Cardiovascular adverse effects of phenytoin

A narrative review and new insights into the protective effects of taurine against drug side effects

Taurine, a non-essential amino acid produced from cysteine, is abundant in body tissues and blood plasma. It plays vital roles in growth, osmosis, lipid metabolism, and neurohormonal modulation. Taurine has antioxidant, anti-apoptotic, and anti-inflammatory properties, and its deficiency can lead to various diseases including cardiovascular, diabetic, renal, and liver disorders. This report provides a comprehensive review of the functional properties of taurine in counteracting pharmaceutical-induced side effects. A search across databases such as Scopus, PubMed, MEDLINE, and Web of Science yielded 109 articles, of which 75 were included in the study. These results suggest that the protective effects of taurine involve mechanisms such as influencing pathways of Nrf2/OH-1, PI3-kinase/AKT and ERK2, boosting antioxidants (SOD, GPx and CAT), and suppression of inflammatory cytokines (TNF-α, IL-1β and IL-6). Overall, supplementation with taurine along with medications with significant side effects may mitigate these effects and enhance their efficacy. Further investigation of the interactions between taurine and other nutrients or compounds may provide insights into synergistic effects and novel therapeutic approaches.

The effect of epilepsy and antiseizure medications on cardiac autonomic functions in children with epilepsy

BACKGROUND

Autonomic manifestations have been frequently studied in adults with epilepsy. Here, we evaluated cardiac autonomic (ANS) functions in children with epilepsy in the interictal period and determined the risks for their dysfunctions.

RESEARCH DESIGN AND METHODS

This study included 60 patients (boys = 25; girls = 35 age: 14.53 ± 2.54 yrs) and 25 controls. Patients were well-controlled on antiseizure medications (ASMs). The battery of testing included measuring resting heart rate (HR) and blood pressure (BP), 30:15 ratio, HR variability (HRV) response to deep breathing, Valsalva ratio and BP changes in response to standing, isometric exercise and cold.

RESULTS

Dizziness was reported in 25%. Autonomic dysfunctions were found in 45% (n = 27). Manifestations included high frequencies of abnormal 30:15 ratio (22%), HRV responses to deep breathing (45%), Valsalava ratio (45%), and BP responses to standing (35%), isometric exercise (27%) and cold (27%), indicating parasympathetic and sympathetic hypofunctions. There were positive correlations between parasympathetic and sympathetic dysfunctions. Logistic analysis showed that the durations of epilepsy and ASMs therapy were associated with ANS dysfunctions [95% CI: 0.895-4.719, p = 0.004].

CONCLUSIONS

Parasympathetic and sympathetic autonomic hypofunctions are common in children with epilepsy. This could be due to the depressant effect of sodium channel blocker ASMs on central and/or cardiac autonomic systems.

[Guidelines for the management of adverse effects of anti-seizure medications (2023)]

Epilepsy is a prevalent neurological disorder with a complex etiology and an unclear pathogenesis. In order to standardize the management of adverse effects caused by anti-seizure medications (ASMs), the Youth Committee of the Chinese Association Against Epilepsy (CAAE), in collaboration with the CAAE Precision Medicines and Adverse Effect Monitoring Committee, has developed a guideline: guidelines for the management of adverse effects of anti-seizure medications (2023). This guideline addresses 13 clinical questions related to the management of adverse effects of ASMs in the nervous system, cardiovascular system, and fetus. Its primary objective is to provide guidance to medical professionals specializing in pediatric neurology, neurology, and neurosurgery in China, and to facilitate their clinical practice.

Black-Box Warnings of Antiseizure Medications: What is Inside the Box?

Antiseizure medications can cause serious adverse reactions and have deleterious drug interactions that often complicate the clinical management of patients. When the US Food and Drug Administration (FDA) wants to alert healthcare providers and patients about the risk of potentially serious or fatal drug reactions, the FDA requires the manufacturers of these medications to format these warnings within a "black-box" border, and prominently display this box on the first section of the package insert; such warnings are called "black-box warnings (BBWs)". The BBW is a way for the FDA to urge physicians to evaluate patients more rigorously and carefully weigh the risks and benefits, before prescribing medication that has the potential to cause serious adverse reactions, and to formulate a plan for close monitoring during therapy. The FDA BBW provides the extra layer of safety but many healthcare providers fail to comply with these warnings. Currently, there are 26 FDA-approved antiseizure medications in the US market, 38% of which have received BBWs, and most of the antiseizure medications with BBWs are older-generation drugs. Some antiseizure medications have multiple BBWs; for example, valproic acid has three BBWs including hepatotoxicity, fetal risk, and pancreatitis, carbamazepine has BBWs of serious skin and hematological reactions, and felbamate also has two BBWs including hepatic failure and aplastic anemia. The purpose of this review is to provide insight into each BBW received by antiseizure medications and discuss the FDA recommendations for evaluating the drug benefit/risk, and for monitoring parameters before the initiation of and during treatment.

Anti-Epileptic Drug Target Perturbation and Intracranial Aneurysm Risk: Mendelian Randomization and Colocalization Study

BACKGROUND

In a genome-wide association study of intracranial aneurysms (IA), enrichment was found between genes associated with IA and genes encoding targets of effective anti-epileptic drugs. Our aim was to assess if this pleiotropy is driven by shared disease mechanisms that could potentially highlight a treatment strategy for IA.

METHODS

Using 2-sample inverse-variance weighted Mendelian randomization and genetic colocalization analyses we assessed: (1) if epilepsy liability in general affects IA risk, and (2) whether changes in gene- and protein-expression levels of anti-epileptic drug targets in blood and arterial tissue may causally affect IA risk.

RESULTS

We found no overall effect of epilepsy liability on IA. Expression of 21 genes and 13 proteins corresponding to anti-epileptic drug targets supported a causal effect (P<0.05) on IA risk. Of those genes and proteins, genetic variants affecting CNNM2 levels showed strong evidence for colocalization with IA risk (posterior probability>70%). Higher CNNM2 levels in arterial tissue were associated with increased IA risk (odds ratio, 3.02; [95% CI, 2.32-3.94]; P=3.39×10^-16). CNNM2 expression was best proxied by rs11191580. The magnitude of the effect of this variant was greater than would be expected if systemic blood pressure was the sole IA-causing mechanism in this locus.

CONCLUSIONS

CNNM2 is a driver of the pleiotropy between IA and anti-epileptic drug targets. Administration of the anti-epileptic drugs phenytoin, valproic acid, or carbamazepine may be expected to decrease CNNM2 levels and therefore subsequently decrease IA risk. CNNM2 is therefore an important target to investigate further for its role in the pathogenesis of IA.

Use of supra-therapeutic phenytoin for management of ventricular arrhythmias in children: Case series and literature review

Phenytoin is a versatile drug with utility in neurological, dermatological, and even cardiac disease processes. Though phenytoin is widely available due to its excellent anti-epileptic properties, it is now rarely used as an antiarrhythmic. Phenytoin has well-studied sodium-channel blocking abilities which can be taken advantage of to treat ventricular arrhythmias. Thus, it should remain in the arsenal of antiarrhythmics for any electrophysiologist. We present two cases of intractable ventricular arrhythmia in children that were controlled with phenytoin at supra-therapeutic serum levels, preventing the need for heart transplantation.

Self-Powered Active Sensing Based on Triboelectric Generators

The demand for portable and wearable chemical or biosensors and their expeditious development in recent years has created a scientific challenge in terms of their continuous powering. As a result, mechanical energy harvesters such as piezoelectric and triboelectric generators (TEGs) have been explored recently either as sensors or harvesters to store charge in small, but long-life, energy-storage devices to power the sensors. The use of energy harvesters as sensors is particularly interesting, as with such multifunctional operations it is possible to reduce the number devices needed in a system, which also helps overcome the integration complexities. In this regard, TEGs are promising, particularly for energy autonomous chemical and biological sensors, as they can be developed with a wide variety of materials, and their mechanical energy to electricity conversion can be modulated by various analytes. This review focuses on this interesting dimension of TEGs and presents various self-powered active chemical and biological sensors. A brief discussion about the development of TEG-based physical, magnetic, and optical sensors is also included. The influence of environmental factors, various figures of merit, and the significance of TEG design are explained in context with the active sensing. Finally, the key applications, challenges, and future perspective of chemical and biological detection via TEGs are discussed with a view to drive further advances in the field of self-powered sensors.

Evaluation of Cardiovascular Concerns of Intravenous Lacosamide Therapy in Epilepsy Patients

Objective

Voltage-gated sodium channels (VGSCs) play an important role in neuronal excitability and epilepsies. In addition to the brain, VGSCs are also abundant enriched in cardiac tissues and are responsible for normal cardiac rhythm. Theoretically, sodium channel blocking antiseizure medications (SCB-ASMs) may have unwanted cardiac side effects. Lacosamide (LCM) is increasingly used in patients with status epilepticus (SE) due to the availability of intravenous formula. The concerns about the proarrhythmic effect are even higher due to the need for rapid administration of LCM. There were limited data on the cardiac safety of intravenous LCM. Hereby, we performed a study to observe the effect of intravenous loading of LCM in patients with seizures in our Neurological Intensive Care Unit (NICU).

Methods

We retrospectively reviewed the patients using parenteral LCM for seizures in NICU. A routine infusion time of 30 min was performed. The electrocardiogram (ECG) and blood pressure were recorded before and after LCM injection.

Results

We retrospectively reviewed the clinical data of 38 patients using LCM for treating seizures. Two patients had cardiac side effects after LCM loading, one (3.0%) with new-onset first-degree AV block and the other (3.0%) with atrial premature complex. For the quantitative changes of ECG parameter analysis, there was no change in QRS complex, corrected QT intervals, and heart rate except that the PR interval was mildly increased. A mild decrease in the diastolic blood pressure and mean arterial pressure were also observed. None of the above-mentioned parameter alterations required clinical intervention.

Conclusion

We evaluated the cardiac safety concern in real-world epilepsy patients requiring intravenous LCM. Near half of this cohort responded to LCM therapy and there was no life-threatening cardiac adverse effect. Intravenous LCM does have some effects on the ECG parameters and blood pressure but without clinical relevance. Despite the theoretical concern of cardiac adverse effects of LCM, the benefit of seizure control outweighed the risk in patients with status epilepticus or seizure clusters, such as hyperthermia, pulmonary edema, cardiac arrhythmias, or cardiovascular collapse.

Cardiac sodium channel inhibition by lamotrigine: in vitro characterization and clinical implications

Lamotrigine, approved for use as an antiseizure medication as well as the treatment of bipolar disorder, inhibits sodium channels in the brain to reduce repetitive neuronal firing and pathological release of glutamate. The shared homology of sodium channels and lack of selectivity associated with channel blocking agents can cause slowing of cardiac conduction and increased proarrhythmic potential. The Vaughan‐Williams classification system differentiates sodium channel blockers using biophysical properties of binding. As such, Class Ib inhibitors, including mexiletine, do not slow cardiac conduction as measured by the electrocardiogram, at therapeutically relevant exposure. Our goal was to characterize the biophysical properties of Na_V1.5 block and to support the observed clinical safety of lamotrigine. We used HEK‐293 cells stably expressing the hNa_V1.5 channel and voltage clamp electrophysiology to quantify the potency (half‐maximal inhibitory concentration) against peak and late channel current, on‐/off‐rate binding kinetics, voltage‐dependence, and tonic block of the cardiac sodium channel by lamotrigine; and compared to clinically relevant Class Ia (quinidine), Ib (mexiletine), and Ic (flecainide) inhibitors. Lamotrigine blocked peak and late Na_V1.5 current at therapeutically relevant exposure, with rapid kinetics and biophysical properties similar to the class Ib inhibitor mexiletine. However, no clinically meaningful prolongation in QRS or PR interval was observed in healthy subjects in a new analysis of a previously reported thorough QT clinical trial (SCA104648). In conclusion, the weak Na_V1.5 block and rapid kinetics do not translate into clinically relevant conduction slowing at therapeutic exposure and support the clinical safety of lamotrigine in patients suffering from epilepsy and bipolar disorder.

Secular Trends in the Incidence, Prevalence, and Medications for Epilepsy from 2007 to 2015 in Taiwan: A Nationwide Population-Based Study

BACKGROUND

Patients with epilepsy have a higher mortality rate than the general population. Up-to-date estimates of epilepsy incidence, prevalence, and medication use are critical to assist policymaking.

METHODS

Using the National Taiwan Insurance Research Database, the standardized incidence and prevalence of epilepsy were estimated in each calendar year from 2007 to 2015. We used the incident cases of epilepsy to analyze the change in prescribing patterns from 2007 to 2015. Joinpoint regression was used to estimate secular trends.

RESULTS

From 2007 to 2015, the age- and sex-standardized incidence decreased from 0.72 (95% confidence interval [CI] 0.70-0.73) to 0.54 (95% CI 0.53-0.55) per 1,000 person-years, giving an annual percentage change (APC) of -2.73 (p < 0.05). Among patients younger than 20 years, the incidence did not change significantly. The age- and sex-standardized prevalence decreased from 6.94 (95% CI 6.90-6.98) to 6.86 (95% CI, 6.82-6.89) per 1,000 people, giving an APC of -0.31 (p < 0.05). However, the prevalence increased in the 35- to 49- and 50- to 64-year age-groups. The most common first-line anticonvulsant was phenytoin in 2007 and valproate in 2015. The use of levetiracetam, clobazam, and valproate increased during the study period, with APCs of 25.48% (95% CI 19.97-31.24), 6.41 (3.09-9.85), and 2.83 (1.51-4.16), respectively. The use of carbamazepine, phenytoin, and topiramate decreased; the APCs were -23.86% (95% CI -25.25 to -22.44), -6.61 (-8.40 to -4.79), and -4.29% (-7.87 to -0.57), respectively.

CONCLUSIONS

The overall prevalence and incidence of epilepsy decreased slightly from 2007 to 2015. The prescribed first-line anticonvulsant also changed over time.

Efficacy of lacosamide and phenytoin in status epilepticus: A systematic review

OBJECTIVES

To compare the evidence on efficacy, safety, tolerability, and impact on short term/long functional outcome of lacosamide (LCM) and phenytoin (PHT) in patients with status epilepticus.

MATERIALS & METHODS

We conducted a systematic literature search of relevant electronic databases using a suitable search strategy to identify studies directly comparing PHT and LCM, irrespective of dose and duration in patients with convulsive and/or nonconvulsive status epilepticus (SE). We used a standardized assessment form to extract information on the study design, data sources, methodologic framework, efficacy, and adverse events attributed to PHT and LCM from included studies and compared the efficacy and safety outcomes, using a fixed/random effect model.

RESULTS

Five studies were found to be eligible for inclusion out of 192 search items, enrolling a total of 115 and 166 participants (predominantly with SE) in LCM and PHT arm, respectively. Baseline characteristics were comparable between both arms. The proportion with seizure control was comparable between both arms (57.3% in LCM vs. 45.7% in PHT arm, p = 0.28) and even in the subgroup analysis separately for convulsive and non-convulsive SE. Proportion with treatment-emergent adverse events (TEAE) were comparable in both (17.6% vs. 12.2%, p = 0.20), but serious adverse events (SAE) were higher in PHT arm (5.1% vs. 0.8%, p = 0.049). The proportion with all-cause mortality and survival with moderate-severe disability were comparable between both arms (p = 0.23 and 0.37, respectively).

CONCLUSION

LCM has comparable efficacy with fewer SAEs as compared to PHT for achieving seizure control in patients with SE.

Super-Refractory Status Epilepticus: Prognosis and Recent Advances in Management

Super-refractory status epilepticus (SRSE) is a life-threatening neurological emergency with high morbidity and mortality. It is defined as “status epilepticus (SE) that continues or recurs 24 hours or more after the onset of anesthesia, including those cases in which SE recurs on the reduction or withdrawal of anesthesia.” This condition is resistant to normal protocols used in the treatment of status epilepticus and exposes patients to increased risks of neuronal death, neuronal injury, and disruption of neuronal networks if not treated in a timely manner. It is mainly seen in patients with severe acute onset brain injury or presentation of new-onset refractory status epilepticus (NORSE). The mortality, neurological deficits, and functional impairments are significant depending on the duration of status epilepticus and the resultant brain damage. Research is underway to find the cure for this devastating neurological condition. In this review, we will discuss the wide range of therapies used in the management of SRSE, provide suggestions regarding its treatment, and comment on future directions. The therapies evaluated include traditional and alternative anesthetic agents with antiepileptic agents. The other emerging therapies include hypothermia, steroids, immunosuppressive agents, electrical and magnetic stimulation therapies, emergent respective epilepsy surgery, the ketogenic diet, pyridoxine infusion, cerebrospinal fluid drainage, and magnesium infusion. To date, there is a lack of robust published data regarding the safety and effectiveness of various therapies, and there continues to be a need for large randomized multicenter trials comparing newer therapies to treat this refractory condition.

Rapid infusion of excessive phenytoin: A newborn autopsy case

The patient was a two-day-old female infant. The patient's mother was a primigravid in her 20 s who developed premature abruption of the normal placenta on the first day of the 33rd week of gestation. The infant was born by emergency cesarean section with severe neonatal asphyxia with a birth weight of 1928 g. Spontaneous circulation was returned 11 min after birth. The infant was treated under mechanical ventilation in the neonatal intensive care unit, and phenobarbital was administered for repeated seizures. On day 2, spontaneous respiration was observed; however, the patient developed seizures repeatedly. The dose of phenobarbital reached the maximum and was switched to midazolam. In the early morning of day 3, while midazolam was administered up to the maximum dose, the infant developed status epilepticus, and the anticonvulsant drug was changed to phenytoin. Due to a calculation error, the intravenous administration of phenytoin was started at 400 mg/30 min, which is 10-fold of the normal dose. Six minutes later, after 80 mg was administered, the administration was stopped due to a drop in blood pressure; however, the infant died of cardiac arrest. An autopsy, which was performed approximately 25 h after death, revealed the blood phenytoin concentration in the heart was 63.85 μg/mL. The cause of death was determined to be acute phenytoin toxicity. This is the first fatal case reported of the blood concentration of phenytoin caused by rapid intravenous administration.

Effects of long-term anti-seizure medication monotherapy on all-cause death in patients with post-stroke epilepsy: a nationwide population-based study in Taiwan

OBJECTIVE

We aim to compare the effect of long-term anti-seizure medication (ASM) monotherapy on the risk of death and new ischemic stroke in patients with post-stroke epilepsy (PSE).

PATIENTS AND METHODS

We identified all hospitalized patients (≥ 20 years) with a primary diagnosis of ischemic or hemorrhagic stroke from 2001 to 2012 using the National Health Insurance Research Database in Taiwan. The PSE cohort were defined as the stroke patients (1) who had no epilepsy and no ASMs use before the index stroke, and (2) who had epilepsy and ASMs use after 14 days from the stroke onset. The patients with PSE receiving ASM monotherapy were enrolled and were categorized into phenytoin, valproic acid, carbamazepine, and new ASM groups. We employed the Cox regression model to estimate the unadjusted and adjusted hazard ratios (HRs) with 95 % confidence intervals (CIs) of death and new ischemic stroke within 5 years across all groups, using the new ASM group as the reference.

RESULTS

Of 6962 patients with PSE using ASM monotherapy, 3917 (56 %) were on phenytoin, 1623 (23 %) on valproic acid, 457 (7 %) on carbamazepine, and 965 (14 %) on new ASMs. After adjusting for confounders, compared with new ASM users, phenytoin users had a higher risk of death in 5 years (HR: 1.64; 95 % CI: 1.06-2.55). On the other hand, all ASM groups showed a similar risk of new ischemic stroke in 5 years.

CONCLUSIONS

Among patients with PSE on first-line monotherapy, compared to new ASMs, use of phenytoin was associated with a higher risk of death in 5 years.

A 'shark'-masked electrocardiogram: case report of a Tako-Tsubo syndrome

Background

Triangular ST-segment elevation or 'shark-fin' sign has been described as a specific indicator of acute coronary occlusion and large myocardial ischaemia, translating into poorer prognosis. However, this electrocardiographic presentation has been reported in rare cases of Tako-Tsubo syndrome and associated with more severe physical stressors and neurological involvement.

Case summary

We present a rare case of a 51-year-old woman presenting with incoming epileptic attacks and concomitant pyometra. Despite controlling epilepsy with phenytoin and the surgical treatment of the infection, she developed sepsis requiring vasopressors, and thereafter sustained ventricular tachycardia and diffuse ST-segment elevation with the 'shark-fin' sign. TTC was confirmed by the documentation of normal coronary arteries and the complete recovery of wall motion abnormalities at discharge.

Discussion

Heterogeneous presentation and triggering conditions often challenge the diagnosis of Tako-Tsubo syndrome. The acknowledgement of different electrocardiographic and clinical manifestations can ease the diagnosis and the successful management of these patients, whose prognosis can be extremely severe in the acute phase, if unidentified.

Effects of acute neurologic disease on the heart

Patients with acute neurologic disease often also have evidence of cardiac dysfunction. The cardiac dysfunction may result in a number of clinical signs including abnormal EKG changes, variations in blood pressure, development of cardiac arrhythmias, release of cardiac biomarkers, and reduced ventricular function. Although typically reversible, these cardiac complications are important to recognize as they are associated with increased morbidity and mortality. In this chapter, we discuss the suspected pathophysiology, clinical presentation, and management of the cardiac dysfunction that occur as a consequence of different types of acute neurologic illness.

Levetiracetam vs. phenytoin as 2nd-line treatment for status epilepticus: A systematic review and meta-analysis

OBJECTIVE

The objective of the study was to perform a systematic review and meta-analysis to evaluate the efficacy and safety of levetiracetam (LEV) or phenytoin (PHT) as second-line treatment for status epilepticus (SE).

METHODS

PubMed, Cumulative Index to Nursing and Allied Health Literature (CINAHL), Latin American and Caribbean Health Sciences Literature (LILACS), Scopus, the Cochrane Database of Systematic Reviews, the Cochrane Central Register of Controlled Trials, and Google Scholar were assessed for prospective randomized trials comparing LEV with PHT as second-line treatment of SE published from inception until December 18th, 2019. The primary outcome was seizure cessation. Data were analyzed using a random-effects model. Quality analysis was performed using version 2 of the Cochrane risk-of-bias tool (RoB 2). The study protocol was registered on PROSPERO (CRD42020136417).

RESULTS

Nine studies with a total of 1732 patients were included. Overall, seizure cessation occurred in 657 of 887 (74%) of patients in the LEV group and 600 of 845 (71%) in the PHT group. Treatment success did not differ significantly between groups, and the relative risk (RR) was 1.05 (95% confidence interval (CI): 0.98-1.12; I² = 53%). Six of the studies were at low risk of bias, one study had some risk, and two studies had high risk.

CONCLUSIONS

The use of LEV or PHT as second-line agents after benzodiazepine (BZD) for the treatment of SE was not associated with a difference in seizure cessation. Because there are minimal differences in efficacy at this time, clinicians should consider alternative factors when deciding on an antiepileptic drug (AED).

36-year-old Male with Syncope

CASE PRESENTATION

A 36-year-old incarcerated male presented to the emergency department (ED) after an episode concerning for syncope. The patient had nystagmus and ataxia on initial examination.

DISCUSSION

There is a broad differential diagnosis for syncope, and for patients presenting to the ED we tend to focus on cardiogenic and neurologic causes. This case takes the reader through the differential diagnosis and systemic work-up of a patient presenting to the ED with syncope.

Use of phenytoin for treatment of tacrolimus toxicity with superimposed sepsis

A 40-year-old woman with a history of chronic graft-versus-host-disease on immunosuppression with tacrolimus presented to the hospital with somnolence, confusion and muscle cramps over a few days. She was found to have hypertension, hyperglycaemia and acute kidney injury with an elevated blood tacrolimus level of greater than 120 ng/mL (reference range 5-15 ng/mL). Discontinuation of tacrolimus with concomitant administration of intravenous phenytoin led to the successful reduction of elevated tacrolimus concentrations and the resolution of her symptoms. Tacrolimus is metabolised by the cytochrome P (CYP) 450 3A enzyme system, and utilisation of CYP 3A inducers to accelerate its clearance may be used as a successful therapy to treat tacrolimus toxicity.

Levetiracetam vs. Fosphenytoin for Second-Line Treatment of Status Epilepticus: Propensity Score Matching Analysis Using a Nationwide Inpatient Database

Objective: Status epilepticus is a major emergency condition. The choice of antiepileptic drugs for second-line treatment after benzodiazepine remains controversial, including levetiracetam vs. fosphenytoin. We compare the safety of intravenous levetiracetam and fosphenytoin as a second-line treatment in patients with status epilepticus using a nationwide database.

Methods: An observational study conducted with the Japanese Diagnosis Procedure Combination inpatient database identified adult patients who had been admitted for status epilepticus and who had received intravenous diazepam on the day of admission from March 1, 2011 to March 31, 2018. Patients who received intravenous levetiracetam on the day of admission were defined as the levetiracetam group and those who received intravenous fosphenytoin on the day of admission were defined as the fosphenytoin group. Propensity score matching was performed to compare outcomes obtained for the levetiracetam and fosphenytoin groups.

Results: The analysis examined data of 5,667 patients. Overall, 1,403 (25%) patients received levetiracetam; 4,264 (75%) received fosphenytoin. One-to-one propensity score matching created 1,363 matched pairs. No significant difference was found in in-hospital mortality (5.2 vs. 5.1%; odds ratio, 1.03; 95% confidence interval, 0.73–1.46). The proportion of vasopressor use on the day of admission was significantly lower for the levetiracetam group than for the fosphenytoin group (3.2 vs. 4.9%; odds ratio, 0.63; 95% confidence interval, 0.43–0.92). No significant difference was found in other secondary outcomes including total hospitalization cost.

Conclusion: Levetiracetam was related to significantly reduced vasopressor use on the day of admission than that found for fosphenytoin, in adult status epilepticus.

Clinical Effectiveness of Levetiracetam Compared to Fosphenytoin in the Treatment of Benzodiazepine Refractory Convulsive Status Epilepticus

OBJECTIVES

To determine whether levetiracetam is an alternative to fosphenytoin to control Benzodiazepine Refractory Status Epilepticus (BRSE) in pediatric population and also to compare the acute drug related side-effects and ventilation requirement among the both arms of anti-epileptic drug therapy.

METHODS

All consecutive children admitted with BRSE were randomized to group A, who received fosphenytoin at 20 mg/kg phenytoin equivalents (PE) dose and group B who received levetiracetam at 40 mg/kg over 10 min. Time to terminate seizure (response latency) was measured. If seizure remained refractory after 20 min of test drug administration, appropriate drug escalation was made according to pediatrician's discretion. All primary and secondary outcome measures were compared between the two therapeutic groups.

RESULTS

Of 61 children enrolled over 18 mo period, 29 (47.5%) were randomized to group A and 32 (52.5%) were randomized to Group B. Baseline characteristics were comparable between the two groups. Among 61 children, 58(98%) required Pediatric Intensive Care Unit (PICU) admission and among those 5(8.2%) children required mechanical ventilation. Duration of PICU stay, hospital stay, the response latency and seizure recurrence were compared between both groups. Significant number of children received additional anti-epileptic drugs (AEDs) in fosphenytoin group [9/29(31%)] compared to levetiracetam group [2/32(7%)] to control seizure.

CONCLUSIONS

Levetiracetam may be an effective alternative to fosphenytoin in management of BRSE in children but multicentric trials with large sample size are needed to substantiate this observation.

Nizam MN, Alshammari A. An Update on the Mechanisms of Phenytoin Induced Gingival Overgrowth

Background:

Phenytoin induced gingival overgrowth, a side effect with multifactorial aetiology, is characterized by an increase in the volume of extracellular tissues, particularly collagenous components, with varying degrees of inflammation.

Objective:

The aim of this paper is to review the available literature regarding the pathophysiological mechanisms of phenytoin induced gingival overgrowth.

Methods:

A thorough literature search of the PubMed/ Embase/ Web of science/ Cochrane central database was conducted to identify the mechanisms involved in the process of phenytoin-induced gingival overgrowth using the following keywords: Phenytoin; Anticonvulsant; Gingival Overgrowth; Gingival Enlargement, Gingival Hyperplasia; Drug Induced Gingival Enlargement; Drug Induced Gingival Overgrowth

Results:

According to the available evidence, several mechanisms have been proposed addressing the pathophysiological mechanism of phenytoin induced gingival overgrowth both at a cellular and molecular level. Evidence suggests that the inflammatory changes in the gingival tissues orchestrate the interaction between phenytoin and fibroblasts particularly resulting in an increase in the extracellular matrix content.

Conclusion:

However, the mechanism of production of inflammatory mediators is not fully understood. This, together with the high prevalence of Phenytoin induced gingival overgrowth, warrants further research in this area in order to develop treatment and preventive strategies for the management of this condition.

A Systematic Review of NMDA Receptor Antagonists for Treatment of Neuropathic Pain in Clinical Practice

OBJECTIVE

To investigate the efficacy of N-methyl-D-aspartate receptor (NMDAR) antagonists for neuropathic pain (NeuP) and review literature to determine if specific pharmacologic agents provide adequate NeuP relief.

METHODS

Literature was reviewed on PubMed using a variety of key words for 8 NMDAR antagonists. These key words include: "Ketamine and Neuropathy," "Ketamine and Neuropathic Pain," "Methadone and Neuropathy," "Methadone and Neuropathic Pain," "Memantine and Neuropathic pain," "Memantine and Neuropathy," "Amantadine and Neuropathic Pain," "Amantadine and Neuropathy," "Dextromethorphan and Neuropathic Pain," "Dextromethorphan and Neuropathy," "Carbamazepine and Neuropathic Pain," "Carbamazepine and Neuropathy," "Valproic Acid and Neuropathy," "Valproic Acid and Neuropathic Pain," "Phenytoin and Neuropathy," and "Phenytoin and Neuropathic Pain." With the results, the papers were reviewed using the PRISMA (Preferred Reporting in Systematic and Meta-Analyses) guideline.

RESULTS

A total of 58 randomized controlled trials were reviewed among 8 pharmacologic agents, which are organized by date and alphabetical order. Of the trials for ketamine, 15 showed some benefit for analgesia. Methadone had 3 positive trials, while amantadine and memantine each only had 2 trials showing NeuP analgesic properties. Dextromethorphan and valproic acid both had 4 randomized controlled trials that showed some NeuP treatment benefit while carbamazepine had over 8 trials showing efficacy. Finally, phenytoin only had 1 trial that showed clinical response in treatment.

CONCLUSIONS

There are a variety of NMDAR antagonist agents that should be considered for treatment of NeuP. Nevertheless, continued and further investigation of the 8 pharmacologic agents is needed to continue to evaluate their efficacy for treatment of NeuP.

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.

Blood Pressure in Seizures and Epilepsy

In this narrative review, we summarize the current knowledge of neurally mediated blood pressure (BP) control and discuss how recently described epilepsy- and seizure-related BP alterations may contribute to premature mortality and sudden unexpected death in epilepsy (SUDEP). Although people with epilepsy display disturbed interictal autonomic function with a shift toward predominant sympathetic activity, prevalence of arterial hypertension is similar in people with and without epilepsy. BP is transiently increased in association with most types of epileptic seizures but may also decrease in some, illustrating that seizure activity can cause both a decrease and increase of BP, probably because of stimulation or inhibition of distinct central autonomic function by epileptic activity that propagates into different neuronal networks of the central autonomic nervous system. The principal regulatory neural loop for short-term BP control is termed baroreflex, mainly involving peripheral sensors and brain stem nuclei. The baroreflex sensitivity (BRS, expressed as change of interbeat interval per change in BP) is intact after focal seizures, whereas BRS is markedly impaired in the early postictal period following generalized convulsive seizures (GCS), possibly due to metabolically mediated muscular hyperemia in skeletal muscles, a massive release of catecholamines and compromised brain stem function. Whilst most SUDEP cases are probably caused by a cardiorespiratory failure during the early postictal period following GCS, a profoundly disturbed BRS may allow a life-threatening drop of systemic BP in the aftermath of GCS, as recently reported in a patient as a plausible cause of SUDEP in a few patients.

New mechanisms of phenytoin in calcium homeostasis: competitive inhibition of CD38 in hippocampal cells

Purpose

Phenytoin is a major anticonvulsant drug that is effective to improve arrhythmia and neuropathic pain. According to early works, phenytoin affected cell membrane depolarization by sodium channel blocking, guanylyl and adenylyl cyclase suppression that cause to intracellular Na⁺ and Ca²⁺ downregulation. This study was aimed to clarify some ambiguities in pathophysiological action of phenytoin by in vitro and molecular docking analyses.

Methods

In this study intracellular free Ca²⁺ of primary culture of embryonic mouse hippocampus evaluated via Fura 2 as fluorescent probe. The effects of phenytoin on ADP ribosyl cyclase activity was assessed by recently developed fluorometric assay. Molecular docking simulation was also implemented to investigate the possible interaction between phenytoin and CD38.

Results

Our results confirmed phenytoin competitively inhibits cyclase activity of CD38 (IC₅₀ = 8.1 μM) and reduces cADPR content. cADPR is a Ca²⁺-mobilising second messenger which binds to L-type calcium channel and ryanodine receptors in cell and ER membrane and increases cytosolic free Ca²⁺. Ca²⁺ content of cells decreased significantly in the presence of phenytoin in a dose dependent manner (IC₅₀ = 12.74 µM). Based on molecular docking analysis, phenytoin binds to deeper site of CD38 active site, mainly via hydrophobic interactions and consequently inhibits proper contact of substrate with catalytic residues specially Glu 226, Trp 186, Thr221.

Conclusion

Taken together, one of the anticonvulsant mechanisms of phenytoin is Ca²⁺ inhibition from CD38 pathway, therefore could be used in disorders that accompanied by CD38 over production or activation such as heart disease, depression, brain sepsis, airway disease, oxidative stress and inflammation.

Graphical abstract

Why we prefer levetiracetam over phenytoin for treatment of status epilepticus

Over last fifty years, intravenous (iv) phenytoin (PHT) loading dose has been the treatment of choice for patients with benzodiazepine-resistant convulsive status epilepticus and several guidelines recommended this treatment regimen with simultaneous iv diazepam. Clinical studies have never shown a better efficacy of PHT over other antiepileptic drugs. In addition, iv PHT loading dose is a complex and time-consuming procedure which may expose patients to several risks, such as local cutaneous reactions (purple glove syndrome), severe hypotension and cardiac arrhythmias up to ventricular fibrillation and death, and increased risk of severe allergic reactions. A further disadvantage of PHT is that it is a strong enzymatic inducer and it may make ineffective several drugs that need to be used simultaneously with antiepileptic treatment. In patients with a benzodiazepine-resistant status epilepticus, we suggest iv administration of levetiracetam as soon as possible. If levetiracetam would be ineffective, a further antiepileptic drug among those currently available for iv use (valproate, lacosamide, or phenytoin) can be added before starting third line treatment.

The heart of epilepsy: Current views and future concepts

Cardiovascular (CV) comorbidities are common in people with epilepsy. Several mechanisms explain why these conditions tend to co-exist including causal associations, shared risk factors and those resulting from epilepsy or its treatment. Various arrhythmias occurring during and after seizures have been described. Ictal asystole is the most common cause. The converse phenomenon, arrhythmias causing seizures, appears extremely rare and has only been reported in children following cardioinihibitory syncope. Arrhythmias in epilepsy may not only result from seizure activity but also from a shared genetic susceptibility. Various cardiac and epilepsy genes could be implicated but firm evidence is still lacking. Several antiepileptic drugs (AEDs) triggering conduction abnormalities can also explain the co-existence of arrhythmias in epilepsy. Epidemiological studies have consistently shown that people with epilepsy have a higher prevalence of structural cardiac disease and a poorer CV risk profile than those without epilepsy. Shared CV risk factors, genetics and etiological factors can account for a significant part of the relationship between epilepsy and structural cardiac disease. Seizure activity may cause transient myocardial ischaemia and the Takotsubo syndrome. Additionally, certain AEDs may themselves negatively affect CV risk profile in epilepsy. Here we discuss the fascinating borderland of epilepsy and cardiovascular conditions. The review focuses on epidemiology, clinical presentations and possible mechanisms for shared pathophysiology. It concludes with a discussion of future developments and a call for validated screening instruments and guidelines aiding the early identification and treatment of CV comorbidity in epilepsy.