Characteristics and treatment outcomes of newly diagnosed epilepsy in older people: A 30‐year longitudinal cohort study

Central Nervous System Medications: Pharmacokinetic and Pharmacodynamic Considerations for Older Adults

Most drugs have not been evaluated in the older population. Recognizing physiological alterations associated with changes in drug disposition and with the ultimate effect, especially in central nervous system-acting drugs, is fundamental. While considering pharmacokinetics, it should be noted that the absorption of most drugs from the gastrointestinal tract does not change in advanced age. There are only few data about the effect of age on the transdermal absorption of medications such as fentanyl. Absorption from an intramuscular injection may be similar in older adults as in younger patients. The distribution of lipophilic drugs (such as diazepam) is increased owing to a relative increase in the percentage of body fat, causing drug accumulation and prolonged drug elimination following cessation. Phase I drug biotransformation is variably decreased in aging, impacting elimination, and hepatic drug clearance has been shown to decrease in older individuals by 10-40% for most drugs studied. Lower doses of phenothiazines, butyrophenones, atypical antipsychotics, antidepressants (citalopram, mirtazapine, and tricyclic antidepressants), and benzodiazepines (such as diazepam) achieve the same extent of exposure. For renally cleared drugs with no prior metabolism (such as gabapentin), the glomerular filtration rate appropriately estimates drug clearance. Important pharmacodynamic changes in older adults include an increased sedative effect of benzodiazepines at a given drug exposure, and a higher sensitivity to mu opiate receptor agonists and to opioid adverse effects. Artificial intelligence, physiologically based pharmacokinetic modeling and simulation, and concentration-effect modeling enabling a differentiation between the pharmacokinetic and the pharmacodynamic effects of aging might help to close some of the gaps in knowledge.

Distribution, Metabolism, and Excretion of Cenobamate in Adult, Fetal, Neonatal, and Lactating Rats

BACKGROUND AND OBJECTIVE

Cenobamate is an antiseizure medication (ASM) approved for treatment of focal epilepsy in adults. The objective of this study was to characterize the distribution, metabolism, and excretion of cenobamate in adult and pre- and postnatal rats, including pregnant and lactating females and nursing pups.

METHODS

Distribution, metabolic, and excretion profiles were determined for 14C-labeled and unlabeled cenobamate using liquid scintillation counting, radiochromatography, LCMS, and LCMS/MS after oral or intravenous (IV) administration.

RESULTS

Distribution of 14C-cenobamate-related material in adult male rats was widespread throughout the body, with nearly 1:1 tissue-to-plasma ratios observed for most tissues, including brain. Cenobamate administered to pregnant females was also transferred across the placental barrier into amniotic fluid and fetal plasma. Following administration to lactating F0 females, cenobamate was detected in breast milk and in plasma of nursing pups. 14C-cenobamate administered to adult male rats as a single oral dose was extensively metabolized with nine metabolites identified in urine and feces, including a principal dihydrodiol metabolite. Cenobamate was the principal drug-related material in rat plasma. Following a single dose of 14C-cenobamate to male and female rats, radioactivity was excreted equally into urine and feces, with mass balance achieved by 48 h postdose.

CONCLUSIONS

Distribution of cenobamate was widespread into many rat tissues, including brain, amniotic fluid, fetal plasma, breast milk, and breastfeeding rat pups. These distribution findings, along with the results of the metabolism and excretion studies, may help inform treatment decisions for patients with epilepsy being treated with cenobamate, including pregnant or nursing mothers.

Association of comorbid-socioeconomic clusters with mortality in late onset epilepsy derived through unsupervised machine learning

BACKGROUND AND OBJECTIVES

Late-onset epilepsy is a heterogenous entity associated with specific aetiologies and an elevated risk of premature mortality. Specific multimorbid-socioeconomic profiles and their unique prognostic trajectories have not been described. We sought to determine if specific clusters of late onset epilepsy exist, and whether they have unique hazards of premature mortality.

METHODS

We performed a retrospective observational cohort study linking primary and hospital-based UK electronic health records with vital statistics data (covering years 1998-2019) to identify all cases of incident late onset epilepsy (from people aged ≥65) and 1:10 age, sex, and GP practice-matched controls. We applied hierarchical agglomerative clustering using common aetiologies identified at baseline to define multimorbid-socioeconomic profiles, compare hazards of early mortality, and tabulating causes of death stratified by cluster.

RESULTS

From 1,032,129 people aged ≥65, we identified 1048 cases of late onset epilepsy who were matched to 10,259 controls. Median age at epilepsy diagnosis was 68 (interquartile range: 66-72) and 474 (45%) were female. The hazard of premature mortality related to late-onset epilepsy was higher than matched controls (hazard ratio [HR] 1.73; 95% confidence interval [95%CI] 1.51-1.99). Ten unique phenotypic clusters were identified, defined by 'healthy' males and females, ischaemic stroke, intracerebral haemorrhage (ICH), ICH and alcohol misuse, dementia and anxiety, anxiety, depression in males and females, and brain tumours. Cluster-specific hazards were often similar to that derived for late-onset epilepsy as a whole. Clusters that differed significantly from the base late-onset epilepsy hazard were 'dementia and anxiety' (HR 5.36; 95%CI 3.31-8.68), 'brain tumour' (HR 4.97; 95%CI 2.89-8.56), 'ICH and alcohol misuse' (HR 2.91; 95%CI 1.76-4.81), and 'ischaemic stroke' (HR 2.83; 95%CI 1.83-4.04). These cluster-specific risks were also elevated compared to those derived for tumours, dementia, ischaemic stroke, and ICH in the whole population. Seizure-related cause of death was uncommon and restricted to the ICH, ICH and alcohol misuse, and healthy female clusters.

SIGNIFICANCE

Late-onset epilepsy is an amalgam of unique phenotypic clusters that can be quantitatively defined. Late-onset epilepsy and cluster-specific comorbid profiles have complex effects on premature mortality above and beyond the base rates attributed to epilepsy and cluster-defining comorbidities alone.

Seizure outcome in medically treated patients with adult-onset epilepsy and cerebral cavernous malformation

PURPOSE

We evaluated long-term seizure outcomes of antiseizure medications (ASMs) and risk factors for drug resistance in patients with adult-onset epilepsy associated with cerebral cavernous malformation (CCM).

MATERIALS AND METHODS

This retrospective observational study included patients newly diagnosed with adult-onset focal epilepsy associated with CCM. Patients received individualized treatments with ASMs. All patients were followed-up for at least 2 years. The main outcome measure was terminal 2 year seizure freedom (2-YSF).

RESULTS

Forty eight subjects (28 men and 20 women) were included. Thirty-one (64.6%) subjects achieved a terminal 2-YSF (range 2.0-17.0 years). After treatment with the first drug regimen, 31 (64.6%) subjects achieved 2-YSF, with 23 remaining seizure-free until final follow-up visit. Of the 23 subjects treated with the second drug regimen and the six treated with the third drug regimen, ten (43.5%) and one (16.7%), respectively, achieved a terminal 2-YSF. Stepwise logistic regression analyses showed that terminal 2-YSF was negatively associated with epileptiform discharge on EEG at the time of diagnosis (odds ratio = 0.214, p = 0.047) and tended to be associated with age ≥ 45 years at seizure onset (odds ratio = 4.260, p = 0.056).

CONCLUSION

The present study found that 64.6% of CCM patients with adult-onset epilepsy achieved terminal 2-YSF after ASM initiation. Interictal epileptiform discharge on EEG at the time of diagnosis was associated with poor prognosis. Failure to achieve sustained seizure freedom after two ASMs may indicate the need for surgical treatment.

Drug resistance in epilepsy

Drug resistance is estimated to affect about a third of individuals with epilepsy, but its prevalence differs in relation to the epilepsy syndrome, the cause of epilepsy, and other factors such as age of seizure onset and presence of associated neurological deficits. Although drug-resistant epilepsy is not synonymous with unresponsiveness to any drug treatment, the probability of achieving seizure freedom on a newly tried medication decreases with increasing number of previously failed treatments. After two appropriately used antiseizure medications have failed to control seizures, individuals should be referred whenever possible to a comprehensive epilepsy centre for diagnostic re-evaluation and targeted management. The feasibility of epilepsy surgery and other treatments, including those targeting the cause of epilepsy, should be considered early after diagnosis. Substantial evidence indicates that a delay in identifying an effective treatment can adversely affect ultimate outcome and carry an increased risk of cognitive disability, other comorbidities, and premature mortality. Research on mechanisms of drug resistance and novel therapeutics is progressing rapidly, and potentially improved treatments, including those targeting disease modification, are on the horizon.

Anti-seizure medication prescription in epilepsy patients in South Korea: A seven-year population-based retrospective cohort study

BACKGROUND AND OBJECTIVES

This study aimed to explore the natural history of patients with epilepsy using overall antiseizure-medication (ASM) treatment patterns on a nationwide scale in South Korea.

METHODS

We investigated a retrospective longitudinal cohort of patients with epilepsy in South Korea using nationwide data from the Korean National Health Information Database of the Health Insurance and Review Assessment Service between January 1st, 2009, and December 31st, 2018. Histories of each patient's ASM prescription were followed for up to 7 years from the index date, the first observed date of ICD-10 epilepsy diagnosis codes with at least one ASM prescription.

RESULTS

Of 82,390 incident patients analyzed, ten thousand and fifty-nine were followed up to seven years, and nearly 60% of them discontinued the ASM(s). The proportion of patients with possible drug-resistant epilepsy (DRE), who experience three or more types of ASMs, gradually increased, reaching approximately 8.8% of the total number of patients in the seventh year (6.45% for adults, 21.8% for children). The duration of progression for half of the patients with possible DRE was 1.29 years for children, 1.79 years for adults, and 1.62 years for mixed-age patients. However, even in the sixth year, 72 cases progressed to possible DRE, and 6 cases with possible DRE discontinued ASMs in the next year, showing a dynamic process.

DISCUSSION

Our population-based study showed the dynamic changes of anti-seizure medication prescription in epilepsy patients with real-world data, which slowly stabilizes over years after the first diagnosis of epilepsy.

Pharmacological treatment for older adults with epilepsy and comorbid neurodegenerative disorders

PURPOSE OF REVIEW

An increased interest in epilepsy in older adults has emerged as the global population ages. The purpose of this article is to review the literature regarding the pharmacological treatment of epilepsy in older adults, highlighting issues specifically pertinent to those living with comorbid neurodegenerative disorders.

RECENT FINDINGS

Although new original research remains sparse, in the last 5 years, there has been a growing number of studies addressing the relationship between epilepsy and neurodegenerative disorders. Accurate diagnosis is incredibly challenging with electroencephalogram findings often requiring circumspect interpretation. Older individuals are often excluded from or under-represented in clinical trials, and there are sparse guidelines offered on the management of these patients, with even less available in reference to those with neurodegenerative comorbidities.

SUMMARY

We propose that seizures occurring earlier in the neurodegenerative process should be treated aggressively, with the goal to inhibit neuro-excitotoxicity and the associated neuronal loss. By strategically choosing newer antiseizure medications with less adverse effects and a holistic approach to treatment, a patient's time living independently can be conserved. In addition, we advocate for original, multinational collaborative research efforts.

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.

Progress Toward Obtaining Seizure Freedom With New Medications in Older Adults

Characteristics and Treatment Outcomes of Newly Diagnosed Epilepsy in Older People: A 30-Year Longitudinal Cohort Study

Alsfouk BAA, Hakeem H, Chen Z, Walters M, Brodie MJ, Kwan P. Epilepsia. 2020;61(12):2720-2728. doi:10.1111/epi.16721

Objectives:

To describe the clinical characteristics and evaluate the long-term treatment outcomes in older people with newly diagnosed epilepsy over the past 30 years. Methods: We included patients newly diagnosed with epilepsy and commenced on anti-seizure medications (ASMs) at age 65 years or older between July 1982 and October 2012 at the Western infirmary in Glasgow, Scotland. They were followed up until April 2016 or death. Seizure freedom was defined as no seizure for at least 1 year on unchanged medication at the last follow-up. Results: A total of 201 patients (median age 73 years, 59% male) were included. The median duration from initial seizure to starting treatment was 8 months (interquartile range: 3.0-24.0 months); 42.2% (85/201) patients had more than 5 seizures before commencing treatment. Brain imaging showed potentially epileptogenic lesions in 19.7% (38/193) of patients and other abnormalities in 56.5% (109/193); 78.6% patients (158/201) were seizure-free at the last follow-up, of whom 94.9% were taking monotherapy. Concomitant aspirin use (n = 80) was associated with a lower probability of being seizure-free (relative risk 0.82, 95% confidence interval 0.70-0.97; P = .02). The use of second-generation ASMs as the initial monotherapy increased from 31.5% (23/73) before 2000 to 70.3% (90/128, P < .001) from 2000 onward. However, the seizure freedom rates (67.1% vs 55.5%; P = .35) and intolerable adverse-effect rates (16.4% vs 19.5%; P = .45) did not show any significant difference. Significance: There was often a long interval between seizure onset and the initiation of treatment in older people with new-onset epilepsy, although the majority responded well to ASM treatment. Brain imaging showed a high rate of abnormalities. Despite the increased use of second-generation ASMs, treatment outcomes in later-onset epilepsy have not improved over time. The possible effect of aspirin on treatment response warrants further investigation.

Markov modelling of treatment response in a 30-year cohort study of newly diagnosed epilepsy

People with epilepsy have variable and dynamic trajectories in response to antiseizure medications. Accurately modelling long-term treatment response will aid prognostication at the individual level and health resource planning at the societal level. Unfortunately, a robust model is lacking. We aimed to develop a Markov model to predict the probability of future seizure-freedom based on current seizure state and number of antiseizure medication regimens trialled. We included 1,795 people with newly diagnosed epilepsy who attended a specialist clinic in Glasgow, Scotland, between July 1982 and October 2012. They were followed up until October 2014 or death. We developed a simple Markov model, based on current seizure state only, and a more detailed model, based on both current seizure state and number of antiseizure medication regimens trialled. Sensitivity analyses were performed for the regimen-based states model to examine the effect of regimen changes due to adverse effects. The model was externally validated in a separate cohort of 455 newly diagnosis epilepsy patients seen in Perth, Australia, between May 1999 and May 2016. Our models suggested that once seizure-freedom was achieved, it was likely to persist, regardless of the number of antiseizure medications trialled to reach that point. The likelihood of achieving long-term seizure-freedom was highest with the first antiseizure medication regimen, at approximately 50%. The chance of achieving seizure-freedom fell with subsequent regimens. Fluctuations between seizure-free and not seizure-free states were highest earlier on, but decreased with chronicity of epilepsy. Seizure-freedom/recurrence risk tables were constructed with these probability data, similar to cardiovascular risk tables. Sensitivity analyses showed that the general trends and conclusions from the base model were maintained despite perturbing the model and input data with regimen changes due to adverse effects. Quantitative comparison with the external validation cohort showed excellent consistency at year 1, good at year 3 and moderate at year 5. Quantitative models, as used in this study, can provide pertinent clinical insights that are not apparent from simple statistical analysis alone. Attaining seizure freedom at any time in a patient's epilepsy journey will confer durable benefit. Seizure-freedom risk tables may be used to individualise the prediction of future seizure control trajectory.