Animal models and human tissue compared to better understand and treat the epilepsies.

Animal models of human brain disorders permit researchers to explore disease mechanisms and to test potential therapies. However, therapeutic molecules derived from animal models often translate poorly to the clinic. Although human data may be more relevant, experiments on patients are constrained, and living tissue is unavailable for many disorders. Here, we compare work on animal models and on human tissue for three epileptic syndromes where human tissue is excised therapeutically: (1) acquired temporal lobe epilepsies, (2) inherited epilepsies associated with cortical malformations, and (3) peritumoral epilepsies. Animal models rest on assumed equivalencies between human brains and brains of mice, the most frequently used model animal. We ask how differences between mouse and human brains could influence models. General principles and compromises in model construction and validation are examined for a range of neurological diseases. Models may be judged on how well they predict novel therapeutic molecules or new mechanisms. The efficacy and safety of new molecules are evaluated in clinical trials. We judge new mechanisms by comparing data from work on animal models with data from work on patient tissue. In conclusion, we stress the need to cross-verify findings from animal models and from living human tissue to avoid the assumption that mechanisms are identical.

In Vivo and In Vitro Characterization of Close Analogs of Compound KA-11, a New Antiseizure Drug Candidate.

Epilepsy is a neurological disorder involving a number of disease syndromes with a complex etiology. A properly matched antiseizure drug (ASD) gives remission in up to 70% of patients. Nevertheless, there is still a group of about 30% of patients suffering from drug-resistant epilepsy. Consequently, the development of new more effective and/or safer ASDs is still an unmet clinical need. Thus, our current studies were focused on the structural optimization/modifications of one of the leading compounds, KA-11, aiming at the improvement of its antiseizure activity. As a result, we designed and synthesized two close analogs with highly pronounced drug-like physicochemical properties according to in silico predictions, namely KA-228 and KA-232, which were subsequently tested in a panel of animal seizure models, i.e., MES, 6 Hz (32 mA), scPTZ and ivPTZ. Among these compounds, KA-232, which was designed as a water-soluble salt, was distinctly more effective than KA-228 and assured similar antiseizure protection as its chemical prototype KA-11. With the aim of a more detailed characterization of both new molecules, in vitro binding tests were performed to evaluate the potential mechanisms of action. Furthermore, KA-232 was also evaluated in several ADME-Tox studies, and the results obtained strongly supported its drug-like potential. The proposed chemical modification of KA-11 enabled the identification of new pharmacologically active chemotypes, particularly water-soluble KA-232, which, despite the lack of better efficacy than the leading compound, may be used as a chemical prototype for the development of new ASDs, as well as substances potentially active in other neurological or neurodegenerative conditions.

Classification of antiseizure drugs in cultured neuronal networks using multielectrode arrays and unsupervised learning.

OBJECTIVE: Antiseizure drugs (ASDs) modulate synaptic and ion channel function to prevent abnormal hypersynchronous or excitatory activity arising in neuronal networks, but the relationship between ASDs with respect to their impact on network activity is poorly defined. In this study, we first investigated whether different ASD classes exert differential impact upon network activity, and we then sought to classify ASDs according to their impact on network activity. METHODS: We used multielectrode arrays (MEAs) to record the network activity of cultured cortical neurons after applying ASDs from two classes: sodium channel blockers (SCBs) and γ-aminobutyric acid type A receptor-positive allosteric modulators (GABA PAMs). A two-dimensional representation of changes in network features was then derived, and the ability of this low-dimensional representation to classify ASDs with different molecular targets was assessed. RESULTS: A two-dimensional representation of network features revealed a separation between the SCB and GABA PAM drug classes, and could classify several test compounds known to act through these molecular targets. Interestingly, several ASDs with novel targets, such as cannabidiol and retigabine, had closer similarity to the SCB class with respect to their impact upon network activity. SIGNIFICANCE: These results demonstrate that the molecular target of two common classes of ASDs is reflected through characteristic changes in network activity of cultured neurons. Furthermore, a low-dimensional representation of network features can be used to infer an ASDs molecular target. This approach may allow for drug screening to be performed based on features extracted from MEA recordings.

Cardiac morbidity and mortality associated with the use of lamotrigine.

OBJECTIVE: The US Food and Drug Administration recently issued a warning against the use of the antiseizure medication lamotrigine in people at risk of cardiac rhythm and conduction abnormalities. This study assessed the risk of cardiac morbidity and mortality in new users of lamotrigine. METHODS: In a Danish population-based cohort study, we followed cohort members aged ≥15 years for the first 2 years after they initiated lamotrigine therapy. The main outcomes were cardiac conduction disorders in people without pre-existing cardiac morbidity and all-cause mortality in people with pre-existing cardiac morbidity. Cox proportional hazards models provided hazard ratios (HRs) and corresponding 95% confidence intervals (CIs) for comparison of the risk in current versus past users of lamotrigine. RESULTS: There were 91 949 (36 618 males [39.8%]) new users of lamotrigine (median age = 45.7 years, interquartile range = 32.0-60.2 years). Among users without pre-existing cardiac disease (n = 86 769), 194 (.23%) developed a cardiac conduction disorder. Comparison of the risk in current and past lamotrigine treatment periods yielded an adjusted HR of new onset cardiac conduction disorder of 1.03 (95% CI = .76-1.40). Among users with pre-existing cardiac disease (n = 5180), 1150 (22.2%) died. Comparison of the risk in current and past lamotrigine treatment periods yielded an adjusted HR for all cause-mortality of 1.05 (95% CI = .93-1.19). SIGNIFICANCE: In this large population-based study, lamotrigine use was associated neither with a risk of cardiac conduction disorders in people without pre-existing cardiac morbidity nor with all-cause mortality in people with pre-existing cardiac morbidity.

Cognitive reawakening and improved quality of life achieved after discontinuing 16 years of anti-seizure treatment with topiramate.

A 42-year-old female patient with epilepsy and a co-morbid migraine suffered from the severe cognitive side effects of topiramate (TPM) for more than 16 years with detrimental consequences for her daily functioning, career, and social interaction. Even a prodromal stage of dementia was suggested, giving rise to fears of developing a neurodegenerative disease. Recently, cognitive monitoring of attention and executive function before and after withdrawal of TPM revealed a significant recovery from the severe negative cognitive side effects of the long-standing and inefficacious antiseizure medication (ASM). Whereas the side effects were reversible after cessation, their consequences for the patient`s biography were permanent. A considerable increase in quality of life, however, was observed without TPM and family members were impressed by the improvements. This case illustrates the potentially severe consequences of negative cognitive side effects which affect daily functioning, career and social life, thus underscoring the importance of being knowledgeable of the potential cognitive risks when prescribing an ASM. Because cognitive side effects may not depend solely on ASM choice and drug load, but also on individual idiosyncratic intolerances, and patients might stay on their treatment for many years, cognitive monitoring is highly recommended.

Parents' priorities for decision-making of pediatric epilepsy treatments and perceived needs for decision support in multi-ethnic Asian clinical setting: A qualitative analysis.

OBJECTIVE: To identify parents' priorities when making a decision on genetic testing and antiseizure drug (ASD) options for pediatric epilepsy and their support needs for informed decision-making in multi-ethnic Asian clinical settings. METHODS: Qualitative in-depth interviews, using a semi-structured interview guide, were conducted with purposively selected parents of pediatric patients with newly diagnosed epilepsy or known diagnosis of epilepsy (n = 26). Interviews were audio recorded and transcribed verbatim. Thematic analysis was undertaken to generate themes. RESULTS: Parents' narratives showed difficulty assimilating information, while knowledge deficit and emotional vulnerability led parents' desire to defer a decision for testing and ASDs to mitigate decisional burden. Priorities for decisions were primarily based on intuitive ideas of the treatment's risks and benefits, yet very few could elaborate on tradeoffs between risks and efficacy. Priorities outside the purview of the healthcare team, such as children's emotional wellbeing and family burden of ASD administration, were also considered important. Authority-of-medical-professional heuristic facilitated the ASD decision for parents who preferred shared rather than sole responsibility for a decision. Importantly, parents' support needs for informed decision-making were very much related to the availability of support mechanisms in post-treatment decisions owing to perceived uncertainty of the chosen ASD. CONCLUSIONS: Findings suggest that multiple priorities influenced ASD decision process. To address support needs of parents for informed decision-making, more consideration should be given to post-treatment decision support through the provision of educational opportunities, building peer support networks, and developing a novel communication channel between healthcare providers and parents.

Phenobarbital and midazolam suppress neonatal seizures in a noninvasive rat model of birth asphyxia, whereas bumetanide is ineffective.

OBJECTIVE: Neonatal seizures are the most frequent type of neurological emergency in newborn infants, often being a consequence of prolonged perinatal asphyxia. Phenobarbital is currently the most widely used antiseizure drug for treatment of neonatal seizures, but fails to stop them in ~50% of cases. In a neonatal hypoxia-only model based on 11-day-old (P11) rats, the NKCC1 inhibitor bumetanide was reported to potentiate the antiseizure activity of phenobarbital, whereas it was ineffective in a human trial in neonates. The aim of this study was to evaluate the effect of clinically relevant doses of bumetanide as add-on to phenobarbital on neonatal seizures in a noninvasive model of birth asphyxia in P11 rats, designed for better translation to the human term neonate. METHODS: Intermittent asphyxia was induced for 30 minutes by exposing the rat pups to three 7 + 3-minute cycles of 9% and 5% O2 at constant 20% CO2 . Drug treatments were administered intraperitoneally either before or immediately after asphyxia. RESULTS: All untreated rat pups had seizures within 10 minutes after termination of asphyxia. Phenobarbital significantly blocked seizures when applied before asphyxia at 30 mg/kg but not 15 mg/kg. Administration of phenobarbital after asphyxia was ineffective, whereas midazolam (0.3 or 1 mg/kg) exerted significant antiseizure effects when administered before or after asphyxia. In general, focal seizures were more resistant to treatment than generalized convulsive seizures. Bumetanide (0.3 mg/kg) alone or in combination with phenobarbital (15 or 30 mg/kg) exerted no significant effect on seizure occurrence. SIGNIFICANCE: The data demonstrate that bumetanide does not increase the efficacy of phenobarbital in a model of birth asphyxia, which is consistent with the negative data of the recent human trial. The translational data obtained with the novel rat model of birth asphyxia indicate that it is a useful tool to evaluate novel treatments for neonatal seizures.

The ups and downs of alkyl-carbamates in epilepsy therapy: How does cenobamate differ?

Since 1955, several alkyl-carbamates have been developed for the treatment of anxiety and epilepsy, including meprobamate, flupirtine, felbamate, retigabine, carisbamate, and cenobamate. They have each enjoyed varying levels of success as antiseizure drugs; however, they have all been plagued by the emergence of serious and sometimes life-threatening adverse events. In this review, we compare and contrast their predominant molecular mechanisms of action, their antiseizure profile, and where possible, their clinical efficacy. The preclinical, clinical, and mechanistic profile of the prototypical γ-aminobutyric acidergic (GABAergic) modulator phenobarbital is included for comparison. Like phenobarbital, all of the clinically approved alkyl-carbamates share an ability to enhance inhibitory neurotransmission through modulation of the GABAA receptor, although the specific mechanism of interaction differs among the different drugs discussed. In addition, several alkyl-carbamates have been shown to interact with voltage-gated ion channels. Flupirtine and retigabine share an ability to activate K+ currents mediated by KCNQ (Kv7) K+ channels, and felbamate, carisbamate, and cenobamate have been shown to block Na+ channels. In contrast to other alkyl-carbamates, cenobamate seems to be unique in its ability to preferentially attenuate the persistent rather than transient Na+ current. Results from recent randomized controlled clinical trials with cenobamate suggest that this newest antiseizure alkyl-carbamate possesses a degree of efficacy not witnessed since felbamate was approved in 1993. Given that ceno-bamate's mechanistic profile is unique among the alkyl-carbamates, it is not clear whether this impressive efficacy reflects an as yet undescribed mechanism of action or whether it possesses a unique synergy between its actions at the GABAA receptor and on persistent Na+ currents. The high efficacy of cenobamate is, however, tempered by the risk of serious rash and low tolerability at higher doses, meaning that further safety studies and clinical experience are needed to determine the true clinical value of cenobamate.

Alzheimer's Disease and Epilepsy: A Perspective on the Opportunities for Overlapping Therapeutic Innovation.

Early-onset Alzheimer's disease (AD) is associated with variants in amyloid precursor protein (APP) and presenilin (PSEN) 1 and 2. It is increasingly recognized that patients with AD experience undiagnosed focal seizures. These AD patients with reported seizures may have worsened disease trajectory. Seizures in epilepsy can also lead to cognitive deficits, neuroinflammation, and neurodegeneration. Epilepsy is roughly three times more common in individuals aged 65 and older. Due to the numerous available antiseizure drugs (ASDs), treatment of seizures has been proposed to reduce the burden of AD. More work is needed to establish the functional impact of seizures in AD to determine whether ASDs could be a rational therapeutic strategy. The efficacy of ASDs in aged animals is not routinely studied, despite the fact that the elderly represents the fastest growing demographic with epilepsy. This leaves a particular gap in understanding the discrete pathophysiological overlap between hyperexcitability and aging, and AD more specifically. Most of our preclinical knowledge of hyperexcitability in AD has come from mouse models that overexpress APP. While these studies have been invaluable, other drivers underlie AD, e.g. PSEN2. A diversity of animal models should be more frequently integrated into the study of hyperexcitability in AD, which could be particularly beneficial to identify novel therapies. Specifically, AD-associated risk genes, in particular PSENs, altogether represent underexplored contributors to hyperexcitability. This review assesses the available studies of ASDs administration in clinical AD populations and preclinical studies with AD-associated models and offers a perspective on the opportunities for further therapeutic innovation.

Antiseizure drugs and risk of developing smoking-related chronic obstructive pulmonary disease or lung cancer: A population-based case-control study.

AIMS: To determine whether enzyme-inducing antiseizure drugs (ASDs) affect the risk of developing chronic obstructive pulmonary disease (COPD) or lung cancer in smokers. METHODS: Cases of COPD and lung cancer and matched controls without these conditions were identified from a population of smokers with ≥1 prescription for any type of ASD in the Clinical Practice Research Datalink UK database of patients managed in primary care (1995-2016). A matched case-control study was performed utilising multivariate logistic regression analyses of exposure to enzyme-inducing ASDs compared to non-enzyme-inducing ASDs. The duration of ASD exposure and level of tobacco exposure were also assessed. RESULTS: We identified 5952 incident COPD and 1373 incident lung cancer cases, and 59 328 and 13 681 matched controls, respectively. Compared with never use, ever use of enzyme-inducing ASDs was associated with slightly decreased risk estimates of COPD (adjusted odds ratio: 0.85, 95% confidence interval: 0.81-0.89) and lung cancer (adjusted odds ratio: 0.82, 95% confidence interval: 0.73-0.92). These risk estimates were attenuated in heavy smokers. CONCLUSION: We found slightly decreased risk estimates of COPD and lung cancer among smokers taking enzyme-inducing ASDs and hypothesise that this may be related to induction of detoxification of tobacco-specific lung toxins.

Use of antipyretics for preventing febrile seizure recurrence in children: a systematic review and meta-analysis.

The efficacy of antipyretics for preventing febrile seizure recurrence has been reported by a recent study, and the results might overturn previous evidence. We systematically reviewed the efficacy of antipyretics in the prevention of febrile seizure recurrence in children focused on the timing of its administration. We searched the Medline, Embase, and Cochrane Central Register of Controlled Trials databases for randomized and quasi-randomized trials and prospective non-randomized studies of aged up to 60 months, diagnosed with febrile seizure, who were treated with antipyretics. Data were extracted from eight studies. Only one study reported that antipyretics prevented the recurrence of febrile seizures within the same fever episode (9.1% in the acetaminophen group vs. 23.5% in the control group, p < 0.01). Four studies found no evidence for the efficacy of antipyretics in preventing febrile seizure recurrence in distant fever episodes (odds ratio, 0.92; 95% confidence interval, 0.57-1.48, for two randomized controlled studies).Conclusion: This review provides very limited support for the use of antipyretics in preventing febrile seizure recurrence within the same fever episode and no evidence for its use in distant fever episodes. New studies are required to evaluate this topic further and determine whether the effectiveness of antipyretics is based on intervention timing. What is Known: • Reviews of prophylactic drug management among febrile seizure children found that antipyretics had no significant benefits. • Recent data suggest that antipyretics are effective in preventing febrile seizures. What is New: • Weak evidence suggests a possible role in preventing febrile seizure recurrence within the same fever episode. • There is clearly no role for antipyretic prophylaxis in preventing febrile seizures during distant fever episodes.

Analysis of antiseizure drug-related adverse reactions from the electronic health record using the common data model.

OBJECTIVE: Antiseizure drugs (ASDs) are known to cause a wide range of adverse drug reactions (ADRs). Recently, electronic health care data using the common data model (CDM) have been introduced and commonly adopted in pharmacovigilance research. We aimed to analyze ASD-related ADRs using CDM and to assess the feasibility of CDM analysis in monitoring ADR in a single tertiary hospital. METHODS: We selected five ASDs: oxcarbazepine (OXC), lamotrigine (LTG), levetiracetam (LEV), valproic acid (VPA), and topiramate (TPM). Patients diagnosed with epilepsy and exposed to monotherapy with one of the ASDs before age 18 years were included. We measured four ADR outcomes: (1) hematologic abnormality, (2) hyponatremia, (3) elevation of liver enzymes, and (4) subclinical hypothyroidism. We performed a subgroup analysis to exclude the effects of concomitant medications. RESULTS: From the database, 1344 patients were included for the study. Of the 1344 patients, 436 were receiving OXC, 293 were receiving LTG, 275 were receiving LEV, 180 were receiving VPA, and 160 were receiving TPM. Thrombocytopenia developed in 14.1% of patients taking VPA. Hyponatremia occurred in 10.5% of patients taking OXC. Variable ranges of liver enzyme elevation were detected in 19.3% of patients taking VPA. Subclinical hypothyroidism occurred in approximately 21.5% to 28% of patients with ASD monotherapy, which did not significantly differ according to the type of ASD. In a subgroup analysis, we observed similar ADR tendencies, but with less thrombocytopenia in the TPM group. SIGNIFICANCE: The incidence and trends of ADRs that were evaluated by CDM were similar to the previous literature. CDM can be a useful tool for analyzing ASD-related ADRs in a multicenter study. The strengths and limitations of CDM should be carefully addressed.

Evaluation of subchronic administration of antiseizure drugs in spontaneously seizing rats.

OBJECTIVE: Approximately 30% of patients with epilepsy do not experience full seizure control on their antiseizure drug (ASD) regimen. Historically, screening for novel ASDs has relied on evaluating efficacy following a single administration of a test compound in either acute electrical or chemical seizure induction. However, the use of animal models of spontaneous seizures and repeated administration of test compounds may better differentiate novel compounds. Therefore, this approach has been instituted as part of the National Institute of Neurological Disorders and Stroke Epilepsy Therapy Screening Program screening paradigm for pharmacoresistant epilepsy. METHODS: Rats were treated with intraperitoneal kainic acid to induce status epilepticus and subsequent spontaneous recurrent seizures. After 12 weeks, rats were enrolled in drug screening studies. Using a 2-week crossover design, selected ASDs were evaluated for their ability to protect against spontaneous seizures, using a video-electroencephalographic monitoring system and automated seizure detection. Sixteen clinically available compounds were administered at maximally tolerated doses in this model. Dose intervals (1-3 treatments/d) were selected based on known half-lives for each compound. RESULTS: Carbamazepine (90 mg/kg/d), phenobarbital (30 mg/kg/d), and ezogabine (15 mg/kg/d) significantly reduced seizure burden at the doses evaluated. In addition, a dose-response study of topiramate (20-600 mg/kg/d) demonstrated that this compound reduced seizure burden at both therapeutic and supratherapeutic doses. However, none of the 16 ASDs conferred complete seizure freedom during the testing period at the doses tested. SIGNIFICANCE: Despite reductions in seizure burden, the lack of full seizure freedom for any ASD tested suggests that this screening paradigm may be useful for testing novel compounds with potential utility in pharmacoresistant epilepsy.

A perspective on the physicochemical and biopharmaceutic properties of marketed antiseizure drugs-From phenobarbital to cenobamate and beyond.

The success rate from first time in man to regulatory approval of central nervous system (CNS) drugs is lower than the overall success rate across all therapeutic indications (eg, cardiovascular, infectious diseases). To understand the reasons for drug-candidate failure and to capture trends in antiseizure drug (ASD) design, we have analyzed the physicochemical and biopharmaceutical properties of marketed ASDs in comparison with new ASDs in development. Our comparative analysis included molecular weight (MW), logP, polar surface area (PSA), the "Lipinski rule of five," and the CNS Multiparameter Optimization (MPO) score. LogP is the logarithm of a drug-partition coefficient (P) between n-octanol and water. PSA is the molecule's surface sum of its polar atoms. ASDs' biopharmaceutical properties were classified according to their water solubility, permeability, and route of elimination as outlined by the Biopharmaceutics Classification System (BCS) and Biopharmaceutics Drug Disposition Classification System (BDDCS). For old ASDs (1912-1990), logP, PSA, and CNS MPO values ranged between 0.4 and 2.8, 37 and 87 Å2 , and 4.4 and 6.0, respectively. For second-generation ASDs (1990-2008), PSA values ranged between 39 and 116 Å2 . However, logP values showed a difference between the lipophilic (logP = 0.3-3.21) and hydrophilic (logP = -0.6 to -2.16) ASDs. For third-generation ASDs (2008-2020), logP and PSA ranged between 0.3 and 3.5 and between 57 and 76 Å2 , respectively. The mean CNS MPO scores of all marketed ASDs were similar, ranging between 4.9 and 5.4, and were similar to those of the ASDs in development (3.5-5.8). Most ASDs belong to BCS and BDDCS classes 1 and 2. MW, logP, CNS MPO score, and PSA assess lipophilicity and correlate with antiseizure activity. To succeed, a new small-molecule ASD must have MW < 375 and PSA < 140Å2 , belong to BCS and/or BDDCS class 1 or 2, and obey the Lipinski rule of five: logP < 5, MW < 500, and <5 and <10 of hydrogen-bond donors and acceptors, respectively. The similarity in the MW, logP, and PSA values of marketed and new drugs in development indicates a conservative trend in ASD design.

Managing epilepsy in Ramadan: Guidance for healthcare providers and patients.

Ramadan is a regularly recurring period of fasting that takes place in the ninth month of the Islamic calendar. For this period, adult Muslims refrain from eating and drinking between dawn and sunset. The variation in summer daylight hours means that at temperate latitudes, fasting can last up to 20 h. It is already recognized that epilepsy control can deteriorate during Ramadan, and this may be explained by fasting-related changes to adherence to antiseizure drug regimes. This article provides specific advice to help Muslim patients prepare for Ramadan and reduce chances of exacerbation in epilepsy. In addition to advice around sleep hygiene, it explores the use of drugs or preparations of drugs that will demonstrate reduced variation during periods of fasting.

Balance and reaction time do not rapidly improve off antiseizure drugs.

OBJECTIVE: People with epilepsy (PWE) exercise less than the general population and describe a lower level of fitness. Exercise improves comorbidities associated with epilepsy and may help seizure control. We aimed to record balance and reaction time in patients undergoing antiseizure drug (ASD) taper in the epilepsy monitoring unit (EMU) to determine if there is a reversible, dose-dependent effect of these medications. METHODS: We tested 21 patients and 21 controls using a Wii Balance Board (WBB) and online reaction time test. The patients were recruited during an EMU stay and were tested before and after medication taper. Drug levels were also checked. Sway from center of pressure (COP) and speed of sway were tested with eyes open on two legs, eyes closed on two legs, and eyes open on one leg. Reaction time was tested. RESULTS: Compared with controls, patients on ASDs had more sway from COP (with eyes open on two legs: p = 0.0022 in the anterior-posterior axis and p = 0.022 in the medial-lateral axis using linear regression) and worse reaction time (p < 0.001 using linear regression, adjusted for age and gender). There was no difference in reaction time or sway from COP between trials 1 and 2, before and after stopping ASDs (p = 0.2 using a paired t test for reaction time and p = 0.08 using a paired t test for speed of sway with eyes closed). There was no relationship between time since last seizure or duration of seizures and balance or reaction time. DISCUSSION: Balance and reaction time in patients on ASD is impaired compared with controls. There is no immediate improvement in these measures following ASD withdrawal. This difference may result from vestibular or cerebellar effects. More research is needed to determine the individual effects of particular medications on balance and reaction time.

Sexual dysfunction in people with epilepsy.

Sexual dysfunction is a common comorbidity in people with epilepsy (PWE) that adversely affects their quality of life. Nearly one-half of men and women with epilepsy have sexual dysfunction, but in the majority, this often goes unnoticed. The wide variation in the reported prevalence of sexual dysfunction in PWE is due to the significant heterogeneity among the studies with regard to patient population, type and severity of epilepsy, number and type of antiseizure drugs (ASDs) used, and the tools used for assessing sexual dysfunction. Generally, patients with uncontrolled epilepsy, longer duration of epilepsy, focal epilepsy, higher seizure frequency, and those receiving enzyme-inducing and multiple ASDs are more likely to have sexual dysfunction. Women generally have dysfunction in the domains of desire, while males usually have arousal disorders such as erectile dysfunction and premature ejaculation. There is limited evidence to indicate that sexual function improves in patients rendered seizure-free following epilepsy surgery. Multiple mechanisms including direct effects of epilepsy, effects of ASDs, and psychosocial factors contribute to sexual dysfunction in epilepsy. Circumstantial evidence indicates that seizures and interictal epileptiform discharges can directly affect the hypothalamic-pituitary axis as well as production of gonadal steroids. Enzyme-inducing ASDs cause sexual dysfunction by affecting the metabolism of gonadal steroids. Limited data suggest that newer ASDs including oxcarbazepine, lamotrigine, and levetiracetam cause no or minimal sexual dysfunction. Depression and anxiety significantly contribute to sexual dysfunction in PWE. A multipronged and multidisciplinary approach is essential for optimizing the sexual functions. Every effort should be made to identify and treat reversible causes including changing to nonenzyme-inducing ASDs and to provide symptomatic relief. Large, prospective studies are required to improve our understanding on prevalence and mechanisms of sexual dysfunction in PWE.

How often is antiseizure drug-free ketogenic diet therapy achieved?

The ketogenic diet (KD) is often started not only for seizure reduction but also to potentially wean antiseizure drugs (ASDs) in children with epilepsy. Although there have been several publications regarding ASD reduction on the KD, it is unknown how often complete medication withdrawal occurs. We reviewed the charts of all children started on the KD at Johns Hopkins Hospital and Johns Hopkins All Children's Hospital from 1/11 to 4/18. Children were defined as achieving drug-free diet (DFD) status if they started the KD on at least 1 ASD and achieved a period of time where they were on the KD alone. Over the time period, 232 children were evaluated; DFD status occurred in 43 (18.5%), of which 32 (13.8% of the full cohort) remained off ASDs for the remainder of their KD treatment course. Eleven children restarted ASD after a mean of 7 months. Children achieving DFD therapy were more likely to be younger, have fewer ASDs at KD onset, have Glut1 deficiency or epilepsy with myoclonic-atonic seizures, but were less likely to have Lennox-Gastaut syndrome or a gastrostomy tube.

Development and pharmacologic characterization of the rat 6 Hz model of partial seizures.

OBJECTIVE: The mouse 6 Hz model of psychomotor seizures is a well-established and commonly used preclinical model for antiseizure drug (ASD) discovery. Despite its widespread use both in the identification and differentiation of novel ASDs in mice, a corresponding assay in rats has not been developed. We established a method for 6 Hz seizure induction in rats, with seizure behaviors similar to those observed in mice including head nod, jaw clonus, and forelimb clonus. METHODS: A convulsive current that elicits these seizure behaviors in 97% of rats (CC97 ) was determined using a Probit analysis. Numerous prototype ASDs were evaluated in this model using stimulus intensities of 1.5× and 2× the CC97 , which is comparable to the approach used in the mouse 6 Hz seizure model (e.g., 32 and 44 mA stimulus intensities). The ASDs evaluated include carbamazepine, clobazam, clonazepam, eslicarbazepine, ethosuximide, ezogabine, gabapentin, lacosamide, lamotrigine, levetiracetam, phenobarbital, phenytoin, rufinamide, tiagabine, topiramate, and sodium valproate. Median effective dose (ED50 ) and median toxic (motor impairment) dose (TD50 ) values were obtained for each compound. RESULTS: Compounds that were effective at the 1.5 × CC97 stimulus intensity at protective index (PI) values >1 included clobazam, ethosuximide, ezogabine, levetiracetam, phenobarbital, and sodium valproate. Compounds that were effective at the 2 × CC97 stimulus intensity at PI values >1 included ezogabine, phenobarbital, and sodium valproate. SIGNIFICANCE: In a manner similar to the use of the mouse 6 Hz model, development of a rat 6 Hz test will aid in the differentiation of ASDs, as well as in study design and dose selection for chronic rat models of pharmacoresistant epilepsy. The limited number of established ASDs with demonstrable efficacy at the higher stimulus intensity suggests that, like the mouse 6 Hz 44 mA model, the rat 6 Hz seizure model may be a useful screening tool for pharmacoresistant seizures.

Preclinical Comparison of Mechanistically Different Antiseizure, Antinociceptive, and/or Antidepressant Drugs in a Battery of Rodent Models of Nociceptive and Neuropathic Pain.

The series of experiments herein evaluated prototype drugs representing different mechanisms of antiseizure, antinociceptive or antidepressant action in a battery of preclinical pain models in adult male CF#1 mice (formalin, writhing, and tail flick) and Sprague Dawley rats partial sciatic nerve ligation (PSNL). In the formalin assay, phenytoin (PHT, 6 mg/kg), sodium valproate (VPA, 300 mg/kg), amitriptyline (AMI, 7.5 and 15 mg/kg), gabapentin (GBP, 30 and 70 mg/kg), tiagabine (TGB, 5 and 15 mg/kg), and acetominophen (APAP, 250 and 500 mg/kg) reduced both phases of the formalin response to ≤ 25% of vehicle-treated mice. In the acetic acid induced writhing assay, VPA (300 mg/kg), ethosuximide (ETX, 300 mg/kg), morphine (MOR, 5 & 10 mg/kg), GBP (10, 30, and 60 mg/kg), TGB (15 mg/kg), levetiracetam (LEV, 300 mg/kg), felbamate (FBM, 80 mg/kg) and APAP (250 mg/kg) reduced writhing to ≤ 25% of vehicle-treated mice. In the tail flick test, MOR (1.25-5 mg/kg), AMI (15 mg/kg) and TGB (5 mg/kg) demonstrated significant antinociceptive effects. Finally, carbamazepine (CBZ, 20 and 50 mg/kg), VPA, MOR (2 and 4 mg/kg), AMI (12 mg/kg), TPM (100 mg/kg), lamotrigine (LTG, 40 mg/kg), GBP (60 mg/kg), TGB (15 mg/kg), FBM (35 mg/kg), and APAP (250 mg/kg) were effective in the PSNL model. Thus, TGB was the only prototype compound with significant analgesic effects in each of the four models, while AMI, GBP, APAP, and MOR each improved three of the four pain phenotypes. This study highlights the importance evaluating novel targets in a variety of pain phenotypes.