zonisamide) focusing on their side effect profiles and safety in children and adolescents. Many considerations that are specific for children such as the impact of AEDs on the developing brain are not addressed during the development of new AEDs. They are usually approved as adjunctive therapies based upon clinical trials involving adult patients with partial epilepsy. However, 2 of the AEDs reviewed here (rufinamide and vigabatrin) have FDA approval in the U.S. for specific Pediatric epilepsy syndromes, which are discussed below. The Pediatrician or Neurologists decision on the use of a new AED is an evolutionary process largely dependent on the patient characteristics, personal/peer experiences and literature about efficacy and safety profiles of these medications. Evidence based guidelines are limited due to a lack of randomized controlled trials involving pediatric patients for many of these new AEDs.