Carbamazepine- and oxcarbazepine-induced hyponatremia in people with epilepsy

Post-stroke epilepsy

Epilepsy as a result of stroke is currently the most rapidly increasing form of epilepsy. The risk of post-stroke epileptogenesis is higher after haemorrhagic stroke than after ischemic stroke. We provide here a brief clinical review of the topic to highlight the misinterpretation and undertreatment of focal epileptic seizures in stroke patients. Correct diagnosis and treatment are important because recurrent epileptic seizures can reduce quality of life and hinder rehabilitation.

Sex Differences in Adverse Effects of Antiseizure Medications in Adults with Epilepsy: A Systematic Review

BACKGROUND

Sex differences in epilepsy have been described in prevalence, seizure propensity and response to treatment. Therefore, taking into account sex-based differences in epilepsy is important for both diagnostic purposes and therapeutic considerations. However, little is known about sex differences in adverse effects of antiseizure medications (ASMs).

OBJECTIVES

We performed a systematic review searching for sex differences in adverse effects of ASMs in adult persons with epilepsy (PWE) as part of a wider project aimed to assess sex-based differences in efficacy and adverse effects of ASMs in PWE.

METHODS

We conducted a comprehensive literature search in the PubMed database. The search was conducted with no restriction on publication date, and all results up to April 2020 were included. We included articles written in English, Italian, Spanish, or French that evaluated adverse effects of one or more ASMs in PWE, with specific mention of the two sexes. When appropriate, Newcastle-Ottawa or Jadad scales were used to assess study quality.

RESULTS

Of 5164 identified studies, only 167 considered sex in the analysis and were therefore included. Significant sex-related differences were found in 58 of those studies. We found a consistently higher frequency of cutaneous adverse effects in females; higher risk of developing general adverse effects on different ASMs in females; stronger risk of adverse effects on bone metabolism in females, mainly on treatment with enzyme-inducing ASMs; a concordant higher risk of visual field loss was noted in males on vigabatrin; an overall worse lipid profile in males; as well as higher leptin levels and higher body mass index in females treated with various ASMs.

CONCLUSIONS

Our analysis has identified some important sex differences in the adverse effects of ASMs. Clinicians should be aware of these differences when informing patients about the risks associated with ASM treatment in PWE.

Approach to Patients with Seizures and Epilepsy: A Guide for Primary Care Physicians

Seizures and epilepsy are common neurologic conditions that are frequently encountered in the outpatient primary care setting. An accurate diagnosis relies on a thorough clinical history and evaluation. Understanding seizure semiology and classification is crucial in conducting the initial assessment. Knowledge of common seizure triggers and provoking factors can further guide diagnostic testing and initial management. The pharmacodynamic characteristics and side effect profiles of anti-seizure medications are important considerations when deciding treatment and counseling patients, particularly those with comorbidities and in special populations such as patient of childbearing potential.

Eslicarbazepine-induced hyponatremia: A retrospective single-center real clinical practice study

Hyponatremia is a typical side effect of antiseizure drugs from the dibenzazepine family. The study investigated the prevalence of hyponatremia in patients with epilepsy who were treated with eslicarbazepine. We aimed to determine the prevalence of hyponatremia, reveal the factors leading to the discontinuation of treatment, and identify possible risk factors for the development of hyponatremia including the dose dependency. The medical records of 164 patients with epilepsy taking eslicarbazepine in our center were analyzed. The overall prevalence of hyponatremia was 30.5%. The prevalence of mild hyponatremia, seen in 14%-20% of patients, was not dose dependent. The prevalence of moderate and severe hyponatremia was significantly dose dependent. The severity of hyponatremia was significantly dose dependent. Severe hyponatremia was found in 6.1% of patients. Hyponatremia was asymptomatic in the majority of cases, and in 48% did not require any management. Hyponatremia was the reason for discontinuation in 6.2% of patients. The major risk factor for developing hyponatremia was older age. The study shows that eslicarbazepine-induced hyponatremia is usually mild and asymptomatic. It usually does not require any management and seldom leads to treatment discontinuation. Hyponatremia is dose dependent. Another major risk for developing hyponatremia (besides dose) is older age.

Role of Perampanel in the Management of Pediatric Epilepsies in Asia: Expert Opinion

Management of pediatric epilepsies poses unique challenges around diagnosis, treatment options, comorbidities, and the potential for these factors to interact with processes in the developing brain. In pediatric patients, broad-spectrum antiseizure medications (ASMs) with minimal potential for adverse events (AEs) and limited impact on cognition and behavior are preferred. Perampanel is a first-in-class ASM with broad-spectrum efficacy, a tolerable safety profile, minimal negative impact on cognitive function, and other features that make it a viable treatment option in this patient population. However, evidence and experience of its use in pediatric patients are less extensive than in adult patients. Experts in pediatric epilepsy across the region convened at a series of meetings to discuss the use of perampanel in pediatric patients, including dose optimization, AE prevention and management, and considerations in particular groups. This article summarizes key evidence for perampanel in the pediatric population and consolidates the experts' recommendations for using the ASM in managing pediatric epilepsies.

Brain tumor-related epilepsy management: A Society for Neuro-oncology (SNO) consensus review on current management

Tumor-related epilepsy (TRE) is a frequent and major consequence of brain tumors. Management of TRE is required throughout the course of disease and a deep understanding of diagnosis and treatment is key to improving quality of life. Gross total resection is favored from both an oncologic and epilepsy perspective. Shared mechanisms of tumor growth and epilepsy exist, and emerging data will provide better targeted therapy options. Initial treatment with antiseizure medications (ASM) in conjunction with surgery and/or chemoradiotherapy is typical. The first choice of ASM is critical to optimize seizure control and tolerability considering the effects of the tumor itself. These agents carry a potential for drug-drug interactions and therefore knowledge of mechanisms of action and interactions is needed. A review of adverse effects is necessary to guide ASM adjustments and decision-making. This review highlights the essential aspects of diagnosis and treatment of TRE with ASMs, surgery, chemotherapy, and radiotherapy while indicating areas of uncertainty. Future studies should consider the use of a standardized method of seizure tracking and incorporating seizure outcomes as a primary endpoint of tumor treatment trials.

Effect of clinical features on antiseizure medication doses in patients with newly diagnosed epilepsy

Objective

We evaluate the effect of distinct clinical features on anti-seizure medication (ASM) doses in seizure-free and not seizure-free patients aged ≥16 years with new-onset epilepsy.

Materials and methods

This study included 459 patients with a validated diagnosis of epilepsy. The most prescribed ASMs were oxcarbazepine (OXC; n = 307), followed by valproic acid (VPA; n = 115), carbamazepine (CBZ; n = 81), and lamotrigine (LTG; n = 67). The seizure freedom rate with their first or subsequent ASM was 88.0%. A retrospective analysis of patient records was performed to determine any association between doses of ASMs and patient characteristics.

Results

The median OXC dose in seizure-free patients aged >60 years was 600 mg compared to 900 mg in younger patients. When controlling for age but not in an unadjusted model, the median dose of OXC was lower (300 mg, p = 0.018) for seizure-free patients compared to non-seizure-free patients, and the median dose of OXC was also 300 mg lower among older patients aged >60 years (p < 0.001). The median OXC doses for men aged ≤60 years were 300 mg higher than for women aged >60 years (900 mg vs. 600 mg, p = 0.021). The median dose of VPA was 400 mg higher in men than in women (p < 0.001) and 400 mg higher in not seizure-free patients compared to seizure-free patients only when adjusting for sex (p < 0.001). Higher median doses for CBZ were registered with FAS compared with FBTCS (difference in median doses of 200 mg; p = 0.017).

Conclusion

Significant OXC dose differences were detected between age groups, whereas VPA dosing was different in men and women. Moreover, CBZ doses were dependent on some seizure types. These data allow for the individualization of the initial target dosing based on key clinical characteristics.

Characterization in Inhibitory Effectiveness of Carbamazepine in Voltage-Gated Na+ and Erg-Mediated K+ Currents in a Mouse Neural Crest-Derived (Neuro-2a) Cell Line

Carbamazepine (CBZ, Tegretol^®) is an anticonvulsant used in the treatment of epilepsy and neuropathic pain; however, several unwanted effects of this drug have been noticed. Therefore, the regulatory actions of CBZ on ionic currents in electrically excitable cells need to be reappraised, although its efficacy in suppressing voltage-gated Na⁺ current (I_Na) has been disclosed. This study was undertaken to explore the modifications produced by CBZ on ionic currents (e.g., I_Na and erg-mediated K⁺ current [I_K(erg)]) measured from Neuro-2a (N2a) cells. In these cells, we found that this drug differentially suppressed the peak (transient, I_Na(T)) and sustained (late, I_Na(L)) components of I_Na in a concentration-dependent manner with effective IC₅₀ of 56 and 18 μM, respectively. The overall current–voltage relationship of I_Na(T) with or without the addition of CBZ remained unchanged; however, the strength (i.e., ∆area) in the window component of I_Na (I_Na(W)) evoked by the short ascending ramp pulse (V_ramp) was overly lessened in the CBZ presence. Tefluthrin (Tef), a synthetic pyrethroid, known to stimulate I_Na, augmented the strength of the voltage-dependent hysteresis (Hys_(V)) of persistent I_Na (I_Na(P)) in response to the isosceles-triangular V_ramp; moreover, further application of CBZ attenuated Tef-mediated accentuation of I_Na(P)’s Hys_(V). With a two-step voltage protocol, the recovery of I_Na(T) inactivation seen in Neuro-2a cells became progressively slowed by adding CBZ; however, the cumulative inhibition of I_Na(T) evoked by pulse train stimulation was enhanced during exposure to this drug. Neuro-2a-cell exposure to CBZ (100 μM), the magnitude of erg-mediated K⁺ current measured throughout the entire voltage-clamp steps applied was mildly inhibited. The docking results regarding the interaction of CBZ and voltage-gate Na⁺ (Na_V) channel predicted the ability of CBZ to bind to some amino-acid residues in Na_V due to the existence of a hydrogen bond or hydrophobic contact. It is conceivable from the current investigations that the I_Na (I_Na(T), I_Na(L), I_Na(W), and I_Na(P)) residing in Neuro-2a cells are susceptible to being suppressed by CBZ, and that its block on I_Na(L) is larger than that on I_Na(T). Collectively, the magnitude and gating of Na_V channels produced by the CBZ presence might have an impact on its anticonvulsant and analgesic effects occurring in vivo.

Comparison of Lamotrigine and Oxcarbazepine Monotherapy Among Chinese Adult Patients With Newly-Diagnosed Focal-Onset Epilepsy: A Prospective Observational Study

Objective

We performed a prospective cohort study to compare the efficacy, safety, effect on mood, and quality of life between lamotrigine (LTG) and oxcarbazepine (OXC) monotherapy among Chinese adult patients with newly-diagnosed focal-onset epilepsy (FOE) with or without secondarily generalized tonic-clonic seizures.

Methods

We enrolled 106 adult patients with new-onset FOE, of whom 56 were in the OXC group and 50 in the LTG group. Their clinical characteristics were detailly recorded especially basic seizure frequency, seizure types, and drug-related adverse events. Efficacy was evaluated as seizure-free (no seizure for 6 months), effective (seizure reduction by more than 50%), and ineffective (seizure reduction by less than 50%). Both intention-to-treat and per-protocol analyses were performed. We also assessed their mood state with the Zung Self-rating Scale for anxiety (Z-SAS) and Zung Self-rating Scale for Depression (Z-SDS) and quality of life (QOL) with Quality of Life in Epilepsy (QOLIE-31) at their baseline visit, 3-month visits, and 6-month visit. Intra-group comparisons in each group and inter-group comparisons between the two groups were made. Correlation analysis and multiple regression analysis were also conducted.

Results

Except for gender, the two groups were well matched in any other characteristics such as primary seizure frequency and seizure types. In terms of efficacy, 33 patients in the OXC group were evaluated as seizure-free and 15 as effective, while in the LTG group, 31 were seizure-free, and nine were effective. No significant differences could be observed in efficacy between the two groups (P = 0.429). Through multiple logistic regression analysis, we found that OXC monotherapy was more likely to predict a seizure-free state (OR = 1.76) than LTG, but the difference didn't reach statistical significance (P = 0.322) after correcting for other clinical variables. Both groups had adverse events such as fatigue, drowsiness, dizziness, rash, and gastrointestinal discomfort, most of which were mild and transient. In the OXC group, the scores of SAS (P = 0.067) and SDS (P = 0.004) reduced at the 6-month visit, while the score of QOLIE-31 significantly increased (P = 0.001). In the LTG group, a significant decrease in SAS and SDS scores and an increase in QOLIE-31 scores could be witnessed (All P < 0.001). The inter-group comparison showed that improvement of SAS and SDS in the LTG group was more evident than that in the OXC group, which was of statistical significance. Correlational analysis indicated that the improvement of mood and life quality scales in both groups was independent of baseline seizure frequency and treatment efficacy. Multiple linear regression analysis indicated that LTG monotherapy was the only independent factor that could predict a better SAS (P = 0.01) and SDS (P = 0.019) outcome.

Conclusions

OXC and LTG are effective as monotherapy and can be considered first-line selection among adult patients with new-onset FOE. Most adverse events are mild, transient, and tolerable. The two drugs improve the mood state of patients, though LTG is superior to OXC in this respect. OXC and LTG have great power in enhancing patients' quality of life. The positive effect on the psychosocial well-being of epilepsy patients may be one of the intrinsic pharmacological properties of LTG and OXC.

Oxcarbazepine and Hyponatremia

Background and Objectives: Hyponatremia is one of the most common adverse effects in patients treated with oxcarbazepine (OXC). Different risk factors for OXC-induced hyponatremia have been described as age, female gender, dosage, and combination with other drugs During our clinical practice, we noticed that a longer duration of treatment with OXC could be associated with a higher risk of hyponatremia, therefore, in this study, we aimed to evaluate factors that may increase the risk of OXC-induced hyponatremia. Materials and Methods: Data were retrospectively collected from our clinical database at the Department of Neurology of the Hospital of Lithuanian University of Health Sciences Kaunas Clinics. The sample was divided into three groups: OXC consumers (n = 31), other anti-seizure medications (ASMs) consumers (n = 43), and controls absent ASMs (n = 31). All groups were matched by age and gender. Hyponatremia was defined as <136 mmol/L. Results: The frequency of hyponatremia was significantly higher among OXC patients (61.3%) compared to other ASM patients (5.4%) and controls (3.2%). The mean serum sodium concentration in the OXC group was 133.1 ± 5.1 mmol/L. The frequency of severe hyponatremia among OXC-treated patients was 19.4%; this subgroup was older than patients with moderate hyponatremia and normonatremia and had a longer OXC treatment duration compared to a subgroup of normonatremia. The average duration of OXC therapy was 8.7 ± 5.5 years with a range from 1 to 21 years. Serum sodium concentration and duration of treatment with OXC demonstrated a significant negative correlation (r = −0,427, p = 0.017). Each year of therapy with OXC increased the risk of hyponatremia 1.3 times (OR = 1.326, 95% Cl 1.027−1.712, p = 0.031). Other factors (gender, age, polypharmacy, OXC dosage, and serum concentration) did not show a significant association with the development of hyponatremia. Conclusions: Longer duration of treatment with OXC is an important factor in the development and severity of hyponatremia.

Update on Antiseizure Medications 2022

EDITORS NOTE

The article "Update on Antiseizure Medications 2022" by Dr Abou-Khalil was first published in the February 2016 Epilepsy issue of Continuum: Lifelong Learning in Neurology as "Antiepileptic Drugs," and at the request of the Editor-in-Chief was updated by Dr Abou-Khalil for the 2019 issue and again for this issue.

Development and Internal Validation of Machine Learning Algorithms for Predicting Hyponatremia After TJA

BACKGROUND

The development of hyponatremia after total joint arthroplasty (TJA) may lead to several adverse events and is associated with prolonged inpatient length of stay as well as increased hospital costs. The purpose of this study was to develop and internally validate machine learning algorithms for predicting hyponatremia after TJA.

METHODS

A consecutive cohort of 30,703 TJA patients from an institutional registry at a large, tertiary academic hospital were included. A total of 19 potential predictor variables were collected. Hyponatremia was defined as a serum sodium concentration of <135 mEq/L. Five machine learning algorithms were developed using a training set and internally validated using an independent testing set. Algorithm performance was evaluated through discrimination, calibration, decision-curve analysis, and Brier score.

RESULTS

The charts of 30,703 patients undergoing TJA were reviewed. Of those patients, 5,480 (17.8%) developed hyponatremia postoperatively. A combination of 6 variables were demonstrated to optimize algorithm prediction: preoperative serum sodium concentration, age, intraoperative blood loss, procedure time, body mass index (BMI), and American Society of Anesthesiologists (ASA) score. Threshold values that were associated with greater hyponatremia risk were a preoperative serum sodium concentration of ≤138 mEq/L, an age of ≥73 years, an ASA score of >2, intraoperative blood loss of >407 mL, a BMI of ≤26 kg/m2, and a procedure time of >111 minutes. The stochastic gradient boosting (SGB) algorithm demonstrated the best performance (c-statistic: 0.75, calibration intercept: -0.02, calibration slope: 1.02, and Brier score: 0.12). This algorithm was turned into a tool that can provide real-time predictions (https://orthoapps.shinyapps.io/Hyponatremia_TJA/).

CONCLUSIONS

The SGB algorithm demonstrated the best performance for predicting hyponatremia after TJA. The most important factors for predicting hyponatremia were preoperative serum sodium concentration, age, intraoperative blood loss, procedure time, BMI, and ASA score. A real-time hyponatremia risk calculator was developed, but it is imperative to perform external validation of this model prior to using this calculator in clinical practice.

LEVEL OF EVIDENCE

Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Serum Sodium Concentration and Increased Risk for Primary Epiretinal Membrane

Aims: To examine the prevalence of primary epiretinal membranes (ERMs) and associated systemic factors.

Methods: The cross-sectional, community-based Tongren Health Care Study enrolled participants who received regular health examinations in the Beijing Tongren Hospital from 2017 to 2019. Using fundus photographs, retinal specialists assessed the presence of ERMs and their systemic associations.

Results: Primary ERMs were detected in 841/22820 individuals, with a prevalence of 3.7% [95% confidence intervals (CI): 3.4–3.9%] in the total study population (mean age: 44.5 ± 13.8 years) and 6.5% (95% CI: 6.1–7.0%) in individuals aged 40+ years. In multivariable analysis, a higher ERMs prevalence was associated with older age [odds ratio (OR): 1.10; P < 0.001], higher serum cholesterol concentration (OR: 1.14; P = 0.003) and higher serum sodium concentration (SSC) (OR: 1.12; P < 0.001). In women, a higher SSC, even within the normal range, was associated with an increased risk of ERMs (OR: 1.19; P < 0.001). Female participants with an SSC of 144–145mmol/L as compared with those with an SSC of 135–137 mmol/L had a 5-fold increased odds of having ERMs (All women: OR: 5.33; P < 0.001; Women aged 40+years: OR: 4.63; P < 0.001).

Conclusion: Besides older age and higher serum cholesterol concentration, a higher SSC, even if within the normal range, was independently associated with a higher ERM prevalence in women.

Seizures and epilepsy in patients with ischaemic stroke

BACKGROUND

With the increased efficacy of stroke treatments, diagnosis and specific treatment needs of patients with post-stroke seizures (PSS) and post-stroke epilepsy have become increasingly important. PSS can complicate the diagnosis of a stroke and the treatment of stroke patients, and can worsen post-stroke morbidity. This narrative review considers current treatment guidelines, the specifics of antiseizure treatment in stroke patients as well as the state-of-the-art in clinical and imaging research of post-stroke epilepsy. Treatment of PSS needs to consider indications for antiseizure medication treatment as well as individual clinical and social factors. Furthermore, potential interactions between stroke and antiseizure treatments must be carefully considered. The relationship between acute recanalizing stroke therapy (intravenous thrombolysis and mechanical thrombectomy) and the emergence of PSS is currently the subject of an intensive discussion. In the subacute and chronic post-stroke phases, important specific interactions between necessary antiseizure and stroke treatments (anticoagulation, cardiac medication) need to be considered. Among all forms of prevention, primary prevention is currently the most intensively researched. This includes specifically the repurposing of drugs that were not originally developed for antiseizure properties, such as statins. PSS are presently the subject of extensive basic clinical research. Of specific interest are the role of post-stroke excitotoxicity and blood-brain barrier disruption for the emergence of PSS in the acute symptomatic as well as late (> 1 week after the stroke) periods. Current magnetic resonance imaging research focussing on glutamate excitotoxicity as well as diffusion-based estimation of blood-brain barrier integrity aim to elucidate the pathophysiology of seizures after stroke and the principles of epileptogenesis in structural epilepsy in general. These approaches may also reveal new imaging-based biomarkers for prediction of PSS and post-stroke epilepsy.

CONCLUSION

PSS require the performance of individual risk assessments, accounting for the potential effectiveness and side effects of antiseizure therapy. The use of intravenous thrombolysis and mechanical thrombectomy is not associated with an increased risk of PSS. Advances in stroke imaging may reveal biomarkers for PSS.

Management of SIADH-related hyponatremia due to psychotropic medications - An expert consensus from the Association of Medicine and Psychiatry

OBJECTIVE

Hyponatremia is the most common electrolyte imbalance encountered in clinical practice and is associated with negative healthcare outcomes and cost. SIADH is thought to account for one third of all hyponatremia cases and is typically an insidious process. Psychotropic medications are commonly implicated in the etiology of drug induced SIADH. There is limited guidance for clinicians on management of psychotropic-induced SIADH.

METHODS

After an extensive review of the existing literature, clinical-educators from the Association of Medicine and Psychiatry developed expert consensus recommendations for management of psychotropic-induced SIADH. A risk score was proposed based on risk factors for SIADH to guide clinical decision-making.

RESULTS

SSRIs, SNRIs, antipsychotics, carbamazepine, and oxcarbazepine have moderate to high level of evidence demonstrating their association with SIADH. Evaluation for an avoidance of medications that cause hyponatremia is particularly important. Substitution with medication that is less likely to cause SIADH should be considered when appropriate. We propose an algorithmic approach to monitoring hyponatremia with SIADH and corresponding treatment depending on symptom severity.

CONCLUSIONS

The proposed algorithm can help clinicians in determining whether psychotropic medication should be stopped, reduced or substituted where SIADH is suspected with recommendations for sodium (Na+) monitoring. These recommendations preserve a role for clinical judgment in the management of hyponatremia with consideration of the risks and benefits, which may be particularly relevant for complex patients that present with medical and psychiatric comorbidities. Further studies are needed to determine whether baseline and serial Na+ monitoring reduces morbidity and mortality.

Low-Dose Lurasidone-Induced Polydipsia Complicated by Hyponatremia in a Patient With Bipolar Disorder

OBJECTIVE

Atypical antipsychotic-induced hyponatremia has been reported in patients with psychiatric disorders. To date, hyponatremia due to lurasidone, an atypical antipsychotic approved for the treatment of schizophrenia and bipolar depression, has never been reported.

CASE REPORT

A female patient with bipolar depression and a history of subdural hematoma experienced a rapid onset of hyponatremia after the initiation of low-dose lurasidone. The hyponatremia worsened after the dose of lurasidone was increased and resolved only after lurasidone was ceased. According to the Naranjo Adverse Drug Reaction Probability Scale, this case report scores 6 as a possible drug reaction between lurasidone and hyponatremia.

RESULTS

Based on laboratory results, the syndrome of inappropriate antidiuretic hormone secretion and thyroid or adrenal dysfunction as differential diagnoses were excluded. Lurasidone-induced polydipsia complicated by hyponatremia was confirmed. Lurasidone was subsequently discontinued. The sodium level returned to normal within 1 week without any sodium supplementation.

CONCLUSIONS

This case report highlighted that low-dose lurasidone may induce polydipsia complicated by hyponatremia. Physicians should be aware of the adverse reactions of hyponatremia associated with lurasidone, particularly in patients with a history of intracranial hemorrhage.

Potential Use of Pharmacogenetics to Reduce Drug-Induced Syndrome of Inappropriate Antidiuretic Hormone (SIADH)

Syndrome of inappropriate antidiuretic hormone (SIADH) is a common cause of hyponatremia, and many cases represent adverse reactions to drugs that alter ion channel conductance within the peptidergic nerve terminals of the posterior pituitary. The frequency of drug-induced SIADH increases with age; as many as 20% of patients residing in nursing homes have serum sodium levels below 135 mEq/L. Mild hyponatremia is associated with cognitive changes, gait instability, and falls. Severe hyponatremia is associated with cerebral edema, seizures, permanent disability, and/or death. Although pharmacogenetic tests are now being deployed for some drugs capable of causing SIADH (e.g., antidepressants, antipsychotics, and opioid analgesics), the implementation of these tests has been based upon the prior known association of these drugs with other serious adverse drug reactions (e.g., electrocardiographic abnormalities). Work is needed in large observational cohorts to quantify the strength of association between pharmacogene variants and drug-induced SIADH so that decision support can be developed to identify patients at high risk.

Symptomatology of carbamazepine- and oxcarbazepine-induced hyponatremia in people with epilepsy

OBJECTIVE

To ascertain whether adverse effects experienced by people taking carbamazepine or oxcarbazepine could be attributed to carbamazepine- or oxcarbazepine-induced hyponatremia (COIH).

METHODS

We performed an observational study, collecting data between 2017 and 2019 on serum sodium levels and adverse effects retrospectively in people with epilepsy while receiving treatment with either carbamazepine (CBZ) or oxcarbazepine (OXC). We defined hyponatremia as sodium level ≤134 mEq/L and severe hyponatremia as sodium level ≤128 mEq/L. Adverse effects experienced were compared between groups of individuals with and without hyponatremia.

RESULTS

A total of 1370 people using CBZ or OXC were identified, of whom 410 had at least one episode of hyponatremia. We checked for symptoms related to the use of CBZ and OXC in 710 people (410 with and 300 without hyponatremia) and found relevant information in 688. Adverse effects occurred in 65% of people with hyponatremia compared to 21% with normal sodium levels (odds ratio [OR] 7.5, P ≤ .001) and in 83% of people with severe hyponatremia compared to 55% in those with mild hyponatremia (P ≤ .001). Significant predictors of adverse effects were the drug (OXC vs CBZ), and the number of concomitant anti-seizure medications. Dizziness (28% vs 6%), tiredness (22% vs 7%), instability (19% vs 3%), and diplopia (16% vs 4%) were reported more often in the hyponatremia group than in patients with normal levels.

SIGNIFICANCE

People with COIH had a 7-fold increased risk of developing adverse effects during treatment. Clinicians should consider ascertainment of sodium levels in patients taking CBZ and OXC and act upon findings.

Reduced risk for hospitalization due to hyponatraemia in lithium treated patients: A Swedish population-based case-control study

BACKGROUND

Many drugs used in psychiatry have been reported to cause hyponatraemia. However, lithium may be an exception due to its potential for causing nephrogenic diabetes insipidus, but clinical data are largely absent. The objective of this investigation was to study the association between lithium therapy and hospitalization due to hyponatraemia.

METHODS

This study was a register-based case-control investigation of the general Swedish population. Patients hospitalized with a principal diagnosis of hyponatraemia (n=11,213) were compared with matched controls (n=44,801). Analyses using multivariable logistic regression adjusting for co-medication, diseases, previous hospitalizations and socioeconomic factors were deployed to calculate the association between severe hyponatraemia and the use of lithium. Additionally, newly initiated (⩽90 days) and ongoing lithium therapy was studied separately.

RESULTS

Compared with controls, the unadjusted odds ratio (OR) (95% confidence interval (CI)) for hospitalization due to hyponatraemia was 1.07 (0.70-1.59) for lithium. However, after adjustment for confounding factors the risk was reduced (adjusted OR: 0.53 (0.31-0.87)). Newly initiated lithium therapy was not significantly associated with hyponatraemia (adjusted OR 0.73 (0.35-5.38)). In contrast, for ongoing therapy the corresponding adjusted OR was significantly reduced (adjusted OR: 0.52 (0.30-0.87)).

CONCLUSIONS

A marked inverse association was found between ongoing lithium therapy and hospitalization due to hyponatraemia.

Hyponatraemia and hypernatraemia: Disorders of Water Balance in Neurosurgery

Disorders of tonicity, hyponatraemia and hypernatraemia, are common in neurosurgical patients. Tonicity is sensed by the circumventricular organs while the volume state is sensed by the kidney and peripheral baroreceptors; these two signals are integrated in the hypothalamus. Volume is maintained through the renin-angiotensin-aldosterone axis, while tonicity is defended by arginine vasopressin (antidiuretic hormone) and the thirst response. Edelman found that plasma sodium is dependent on the exchangeable sodium, potassium and free-water in the body. Thus, changes in tonicity must be due to disproportionate flux of these species in and out of the body. Sodium concentration may be measured by flame photometry and indirect, or direct, ion-sensitive electrodes. Only the latter method is not affected by changes in plasma composition. Classification of hyponatraemia by the volume state is imprecise. We compare the tonicity of the urine, given by the sodium potassium sum, to that of the plasma to determine the renal response to the dysnatraemia. We may then assess the activity of the renin-angiotensin-aldosterone axis using urinary sodium and fractional excretion of sodium, urate or urea. Together, with clinical context, these help us determine the aetiology of the dysnatraemia. Symptomatic individuals and those with intracranial catastrophes require prompt treatment and vigilant monitoring. Otherwise, in the absence of hypovolaemia, free-water restriction and correction of any reversible causes should be the mainstay of treatment for hyponatraemia. Hypernatraemia should be corrected with free-water, and concurrent disorders of volume should be addressed. Monitoring for overcorrection of hyponatraemia is necessary to avoid osmotic demyelination.

Current role of carbamazepine and oxcarbazepine in the management of epilepsy

Epilepsy is one of the most common neurological disorders, affecting approximately 50 million people worldwide. Despite a dramatic increase in treatment options over the past 30 years, it still ranks fourth in the world's disease burden. There are now close to 30 antiepileptic drugs (AEDs), with more than two thirds introduced to the market after carbamazepine (CBZ) and one third after its derivative, oxcarbazepine (OXC). Following the introduction of these newer AEDs, the role of CBZ and OXC in the therapeutic armamentarium for seizure control and effective epilepsy management needs to be reviewed. The main guidelines list both CBZ and OXC as first-line options or second-line alternatives for the treatment of focal-onset epilepsy and primary generalized tonic-clonic seizures. While evidence suggests that overall AEDs have similar efficacy, some newer AEDs may be better tolerated than CBZ. In line with this, there have been changes in treatment patterns, with many variations across different countries. However, CBZ remains among the two or three most prescribed drugs for focal epilepsy in many countries, and is widely used across Europe, Africa, South America, and Asia, where it represents a good compromise between cost, availability, and effectiveness. OXC is among the first-choice options for the initial treatment of focal-onset seizures in several countries, including the US and China, where the oral suspension is commonly prescribed. This review provides guidance on the optimal use of these two drugs in clinical practice, including in children, the elderly, and in pregnancy.

Pharmacokinetic Monitoring of Levetiracetam in Portuguese Refractory Epileptic Patients: Effect of Gender, Weight and Concomitant Therapy

Levetiracetam is a second-generation antiepileptic drug, widely used in the treatment of focal and generalized epilepsy due to its pharmacokinetic and safety profiles. Its pharmacokinetic monitoring is ascribed as useful to personalize its dosing regimen. The aim of the present study was to describe, for the first time, the pharmacokinetics of levetiracetam in Portuguese refractory epileptic patients. Therefore, a retrospective study was carried out on 65 Portuguese refractory epileptic patients (pharmacokinetic study: 48; validation study: 17) admitted to the Refractory Epilepsy Centre of the Centro Hospitalar e Universitário de Coimbra, Coimbra, Portugal. The pharmacokinetic parameters of levetiracetam were estimated by applying a one-compartment model with first-order absorption and elimination analysis. Male patients showed higher distribution volume (Vd/F) and oral clearance (CL/F) than female patients (median Vd/F: 52.40 L in males and 38.60 L in females, p = 0.011; median CL/F: 4.71 L/h in males and 3.91 L/h in females, p = 0.028). Higher values of Vd/F (p = 0.026) and CL/F (p = 0.003) were also found in overweight patients relative to normal weight and obese patients. Carbamazepine was the co-administered antiepileptic drug that mostly affected the pharmacokinetics of levetiracetam, increasing both Vd/F (61.30 L with carbamazepine and 39.10 L without carbamazepine, p = 0.007) and CL/F (6.71 L/h with carbamazepine and 3.91 L/h without carbamazepine, p < 0.001). The pharmacokinetics of levetiracetam was affected by gender, body mass index, and co-administration of carbamazepine. This study highlights the impact of several factors on the CL/ and Vd/F of levetiracetam when administered to refractory epileptic patients. The importance of its pharmacokinetic monitoring in clinical pharmacy stands out, thereby enabling the optimization of antiepileptic drug therapy.

The effect of normalization of sodium on bone turnover markers in patients with epilepsy. A randomized single-blinded placebo-controlled trial

Hyponatremia [p[Na]<136 mmol/L] is an independent risk factor for decreased bone mineral density (BMD). However, whether hyponatremia represents a surrogate marker, or a direct causal relationship to bone loss remains unknown. The aim of the study was to investigate the effect of salt replacement therapy on bone turnover markers (BTM) and BMD in patients with epilepsy and chronic hyponatremia. This prospective single-blinded randomized trial investigated serum BTM and BMD, evaluated by Dual Energy X-ray Absorptiometry (DXA), in 21 patients at baseline and following three months of salt replacement therapy. Patients with two consecutive measurements of hyponatremia prior to baseline and no known osteoporosis were included from the epilepsy out-patient clinic at Rigshospitalet, Denmark. Seven patients were randomized to placebo and 14 to salt intervention. The baseline p[Na] was 134 (130.5-140) mmol/L (median (IQR)). All patients had BTM within age-specific reference ranges at baseline. Following 3 months of intervention with 3-9 g of salt daily there was no difference in levels of procollagen type 1 N-terminal propeptide (P1NP) or C-terminal cross-linking telopeptide of type 1 collagen (CTX) between placebo and intervention. Nor was there any difference in BMD evaluated at the lumbar spine (L1-L4) or at the femoral neck or total hip. In our study, salt replacement did neither affect BTM nor BMD. However, due to the small size of the study, more studies are needed to further investigate this.

Three cases in which drug-induced hyponatremia was improved by replacing carbamazepine with lacosamide

Carbamazepine often causes drug-induced hyponatremia. Hyponatremia due to carbamazepine may be improved by changing to the same mechanism of action, lacosamide.

[Pitch perception modification due to antiepileptics: A literature and pharmacovigilance databases review]

Pitch perception modifications are among the little-known adverse effects observed with antiepileptics, mainly affecting patients treated with carbamazepine (CBZ). Here, we describe an original French case of pitch perception modification due to CBZ resulting in perfect pitch loss. We also reviewed the literature as well as French and world health organisation global pharmacovigilance database. The case report concerns a 22-year-old patient with perfect pitch with untreated left temporal partial epilepsy. Following a generalized seizure, the introduction of CBZ prolonged release (200mg twice a day) is decided. As soon as CBZ is introduced, the patient notices a change in pitch perception, about a semitone lower. This adverse effect persisted despite a gradual decrease in doses. The patient reported a total recovery of his perfect pitch when CBZ stopped completely 11 years later. In the French pharmacovigilance database, only one other case of pitch perception modification under CBZ was recorded (no cases were found with oxcarbazepine, lacosamide, sodium valproate, lamotrigine, levetiracetam, phenobarbital, phenytoin, primidone, ethosuximide, vigabatrine, felbamate, gabapentin, tiagabine and topiramate). In the literature, 27 cases of pitch perception modification have been published with CBZ, 1 case with oxcarbazepine and 1 case with lacosamide. Pitch perception modification is a very rare adverse effect of CBZ, oxcarbazepine and lacosamide, identified in the literature mainly in the Japanese population, in experienced musicians. A rapid onset after the introduction of treatment, a complete resolution of symptoms, in most cases upon discontinuation of treatment, is observed, with no sequelae reported. Due to the impact on quality of life, especially in patients whose profession is related to music, knowledge of this adverse event seems important to evoke this diagnosis.

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.

Oxcarbazepine for trigeminal neuralgia may induce lower extremity weakness: A case report

BACKGROUND

Although few studies have reported hyponatremia due to carbamazepine or oxcarbazepine in patients with epilepsy, no study has investigated cases of carbamazepine- or oxcarbazepine-induced hyponatremia or unsteady gait in patients with neuropathic pain. Herein, we report a case of oxcarbazepine-induced lower leg weakness in a patient with trigeminal neuralgia and summarize the diagnosis, treatment, and changes of clinical symptoms.

CASE SUMMARY

A 78-year-old male with a history of lumbar spinal stenosis was admitted to the hospital after he experienced lancinating pain around his right cheek, eyes, and lip, and was diagnosed with trigeminal neuralgia at the right maxillary and mandibular branch. He was prescribed oxcarbazepine (600 mg/d), milnacipran (25 mg/d), and oxycodone/naloxone (20 mg/10 mg/d) for four years. Four years later, the patient experienced symptoms associated with spinal stenosis, including pain in the lower extremities and unsteady gait. His serum sodium level was 127 mmol/L. Assuming oxcarbazepine to be the cause of the hyponatremia, oxcarbazepine administration was put on hold and the patient was switched to topiramate. At subsequent visit, the patient’s serum sodium level had normalized to 143 mmol/L and his unsteady gait had improved.

CONCLUSION

Oxcarbazepine-induced hyponatremia may cause lower extremity weakness and unsteady gait, which should be differentiated from those caused by spinal stenosis.

Genetic variations associated with pharmacoresistant epilepsy (Review)

Epilepsy is a common, serious neurological disorder worldwide. Although this disease can be successfully treated in most cases, not all patients respond favorably to medical treatments, which can lead to pharmacoresistant epilepsy. Drug-resistant epilepsy can be caused by a number of mechanisms that may involve environmental and genetic factors, as well as disease- and drug-related factors. In recent years, numerous studies have demonstrated that genetic variation is involved in the drug resistance of epilepsy, especially genetic variations found in drug resistance-related genes, including the voltage-dependent sodium and potassium channels genes, and the metabolizer of endogenous and xenobiotic substances genes. The present review aimed to highlight the genetic variants that are involved in the regulation of drug resistance in epilepsy; a comprehensive understanding of the role of genetic variation in drug resistance will help us develop improved strategies to regulate drug resistance efficiently and determine the pathophysiological processes that underlie this common human neurological disease.

Update on Antiepileptic Drugs 2019

PURPOSE OF REVIEW

This article is an update from the article on antiepileptic drug (AED) therapy published in the last Continuum issue on epilepsy and is intended to cover the vast majority of agents currently available to the neurologist in the management of patients with epilepsy. Treatment of epilepsy starts with AED monotherapy. Knowledge of the spectrum of efficacy, clinical pharmacology, and modes of use for individual AEDs is essential for optimal treatment for epilepsy. This article addresses AEDs individually, focusing on key pharmacokinetic characteristics, indications, and modes of use.

RECENT FINDINGS

Since the previous version of this article was published, three new AEDs, brivaracetam, cannabidiol, and stiripentol, have been approved by the US Food and Drug Administration (FDA), and ezogabine was removed from the market because of decreased use as a result of bluish skin pigmentation and concern over potential retinal toxicity.Older AEDs are effective but have tolerability and pharmacokinetic disadvantages. Several newer AEDs have undergone comparative trials demonstrating efficacy equal to and tolerability at least equal to or better than older AEDs as first-line therapy. The list includes lamotrigine, oxcarbazepine, levetiracetam, topiramate, zonisamide, and lacosamide. Pregabalin was found to be less effective than lamotrigine. Lacosamide, pregabalin, and eslicarbazepine have undergone successful trials of conversion to monotherapy. Other newer AEDs with a variety of mechanisms of action are suitable for adjunctive therapy. Most recently, the FDA adopted a policy that a drug's efficacy as adjunctive therapy in adults can be extrapolated to efficacy in monotherapy. In addition, efficacy in adults can be extrapolated for efficacy in children 4 years of age and older. Both extrapolations require data demonstrating that an AED has equivalent pharmacokinetics between its original approved use and its extrapolated use. In addition, the safety of the drug in pediatric patients has to be demonstrated in clinical studies that can be open label. Rational AED combinations should avoid AEDs with unfavorable pharmacokinetic interactions or pharmacodynamic interactions related to mechanism of action.

SUMMARY

Knowledge of AED pharmacokinetics, efficacy, and tolerability profiles facilitates the choice of appropriate AED therapy for patients with epilepsy.

Prevalence and risk factors for hyponatremia in adult epilepsy patients: Large-scale cross-sectional cohort study

PURPOSE

To evaluate the risk factors and prevalence of hyponatremia among epilepsy patients in relation to use of antiepileptic drugs (AEDs).

METHODS

We retrospectively reviewed 14,620 adult patients (aged 18-103 years) and classified them into the following 3 groups: patients without AED treatment (n = 2165, Group I), patients receiving antiepileptic drugs other than carbamazepine (n = 7442, Group II), and patients treated with carbamazepine (n = 5013, Group III). This study did not include the patients receiving oxcarbazepine or eslicarbazepine acetate because these AEDs are not marketed in Japan. Severe hyponatremia was defined as a serum sodium level < 130 mEq/L.

RESULTS

In Groups I, II, and III, the mean sodium level was 140, 139, and 137 mEq/L, respectively. The highest frequency of severe hyponatremia was observed in Group III (7%), and it was much higher than in Group I (0.8%) or Group II (1.2%). In Groups II and III, old age, low body weight, and concomitant use of phenobarbital, benzodiazepines, or antipsychotics were risk factors for hyponatremia. In Group III, the sodium level decreased as the carbamazepine dose increased. At a carbamazepine dose exceeding 600 mg/day, there was 10.9-fold higher prevalence of hyponatremia, and the risk was potentiated by concomitant use of valproate.

CONCLUSION

The serum sodium level should be monitored carefully when patients are receiving AED polypharmacy combined with antipsychotics. In particular, concomitant administration of valproate enhances the risk of hyperammonemia in patients receiving carbamazepine. These findings may help clinicians to avoid hyponatremia in patients with epilepsy.

Putting a Band-Aid on a Broken Leg: Antiseizure Medications Are Inferior to Immune Therapies in Autoimmune Epilepsy

Evaluation of Seizure Treatment in Anti-LGI1, Anti-NMDAR, and Anti-GABABR Encephalitis

de Bruijn MAAM, van Sonderen A, van Coevorden-Hameete MH, Bastiaansen AEM, Schreurs MWJ, Rouhl RPW, van Donselaar CA, Majoie MHJM, Neuteboom RF, Sillevis Smitt PAE, Thijs RD, Titulaer MJ. Neurology. 2019;92(19): e2185-e2196. doi:10.1212/WNL.0000000000007475. Epub April 12, 2019. PMID: 30979857

OBJECTIVE:

This nationwide cohort study evaluates seizure responses to immunotherapy and antiepileptic drugs (AEDs) in patients with anti-leucine-rich glioma-inactivated 1 (LGI1), anti-NMDA receptor (NMDAR), and anti-gamma-aminobutyric-acid B receptor (GABABR) encephalitis.

METHODS:

Anti-LGI1, anti-NMDAR, and anti-GABABR encephalitis patients with new-onset seizures were included. Medical information about disease course, AEDs, and immunotherapies used, effects, and side effects were collected. Outcome measures were (1) seizure freedom while using AEDs or immunotherapy, (2) days to seizure freedom from start of AEDs or immunotherapy, and (3) side effects.

RESULTS:

Of 153 patients with autoimmune encephalitis (AIE; 53 LGI1, 75 NMDAR, 25 GABABR), 72% (n = 110) had epileptic seizures and 89% reached seizure freedom. At least 53% achieved seizure freedom shortly after immunotherapy and 14% achieved seizure freedom while using only AEDs (P < .0001). This effect was similar in all types (P = .0001; P = .0005; P = .013, respectively). Median time to seizure freedom from AEDs start was 59 days (interquartile range [IQR]: 27-160), and 28 days from start of immunotherapy (IQR: 9-71, P < .0001). Side effects were psychotic behavior and suicidal thoughts by the use of levetiracetam and rash by the use of carbamazepine. Carbamazepine was more effective than levetiracetam in reducing seizures in anti-LGI1 encephalitis (P = .031). Only 1 patient, of 86 surviving patients, developed epilepsy after resolved encephalitis.

CONCLUSION:

Epilepsy after resolved encephalitis was rare in our cohort of patients with AIE treated with immunotherapy. In addition, seizure freedom is achieved faster and more frequently after immunotherapy. Therefore, AEDs should be considered as add-on treatment, and similar to treatment of other encephalitis symptoms, immunotherapy is crucial.

Serum sodium levels and related treatment-emergent adverse events during eslicarbazepine acetate use in adults with epilepsy

Objective

To examine the frequency of hyponatremia and potentially related symptoms in clinical trials of eslicarbazepine acetate (ESL) in adults with focal‐ (partial‐) onset seizures.

Methods

This post hoc, exploratory analysis included data from three controlled phase 3 trials of adjunctive ESL (400‐1200 mg once daily), two phase 3 trials of ESL monotherapy (1200‐1600 mg once daily), and their open‐label extension studies. Exploratory endpoints included clinical laboratory measurements of serum sodium concentrations ([Na⁺]), incidences of hyponatremia‐related treatment‐emergent adverse events (TEAEs), and incidences of TEAEs that are potential symptoms of hyponatremia.

Results

The controlled trials of adjunctive ESL and ESL monotherapy included 1447 (placebo, n = 426; ESL, n = 1021) and 365 (ESL, n = 365) patients, respectively; 639 and 274 patients continued onto uncontrolled, open‐label extensions. In the controlled and uncontrolled trials ≤3.3% of patients taking ESL had a minimum postdose [Na⁺] measurement ≤125 mEq/L, <9% had a >10 mEq/L decrease in [Na⁺] from baseline, <6% had a hyponatremia‐related TEAE, and <2% discontinued the controlled trials due to a hyponatremia‐related TEAE. Hyponatremia appeared to be more frequent in the monotherapy (vs adjunctive therapy) trials; in the controlled trials of adjunctive ESL and ESL monotherapy, incidence generally increased with increasing ESL dose. The majority of patients with an investigator‐reported TEAE of “hyponatremia” or “blood sodium decreased” did not have a corresponding laboratory [Na⁺] measurement ≤125 mEq/L. Some symptoms potentially related to hyponatremia (including nausea and vomiting) were more frequent in patients with a minimum postdose [Na⁺] measurement ≤125 mEq/L.

Significance

Reductions in serum sodium concentrations and hyponatremia‐related TEAEs occurred in a small number of patients taking ESL. Suspected hyponatremia should be confirmed and monitored via [Na⁺] measurements.

Antiepileptic drug therapy in the elderly: a clinical pharmacological review

Seizure disorder is the third most common neurological disorder in the elderly after stroke and dementia. With the increasing geriatric population, the situation of clinicians seeing more and more elderly epilepsy patients is very likely. Not only is the diagnosis of epilepsy tedious in the elderly, its management raises many challenging issues for the treating physicians. Altered physiology, age-related decline in organ function, and plasma protein binding and altered pharmacodynamics make the elderly patients with seizure disorder a difficult group to treat. This is further complicated by the presence of comorbidities and polypharmacy which increase the chances of drug interactions. The adverse effects that might be tolerated well in younger populations may be disastrous for the aged. Although the newer antiepileptic drugs are found to have a favorable safety profile, there is relative scarcity of randomized-controlled trials involving older and newer antiepileptics in the geriatric population. This review tries to compile the available literature on management of epilepsy in the elderly population including evidence of safety and efficacy of newer and older antiepileptics with special reference to the 'geriatric giants'. It also deals with the interactions between antiepileptic medications and other commonly prescribed drugs in the elderly such as anti-hypertensives and antiischemic agents. The recommended guidelines of various international bodies are also analyzed from the perspective of elderly with seizure disorder.

A genome-wide association study of sodium levels and drug metabolism in an epilepsy cohort treated with carbamazepine and oxcarbazepine

OBJECTIVE

To ascertain the clinical and genetic factors contributing to carbamazepine- and oxcarbazepine-induced hyponatremia (COIH), and to carbamazepine (CBZ) metabolism, in a retrospectively collected, cross-sectional cohort of people with epilepsy.

METHODS

We collected data on serum sodium levels and antiepileptic drug levels in people with epilepsy attending a tertiary epilepsy center while on treatment with CBZ or OXC. We defined hyponatremia as Na+ ≤134 mEq/L. We estimated the CBZ metabolic ratio defined as the log transformation of the ratio of metabolite CBZ-diol to unchanged drug precursor substrate as measured in serum.

RESULTS

Clinical and genetic data relating to carbamazepine and oxcarbazepine trials were collected in 1141 patients. We did not observe any genome-wide significant associations with sodium level in a linear trend or hyponatremia as a dichotomous trait. Age, sex, number of comedications, phenytoin use, phenobarbital use, and sodium valproate use were significant predictors of CBZ metabolic ratio. No genome-wide significant associations with CBZ metabolic ratio were found.

SIGNIFICANCE

Although we did not detect a genetic predictor of hyponatremia or CBZ metabolism in our cohort, our findings suggest that the determinants of CBZ metabolism are multifactorial.

Patient Survival After Acute Voluntary Poisoning With a Huge Dose of Oxcarbazepine and Olanzapine

INTRODUCTION

Oxcarbazepine is a carbamazepine pre-drug with less drug interactions. Its adverse effects, including hyponatremia, somnolence and ataxia, are dose dependent. Olanzapine is an atypical antipsychotic drug most commonly used to manage psychoses and symptoms of irritability and aggressive behavior. Main side effects include extrapyramidal and anticholinergic symptoms, weight gain, and hyperglycemia.

CASE REPORT

In this manuscript a case of oxcarbazepine and olanzapine intoxication is discussed. A 45-year-old woman, previously diagnosed with bipolar disorder and chronic alcoholism, was presented two hours after ingestion of 30,000mg of oxcarbazepine and 140 mg of olanzapine, combined with alcohol. She was immediately treated with gastric lavage and administration of activated charcoal. During her hospitalization she was hemodynamically and respiratory stable with no neurological signs and symptoms except for somnolence. Another side effect was hyponatremia. She was discharged from our department in stable clinical condition after being evaluated by a psychiatrist.

CONCLUSION

Early approach is crucial for the management of drug intoxication. Late symptoms can be avoided through close monitoring of vital signs, mental status and laboratory values. Psychiatric consultation is essential for a better long-term outcome.

Differences in associations of antiepileptic drugs and hospitalization due to hyponatremia: A population-based case-control study

PURPOSE

Hyponatremia induced by antiepileptic drugs is common, but detailed evidence is lacking. This can be problematic for the treating neurologist confronted with a patient with severe hyponatremia in need of an alternative drug. The objective of this study was to examine the association between individual antiepileptic drugs and hospitalization due to hyponatremia.

METHODS

This was a register-based case-control study of patients in the general Swedish population. We included 14,359 individuals with a principal diagnosis of hyponatremia and 57,383 matched controls. The association between newly initiated (≤90 days) and ongoing antiepileptic treatment was investigated using multivariable logistic regression adjusting for concomitant drugs, medical conditions, previous hospitalizations and sociaoeconomic factors.

RESULTS

For newly initiated antiepileptic drugs, adjusted ORs (95% CI) for hospitalization due to hyponatremia, compared to controls, were: carbamazepine 9.63 (6.18-15.33); phenytoin 4.83 (1.14-25.76); valproate 4.96 (2.44-10.66); lamotrigine 1.67 (0.70-4.08); levetiracetam 9.76 (4.02-27.59) and gabapentin 1.61 (1.08-2.38). Newly initiated oxcarbazepine treatment was only found in the hyponatremia group and not in controls. Adjusted ORs (CI) for individuals with ongoing treatment ranged from 7.97 (3.70-18.50) for oxcarbazepine to 0.83 (0.64-1.06) for gabapentin.

CONCLUSION

There was a strong association between newly initiated treatment with carbamazepine, oxcarbazepine and levetiracetam, and hospitalization due to hyponatremia. The corresponding association for phenytoin and valproate was moderate. The risk for hyponatremia was lower during ongoing treatment. Lamotrigine and gabapentin had the lowest risk both during initiation and ongoing treatment and may be advantageous in patients at risk of developing hyponatremia.

Antiepileptic drugs-induced hyponatremia: Review and analysis of 560 hospitalized patients

Recent evidence suggests that eslicarbazepine acetate (ESL) might be an appropriate alternative to carbamazepine (CBZ) and oxcarbazepine (OXC) due to its better safety profile. Hyponatremia may be one of the limiting safety problems in CBZ and OXC whereas it has been indicated that ESL is less sensitive for the adverse event. Since our clinical experience is different we investigated the incidence of hyponatremia in 560 consecutive adult inpatients treated at our center in 2015 by reviewing their medical records. Only CBZ, OXC and ESL were associated with hyponatremia. The incidence of hyponatremia induced by ESL was not statistically different from that induced by OXC (43% of patients with OXC and 33% with ESL, p > 0.05). Both were associated with hyponatremia more often than CBZ (16%). OXC-induced hyponatremia was dose-related, ESL-induced hyponatremia was not. Furthermore, both OXC- and ESL-induced hyponatremia occurred particularly often in elderly epilepsy patients. Thus, for elderly patients, both OXC and ESL should be considered with caution.