Antiseizure Drugs and Movement Disorders

Chronic Treatment with Oxcarbazepine Attenuates Its Anticonvulsant Effect in the Maximal Electroshock Model in Mice

The objective of this study was to assess the impact of acute and chronic treatment with oxcarbazepine on its anticonvulsant activity, neurological adverse effects, and protective index in mice. Oxcarbazepine was administered in four protocols: once or twice daily for one week (7 × 1 or 7 × 2) and once or twice daily for two weeks (14 × 1 or 14 × 2). A single dose of the drug was employed as a control. The anticonvulsant effect was evaluated in the maximal electroshock test in mice. Motor and long-term memory impairment were assessed using the chimney test and the passive avoidance task, respectively. The concentrations of oxcarbazepine in the brain and plasma were determined via high-performance liquid chromatography. Two weeks of oxcarbazepine treatment resulted in a significant reduction in the anticonvulsant (in the 14 × 1; 14 × 2 protocols) and neurotoxic (in the 14 × 2 schedule) effects of this drug. In contrast, the protective index for oxcarbazepine in the 14 × 2 protocol was found to be lower than that calculated for the control. No significant deficits in memory or motor coordination were observed following repeated administration of oxcarbazepine. The plasma and brain concentrations of this anticonvulsant were found to be significantly higher in the one-week protocols. Chronic treatment with oxcarbazepine may result in the development of tolerance to its anticonvulsant and neurotoxic effects, which appears to be dependent on pharmacodynamic mechanisms.

An isotope dilution-liquid chromatography-tandem mass spectrometry (ID-LC-MS/MS)-based candidate reference measurement procedure (RMP) for the quantification of gabapentin in human serum and plasma

OBJECTIVES

To describe and validate a reference measurement procedure (RMP) for gabapentin, employing quantitative nuclear magnetic resonance (qNMR) spectroscopy to determine the absolute content of the standard materials in combination with isotope dilution-liquid chromatograph-tandem mass spectrometry (ID-LC-MS/MS) to accurately measure serum and plasma concentrations.

METHODS

A sample preparation protocol based on protein precipitation in combination with LC-MS/MS analysis using a C8 column for chromatographic separation was established for the quantification of gabapentin. Assay validation and determination of measurement uncertainty were performed according to guidance from the Clinical and Laboratory Standards Institute, the International Conference on Harmonization, and the Guide to the expression of uncertainty in measurement. ID-LC-MS/MS parameters evaluated included selectivity, specificity, matrix effects, precision and accuracy, inter-laboratory equivalence, and uncertainty of measurement.

RESULTS

The use of qNMR provided traceability to International System (SI) units. The chromatographic assay was highly selective, allowing baseline separation of gabapentin and the gabapentin-lactam impurity, without observable matrix effects. Variability between injections, preparations, calibrations, and days (intermediate precision) was <2.3%, independent of the matrix, while the coefficient of variation for repeatability was 0.9-2.0% across all concentration levels. The relative mean bias ranged from -0.8-1.0% for serum and plasma samples. Passing-Bablok regression analysis indicated very good inter-laboratory agreement; the slope was 1.00 (95% confidence interval [CI] 0.98 to 1.03) and the intercept was -0.05 (95% CI -0.14 to 0.03). Pearson's correlation coefficient was ≥0.996. Expanded measurement uncertainties for single measurements were found to be ≤5.0% (k=2).

CONCLUSIONS

This analytical protocol for gabapentin, utilizing traceable and selective qNMR and ID-LC-MS/MS techniques, allows for the standardization of routine tests and the reliable evaluation of clinical samples.

Overview of Movement Disorders Secondary to Drugs

Drug-induced movement disorders affect a significant percentage of individuals, and they are commonly overlooked and underdiagnosed in clinical practice. Many comorbidities can affect these individuals, making the diagnosis even more challenging. Several variables, including genetics, environmental factors, and aging, can play a role in the pathophysiology of these conditions. The Diagnostic and Statistical Manual of Mental Disorders (DSM) and the International Statistical Classification of Diseases and Related Health Problems (ICD) are the most commonly used classification systems in categorizing drug-induced movement disorders. This literature review aims to describe the abnormal movements associated with some medications and illicit drugs. Myoclonus is probably the most poorly described movement disorder, in which most of the reports do not describe electrodiagnostic studies. Therefore, the information available is insufficient for the diagnosis of the neuroanatomical source of myoclonus. Drug-induced parkinsonism is rarely adequately evaluated but should be assessed with radiotracers when these techniques are available. Tardive dyskinesias and dyskinesias encompass various abnormal movements, including chorea, athetosis, and ballism. Some authors include a temporal relationship to define tardive syndromes for other movement disorders, such as dystonia, tremor, and ataxia. Antiseizure medications and antipsychotics are among the most thoroughly described drug classes associated with movement disorders.

Cenobamate (YKP3089) and Drug-Resistant Epilepsy: A Review of the Literature

Cenobamate (CNB), ([(R)-1-(2-chlorophenyl)-2-(2H-tetrazol-2-yl)ethyl], is a novel tetrazole alkyl carbamate derivative. In November 2019, the Food and Drug Administration approved Xcopri®, marketed by SK Life Science Inc., (Paramus, NJ, USA) for adult focal seizures. The European Medicines Agency approved Ontozry® by Arvelle Therapeutics Netherlands B.V.(Amsterdam, The Neatherlands) in March 2021. Cenobamate is a medication that could potentially change the perspectives regarding the management and prognosis of refractory epilepsy. In this way, this study aims to review the literature on CNB's pharmacological properties, pharmacokinetics, efficacy, and safety. CNB is a highly effective drug in managing focal onset seizures, with more than twenty percent of individuals with drug-resistant epilepsy achieving seizure freedom. This finding is remarkable in the antiseizure medication literature. The mechanism of action of CNB is still poorly understood, but it is associated with transient and persistent sodium currents and GABAergic neurotransmission. In animal studies, CNB showed sustained efficacy and potency in the 6 Hz test regardless of the stimulus intensity. CNB was revealed to be the most cost-effective drug among different third-generation antiseizure medications. Also, CNB could have neuroprotective effects. However, there are still concerns regarding its potential for abuse and suicidality risk, which future studies should clearly assess, after which protocols should be changed. The major drawback of CNB therapy is the slow and complex titration and maintenance phases preventing the wide use of this new agent in clinical practice.

Mining and analysis of adverse drug reactions associated with perampanel based on FAERS database

INTRODUCTION

Perampanel (PER) is a non-competitive AMPA glutamate receptor antagonist used as an anti-seizure medication. Large post-marketing databases are still lacking for safety analysis of the new generation of anti-seizure medications. Based on the FDA's adverse event reporting system (FAERS) database, this study aimed to investigate, assess, and offer evidence for the safety of PER to support clinical decision-making.

METHODS

Perampanel-related adverse reaction signals were mined using the reporting odds ratio (ROR), medicines and healthcare products regulatory agency (MHRA), and Bayesian confidence propagation neural network (BCPNN). The rate and occurrence of reported adverse responses were examined.

RESULTS

With the three methodologies used in combination, 83 signals mostly related to psychosis and different nervous system disorders were detected. Among them, suicide behavior, respiratory depression, hepatotoxicity, cognitive impairment, and other possible novel signals warranted consideration. Further examination of the age and gender differences in the detected signals revealed that elderly patients should be closely monitored for any change in consciousness and the occurrence of movement disorders; male patients should be observed for negative mental reactions like a personal attack and homicidal ideation; and female patients should be watched for the occurrence of negative reactions in memory, weight, vision, liver function, and other specific areas.

CONCLUSIONS

This study found that PER had the risk of causing suicide behavior, respiratory depression, hepatotoxicity, and cognitive impairment among other adverse effects. When used clinically, PER should be closely monitored for the occurrence of adverse effects on mental health and behavior. However, these results should be interpreted with caution.

Association between Antiepileptic Drugs and Incident Parkinson’s Disease among Patients Followed in German Primary Care Practices

Background: The aim of this study was to analyze whether prescriptions of antiepileptic drugs (AEDs) are significantly associated with an increased incidence of Parkinson’s disease (PD) in the German population. Methods: This study used data from German primary care practices found in the Disease Analyzer database (IQVIA) and included all patients aged ≥18 years who were diagnosed with PD between January 2010 and December 2021 (index date). The controls were patients without PD matched (1:1) by age, sex, and pre-diagnostic observation time in years. Associations between AED prescriptions (any AED as well as separate evaluations for carbamazepine, lamotrigine, levetiracetam, sodium valproate, gabapentin, and pregabalin) and subsequent diagnosis of PD were examined using a logistic regression model adjusted for epilepsy, restless legs syndrome, and neuropathy diagnoses. Results: We identified 24,950 cases that were matched with 24,950 controls (mean age 75.2 years, 47.3% women). Diagnoses of epilepsy, restless legs syndrome, and neuropathy as well as AED prescription were significantly associated with an increased incidence of PD. In the multivariate analysis, incidence of PD was significantly associated with epilepsy (OR: 1.91; 95% CI: 1.69–2.15), restless legs syndrome (OR: 3.02; 95% CI: 2.73–3.34), and neuropathy (OR: 1.53; 95% CI: 1.44–1.62)), as well as the prescription of any AED (OR: 1.43; 95% CI: 1.33–1.53), sodium valproate (OR: 2.39; 95% CI: 1.84–3.11), gabapentin (OR: 1.36; 95% CI: 1.22–1.52), and pregabalin (OR: 1.28; 95% CI: 1.15–1.41). Conclusion: Prescriptions of AEDs, including sodium valproate, gabapentin, and pregabalin, were associated with an increased risk of subsequent PD, even after adjustment for underlying diagnoses. Further studies are needed to confirm the present results.

Effective Management of "OFF" Episodes in Parkinson's Disease: Emerging Treatment Strategies and Unmet Clinical Needs

Motor complications related to the chronic administration of levodopa and failure to prevent the neurodegenerative disease process counterbalance the pivotal discovery of levodopa as the cornerstone of PD treatment. Excellent motor control is offered early during the course of treatment, but this diminishes as pathological changes in the striatum lead to synaptic dopamine levels becoming completely dependent on exogenous dopamine. This non-physiologic stimulation of dopamine receptors eventually manifests as OFF episodes. As no disease modifying therapy exists for PD that can disrupt these pathological changes, most research and treatment focuses on optimization of dopaminergic stimulation of striatal receptors so that they mimic tonic, physiologic stimulation as closely as possible. Strategies focusing on these challenges have included non-pharmacologic approaches, optimizing levodopa pharmacokinetics, using adjunctive treatments including those with non-dopaminergic mechanisms, and implementing rescue therapies. Device aided therapies, including surgery, are also available. In this review, we will focus on effective management of motor symptoms related to OFF periods, including emerging strategies. Unmet clinical needs will be discussed, including non-motor symptoms, targeted molecular therapies and disease modifying therapy.

Chorea Associated with Lamotrigine Use

Background

Movement disorders, including chorea, have been cited as a side effect of lamotrigine use. However, the association is controversial and clinical characteristics in such cases are unclear. We sought to explore whether chorea may be associated with lamotrigine use.

Methods

We performed a retrospective chart review of all patients diagnosed with chorea who had concurrent use of lamotrigine between 2000-2022. Demographic information and clinical characteristics were analyzed, including medical comorbidities and concurrent medication use. A literature search and review were conducted, with additional cases of lamotrigine-associated chorea analyzed.

Results

Eight patients met the inclusion criteria for the retrospective review. In 7 patients, other causes of chorea were considered more likely. However, a 58-year-old woman with bipolar disorder on lamotrigine for mood stabilization had a clear association of chorea induced by lamotrigine. The patient was on multiple centrally active medications. Three additional cases of lamotrigine-associated chorea were identified through a literature review. In 2 of these cases, other centrally acting agents were used, and chorea was resolved with weaning lamotrigine.

Discussion

Chorea is infrequently seen in the setting of lamotrigine use. In these rare cases, the presence of other centrally acting medications with lamotrigine may contribute to chorea.

Highlights

Lamotrigine use is associated with movement disorders, including chorea, but the characteristics are not clearly defined. From our retrospective review, one adult had clear temporal and dose-related association between chorea and lamotrigine. We analyzed this case in conjunction with a literature review of cases of chorea associated with lamotrigine.