GABA(A) receptor physiology and its relationship to the mechanism of action of the 1,5-benzodiazepine clobazam

Prophylactic antiseizure medications for recurrent status epilepticus in nonsyndromic childhood epilepsy

PURPOSE

The management of status epilepticus (SE) has mainly focused on the termination of ongoing SE episodes. However, long-term therapeutic strategies for the prevention of SE are lacking. This study aimed to investigate the effectiveness of prophylactic antiseizure medications (ASMs) for SEs in nonsyndromic childhood epilepsy.

METHODS

This retrospective study was conducted at Jikei University Hospital. Patients <18 years of age, diagnosed with epilepsy, and experiencing three or more SE episodes within 1 year between April 1, 2017, and October 1, 2021, were included. ASMs introduced for seizure types that developed into SE were evaluated. The effectiveness of ASMs was determined by using the "Rule of Three": An ASM was determined effective if patients were free of SE for a duration at least three times that of their longest SE interval in 12 months prior to intervention.

RESULTS

The investigation included a total of 32 ASMs administered to 13 patients. The longest interval between SE episodes before ASM administration was 28-257 d. The first SE interval after ASM administration was 12-797 d. Levetiracetam (LEV) and clobazam (CLB) showed effectiveness in 2/10 and 5/6 patients, respectively. Other ASMs were ineffective. The leading etiology of epilepsy was perinatal brain injury, identified in four patients, and CLB was effective in all of them.

CONCLUSIONS

The present study suggests that CLB and LEV may prolong the SE interval in some cases of nonsyndromic childhood epilepsy. CLB may be beneficial, particularly in patients with perinatal brain injury.

Alprazolam Reduces Freezing of Gait (FOG) and Improves FOG-Related Gait Deficiencies

Background

Freezing of gait (FOG) is an intractable motor symptom in Parkinson's disease (PD) that increases fall risk and impairs the quality of life. FOG has been associated with anxiety, with experimental support for the notion that anxiety itself provokes FOG. We investigated the effect of acute anxiety reduction via alprazolam on FOG in PD.

Methods

In ten patients with PD, FOG, and normal cognition, we administered 0.25 mg alprazolam in one session and placebo in another, in counterbalanced order. At each session, on separate days, patients walked on a pressure-sensitive walkway. Using Oculus Rift virtual-reality goggles, patients walked along a plank that appeared to be (a) level with the floor, in the low-anxiety condition or (b) raised high above the ground, in the high-anxiety conditions. In this way, we assessed the impacts of anxiety and alprazolam (i.e., anxiety reduction) on FOG frequency and other gait parameters.

Results

FOG events appeared only in the high-anxiety conditions. Alprazolam significantly reduced subjective and objective measures of anxiety, as well as the prevalence of FOG (p = 0.05). Furthermore, alprazolam improved swing time (p < 0.05) and gait variability in all conditions, particularly during the elevated plank trials. Interpretation. Our results suggest that (1) anxiety induces FOG, and (2) alprazolam concomitantly reduces anxiety and FOG. Alprazolam further improved gait stability (i.e., swing time and gait variability). These findings reveal that anxiety triggers FOG in PD. Treating anxiety can reduce FOG and improve gait stability, potentially offering new therapeutic avenues for this intractable and disabling symptom in PD.

Recent Progress in the Development of New Antiepileptic Drugs with Novel Targets

Background

Epilepsy is a chronic neurological disorder that affects approximately 50-70 million people worldwide. Epilepsy has a significant economic and social burden on patients as well as on the country. The recurrent, spontaneous seizure activity caused by abnormal neuronal firing in the brain is a hallmark of epilepsy. The current antiepileptic drugs provide symptomatic relief by restoring the balance of excitatory and inhibitory neurotransmitters. Besides, about 30% of epileptic patients do not achieve seizure control. The prevalence of adverse drug reactions, including aggression, agitation, irritability, and associated comorbidities, is also prevalent. Therefore, researchers should focus on developing more effective, safe, and disease-modifying agents based on new molecular targets and signaling cascades.

Summary

This review overviews several clinical trials that help identify promising new targets like lactate dehydrogenase inhibitors, c-jun n-terminal kinases, high mobility group box-1 antibodies, astrocyte reactivity inhibitors, cholesterol 24-hydroxylase inhibitors, glycogen synthase kinase-3 beta inhibitors, and glycolytic inhibitors to develop a new antiepileptic drug.

Key messages

Approximately 30% of epileptic patients do not achieve seizure control. The current anti-seizure drugs are not disease modifying, cure or prevent epilepsy. Lactate dehydrogenase inhibitor, cholesterol 24-hydroxylase inhibitor, glycogen synthase kinase-3 beta inhibitors, and mTOR inhibitors have a promising antiepileptogenic effect.

Elevations in Norclobazam Concentrations and Altered Mental Status in CYP2C19 Poor Metabolizer Phenotype: A Case Report

Clobazam is a 1,5-benzodiazepine frequently used as an adjunctive agent for refractory seizures and status epilepticus. Clobazam undergoes metabolism to an active metabolite norclobazam which is subsequently hydroxylated by CYP2C19, a cytochrome with several pharmacogenetic variants. Patients with poor metabolizer phenotypes may have elevated norclobazam levels and subsequent adverse effects. We present a case of an Asian American male receiving clobazam at a standard therapeutic dose for seizure disorder who became comatose secondary to significantly elevated norclobazam concentrations. Genetic testing revealed the patient was a poor CYP2C19 metabolizer, accounting for the impaired clearance. Clinicians should be aware of the patient populations at risk for these genetic polymorphisms and adjust initial doses based on package labeling or consider therapeutic drug monitoring to avoid adverse effects.

Proposed anti-seizure medication combinations with rufinamide in the treatment of Lennox-Gastaut syndrome: Narrative review and expert opinion

Lennox-Gastaut syndrome (LGS) is a severe, chronic, complex form of early childhood-onset epilepsy characterized by multiple seizure types, generalized slow (≤2.5 Hz) spike-and-wave activity and other electroencephalography abnormalities, and cognitive impairment. A key treatment goal is early seizure control, and several anti-seizure medications (ASMs) are available. Due to the low success rate in achieving seizure control with monotherapy and an absence of efficacy data supporting any particular combination of ASMs for treating LGS, a rational approach to selection of appropriate polytherapy should be applied to maximize benefit to patients. Such "rational polytherapy" involves consideration of factors including safety (including boxed warnings), potential drug-drug interactions, and complementary mechanisms of action. Based on the authors' clinical experience, rufinamide offers a well-considered first adjunctive therapy for LGS, particularly in combination with clobazam and other newer agents for LGS, and may be particularly useful for reducing the frequency of tonic-atonic seizures associated with LGS.

Tolerability of clobazam as add-on therapy in patients aged 50 years and older with drug-resistant epilepsy

OBJECTIVE

To evaluate the tolerability of clobazam in patients with drug-resistant epilepsy aged 50 years and older.

METHODS

We performed a single center, retrospective chart review of patients at least 50 years of age with drug resistant epilepsy of any type who started clobazam as an add on therapy. Retention rate, safety, and tolerability at 6 and 12 months and last follow-up, and the discontinuation rate due to side effects were analyzed.

RESULTS

A total of 26 patients met inclusion criteria. Mean age was 62 ± 7.1 years, and 69.2% of patients were female. The mean baseline seizure frequency before initiation of clobazam was 2 (range 1-30) seizures per month. The mean total daily dose of clobazam administered was 13 (range 5 to 30) mg/day. At the 12-month follow-up visit after clobazam initiation, 40% of patients were seizure-free and an additional 45% of patients had > 50% reduction in seizure frequency. The mean seizure frequency at 12-month follow-up was 1.5 (range 0-24) seizures per month. The mean total dose of clobazam at 12-month follow-up was 14.25 (range 5 to 25) mg/day. The mean duration of clobazam at last follow was 55.2 ± 27.02 (mean ± SD months) and 18 (69.2%) patients remained on clobazam. Twenty out of 26 (76.9%) patients reported at least one side effect and 6/26 (23%) discontinued the medication within a month of initiation. At last follow-up, 40% remained seizure free on stable dosing.

CONCLUSION

Clobazam can be a safe and tolerable, add-on treatment older adults with drug-resistant epilepsy. Those who responded tolerated the medication well. Discontinuation due to side effects occurred soon after initiation of therapy.

Pharmacodynamic synergism contributes to the antiseizure action of cannabidiol and clobazam

The management of refractory epilepsy involves treatment with more than one antiseizure medication (ASM). Combination of ASMs with distinct mechanisms of action are hypothesized to improve overall treatment effectiveness. In clinical trials, concomitant use of cannabidiol (CBD) and clobazam (CLB) was associated with increased seizure reduction and bidirectional elevation in levels of their active metabolites, 7-hydroxy-cannabidiol (7-OH-CBD) and nor-clobazam (n-CLB). Using isobolographic analysis, we investigated whether CBD and CLB interacted pharmacodynamically. In the mouse maximal electroshock seizure (MES) test, brain tissue levels of CBD and CLB corresponding to seizure prevention in 50% of animals (brain Effective Exposure, bEE₅₀) were 7.9 μM and 1.6 μM, respectively. In the 6 Hz psychomotor seizure model, 7-OH-CBD displayed a 5-fold greater potency than CBD (b-EE₅₀, 8.7 μM vs 47.3 μM). Isobolographic analysis performed on combination of CBD/CLB at 1:1, 3:1, and 1:3 ratios based on equi-effective bEE₅₀ values revealed synergism at all doses with combination indices (CI) of 0.43, 0.62 and 0.75 respectively. These outcomes were independent of pharmacokinetic interaction between CBD and CLB. These findings identify pharmacodynamic synergism as an important factor underlying enhanced antiseizure effect during concomitant CBD and CLB use.

Isobolographic analysis of adjunct antiseizure activity of the FDA-approved cannabidiol with neurosteroids and benzodiazepines in adult refractory focal onset epilepsy

Epilepsy is a serious neurological disorder associated with recurrent and unpredictable seizures and extensive neuropsychiatric comorbidities. There is no cure for epilepsy, and over one third of epileptic patients have been diagnosed with drug-refractory epilepsy, indicating the critical need for novel antiseizure medications (ASMs). Cannabidiol (CBD) has been shown to decrease seizures in pediatric epilepsies, such as Dravet and Lennox-Gastaut syndromes; however, it has not been rigorously tested for adult seizures or in models of refractory focal epilepsy. Although the exact mechanism is unknown, it is likely to act in a way that is unique to certain GABA-A receptor-modulating drugs, such as neurosteroids and benzodiazepines. In this study, we sought to determine the adjunct antiseizure activity of a clinical CBD product in an adult 6-Hz model of focal refractory epilepsy. CBD was evaluated alone in both a dose-response and time-course manner and in an adjunct combination with two ASMs ganaxolone (neurosteroid) and midazolam (benzodiazepine) against 6-Hz-induced refractory focal onset, generalized seizures. In pharmacological studies, CBD produced dose-dependent protection against seizures (ED50, 53 mg/kg, i.p.) without any side effects. CBD significantly reduced both electrographic activity and behavioral ictal responses with no apparent sex differences. CBD was evaluated in an isobologram design in conjunction with ganaxolone or midazolam at three standard ratios (1:1, 1:3, 3:1). Isobolographic analysis shows the combination regimens of CBD + ganaxolone and CBD + midazolam exerted combination index of 0.313 and 0.164, indicating strong synergism for seizure protection, with little to no toxicity. Together, these results demonstrate the therapeutic potential of CBD monotherapy and as an adjunct therapy for adult focal refractory epilepsy in combination with GABAergic ASMs.

Providing a Primary Care Medical Home for Children and Youth With Cerebral Palsy

Cerebral palsy (CP) is the most common motor disorder of childhood, with prevalence estimates ranging from 1.5 to 4 in 1000 live births. This clinical report seeks to provide primary care physicians with guidance to detect children with CP; collaborate with specialists in treating the patient; manage associated medical, developmental, and behavioral problems; and provide general medical care to their patients with CP.

Rescue therapies for seizure clusters: Pharmacology and target of treatments

The primary goal of treatment for seizure clusters is cessation of the cluster to avoid progression to more severe conditions, such as prolonged seizures and status epilepticus. Rescue therapies are key components of treatment plans for patients with seizure clusters. Three rescue therapies are approved in the United States for the treatment of seizure clusters: diazepam rectal gel, midazolam nasal spray, and diazepam nasal spray. This review characterizes the pharmacological function of rescue therapies for seizure clusters, as well as describing γ‐aminobutyric acid A (GABA_A) receptor functions. GABA_A receptors are heteropentamers, consisting primarily of α1‐6, β1‐3, γ2, and δ subunits in the central nervous system. These subunits can traffic to and from the membrane to regulate membrane potential. Benzodiazepines, such as diazepam and midazolam, are positive allosteric modulators of GABA_A receptors, the activation of which leads to an increase in intracellular chloride, hyperpolarization of the cell membrane, and a reduction in excitation. GABA_A receptor subunit mutations, dysregulation of trafficking, and degradation are associated with epilepsy. Although benzodiazepines are effective GABA_A receptor modulators, individual formulations have unique profiles in practice. Diazepam rectal gel is an effective rescue therapy for seizure clusters; however, adults and adolescents may have social reservations regarding its administration. Intranasal delivery of midazolam or diazepam is a promising alternative to rectal administration because these formulations offer easy, socially acceptable administration and exhibit a rapid onset. Off‐label benzodiazepines, such as orally disintegrating lorazepam and intranasal use of an intravenous formulation of midazolam via nasal atomizer, are less well characterized regarding bioavailability and tolerability compared with approved agents.

GABAkines - Advances in the discovery, development, and commercialization of positive allosteric modulators of GABAA receptors

Positive allosteric modulators of γ-aminobutyric acid-A (GABA_A) receptors or GABAkines have been widely used medicines for over 70 years for anxiety, epilepsy, sleep, and other disorders. Traditional GABAkines like diazepam have safety and tolerability concerns that include sedation, motor-impairment, respiratory depression, tolerance and dependence. Multiple GABAkines have entered clinical development but the issue of side-effects has not been fully solved. The compounds that are presently being developed and commercialized include several neuroactive steroids (an allopregnanolone formulation (brexanolone), an allopregnanolone prodrug (LYT-300), Sage-324, zuranolone, and ganaxolone), the α2/3-preferring GABAkine, KRM-II-81, and the α2/3/5-preferring GABAkine PF-06372865 (darigabat). The neuroactive steroids are in clinical development for post-partum depression, intractable epilepsy, tremor, status epilepticus, and genetic epilepsy disorders. Darigabat is in development for epilepsy and anxiety. The imidazodiazepine, KRM-II-81 is efficacious in animal models for the treatment of epilepsy and post-traumatic epilepsy, acute and chronic pain, as well as anxiety and depression. The efficacy of KRM-II-81 in models of pharmacoresistant epilepsy, preventing the development of seizure sensitization, and in brain tissue of intractable epileptic patients bodes well for improved therapeutics. Medicinal chemistry efforts are also ongoing to identify novel and improved GABAkines. The data document gaps in our understanding of the molecular pharmacology of GABAkines that drive differential pharmacological profiles, but emphasize advancements in the ability to successfully utilize GABA_A receptor potentiation for therapeutic gain in neurology and psychiatry.

Enhancing GABA inhibition is the next generation of medications for essential tremor

γ-Aminobutyric acid (GABA) is the most prevalent inhibitory CNS neurotransmitter. Activating GABA-A receptors hyperpolarizes cells via Cl^- influx, which inhibits action potentials. Although the exact pathophysiologies of tremor are incompletely understood, proposed neuroanatomy extensively implicates GABA pathways. Pathological studies and imaging studies also show GABA abnormalities in patients with ET. Most importantly, medications that activate GABA-A receptors, such as primidone, often improve tremor. Ongoing clinical trials and physiology research should further refine potential future GABAergic targets and treatments, which are currently the most promising targets for pharmacological intervention.

Correction of the hypomorphic Gabra2 splice site variant in mouse strain C57BL/6J modifies the severity of Scn8a encephalopathy

De novo gain-of-function mutations of SCN8A are a significant cause of developmental and epileptic encephalopathy (DEE) (MIM: 614558). The severely affected individuals exhibit refractory seizures, developmental delay, and cognitive disabilities, often accompanied by impaired movement. Individuals with the identical SCN8A variant often differ in clinical course, suggesting a role for modifier genes in disease severity. In a previous study we demonstrated genetic linkage between a hypomorphic mutation in the Gabra2 gene and seizure severity in a mouse model of the human SCN8A pathogenic variant p.Arg1872Trp. Homozygosity for the hypomorphic Gabra2 mutation was associated with early seizure onset and shortened lifespan. We have now confirmed Gabra2 as the modifier gene using a knock-in allele that corrects the splice site variant in strain C57BL/6J. Correction of the Gabra2 variant restores transcript abundance, increases the age of seizure onset, and extends survival of the Scn8a mutant mice. GABRA2 encodes the α2 subunit of the GABA_A receptor that provides inhibitory input to dendrites and the the axon initial segment of excitatory neurons. Quantitative variation in human GABA_A receptor expression could contribute to variation in the severity of genetic epilepsies and suggests a potential therapeutic intervention.

Efficacy and Tolerability of Clobazam in Adults With Drug-Refractory Epilepsy

OBJECTIVES

To evaluate the effectiveness and tolerability of clobazam as an adjunctive treatment for adults with drug-resistant epilepsy.

METHODS

We performed a single-center, retrospective chart review of patients aged ≥18 years with drug-resistant epilepsy who started clobazam between 2010 and 2018. Included patients had outpatient visits both before and ≥1 month after clobazam initiation. Epilepsy classification, seizure frequency before and after clobazam, duration of clobazam treatment, and adverse effects were analyzed.

RESULTS

A total of 417 patients met the inclusion criteria. Mean age was 37.5 years, and 54% of patients were female. Patients were on a mean of 2.4 antiepileptic drugs at the time of initiation of clobazam. Epilepsy types were focal (56.8%), Lennox-Gastaut syndrome (LGS) (21.1%), generalized (15.1%), and unclassified (7.0%). At the first follow-up visit ≥1 month after clobazam initiation, 50.3% of patients had >50% reduction in seizure frequency, and 20.5% were seizure free. Of the initial cohort, 17.1% were followed >1 year and were seizure free at last follow-up. Response rates did not differ between different epilepsy classifications. Fifty-one percent of patients experienced ≥1 side effect, most commonly lethargy/fatigue (30.7%) or mood changes (10.8%). A total of 178 (42.6%) patients discontinued clobazam, most commonly due to adverse effects (55%).

CONCLUSIONS

Clobazam is effective and safe as a long-term adjunctive therapy for adults with drug-resistant epilepsy; efficacy in off-label use is similar to that in LGS.

CLASSIFICATION OF EVIDENCE

This study provides Class IV evidence that clobazam is an effective treatment for adults with drug-resistant epilepsy, independent of epilepsy classification.

Drug treatment of epilepsy: From serendipitous discovery to evolutionary mechanisms

Epilepsy is a chronic brain disorder caused by abnormal firing of neurons. Up to now, using antiepileptic drugs is the main method of epilepsy treatment. The development of antiepileptic drugs lasted for centuries. In general, most agents entering clinical practice act on the balance mechanisms of brain "excitability-inhibition". More specifically, they target voltage-gated ion channels, GABAergic transmission and glutamatergic transmission. In recent years, some novel drugs representing new mechanisms of action have been discovered. Although there are about 30 available drugs in the market, it is still in urgent need of discovering more effective and safer drugs. The development of new antiepileptic drugs is into a new era: from serendipitous discovery to evolutionary mechanism-based design. This article presents an overview of drug treatment of epilepsy, including a series of traditional and novel drugs.

Neuropharmacological Assessment of the Hydroethanolic Leaf Extract of Calotropis procera (Ait). R. Br. (Apocynaceae) in Mice

BACKGROUND

Calotropis procera has been widely used traditionally for its analgesic and anti-inflammatory effects. It is also reportedly used in ethnomedicine for mental health disorders including epilepsy even in the absence of supporting scientific data. Thus, the potential of the plant to affect neurological functions was evaluated.

METHODS

Irwin's test was performed to determine the effect of the oral administration of the extract (30-3000 mg kg^-1) on gross behaviour and physiological function. The activity meter, rotarod, pentylenetetrazol- (PTZ-) induced convulsion, pentobarbitone-induced sleep test, and the tail immersion tests were used to evaluate the spontaneous activity, neuromuscular function, convulsive threshold, sedation, and analgesic effects of the Calotropis procera extract (30-1000 mg/kg), respectively, in mice.

RESULTS

Calotropis procera extract (CPE) exhibited significant (p < 0.0001) anticonvulsant and analgesic effects. There was a significant increase in withdrawal latency of the CPE-treated animals in the tail immersion test for analgesia (p < 0.0001), while latency and duration of PTZ-induced convulsions were positively modulated. Calotropis procera extract showed significant (p < 0.0001) central nervous system depressant effects in pentobarbitone-induced hypnosis at 100-1000 mg/kg and spontaneous activity test (30-1000 mg/kg). The extract also depicted impaired motor coordination at 100-1000 mg/kg dose levels. LD₅₀ was estimated to be above 1000 mg kg^-1.

CONCLUSIONS

Calotropis procera extract has significant central nervous system depressant and analgesic effects in mice.

Molecular Targets of Cannabidiol in Experimental Models of Neurological Disease

Cannabidiol (CBD) is a non-psychoactive phytocannabinoid known for its beneficial effects including antioxidant and anti-inflammatory properties. Moreover, CBD is a compound with antidepressant, anxiolytic, anticonvulsant and antipsychotic effects. Thanks to all these properties, the interest of the scientific community for it has grown. Indeed, CBD is a great candidate for the management of neurological diseases. The purpose of our review is to summarize the in vitro and in vivo studies published in the last 15 years that describe the biochemical and molecular mechanisms underlying the effects of CBD and its therapeutic application in neurological diseases. CBD exerts its neuroprotective effects through three G protein coupled-receptors (adenosine receptor subtype 2A, serotonin receptor subtype 1A and G protein-coupled receptor 55), one ligand-gated ion channel (transient receptor potential vanilloid channel-1) and one nuclear factor (peroxisome proliferator-activated receptor γ). Moreover, the therapeutical properties of CBD are also due to GABAergic modulation. In conclusion, CBD, through multi-target mechanisms, represents a valid therapeutic tool for the management of epilepsy, Alzheimer’s disease, multiple sclerosis and Parkinson’s disease.

Regiospecific Synthesis and Structural Studies of 3,5-Dihydro-4H-pyrido[2,3-b][1,4]diazepin-4-ones and Comparison with 1,3-Dihydro-2H-benzo[b][1,4]diazepin-2-ones

Nine 3,5-dihydro-4H-pyrido[2,3-b][1,4]diazepin-4-ones (17-25), some of which contain fluoro-substituents, have been regiospecifically prepared by reaction of 2,3-diaminopyridines with ethyl aroylacetates. In two cases, open intermediates have been isolated and these are related to the reaction pathway. The X-ray crystal structure of 1-methyl-4-phenyl-3,5-dihydro-4H-pyrido[2,3-b][1,4]diazepin-4-one (23) has been solved (formula, C₁₅H₁₃N₃O; crystal system, monoclinic; space group, C2/c). This is an asymmetric unit constituted by a single nonplanar molecule and its conformational enantiomer due to the presence of the seven-membered diazepin-2-one moiety, which introduces a certain degree of torsion in the adjacent pyridine ring. The ¹H, ¹³C, ¹⁵N, and ¹⁹F NMR spectra were obtained and the chemical shifts, together with those of the previously published 1,3-dihydro-2H-benzo[b][1,4]diazepin-2-ones (1-16), i.e., a total of 544 values, were successfully compared with the chemical shifts calculated at the gauge invariant atomic orbital (GIAO)/Becke, three-parameter, Lee-Yang-Parr (B3LYP)/6-311++G(d,p) level. The seven-membered ring inversion barrier in 5-benzyl-2-phenyl-3,5-dihydro-4H-pyrido[2,3-b][1,4]diazepin-4-one (25) was determined and, in conjunction with the data from the literature, compared with the B3LYP/6-311++G(d,p) computed values. This allowed the determination of several structural effects. The rotation about the exocyclic N1-CR bond was also calculated and its dynamic properties were discussed.

Efficacy and Side Effect Profile of Clobazam in Children with Different Etiologies of Epilepsy from a Single Center

Objectives:

Clobazam is a long-acting antiepileptic drug that belongs to benzodiazepines used in the polytherapy of childhood epilepsy. In this study, our aim is to retrospectively evaluate the effectiveness and side effect profile of clobazam in children with different etiologies of epilepsy, mostly drug resistant.

Methods:

Forty patients aged 0-18 years that were admitted to Okmeydanı Training and Research Hospital pediatric neurology outpatient clinic between January 2017–January 2019 and prescribed clobazam were included in this study. The data of the patients who gave informed consent were extracted retrospectively from the outpatient clinic files. The patients with no seizures over 50% reduction in seizures were classified as clobazam-responsive, whereas the patients with less than 50% reductions in seizures, patients who had no response, and who manifested side effects and stopped using the drug were classified as clobazam-unresponsive.

Results:

Twenty-three of the patients (57.5%) were male, 17 were (42.5%) were female. The average onset age of epilepsy was 31.8±37.2 months, while the average age for the prescription of clobazam was 70.6±48.9 months. The types of seizures were focal in 23 patients (57.5%) and generalized in 17 (42.5%) patients. Thirty-three (82.5%) patients had been using double or triple combinations of eight different antiepileptic drugs when clobazam was added to their treatment and accepted as drug-resistant epilepsy. The etiology of twenty one patients (52.5%) was unknown. In the remaining 19 patients (47.5%), the most common cause was structural and others were genetic, infectious and metabolic. Thirty one of the patients (77.5%) were responsive to clobazam. Of them, fifteen (37.5%) had no seizures, and 16 had a reduction in seizures (>50%). Nine (22.5%) patients were accepted as unresponsive to clobazam. The mean dose per kg was 0.7±0.3 mg/kg/day with a median of 0.63 mg/kg/day. Side effects of clobazam were encountered in 18 patients (45%); these resulted in the cessation of administration in only six (15%) patients. The side effects that cause the cessation of clobazam were sedation, refusal to take the drug due to the taste, irritability, hypersalivation, and malaise. Four patients (10%) had their doses reduced, seven patients (17.5%) responsive to clobazam although with side effects continued taking the drug as prescribed. The most common side effects of all were hyperactivity and sedation consecutively.

Conclusion:

Clobazam is an effective treatment for ensuring seizure freedom in pediatric epilepsy, mostly drug-resistant. The side effects are at tolerable levels in patients who are responsive to the drug.

Late-onset post-lesional paroxysmal hypothermia: a case series and literature review

BACKGROUND

Paroxysmal hypothermia (PH) is a rare condition characterized by recurrent episodes of spontaneous hypothermia, bradycardia, disorders of consciousness and, in some cases, hyperhidrosis. When associated with a detectable hypothalamic lesion, PH episodes usually occur shortly after the brain insult.

METHODS

We performed a retrospective study to identify patients who had demonstrated at least one episode of symptomatic spontaneous PH as defined by (i) tympanic temperature < 35 °C; (ii) drowsiness and/or confusion state and/or coma; (iii) duration of the episode ≥ 24 h; (iv) absence of other condition resulting in hypothermia RESULTS: Among 8824 patients, we identified four patients with recurrent late-onset PH episodes of 1-26-day duration that occurred 6-46 years after the brain insult. The lesion always involved the diencephalon. All patients suffered from epilepsy and three of hypopituitarism. PH episode typically included severe hypothermia, bradycardia, drowsiness, thrombocytopenia and in some patients central hypoventilation and narcolepsy-like hypersomnia. In ¼ of episodes, confusion was mistaken as non-convulsive epileptic manifestation resulting in benzodiazepine administration which aggravated symptoms. In the two patients with nocturnal hypoventilation, chronic non-invasive ventilation with bi-level positive airway pressure allowed cessation of symptomatic episodes.

DISCUSSION

Late-onset post-lesional PH is exceptional with only a single case hitherto reported in the literature. Distinguishing hypothermia-related disturbances of consciousness from epileptic seizures or post-ictal phenomena is crucial since treatment with benzodiazepines may worsen hypothermia through their action on GABAa receptors. Lastly, PH may be associated with sleep disorders and hypoventilation, for which investigations and treatment should be considered.

HAP1 Modulates Epileptic Seizures by Regulating GABAAR Function in Patients with Temporal Lobe Epilepsy and in the PTZ-Induced Epileptic Model

The number of γ-aminobutyric acid type A receptors (GABA_ARs) expressed on the surface membrane and at synaptic sites is implicated in the enhanced excitation of neuronal circuits and abnormal network oscillations in epilepsy. Huntingtin-associated protein 1 (HAP1), a key mediator of pathological alterations in protein trafficking, directly interacts with GABA_ARs and facilitates their recycling back to synapses after internalization from the surface; thus, HAP1 regulates the strength of inhibitory synaptic transmission. Here, we show that HAP1 modulates epileptic seizures by regulating GABA_AR function in patients with temporal lobe epilepsy (TLE) and in the pentylenetetrazol (PTZ)-induced epileptic model. We demonstrate that GABA_ARβ^2/3 and HAP1 expression are decreased and that the HAP1-GABA_ARβ^2/3 complex is disrupted in the epileptic rat brain. We found that HAP1 upregulation exerts antiepileptic activity in the PTZ-induced seizure and that these changes are associated with increased surface GABA_ARβ^2/3 expression and the amplitude of miniature inhibitory postsynaptic currents (mIPSCs). This study provides evidence that hippocampal HAP1 is linked to GABA_ARs in evoking seizures and suggests that this mechanism is involved in epileptic seizures in the brain, representing a potential therapeutic target for epilepsy.

Persistent Hypersomnolence Following Clobazam in a Child With Epilepsy and Undiagnosed CYP2C19 Polymorphism

We describe an 11-year-old female who presented with severe hypersomnolence after receiving 1 week of modest doses of clobazam (CLB). In reviewing the above case, we considered that the hypersomnolence could be related to a pharmacodynamic, pharmacokinetic, or pharmacogenomic issue associated with CLB or to a combination of these factors. Although serum concentrations of CLB and its active metabolite are sensitive to factors that affect cytochrome-dependent metabolism, drug-drug interactions were omitted as a cause of the hypersomnolence. Subsequent DNA analysis of the cytochrome P450 2C19 gene revealed the patient as *2/*2 genotype with poor metabolizer enzyme activity. Because genetic testing of all patients treated with CLB is currently not practical, CLB dose/concentration ratios and pharmacokinetic drug-drug interaction impact models may be indicated. Genetic testing should be considered when an adverse effect suggests the possibility of a polymorphism important to drug metabolism.

Pharmacological Management of the Genetic Generalised Epilepsies in Adolescents and Adults

Common genetic generalised epilepsy syndromes encountered by clinicians include childhood and juvenile absence epilepsies, juvenile myoclonic epilepsy and generalised tonic-clonic seizures on awakening. Treatment of these syndromes involves largely the use of broad-spectrum antiseizure drugs. Those effective for the generalised epilepsies include sodium valproate, phenobarbital, ethosuximide, clobazam, clonazepam, lamotrigine, levetiracetam, topiramate, zonisamide and, more recently, perampanel and brivaracetam. Results from the few rigorous studies comparing outcomes with drugs for genetic generalised epilepsies show valproate to be the most effective. The majority of patients with genetic generalised epilepsy syndromes will become seizure free on antiseizure monotherapy; those for whom control proves elusive may benefit from combination regimens. Early counselling regarding management may assist the patient to come to terms with their diagnosis and improve long-term outcomes. Treatment can be lifelong in some individuals, although others may remain seizure free without medication. Choice of antiseizure medication depends on the efficacy for specific seizure types, as well as tolerability. For patients prescribed comedication, drug interactions should be considered. In particular, for young women taking oral hormonal contraceptives, ≥ 200 mg/day of topiramate can decrease the circulating concentration of ethinylestradiol and ≥ 12 mg/day of perampanel can induce levonorgestrel metabolism. The use of valproate in women of childbearing potential is limited by associated teratogenic and neurodevelopmental effects in offspring. Given that valproate is often the antiseizure drug of choice for genetic generalised epilepsies, this creates a dilemma for patients and clinicians. Decision making can be aided by comprehensive assessment and discussion of treatment options. Psychiatric comorbidities are common in adolescents and adults with genetic generalised epilepsies. These worsen the prognosis, both in terms of seizure control and quality of life. Attendant lifestyle issues can impact significantly on the individual and society. Frontal lobe dysfunction, which can present in patients with juvenile myoclonic epilepsy, can adversely affect the long-term outlook, regardless of the nature of seizure control. Ongoing management requires consideration of psychosocial and behavioural factors that can complicate diagnosis and treatment. An assured supportive attitude by the neurologist can be an important contributor to a positive outcome. The mechanisms underlying genetic generalised epilepsies, including genetic abnormalities, are unclear at present. As the pathophysiology is unravelled, this may lead to the development of novel therapies and improved outcomes for patients with these syndromes.

Rare but life-threatening aspiration pneumonia related to initiation of clobazam therapy

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Screening for aspiration-predisposing factors is recommended before initiation of CLB.

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If a patient has aspiration-predisposing factors, CLB should be initiated cautiously.

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Caregiver should raise awareness on early signs of aspiration after initiation of CLB.

Clobazam (CLB) was approved in October 2011 by the United States FDA as an adjunctive therapy for the treatment of seizures associated with Lennox-Gastaut syndrome (LGS) in patients older than the age of 2. Due to its unique chemical design and selective binding to the alpha-2 GABA-receptor, CLB has a decreased tendency for sedation compared to other benzodiazepines. A recent literature review shows that sedation, hypersalivation (drooling), and behavior changes are the most common side effects of CLB. It has also been shown that a patient's level of consciousness is indirectly related to the risk of aspiration. Hypersalivation is too is a significant predisposing factor for aspiration. In this report, we present three adult patients with epilepsy who had aspiration pneumonia during treatment with CLB. We would like to raise awareness of increased drooling and somnolence in patients with predisposing factors for aspiration such as treatment with CLB and emphasize vigilance in this regard.

Coadministered cannabidiol and clobazam: Preclinical evidence for both pharmacodynamic and pharmacokinetic interactions

OBJECTIVE

Cannabidiol (CBD) has been approved by the US Food and Drug Administration (FDA) to treat intractable childhood epilepsies, such as Dravet syndrome and Lennox-Gastaut syndrome. However, the intrinsic anticonvulsant activity of CBD has been questioned due to a pharmacokinetic interaction between CBD and a first-line medication, clobazam. This recognized interaction has led to speculation that the anticonvulsant efficacy of CBD may simply reflect CBD augmenting clobazam exposure. The present study aimed to address the nature of the interaction between CBD and clobazam.

METHODS

We examined whether CBD inhibits human CYP3A4 and CYP2C19 mediated metabolism of clobazam and N-desmethylclobazam (N-CLB), respectively, and performed studies assessing the effects of CBD on brain and plasma pharmacokinetics of clobazam in mice. We then used the Scn1a+/- mouse model of Dravet syndrome to examine how CBD and clobazam interact. We compared anticonvulsant effects of CBD-clobazam combination therapy to monotherapy against thermally-induced seizures, spontaneous seizures and mortality in Scn1a+/- mice. In addition, we used Xenopus oocytes expressing γ-aminobutyric acid (GABA)A receptors to investigate the activity of GABAA receptors when treated with CBD and clobazam together.

RESULTS

CBD potently inhibited CYP3A4 mediated metabolism of clobazam and CYP2C19 mediated metabolism of N-CLB. Combination CBD-clobazam treatment resulted in greater anticonvulsant efficacy in Scn1a+/- mice, but only when an anticonvulsant dose of CBD was used. It is important to note that a sub-anticonvulsant dose of CBD did not promote greater anticonvulsant effects despite increasing plasma clobazam concentrations. In addition, we delineated a novel pharmacodynamic mechanism where CBD and clobazam together enhanced inhibitory GABAA receptor activation.

SIGNIFICANCE

Our study highlights the involvement of both pharmacodynamic and pharmacokinetic interactions between CBD and clobazam that may contribute to its efficacy in Dravet syndrome.

Development of 1,3-thiazole analogues of imidazopyridines as potent positive allosteric modulators of GABAA receptors

Structure-activity relationship studies were conducted in the search for 1,3-thiazole isosteric analogs of imidazopyridine drugs (Zolpidem, Alpidem). Three series of novel γ-aminobutyric acid receptor (GABA_AR) ligands belonging to imidazo[2,1-b]thiazoles, imidazo[2,1-b][1,3,4]thiadiazoles, and benzo[d]imidazo[2,1-b]thiazoles were synthesized and characterized as active agents against GABA_AR benzodiazepine-binding site. In each of these series, potent compounds were discovered using a radioligand competition binding assay. The functional properties of highest-affinity compounds 28 and 37 as GABA_AR positive allosteric modulators (PAMs) were determined by electrophysiological measurements. In vivo studies on zebrafish demonstrated their potential for the further development of anxiolytics. Using the OECD "Fish, Acute Toxicity Test" active compounds were found safe and non-toxic. Structural bases for activity of benzo[d]imidazo[2,1-b]thiazoles were proposed using molecular docking studies. The isosteric replacement of the pyridine nuclei by 1,3-thiazole, 1,3,4-thiadiazole, or 1,3-benzothiazole in the ring-fused imidazole class of GABA_AR PAMs was shown to be promising for the development of novel hypnotics, anxiolytics, anticonvulsants, and sedatives drug-candidates.

Safety and Efficacy of Supratherapeutic Doses of Clobazam

Clobazam is a commonly used long-acting benzodiazepine approved by the US Food and Drug Administration (FDA) to treat seizures associated with Lennox Gastaut syndrome. The FDA approved maximum dosage of clobazam is 1 mg/kg/d or a total of 40 mg a day. Many providers exceed this dosage but there is limited data on the safety, tolerability, and efficacy of supratherapeutic doses. We reviewed retrospective data at our institution and compared patients on supratherapeutic doses to patients on therapeutic doses. A total of 133 patients met inclusion criteria (65 supratherapeutic, 67 therapeutic). There was no statistically significant difference in terms of seizure control, health care utilization, or side effects between patients on supratherapeutic doses and those on therapeutic doses. This study lends further support to the safety and tolerability of supratherapuetic doses of clobazam.

Need of Immediate Drug Reduction after Epilepsy Surgery - A Prospective Observational Study

Background

Patients undergoing epilepsy surgery are on polytherapy. Drug tapering is usually done after 1 year in adults and after 6 months in children. Sometimes, drugs have to be altered during the perioperative period, which is more commonly seen in hemispherotomy (HS) patients. The present study was done to compare perioperative drug alterations between HS and temporal (TL) lobectomy patients.

Materials and Methods

Prospective analysis of postoperative HS and TL patients was done. Primary outcomes were drug number, dosage changes, and seizure outcome. Secondary outcome studied was a change in intelligence quotient (IQ) in the two groups.

Results

At total of 71 patients were included. Perioperative drug stopping (clobazam - CLB) was needed in 3/38 patients in the HS group, due to sedation. Dosage was reduced in 23/38 (60.52%) in HS group, and in 2/33 (6%) in TL group P < 0.001. The most common drug was CLB, with reduction in 21/27 (77.77%) patients, with a mean reduction of 41.21 ± 4.01%. Two patients required drug substitution in the HS group. About 64/71 (90.1%) patients achieved Class I outcome at a 1-year postoperative time point (TL - 90.9%, HS - 89.47%). There was no change in IQ in any of the groups.

Conclusion

Perioperative drug alteration is often needed in the HS patients as compared to TL patients. Benzodiazepines have to be reduced to maintain alertness in the HS patients. The increased sedation postoperatively can be due to decreased cortical drive over the reticular activating system, gamma-aminobutyric acid (GABA) receptor denervation hypersensitivity, or increased activity of drugs over the remaining active hemisphere.

GABAergic Inhibition Gates Perceptual Awareness During Binocular Rivalry

Binocular rivalry is a classic experimental tool to probe the neural machinery of perceptual awareness. During rivalry, perception alternates between the two eyes, and the ebb and flow of perception is modeled to rely on the strength of inhibitory interactions between competitive neuronal populations in visual cortex. As a result, rivalry has been suggested as a noninvasive perceptual marker of inhibitory signaling in visual cortex, and its putative disturbance in psychiatric conditions, including autism. Yet, direct evidence causally implicating inhibitory signaling in the dynamics of binocular rivalry is currently lacking. We previously found that people with higher GABA levels in visual cortex, measured using magnetic resonance spectroscopy, have stronger perceptual suppression during rivalry. Here, we present direct causal tests of the impact of GABAergic inhibition on rivalry dynamics, and the contribution of specific GABA receptors to these dynamics. In a crossover pharmacological design with male and female adult participants, we found that drugs that modulate the two dominant GABA receptor types in the brain, GABA_A (clobazam) and GABA_B (arbaclofen), increase perceptual suppression during rivalry relative to a placebo. Crucially, these results could not be explained by changes in reaction times or response criteria, as determined through rivalry simulation trials, suggesting a direct and specific influence of GABA on perceptual suppression. A full replication study of the GABA_B modulator reinforces these findings. These results provide causal evidence for a link between the strength of inhibition in the brain and perceptual suppression during rivalry and have implications for psychiatric conditions including autism.SIGNIFICANCE STATEMENT How does the brain accomplish perceptual gating? Here we use a direct and causal pharmacological manipulation to present insight into the neural machinery of a classic illusion of perceptual awareness: binocular rivalry. We show that drugs that increase GABAergic inhibition in the brain, clobazam (GABA_A modulator) and arbaclofen (GABA_B modulator), increase perceptual suppression during rivalry relative to a placebo. These results present the first causal link between GABAergic inhibition and binocular rivalry in humans, complementing classic models of binocular rivalry, and have implications for our understanding of psychiatric conditions, such as autism, where binocular rivalry is posited as a behavioral marker of disruptions in inhibitory signaling in the brain.

An evaluation of clobazam tablets and film (AQST-120) for the treatment of Lennox-Gastaut syndrome

Introduction: Lennox-Gastaut syndrome (LGS) is a chronic, epileptic encephalopathy, characterized by multiple seizure types, distinctive slow spike-wave patterns in the electroencephalogram (EEG), and severe cognitive and behavioral comorbidities. Seizures are typically refractory and long-term prognosis is poor. No antiseizure drug (ASD) is fully effective as a monotherapy. Clobazam (CLB) was licensed in the United States in 2011 as an adjunctive therapy for seizures in LGS. In 2018, a new formulation, CLB oral soluble film (COSF) (AQST-120), was approved by the Federal Drug Administration (FDA) for the same indication. Areas covered: The authors summarize current pharmacological options and guidelines for the management of seizures in LGS and efficacy and safety findings from phase II and III randomized controlled trials of adjunctive CLB in patients with LGS. An open-label extension trial is also considered. A pharmacokinetic comparison of COSF and CLB tablets is also undertaken. Expert opinion: CLB is partly effective as an add-on therapy in treating seizures in LGS. Adverse effects, pharmacokinetic interactions and the potential for tolerance with long-term treatment should be weighed against the clinical benefit when considering the introduction of CLB in this population. COSF has a similar pharmacokinetic profile to CLB tablets and may help to improve adherence to treatment.

Pharmacotherapy for Focal Seizures in Children and Adolescents

Focal-onset seizures are among the most common forms of seizures in children and adolescents and can be caused by a wide diversity of acquired or genetic etiologies. Despite the increasing array of antiseizure drugs available, treatment of focal-onset seizures in this population remains problematic, with as many as one-third of children having seizures refractory to medications. This review discusses contemporary concepts in focal seizure classification and pathophysiology and describes the antiseizure medications most commonly chosen for this age group. As antiseizure drug efficacy is comparable in children and adults, here we focus on pharmacokinetic aspects, drug-drug interactions, and side effect profiles. Finally, we provide some suggestions for choosing the optimal medication for the appropriate patient.

Drug interactions in maternal intensive care: prevalence, risk factors, and potential risk medications

Objective:

To characterize severe potential drug interactions in maternal intensive care, and to determine their frequency, risk factors and potential risk medications.

Methods:

An observational and longitudinal study conducted between December 2014 and December 2015 in a maternal intensive care unit. Clinical data were collected and severe potential drug interactions were identified on pregnant inpatients. The drug interactions were classified by type, prevalence and exposure rate. A multivariate logistic regression model was used to identify the severe potential drug interactions and the related drugs (p<0.05).

Results:

A total of 95.1% of patients were exposed to, at least, one potential drug interaction; in that, 91.7% 33.9% were related to, respectively, moderate and severe potential drug interactions. The patients were exposed, on average, on 69.2% of days they were in the intensive care unit. The main drugs involved in more severe drug interactions were magnesium sulfate, metoclopramide, propranolol and diazepam.

Conclusion:

The severe potential drug interactions were observed in almost all patients of the study, and, approximately one third of those interactions were related to greater severity and resulted in exposure during long hospital stay. The higher number of prescribed drugs and its previous use of medications at home increase the occurrence of severe potential drug interactions.

A Practical Guide to Treatment of Childhood Absence Epilepsy

Childhood absence epilepsy (CAE) is a common pediatric epilepsy syndrome with distinct seizure semiology, electroencephalography (EEG) features, and treatment. A diagnosis of CAE can be obtained during an office visit with a careful history, physical exam including prolonged hyperventilation, and a routine EEG. The treatment of choice for CAE with absence seizures only is ethosuximide. Valproic acid and lamotrigine are also effective treatments for many patients, but when compared to ethosuximide, valproic acid has more adverse effects and lamotrigine is less effective. Attention to predictors of response to treatment, including clinical, electrographic, and genetic factors, is increasing. Refractory CAE occurs in fewer than half of patients, and treatment strategies are available, though efficacy data are lacking. Careful assessment and treatment of psychosocial comorbidities is essential in caring for patients with CAE.

Pharmacokinetics of clobazam oral soluble film

OBJECTIVE

Clobazam oral soluble film (COSF) is a novel dosage form under development for the adjunctive treatment of seizures associated with Lennox-Gastaut syndrome. The present study was undertaken to assess the pharmacokinetics of clobazam administered as single doses of COSF 20 and 10 mg compared with clobazam tablets (CTAB) 20 and 10 mg in healthy adults. A secondary objective was to assess the safety and tolerability of single doses of COSF 20 and 10 mg.

METHODS

A total of 51 adult volunteers were enrolled in a single-dose, open-label, randomized four-sequence, four-period, crossover study with treatments (A) COSF 20 mg, (B) CTAB 20 mg, (C) COSF 10 mg, and (D) CTAB 10 mg. Pharmacokinetic sampling for clobazam and N-desmethylclobazam was carried out until 21 days postdose with a 28-day washout. Subjects were monitored for adverse events (AEs) throughout the study. Visual inspections of the administration site were performed before and after COSF administration to monitor for mucosal irritation.

RESULTS

COSF at single doses of 10 and 20 mg was bioequivalent to CTAB at equivalent doses for both clobazam and its active metabolite N-desmethylclobazam. The pharmacokinetics of both formulations was dose-proportional at doses of 10 and 20 mg. The number of AEs and the number of subjects experiencing AEs were dose-related across the treatment groups, with somnolence the most common event. None of these events was severe or serious, and most were mild. There was no evidence for local irritation at the administration site following COSF.

SIGNIFICANCE

COSF is a novel clobazam dosage form that is bioequivalent to CTAB. Because of its ease of administration, COSF may be expected to improve adherence, reduce likelihood of dosing error, and provide more accurate dosing than formulations of clobazam that are currently available.

A Comprehensive Overview of the Clinical Pharmacokinetics of Clobazam

Clobazam (CLB) is a 1,5‐benzodiazepine that has been widely used as an anxiolytic and antiseizure drug (ASD) since it was first synthesized over 50 years ago. CLB was approved in the United States in 2011 as adjunctive therapy for seizures in patients ≥2 years old with Lennox‐Gastaut syndrome. CLB pharmacokinetics (PK) have been studied in single‐ and multiple‐dose administrations in healthy subjects. Salient features include high bioavailability, linear PK, and negligible effects from coadministration of other ASDs. CLB is highly and extensively absorbed, with little effect from food; time to maximum plasma concentration is 0.5 to 4 hours following the dose. After CLB doses of 20 to 40 mg/day, the volume of distribution is 99 to 120 L, with oral clearance ranging from 1.9 to 2.3 L/h. CLB is lipophilic and distributes throughout the body after oral administration. It is metabolized in the liver by cytochrome P450 (CYP) isoenzymes CYP3A, CYP2C19, and CYP2B6, and its main active metabolite is N‐desmethylclobazam. The half‐life of CLB after a single oral dose ranges from 36 to 42 hours; the half‐life of N‐desmethylclobazam ranges from 59 to 74 hours. The metabolites of CLB are primarily excreted renally. Population PK modeling using data from healthy subjects and patients with Lennox‐Gastaut syndrome indicates that race, sex, age, weight, and renal function do not influence CLB PK. As CLB has been extensively studied since the 1970s, this review is meant to provide a consolidated and comprehensive resource on CLB PK for both prescribers and scientists alike.

GABAA Receptor Density Is Not Altered by a Novel Herbal Anxiolytic Treatment

Anxiety disorders are highly prevalent and considered a major public health concern worldwide. Current anxiolytics are of limited efficacy and associated with various side effects. Our novel herbal treatment (NHT), composed of four constituents, was shown to reduce anxiety-like behavior while precluding a common side effect caused by current anxiolytics, i.e., sexual dysfunction. Nevertheless, NHT's mechanism of action is yet to be determined. There is evidence that some medicinal herbs interact with the GABAergic system. Therefore, we aimed to examine whether NHT's anxiolytic-like effect is exerted by alterations in GABA_A receptor density in the hippocampus, prefrontal cortex, and hypothalamus. The effects of 3-weeks treatment with NHT on anxiety-like behavior and locomotion were assessed using the elevated plus maze (EPM) and the open field test (OFT), respectively. Regional GABA_A receptor levels were analyzed using [³H] RO15-1788 high-affinity binding assays. In stressed mice, NHT reduced anxiety-like behavior similarly to the benzodiazepine, clonazepam, while locomotion remained intact. Lack of changes or minor changes in regional GABA_A receptor density in the brain were induced by NHT or clonazepam. In naive mice, performance in the EPM, locomotion and GABA_A receptor densities were not altered by treatment with NHT or clonazepam. These findings support NHT as an efficacious and safe anxiolytic, although the GABAergic involvement remains to be further elucidated.

Treatment Strategies for Dravet Syndrome

Dravet syndrome (DS) is a medically refractory epilepsy that onsets in the first year of life with prolonged seizures, often triggered by fever. Over time, patients develop other seizure types (myoclonic, atypical absences, drops), intellectual disability, crouch gait and other co-morbidities (sleep problems, autonomic dysfunction). Complete seizure control is generally not achievable with current therapies, and the goals of treatment are to balance reduction of seizure burden with adverse effects of therapies. Treatment of co-morbidities must also be addressed, as they have a significant impact on the quality of life of patients with DS. Seizures are typically worsened with sodium-channel agents. Accepted first-line agents include clobazam and valproic acid, although these rarely provide adequate seizure control. Benefit has also been noted with stiripentol, topiramate, levetiracetam, the ketogenic diet and vagal nerve stimulation. Several agents presently in development, specifically fenfluramine and cannabidiol, have shown efficacy in clinical trials. Status epilepticus is a recurring problem for patients with DS, particularly in their early childhood years. All patients should be prescribed a home rescue therapy (usually a benzodiazepine) but should also have a written seizure action plan that outlines when rescue should be given and further steps to take in the local hospital if the seizure persists despite home rescue therapy.

Anxiolytic Effect of Exogenous Ketone Supplementation Is Abolished by Adenosine A1 Receptor Inhibition in Wistar Albino Glaxo/Rijswijk Rats

Anxiety disorders are one of the most common mental health problems worldwide, but the exact pathophysiology remains largely unknown. It has been demonstrated previously that administration of exogenous ketone supplement KSMCT (ketone salt/KS + medium chain triglyceride/MCT oil) by intragastric gavage for 7 days decreased the anxiety level in genetically absence epileptic Wistar Albino Glaxo/Rijswijk (WAG/Rij) rats. To investigate the potential role of the adenosinergic system in the pathomechanism of anxiety we tested whether the inhibition of adenosine A₁ receptors (A₁Rs) influence the anxiolytic effect of the exogenous ketone supplement. As A₁Rs may mediate such an effect, in the present study we used a specific A₁R antagonist, DPCPX (1,3-dipropyl-8-cyclopentylxanthine) to test whether it modulates the anxiolytic effect of sub-chronically (7 days) applied KSMCT in the previously tested animal model by using elevated plus maze (EPM) test. We administered KSMCT (2.5 g/kg/day) alone by intragastric gavage and in combination with intraperitoneally (i.p.) injected of DPCPX in two doses (lower: 0.15 mg/kg, higher: 0.25 mg/kg). Control groups represented i.p saline and water gavage with or without i.p. DPCPX administration (2.5 g/kg/day). After treatments, the level of blood glucose and beta-hydroxybutyrate (βHB), as well as body weight were recorded. KSMCT alone significantly increased the time spent in the open arms and decreased the time spent in the closed arms, supporting our previous results. Injection of lower dose of DPCPX decreased, while higher dose of DPCPX abolished the effect of KSMCT administration on EPM. Blood βHB levels were significantly increased after administration of KSMCT, while DPCPX did not change the KSMCT induced increase in blood βHB levels. These results demonstrate that A₁R inhibition modified (decreased) the anti-anxiety effect of KSMCT administration implying that the adenosinergic system, likely via A₁Rs, may modulate the exogenous ketone supplement induced anxiolytic influence.

Sustained consumption of cocoa-based dark chocolate enhances seizure-like events in the mouse hippocampus

While the consumption of caffeine and cocoa has been associated with a variety of health benefits to humans, some authors have proposed that excessive caffeine intake may increase the frequency of epileptic seizures in humans and reduce the efficiency of antiepileptic drugs. Little is known, however, about the proconvulsant potential of the sustained, excessive intake of cocoa on hippocampal neural circuits. Using the mouse as an experimental model, we examined the effects of the chronic consumption of food enriched in cocoa-based dark chocolate on motor and mood-related behaviours as well as on the excitability properties of hippocampal neurons. Cocoa food enrichment did not affect body weights or mood-related behaviours but rather promoted general locomotion and improved motor coordination. However, ex vivo electrophysiological analysis revealed a significant enhancement in seizure-like population spike bursting at the neurogenic dentate gyrus, which was paralleled by a significant reduction in the levels of GABA-α1 receptors thus suggesting that an excessive dietary intake of cocoa-enriched food might alter some of the synaptic elements involved in epileptogenesis. These data invite further multidisciplinary research aiming to elucidate the potential deleterious effects of chocolate abuse on behaviour and brain hyperexcitability.

The Pharmacology and Toxicology of Third-Generation Anticonvulsant Drugs

Epilepsy is a neurologic disorder affecting approximately 50 million people worldwide, or about 0.7% of the population [1]. Thus, the use of anticonvulsant drugs in the treatment of epilepsy is common and widespread. There are three generations of anticonvulsant drugs, categorized by the year in which they were developed and released. The aim of this review is to discuss the pharmacokinetics, drug-drug interactions, and adverse events of the third generation of anticonvulsant drugs. Where available, overdose data will be included. The pharmacokinetic properties of third-generation anticonvulsant drugs include relatively fewer drug-drug interactions, as well as several unique and life-threatening adverse events. Overdose data are limited, so thorough review of adverse events and knowledge of drug mechanism will guide expectant management of future overdose cases. Reporting of these cases as they occur will be necessary to further clarify toxicity of these drugs.

Influence of perfluorocarbons on Carbamazepine and Benzodiazepine for a neuro-lung protective strategy

Lennox-Gastaut syndrome (LGS) is commonly characterized by a triad of features including multiple seizure types, intellectual disability or regression. LGS type of seizures is epilepsy which is due to abnormal vibrations occurring in seizures. During the time of such abnormal vibrations, both the seizures and the lungs suffer a lack in oxygen content to a considerable extent. This results in prolonged vibrations and loses of nervous control. As a neuro-lung protective strategy, a novel attempt has been made to enrich both seizures and lungs with oxygen content through the support of Perfluorodecalin (an excellent oxygen carrier) C₁₀F₁₈ (PFD) and Perfluorohexane C₆F₁₄ (PFH) along with an enhancement in the antiepileptic activity by the two chosen antiepileptic drugs (AEDs) Carbamazepine (CBZ) and Benzodiazepine (BDZ). Perfluorodecalin C₁₀F₁₈ (PFD) and Perfluorohexane C₆F₁₄ (PFH) emulsions were prepared by sonication process with combination of nonionic emulsifier, Lecithin (l-α-phosphatidylcholine) as a surfactant in Aqueous phase medium. These emulsions were mixed with Carbamazepine (CBZ) and Benzodiazepine (BDZ) drugs maintained at a temperature of about -20°C to 20°C and were set to slow evaporation process. The products are subjected to Optical microscope, Transmission electron microscopy (TEM) and Scanning Electron Microscope (SEM) - Energy dispersive X-ray Spectroscopy (EDS). Study reveals the co-existence of fluorine and drug ensuring the oxygen uptake by the drug. Morphology of TEM, Optical microscopic images and the particle diameter estimated through Image_J confirms this analysis.

Tolerability and Safety of Commonly Used Antiepileptic Drugs in Adolescents and Adults: A Clinician's Overview

This paper discusses the issues surrounding the tolerability and safety of the commonly used antiepileptic drugs (AEDs) in adolescents and adults. The content includes dose-related adverse effects, idiosyncratic reactions, behavioural and psychiatric comorbidities, chronic problems, enzyme induction and teratogenesis. Twenty-one AEDs are discussed in chronological order of their introduction into the UK, starting with phenobarbital and ending with brivaracetam. Wherever possible, advice is given on anticipating, recognising and managing these issues and thereby improving the lives of people with epilepsy, most of whom will need to take one or more of these agents for life. Avoidance of side effects will increase the possibility of achieving and maintaining long-term seizure freedom. Alternatively, adverse events from AEDs will substantially reduce quality of life and often result in higher healthcare costs.

Synthesis of a new polycyclic heterocyclic ring system. Part III. Benzo[b]imidazo[1,5-d][1,4]oxazepine-1,4(2H,5H)-diones

A series of novel tricyclic benzoxazepines with fused imidazolone ring was prepared in five steps starting from the corresponding benzoxazolones

Cytisine inhibits the protective activity of various classical and novel antiepileptic drugs against 6 Hz-induced psychomotor seizures in mice

BACKGROUND

Cytisine (CYT) is a partial agonist of brain α4β2 nicotinic acetylcholine receptors widely used in Central/Eastern Europe for smoking cessation.

OBJECTIVES

This study evaluated the effect of CYT on the ability of classical and novel antiepileptic drugs to prevent seizures evoked by the 6-Hz test, a model of psychomotor seizures in mice thought as a model of drug-resistant seizures.

RESULTS

CYT administered intraperitoneally (i.p.) in a dose of 2 mg kg^-1 significantly inhibited the anticonvulsant activity of lacosamide, levetiracetam, and pregabalin, increasing their median effective doses 50 (ED₅₀) values from 6.88 to 10.52 mg kg^-1 (P < 0.05) for lacosamide, from 22.08 to 38.26 mg kg^-1 (P < 0.05) for levetiracetam, and from 40.48 to 64.61 mg kg^-1 (P < 0.01) for pregabalin, respectively. There were no significant changes in total brain concentrations of lacosamide, levetiracetam, and pregabalin following CYT i.p. administration. CYT administered in a dose of 2 mg kg^-1 failed to change the protective action of clobazam, clonazepam, phenobarbital, tiagabine, and valproate in the 6-Hz test. Neither CYT (2 mg kg^-1) alone nor its combination with the anticonvulsant drugs (at their ED₅₀ values from the 6-Hz test) affected motor coordination; skeletal muscular strength and long-term memory, as determined in the chimney; and grip strength and passive avoidance tests, respectively.

CONCLUSION

CYT-evoked alterations in the protection provided by some antiepileptic drugs against seizures can be of serious concern for epileptic smokers, who might demonstrate therapeutic failure to lacosamide, levetiracetam, and pregabalin, resulting in possible breakthrough seizure attacks.