Tag: antiepileptics

Categories : NeurologyTags :

Could a New Role for Propofol be Treating Epilepsy?

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The general anaesthetic propofol may hold the keys to developing new treatment strategies for epilepsy and other neurological disorders, according to a study led by researchers at Weill Cornell Medicine and Linköping University in Sweden.

In their study, published in Nature, the researchers determined the high-resolution structural details of how propofol inhibits the activity of HCN1, an ion channel protein found on many types of neurons. Drug developers consider inhibiting HCN1 a promising strategy for treating neurologic disorders including epilepsy and chronic pain. The researchers also found, to their surprise, that when HCN1 contains either of two epilepsy-associated mutations, propofol binds to it in a way that restores its functionality.

“We might be able to exploit propofol’s unique way of binding to HCN1 for the treatment of these drug-resistant epilepsies and other HCN1-linked disorders, either by directly repurposing propofol or by designing new, more selective drugs that have the same mechanism of action,” said study co-senior author Dr Crina Nimigean, professor of physiology and biophysics in anaesthesiology at Weill Cornell Medicine.

The study’s first author was Dr Elizabeth Kim, a postdoctoral research associate in the Nimigean laboratory.  

HCN ion channels in humans come in four basic forms, HCN1 to HCN4, and are found especially on cells in the heart and nervous system. They work as switches to control the electrical voltage across the cell membrane, opening to admit an inward flow of positively charged potassium and sodium ions – thus “depolarising” the cell – when the voltage reaches a certain threshold. This function underpins much of the rhythmic activity of brain and heart muscle cells, which is why HCN channels are also called pacemaker channels.

In the study, the researchers used cryo-electron microscopy and other methods to determine, at near-atomic scale, how propofol reduces HCN1 activity – which it does with selectivity for HCN1 over other HCNs. They found that the drug inhibits HCN1 by binding within a groove between two elements of the channel protein’s central pore structure, making it harder for the pore to open.

As they investigated propofol’s action on HCN1, the researchers examined how the drug affects different known mutants of the channel, including mutants that leave it excessively open and are associated with hard-to-treat epilepsy syndromes such as early infantile epileptic encephalopathy (EIEE). The researchers were surprised to find that for two different HCN1 mutations that cause EIEE, propofol restores the mutant channels to normal or near-normal function.

From their experiments, the researchers derived a model in which the mutations decouple HCN1’s voltage-sensing and pore mechanisms, while propofol effectively recouples them, allowing membrane voltage to control ion flow again.

The results suggest at least two possibilities for translation to therapies. One is simply to use propofol, an existing, approved drug, to treat these HCN1-mutation epilepsies and potentially other HCN1-linked disorders. Propofol is a potent anesthetic that requires careful monitoring by anaesthesiologists, but it might be able to restore HCN1 function at doses below those used for general anaesthesia.

The other possibility, the researchers said, is to use the new structural data on propofol’s binding to design modified, non-anesthetic versions of propofol, or even completely different compounds, that bind to HCN1 with a similar effect but much more selectively—in other words, without binding to other channels, including other HCNs, in the body and thereby potentially causing unwanted side effects.

“For that we will need a better understanding of how propofol inhibits HCN1 better than other HCN channels,” Dr Kim said.

Source: Weill Cornell Medicine

Categories : Cancer NeurologyTags :

Scientists Evaluate Old Epilepsy Drug for Glioma Prevention

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A drug used to treat children with epilepsy prevents brain tumour formation and growth in two mouse models of neurofibromatosis type 1 (NF1), according to a study by researchers at Washington University School of Medicine in St. Louis. NF1 is a genetic condition that causes tumours to grow on nerves throughout the body.

The findings lay the groundwork for a clinical trial to assess whether the drug, lamotrigine, can prevent or delay brain tumours in children with NF1. The study is published online in the journal Neuro-Oncology.

“Based on these data, the Neurofibromatosis Clinical Trials Consortium is considering launching a first-of-its-kind prevention trial,” said senior author David H. Gutmann, MD, PhD, professor of neurology. “The plan is to enrol kids without symptoms, treat them for a limited time, and then see whether the number of children who develop tumours that require treatment goes down.

“This is a novel idea, so we took it to an NF1 patient focus group,” Gutmann continued. “They said, ‘This is exactly what we’re looking for.’ A short-term treatment with a drug that has been used safely for 30 years was acceptable to them if it reduced the chance their children would develop tumours and need chemotherapy that might have all kinds of side effects.”

Optic gliomas, tumours on the optic nerve are the most serious type that those with NF1 get. Such tumours typically appear between ages 3 to 7. Though rarely fatal, they cause vision loss in up to a third of patients as well as other symptoms, including early puberty. Standard chemotherapy for optic gliomas is only moderately effective at preventing further vision loss and can affect children’s developing brains, resulting in cognitive and behavioural problems.

In a previous study, Gutmann and Corina Anastasaki, PhD, an assistant professor of neurology and the first author on the new paper, showed that lamotrigine stopped optic glioma growth in NF1 mice by suppressing neuronal hyperactivity. Intrigued, the Neurofibromatosis Clinical Trial Consortium asked Gutmann and Anastasaki to clarify the connection between NF1 mutation, neuronal excitability and optic gliomas; assess whether lamotrigine was effective at the doses already proven safe in children with epilepsy; and conduct these studies in more than one strain of NF1 mice.

In humans, NF1 could be caused by any one of thousands of different mutations in the NF1 gene, with different mutations causing different medical problems. Repeating experiments in multiple strains of mice was a way of gauging whether lamotrigine was likely to work in people regardless of the underlying mutation.

Anastasaki and Gutmann not only showed that lamotrigine worked in two strains of NF1 mice, they also showed that the drug worked at lower doses than those used for epilepsy, meaning that it was probably safe. Even better, they found that a short course of the drug had lasting effects, both as a preventive and a treatment. Mice with tumours and that were treated for four weeks starting at 12 weeks of age saw their tumours stop growing and even showed no further damage to the retinas. Mice that received a four-week course of the drug starting at 4 weeks of age, before tumours typically emerge, showed no tumour growth even four months after treatment had ended.

These findings have led Gutmann to suggest that a one-year course of treatment for young children with NF1, maybe between the ages of 2 to 4, might be enough to reduce their risk of brain tumours.

“The idea that we might be able to change the prognosis for these kids by intervening within a short time window is so exciting,” Gutmann said. “If we could just get them past the age when these tumours typically form, past age 7, they may never need treatment. I’d love it if I never again had to discuss chemotherapy for kids who aren’t even in first grade yet.”

Source: Washington University School of Medicine

Categories : Ageing Diseases, Syndromes and ConditionsTags :

Promising Results for Epilepsy Drug in Slowing Osteoarthritis

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Yale researchers report in the journal Nature that they have identified a drug target that may alleviate joint degeneration associated with osteoarthritis.

The most common therapies for the degenerative disease have been pain relievers and lifestyle changes, to reduce pain and stiffness, but there is a pressing need for therapies that can prevent joint breakdown that occurs in osteoarthritis, which occurs as a result of the breakdown of cartilage in the joints.

Sodium channels found in cell membranes produce electrical impulses in “excitable” cells within muscles, the nervous system, and the heart. And in previous research, Yale’s Stephen G. Waxman identified the key role of one particular sodium channel, called Nav1.7, in the transmission of pain signals.

Now, the labs of Chuan-Ju Liu, professor of orthopaedics, and Waxman, professor neurology, neuroscience and pharmacology, have found that the same Nav1.7 channels are also present in non-excitable cells that produce collagen and help maintain the joints in the body. These channels can be targeted by existing drugs to block them.

In the new study, the researchers deleted Nav1.7 genes from these collagen-producing cells and significantly reduced joint damage in two osteoarthritis models in mice.

They also demonstrated that drugs used to block Nav1.7 – including carbamazepine, a sodium channel blocker currently used to treat epilepsy and trigeminal neuralgia – also provided substantial protection from joint damage in the mice.

“The function of sodium channels in non-excitable cells has been a mystery,” Waxman said.

“This new study provides a window on how small numbers of sodium channels can powerfully regulate the behaviour of non-excitable cells.”

“The findings open new avenues for disease-modifying treatments,” added Wenyu Fu, a research scientist in the Liu laboratory and first author of the study.

Source: Yale University

Categories : Neurology New Compounds and TreatmentsTags :

A New Drug Could Provide Hope in Treatment-resistant Epilepsy

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In cases where standard therapies fail, an in-development drug called XEN1101 reduces seizure frequency by more than 50% in some patients and in some cases eliminates them, according to a new study published in JAMA Neurology. Unlike several treatments that must be started at low doses and slowly ramped up, the new drug can safety be taken at its most effective dose from the start, the authors say.

Focal seizures, the most common type seen in epilepsy, occur when nerve cells in a particular brain region send out a sudden, excessive burst of electrical signals. Along with seizures, this uncontrolled activity can lead to abnormal behaviour, periods of lost awareness, and mood changes. While many available therapies control or reduce seizures, they fail to stop seizures in about one-third of patients and may cause harsh side effects, experts say.

Led by researchers at NYU Grossman School of Medicine, a new clinical trial found that patients who added XEN1101 to their current antiseizure treatments saw a 33% to 53% drop in monthly seizures, depending on their dose. By contrast, those given a placebo had on average 18% fewer seizures during the treatment phase of the trial, which lasted eight weeks. Most patients then volunteered to extend the trial, with about 18% of those treated with the new drug remaining entirely seizure free after six months, and about 11% having no seizures after a year or longer.

“Our findings show that XEN1101 may offer a swift, safe, and effective way to treat focal epilepsy,” said study lead author, neurologist Jacqueline French, MD. “These promising results offer hope for those who have struggled for decades to get their symptoms under control.”

French, a professor in the Department of Neurology at NYU Langone Health, notes that XEN1101 was well tolerated by the study participants, who reported side effects similar to other antiseizure treatments, including dizziness, nausea, and fatigue, and the majority felt well enough to continue the regimen. Another benefit of the drug, she adds, is that it takes more than a week to break down, so levels in the brain remain consistent over time. This steadiness allows the treatment to be started at full strength and helps to avoid dramatic spikes that worsen side effects, and dips that allow seizures to return. This lengthy breakdown time also allows for a “grace period” if a dose is accidently skipped or taken late.

XEN1101 is part of a class of chemicals called potassium-channel openers, which avert seizures by boosting the flow of potassium out of nerves, stopping them from firing. French notes that while other drugs of this kind have been explored for epilepsy patients in the past, such treatments were taken out of use because the compounds were later found to gradually build up in the skin and eyes, prompting safety concerns, the researchers say.

Meanwhile, XEN1101 combines the effectiveness of potassium-channel openers with the safety of more traditional drugs, says French, who is also a member of NYU Langone’s Comprehensive Epilepsy Center.

For the study, which included 285 men and women with epilepsy and ran from January 2019 to September 2021, the research team recruited adults with epilepsy who had already tried and stopped taking an average of six drugs that failed to treat their focal seizures. Patients in the trial had to have experienced at least four episodes a month despite ongoing treatment to qualify. The patients were randomly provided either a daily oral capsule of XEN1101 (in 10mg, 20mg, or 25mg doses) or placebo.

Among the results, the trial revealed no signs of dangerous side effects such as heart problems, allergic reactions, or concerning skin discolourations. However, French says that the research team plans to expand the number of patients exposed to the drug and monitor for potential issues that could arise in the long term, or include specific groups of people, such as pregnant women. In addition, the team also intends to explore XEN1101 for other types of seizures, including those that broadly affect the brain at the same time (generalised seizures).

“Our study highlights the importance of finding as many therapeutic options as possible for those who suffer from seizures,” says French. “Since everyone responds differently, treating epilepsy cannot be a one-size-fits-all approach.”

Source: NYU Langone Health / NYU Grossman School of Medicine

Categories : Diseases, Syndromes and ConditionsTags :

Guidelines for Cannabinoid Treatments in Drug Resistant Epilepsy

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Due to the sizeable interest in the use of cannabis-based medications in treating drug resistant epilepsy and comparative lack of clinical guidance on prescription, an expert working group in Australia recently developed an interim “consensus advice” for prescribers and published it in the British Journal of Clinical Pharmacology.

The working group was made up of paediatric and adult epilepsy specialists, clinical pharmacists, pharmacologists, and cannabis researchers. Epilepsy occurs in 1–2% of the population, and about one in three people with epilepsy are considered drug resistant to standard antiseizure medications.

Since there are few clinical data available on comparative efficacy of cannabinoids with registered epilepsy treatments, the authors recommend cannabinoids only in drug resistant epilepsy, in carefully selected compliant patients with specific epilepsy phenotypes.

The document provides an overview of the different cannabis medicines currently available for treating epilepsy in children and adults, with information on dose, drug interactions, toxicity, and type and frequency of symptom and seizure relief. The consensus advice will be updated as new evidence emerges and will provide the structure for a more definitive guideline in the future.

“In the absence of a registration dossier, scientific experiments and case reports are helpful to provide some guidance to optimised dosing. However as in this guidance, observational data obtained from clinical practice – which often includes information not included in scientific experiments or even early clinical trial data, such as treating patients with other comorbidities, taking multiple medications, and patient diversity – can be very helpful to clinical practice,” said senior author Jennifer H. Martin, MBChB, MA, PhD, FRACP, a researcher at the University of Newcastle and the Director of the Australian Centre for Cannabis Clinical and Research Excellence.

Source: Wiley

Categories : Cardiovascular Disease NeurologyTags :

Antiepileptics in Comatose Cardiac Arrest Survivors are Ineffective, Study Shows

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A large scale study of comatose intensive care (ICU) patients admitted after cardiac arrest and resuscitation has shown that antiepileptics to treat epilepsy-like brain activity has no effect, and may even prolong ICU stay.

Following a cardiac arrest and resuscitation, patients may need an ICU stay, and are in a coma. By that stage, the cardiac arrest may have damaged the brain to such an extent that half of the patients will not recover from coma. The other half will also have permanent damage, for example of memory functions. It is extremely difficult to predict if a patient will awaken and what their prognosis is, so clinicians make use of EEG (electroencephalography).

In 10–20% of the patients admitted to the ICU after cardiac arrest and resuscitation, there are signs of brain activity that appear similar to epilepsy: unlike an attack this activity is continuous. For a long time, it was unclear if anti-epileptic medication could help better recovery. As a result, some patients received this medication and some did not.

Now, a large-scale study done between 2014 and 2021 on 172 patients has proven that this medication is ineffective: it does not help recovery, even necessitating a longer ICU stay. The researchers, led by Professor Jeannette Hofmeijer of the University of Twente and Rijnstate Hospital in Arnhem, published their findings in the New England Journal of Medicine.

The conclusion from this study is that anti-epileptic medication does not lead to an improved recovery. The findings show that patients may need to stay longer at the ICU: for the patient an undesired situation, and it puts extra pressure on the health care system. 

Aside from patients who show continuous epileptic signals, a small group of patients show signs of a typical epileptic seizure: a short and heavy attack. In these situations, anti-epileptics could help, but this still needs further research.

“Although the outcome of the trial may be disappointing in terms of chances of recovery, it also takes away uncertainties from the family. The signals point at serious brain damage that would lead to a much longer stay at the ICU,” said Prof Hofmeijer.

Source: University of Twente

Categories : Neurology Obstetrics & GynaecologyTags :

Reduced Antiepileptic Drug Effectiveness in Pregnancy Uncovered

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Blood levels of many commonly used antiepileptic drugs drop dramatically with the onset of pregnancy, which can result in ‘breakthrough seizures’ according to a study published in JAMA Neurology.

The findings, collected as part of the multicentre study Maternal Outcomes and Neurodevelopmental Effects of Antiepileptic Drugs (MONEAD), explain why many people with epilepsy start experiencing breakthrough seizures after conception, underscoring the need to increase antiseizure medication doses and closely monitor blood levels over the course of pregnancy.

A fine-tuned medication regime is critical in epilepsy. “Some people mistakenly believe that changes in the drugs’ blood concentration won’t occur until after 20 weeks of pregnancy, but our study shows how important it is to start monitoring and adjusting patients’ medication dosages early on,” said lead author Dr Page Pennelll. “Nearly half of all pregnancies in the United States are unplanned, so it is important to ensure that doctors have a clear picture of each patient’s baseline drug level even if they are not trying to conceive.”

A life-altering neurological condition, two-thirds of epilepsy cases do not have a known cause. In people with epilepsy, nerve cells in the brain are hyper-reactive, causing them to change the pattern of their electrical activity and become spontaneously active. That synchronous activation is manifested in seizures.

Epilepsy has a fraught history of diagnosis and management; people with epilepsy go undiagnosed or under-treated. First-generation drugs to control it had many dangerous side effects and were contraindicated for people who are trying to conceive.

Since then, safer medications have entered the U.S. market and become widely available, but clinicians started noticing a new problem – patients whose epilepsy was successfully managed with medications started having seizures soon after becoming pregnant.

“Identifying which antiseizure medications may have changes in concentrations and at what point in pregnancy those changes occur is important for determining which patients may need to be monitored more closely during pregnancy and after delivery,” said senior author Professor Angela Birnbaum at the University of Minnesota.

To solve the mystery, the researchers embarked on a study to analyse blood concentrations of 10 commonly used antiseizure drugs and compare them across different stages of pregnancy and after childbirth.

The study found that blood levels of seven out of 10 of the medications they examined dropped dramatically — from 29.7% for lacosamide, a commonly prescribed anticonvulsant, and up to 56.4% for lamotrigine.

In addition, the researchers noted that the drop in drug levels occurred mere days after conception.

Source: University of Pittsburgh