Intravenous valproate in status epilepticus

Pre-hospital and emergency department treatment of convulsive status epilepticus in adults: an evidence synthesis

BACKGROUND

Convulsive status epilepticus is defined as ≥ 5 minutes of either continuous seizure activity or repetitive seizures without regaining consciousness. It is regarded as an emergency condition that requires prompt treatment to avoid hospitalisation and to reduce morbidity and mortality. Rapid pre-hospital first-line treatment of convulsive status epilepticus is currently benzodiazepines, administered either by trained caregivers in the community (e.g. buccal midazolam, rectal diazepam) or by trained health professionals via intramuscular or intravenous routes (e.g. midazolam, lorazepam). There is a lack of clarity about the optimal treatment for convulsive status epilepticus in the pre-hospital setting.

OBJECTIVES

To assess the current evidence on the clinical effectiveness and cost-effectiveness of treatments for adults with convulsive status epilepticus in the pre-hospital setting.

DATA SOURCES

We searched major electronic databases, including MEDLINE, EMBASE, PsycInfo®, CINAHL, CENTRAL, NHS Economic Evaluation Database, Health Technology Assessment Database, Research Papers in Economics, and the ISPOR Scientific Presentations Database, with no restrictions on publication date or language of publication. Final searches were carried out on 21 July 2020.

REVIEW METHODS

Systematic review of randomised controlled trials assessing adults with convulsive status epilepticus who received treatment before or on arrival at the emergency department. Eligible treatments were any antiepileptic drugs offered as first-line treatments, regardless of their route of administration. Primary outcomes were seizure cessation, seizure recurrence and adverse events. Two reviewers independently screened all citations identified by the search strategy, retrieved full-text articles, extracted data and assessed the risk of bias of the included trials. Results were described narratively.

RESULTS

Four trials (1345 randomised participants, of whom 1234 were adults) assessed the intravenous or intramuscular use of benzodiazepines or other antiepileptic drugs for the pre-hospital treatment of convulsive status epilepticus in adults. Three trials at a low risk of bias showed that benzodiazepines were effective in stopping seizures. In particular, intramuscular midazolam was non-inferior to intravenous lorazepam. The addition of levetiracetam to clonazepam did not show clear advantages over clonazepam alone. One trial at a high risk of bias showed that phenobarbital plus optional phenytoin was more effective in terminating seizures than diazepam plus phenytoin. The median time to seizure cessation from drug administration varied from 1.6 minutes to 15 minutes. The proportion of people with recurrence of seizures ranged from 10.4% to 19.1% in two trials reporting this outcome. Across trials, the rates of respiratory depression among participants receiving active treatments were generally low (from 6.4% to 10.6%). The mortality rate ranged from 2% to 7.6% in active treatment groups and from 6.2% to 15.5% in control groups. Only one study based on retrospective observational data met the criteria for economic evaluation; therefore, it was not possible to draw any robust conclusions on cost-effectiveness.

LIMITATIONS

The limited number of identified trials and their differences in terms of treatment comparisons and outcomes hindered any meaningful pooling of data. None of the included trials was conducted in the UK and none assessed the use of buccal midazolam or rectal diazepam. The review of economic evaluations was hampered by lack of suitable data.

CONCLUSIONS

Both intravenous lorazepam and intravenous diazepam administered by paramedics are more effective than a placebo in the treatments of adults with convulsive status epilepticus, and intramuscular midazolam is non-inferior to intravenous lorazepam. Large well-designed clinical trials are needed to establish which benzodiazepines are more effective and preferable in the pre-hospital setting.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42020201953.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Evidence Synthesis programme and will be published in full in Health Technology Assessment; Vol. 26, No. 20. See the NIHR Journals Library website for further project information.

Steady-state pharmacokinetic simulation of intermittent vs. continuous infusion valproic acid therapy in non-critically ill and critically ill patients

OBJECTIVES

Valproic acid (VPA) is a broad-spectrum antiepileptic drug used for a variety of neurologic disorders. The relatively short half-life seen with intermittent intravenous bolus doing may lead to serum concentration variability. Continuous infusion VPA therapy is an approach to mitigate these effects. The objective of this study is to characterize the pharmacokinetics of continuous infusion of VPA in acutely ill patients and to determine dosing regimens that most frequently obtain goal steady-state serum concentrations.

METHODS

This is a retrospective pharmacokinetics study in adult patients receiving continuous infusion VPA per institutional protocol for seizure or status migrainosus. Pharmacokinetic parameters were reviewed for 234 patients (25 critically ill) and compared between the two groups (non-critically ill vs. critically ill). Intermittent and continuous infusion dosing strategies were modeled utilizing Monte Carlo simulations for both cohorts. Frequencies of serum concentration attainment were reported.

RESULTS

The percent target attainment for the non-critically ill group and critically ill group were 69.4 and 58.3% (p = 0.282) post-loading dose and 69.7 and 37.5% (p = 0.004) steady state, respectively. The volume of distribution was significantly different between the two groups (0.35 vs. 0.68 L/kg, p = < 0.0001). Highest frequency of target attainment (50-100 mcg/ml) occurred in the continuous infusion 2 mg/kg/h simulation for both critically ill (45.19%) and acutely ill (48.16%) groups.

DISCUSSION

Critically ill patients have an increased volume of distribution. Increasing the volume of distribution requires higher loading doses of VPA to obtain desired therapeutic concentrations. Continuous infusion VPA provides more consistent serum steady-state concentrations while mitigating pharmacokinetic variability.

Pharmacotherapy Overview of Seizure Management in the Adult Emergency Department

Seizures are a common cause of emergency department visits, and approximately 28% of epilepsy patients present to an emergency department annually for treatment. This article will provide an overview of the pharmacotherapeutic management of seizures and anticonvulsant therapy for patients who present to the adult emergency department, including practical information for pharmacists covering or cross-covering this practice area. The benzodiazepines are reviewed as a class, including dosing strategies, pharmacodynamic considerations, and advantages and disadvantages of lorazepam, diazepam, and midazolam. Indications for the use of phenytoin and fosphenytoin will be reviewed, as well as dosing, adverse effects, and cost-effectiveness data. In addition, dosing, administration, pharmacokinetics, and adverse effects of phenobarbital, carbamazepine, and valproate will be discussed. Clinical indications for serum anticonvulsant concentration monitoring and subsequent calculation of loading doses from serum concentrations are reviewed. Since status epilepticus is a life-threatening emergency, its therapeutic management is reviewed, including the use of continuous infusion midazolam, pentobarbital, and propofol. There are many opportunities for clinical pharmacists to collaborate with other members of the health care team to optimize efficacy and minimize adverse effects of anticonvulsant agents in the emergency department setting.

Pharmacokinetics and Clinical Utility of Valproic Acid Administered via Continuous Infusion

INTRODUCTION

Valproic acid is a versatile antiepileptic drug that is often used in the acute care setting. Intravenous valproic acid lends itself well to a continuous infusion as it exhibits a relatively short half-life. We evaluated the pharmacokinetics and clinical efficacy of continuous infusion valproic acid in hospitalized patients with migraine and seizures.

METHODS

A retrospective cohort study was performed utilizing information from the medical records of patients receiving an intravenous continuous infusion of valproic acid. Patients were included if they were aged 1 month to 85 years and they received a continuous infusion of valproic acid. Therapeutic response, common adverse effects, and the pharmacokinetic profile of valproic acid were evaluated.

RESULTS

Continuous infusion valproic acid led to a concentration within the desired range (50-100 μg/ml) in 83.4% of patients, a rate that was higher in pediatric patients. The clinical response rate was also higher in pediatric patients with seizures or migraines and appeared to be better when the concentration was >75 μg/ml. Analysis of safety parameters suggests similar safety considerations to valproic acid when administered via intermittent infusion.

CONCLUSIONS

Continuous infusion valproic acid appears to be a safe, effective, and predictable manner by which to administer valproic acid to pediatric and adult patients admitted to the hospital.

Pharmacologic management of convulsive status epilepticus in childhood

The incidence of convulsive status epilepticus in children is approximately 20-50/100,000/year, and is an emergency requiring prompt medical intervention. Prolonged seizures lasting over 5 min are unlikely to stop spontaneously, and time-to-treatment influences treatment response. Prolonged seizures should thus be treated as early status epilepticus. Mortality and morbidity increase significantly with the length of ongoing seizure activity, especially after 60 min. Benzodiazepines remain the first-line drug therapy due to their rapid onset of action. Recent studies imply that buccal midazolam is more effective and easier to administer than rectal diazepam. Phenytoin/fosphenytoin and phenobarbital administered intravenously remain the second-line treatments of choice, whilst barbiturates and midazolam as intravenous anesthetics are used for third-line treatment. Electroencephalogram monitoring is essential to evaluate the electrophysiologic treatment response and depth of anesthesia, especially in refractory status epilepticus. In the future, more individualized protocols and pathways are needed in order to optimize treatment responses. Randomized clinical trials are needed to evaluate new treatment protocols, which should not only stop the seizures more effectively but also be safer and include some neuroprotective elements to halt the cascade of neuronal injury and minimize the risk for neurologic morbidity caused by the convulsive status epilepticus.

Practice variations in the management of status epilepticus

BACKGROUND

Numerous anticonvulsant agents are now available for treating status epilepticus (SE). However, a paucity of data is available to guide clinicians in the initial treatment of seizures or SE. This study describes the current strategies being employed to treat SE in the U.S.A.

METHODS

Fifteen American academic medical centers completed a retrospective, multicenter, observational study by reviewing 10-20 of the most recent cases of SE at their institution prior to December 31, 2009. A multivariate analysis was performed to determine factors associated with cessation of seizures.

RESULTS

A total of 150 patients were included. Most patients with SE had a seizure disorder (58%). SE patients required a median of 3 AEDs for treatment. Three quarters of patients received a benzodiazepine as first-line therapy (74.7%). Phenytoin (33.3%) and levetiracetam (10%) were commonly used as the second AED. Continuous infusions of propofol, barbiturate, or benzodiazepine were used in 36% of patients. Median time to resolution of SE was 1 day and was positively associated with presence of a complex partial seizure, AED non-compliance prior to admission, and lorazepam plus another AED as initial therapy. Prolonged ICU length of stay and topiramate therapy prior to admission were negatively associated with SE resolution. Mortality was higher in patients without a history of seizure (22.2 vs. 6.9%, p = 0.006).

CONCLUSIONS

The use of a benzodiazepine followed by an AED, such as phenytoin or levetiracetam, is common as first and second-line therapy for SE and appears to be associated with a shorter time to SE resolution. AED selection thereafter is highly variable. Patients without a history of seizure who develop SE had a higher mortality rate.

Efficacy and safety of intravenous sodium valproate versus phenobarbital in controlling convulsive status epilepticus and acute prolonged convulsive seizures in children: a randomised trial

Status epilepticus and acute prolonged seizures are the most commonly occurring neurological emergencies in children. Such events have high morbidity and mortality rates along with poor long-term outcomes, depending on their duration and causes. Therefore, such seizures warrant urgent treatment using appropriate doses of anticonvulsants. Benzodiazepines, phenobarbital, and phenytoin are the most commonly used anticonvulsants for controlling status epilepticus and acute prolonged seizures. However, these medications have several well-known adverse effects. Previous studies on both adults and children have shown the efficacy and safety of rapid infusion of valproate in controlling status epilepticus. However, few well-designed randomised trials have been carried out in children, and there remains a paucity of data regarding intravenous sodium valproate use in children. Therefore, our aim was to compare the efficacy and safety of rapid loading of valproate with those of intravenous phenobarbital in children with status epilepticus and acute prolonged seizures. Sixty children (30 in each group) with convulsive status epilepticus and acute prolonged seizures were enrolled and randomly assigned to receive either valproate or phenobarbital. The main outcome variable was termination of all convulsive activity within 20 min of starting anticonvulsant infusion. Intravenous rapid loading of valproate was successful in seizure termination in (27/30, 90%) of patients compared to phenobarbital (23/30, 77%) (p = 0.189). Clinically significant adverse effects occurred in 74% patients of the phenobarbital group and 24% patients of the valproate group (p < 0.001). In conclusion, rapid loading of valproate is effective and safe in controlling convulsive status epilepticus and acute prolonged convulsive seizures in children. Intravenous valproate should be considered as a suitable choice for terminating status epilepticus and acute prolonged seizures in children.

A systematic review of randomized controlled trials on the theraputic effect of intravenous sodium valproate in status epilepticus

We performed this systematic review to determine whether intravenous sodium valproate was more effective or safer than other drugs in patients with status epilepticus (SE). A literature search was performed using Medline, Embase, and the Cochrane Central Register of Controlled Trials (CENTRAL). From 544 articles screened, 5 were identified as randomized controlled trials and were included for data extraction. The main outcomes were SE controlled and risk of seizure continuation. The meta-analysis was performed with the Random-effect model. The quality of the included studies was evaluated by GRADE (Grading of Recommendations Assessment, Development, and Evaluation). There was no significant statistics in SE controlled between intravenous sodium valproate and phenytoin. Compared with diazepam, sodium valproate had a statistically significant lower risk of time interval for control of refractory SE (RSE) after having drugs; however, there was no statistically significant difference in SE controlled within 30 min between the two groups. There was no statistically significant difference in cessation from status between intravenous sodium valproate and levetiracetam. Intravenous sodium valprate was as effective as intravenous phenytoin for SE controlled and risk of seizure continuation.

Pharmacological management of seizures and status epilepticus in critically ill patients

Seizures are serious complications seen in critically ill patients and can lead to significant morbidity and mortality if the cause is not identified and treated quickly. Uncontrolled seizures can lead to status epilepticus (SE), which is considered a medical emergency. The first-line treatment of seizures is an intravenous (IV) benzodiazepine followed by anticonvulsant therapy. Refractory SE can evolve into a nonconvulsive state requiring IV anesthetics or induction of pharmacological coma. To prevent seizures and further complications in critically ill patients with acute neurological disease or injury, short-term seizure prophylaxis should be considered in certain patients.

Intravenous sodium valproate in mainland China for the treatment of diazepam refractory convulsive status epilepticus

The purpose of this study was to identify the short-term safety and efficacy of treating patients with intravenous (i.v.) sodium valproate (VPA) for diazepam (DZP) refractory convulsive status epilepticus (CSE). We prospectively registered 48 patients with refractory CSE who were treated at West China Hospital with i.v. VPA (30mg/kg, 6mg/kg per hour) after a loading dose of i.v. DZP and intramuscular phenobarbitone (PBT) failed. VPA stopped seizures in 87.5% of patients within 1h, and patients regained baseline mental status within 1h of seizure cessation. CSE did not recur in patients within the next 12h, and no significant VPA-related systemic or local side effects were found during their hospital stay. In conclusion, this study suggests that i.v. VPA is a promising option for DZP refractory CSE in mainland China, since i.v. PBT is unavailable in most hospitals, and anesthesia is unacceptable to most of the Chinese population.

Treatment of status epilepticus and acute repetitive seizures with i.v. valproic acid vs phenytoin

OBJECTIVE

To evaluate the efficacy and tolerability of the treatment with valproic acid (VPA) in patients with status epilepticus (SE) or acute repetitive seizures (ARS) comparing it with phenytoin (PHT) treatment.

MATERIALS AND METHODS

Patients with SE or ARS were treated in a consecutive manner with either VPA or PHT intravenously. The primary endpoint was defined as clinical seizure cessation; the secondary endpoint was evaluation of drug tolerability.

RESULTS

Seventy-four adult patients with SE or ARS participated in the study, 49 with VPA i.v. and 25 PHT i.v. In 43 (87.8%) of the VPA patients, the seizures discontinued, and no rescue medication was needed. Similar results were found in the PHT group in which seizures of 22 (88%) patients were well controlled. Side effects were found in 12% of the PHT group, and in none of the VPA group.

CONCLUSIONS

VPA i.v. seems to be effective and well tolerated in adult patients with SE or ARS.

Nonconvulsive status epilepticus in terminally ill patients-a diagnostic and therapeutic challenge

Nonconvulsive status epilepticus (NCSE) is rarely considered as a cause of confusion in terminally ill patients. The clinical presentation varies from altered mental status to coma, without visible convulsions. Electroencephalogram is the most important diagnostic tool to identify epileptiform activity. Treatment should be initiated following a stepwise model, avoiding intubation and transfer to the intensive care unit. Although mortality rates are high, in some patients NCSE can be reversed by treatment. NCSE should be considered in a differential diagnosis of all terminally ill patients with sudden mental status changes. We present two cases and discuss treatment options and the borders of therapy.

Status epilepticus

Status epilepticus (SE) in adults is a state of continuous seizures lasting more than 5 minutes, or rapidly recurrent seizures without regaining consciousness. The overall US and European estimated crude incidence rate of SE ranges from 6.8 to 41/100,000/yr. The etiologies of SE include primary central nervous system pathologies and systemic disorders. The two basic mechanisms involved in the genesis of SE are an excess of excitatory activity and a loss of normal inhibitory neurotransmission. Mortality associated with SE can be as high as 26% for the average adult. Early recognition and treatment are important for improving the chances for a good outcome. The first line of treatment is an intravenous benzodiazepine, with lorazepam being the current preferred agent. All patients with SE who remain with altered awareness 20 to 30 minutes after cessation of clinical seizures should undergo electroencephalographic studies, because up to 20% of patients without clinical evidence of seizures after initial treatment can have nonconvulsive SE.

Status epilepticus: evidence and controversy

Status Epilepticus (SE) is a potential and relatively common complication of epileptic seizures. Traditionally, SE was defined as 30 minutes of continuous seizure activity or a series of seizures without return to full consciousness between the seizures. As a practical rule, it is admitted that all patients arriving at the emergency room suffering from epileptic seizures could have SE and should be treated accordingly. It is well known that the longer an attack has lasted, the more difficult it is to control in the next 5 to 10 minutes. On the other hand, once an attack has lasted for over 5 to 10 minutes, it is unlikely to cease spontaneously. Ambulatory intervention should focus on this "therapeutic interval" in acute attacks with the use of first-line drugs such as the intramuscular, rectal, oral, and/or intranasal application of benzodiazepines (BZD). Treatment of SE is a medical emergency, which should include 3 priority objectives: (1) to stop the seizures; (2) to maintain internal homeostasis; and (3) to treat possible complications. Current consensus is that a BZD, notably lorazepam or diazepam, is the initial class of drug for the treatment of SE. Phenytoin, fosphenytoin, or valproate generally is agreed upon as the next drugs to be administered. Failure to respond to optimal BZD and phenytoin loading operationally defines refractory SE.

Diagnosis and management of nonconvulsive status epilepticus in children

Nonconvulsive status epilepticus (NCSE) encompasses a wide range of diagnoses with variable outcomes and treatment recommendations. In children, NCSE can be observed in various conditions, including acute neurological injuries, specific childhood epilepsy syndromes and other neurological conditions, and can also be observed in individuals with learning difficulties. NCSE in children is thought to be under-recognized, and further studies examining the electrographic characteristics of very young children in NCSE would aid the prompt recognition of additional patients. Some subtypes of NCSE are probably more harmful than others, and long-term prospective studies are needed to evaluate the damaging potential of NCSE itself as opposed to that of the underlying circumstances in which it occurs. Specific data in childhood are clearly lacking, but extrapolation from adult studies indicates that aggressive treatment is most warranted in comatose patients. By contrast, a cautious approach seems to be indicated for absence status epilepticus, complex partial status epilepticus and electrical status epilepticus during sleep.

Valproate protein binding following rapid intravenous administration of high doses of valproic acid in patients with epilepsy

OBJECTIVE

To characterize protein binding in patients with epilepsy who achieve transient high (>150 mg/L) total plasma concentrations following rapid valproate infusion at very high doses.

METHODS

Patients with epilepsy (n = 40) were administered 20 or 30 mg/kg loading doses (6 or 10 mg/kg/min) of undiluted valproate sodium injection. Total and unbound valproic acid (VPA) concentrations were used to assess VPA binding to plasma albumin. One- and two-binding site models were explored in a nonlinear mixed effects population analysis framework. The relative importance of weight, age, sex, race and enzyme-inducing comedications on the binding site association constant (K) was examined using the likelihood ratio test. Intersubject and intrasubject variabilities were characterized using exponential or proportional error models.

RESULTS

Optimal characterization of the data was achieved using the one-binding site model. Population binding parameter estimates (standard error) for number of binding sites (N) and K were 1.98 (0.0865) and 15.5 [2.28 (1/mM)], respectively. No significant covariates were identified for VPA protein binding. The intersubject and intrasubject coefficients of variation were 32% and 14%, respectively.

CONCLUSIONS

A one-binding site model without any significant covariates for binding constants optimally described VPA protein binding. As the estimated dissociation constant (1/K, 64.5 microm or 9.3 mg/L) was within the therapeutic range (5-15 mg/L) for unbound VPA concentrations, protein binding was nonlinear. Although the range of unbound fraction and VPA concentrations were much higher than previous studies, the dissociation constant was consistent with historical data in normal healthy adults and epilepsy patients receiving lower doses.

Randomized study of intravenous valproate and phenytoin in status epilepticus

INTRODUCTION

The evidence based data to guide management in patients of benzodiazepine refractory status epilepticus (SE) is still lacking. We conducted a randomized study to evaluate the comparative effect of intravenous (IV) phenytoin and intravenous valproate (IV VA) in patients of benzodiazepine refractory SE.

BACKGROUND AND METHODS

Hundred, age and sex matched, patients of benzodiazepine refractory SE were randomly divided into Group A (50 patients), treated with IV VA and Group B (50 patients) treated with IV phenytoin. Twelve patients, in whom SE was not controlled with a single drug, were switched over to the other group. Treatment was considered successful when all motor or EEG seizure activity ceased within 20 min after the beginning of the drug infusion and no return of seizure activity during the next 12h. Secondary study end points were adverse events to treatment, in-hospital complications and the neurological outcome at discharge.

RESULTS

In this study, IV VA was successful in 88% and IV phenytoin in 84% (p>0.05) of patients of SE with a significantly better response in patients of SE <2h (p<0.05). The total number of adverse events did not differ significantly between the two groups (p>0.05). There were no differences among the treatments with respect to recurrence after 12-h study period or the outcome at 7 days.

CONCLUSION

IV VA is as effective as IV phenytoin. It is easy to use, better tolerated and can be used as an alternative to IV phenytoin in patients of benzodiazepine refractory SE, especially in patients of cardio-respiratory disease. The better outcome in patients having shorter duration of SE (<2h) suggests need of immediate treatment.

Comparative Efficacy and Safety of Antiepileptic Drugs for the Treatment of Status Epilepticus

Status epilepticus (SE) is a medical emergency with high mortality rate. Common causes of SE include noncompliance with antiepileptic medications, drug- and alcohol-related etiologies, and central nervous system (CNS) infections. Because prolonged seizures can cause neuronal damage, treatment should be initiated promptly to avoid potential complications. Previous studies support intravenous (IV) lorazepam as first-line therapy and IV phenytoin or fosphenytoin as a second-line medication. If first-and second-line medications fail to control SE, further treatment with propofol, pentobarbital, midazolam, or other medications should be considered. Many of the drugs currently used to control SE are associated with sedation, respiratory suppression, hypotension, cardiac dysrhythmia, and anaphylactic reactions. Therefore, IV valproate or other newer antiepileptic drugs may be considered as an alternative third-line therapy for those who cannot tolerate the hypotensive effects of other anticonvulsants. This paper reviews comparative effectiveness and safety concerns among frequently used medications for SE.

Clinical Utility of a Continuous Intravenous Infusion of Valproic Acid in Pediatric Patients

STUDY OBJECTIVE

To describe the dose-concentration relationship of a continuous intravenous infusion of valproic acid (VPA) in pediatric patients when a dosing protocol is used.

DESIGN

Retrospective and concurrent chart review.

SETTING

Tertiary care, 473-bed, academic medical center with a 120-bed, dedicated children's hospital.

PATIENTS

Twenty-six pediatric patients (< 18 yrs old) who received VPA according to the protocol for continuous intravenous infusions between January 1, 2004, and March 31, 2006, identified by using a pharmacy order-entry system.

MEASUREMENTS AND MAIN RESULTS

Patient demographics, VPA treatment regimens, clinical responses, and safety data were recorded and analyzed. Median patient age was 8.5 years (range 1.4-16 yrs). Approximately two thirds received VPA for seizures, and one third for migraines. Patients were given a mean +/- SD VPA loading dose of 28.5 +/- 5.2 mg/kg followed by a continuous infusion rate of 1 +/- 0.2 mg/kg/hour. Mean +/- SD serum concentration measured 4.5 +/- 1.6 hours after the loading dose was 83.3 +/- 22.8 microg/ml. Steady-state concentration at 23.3 +/- 3.0 hours after the start of the continuous infusion was 80.0 +/- 26.0 microg/ml. Postload and steady-state serum concentrations were within the target concentration of 50-100 microg/ml in 77% and 69% of patients, respectively. On further analysis, when the target range was expanded to 50-125 microg/ml (125 microg/ml was deemed acceptable if no adverse effects were noted), 89% and 92% of patients, respectively, had postload and steady-state VPA serum concentrations within this range. The response rate was excellent, with nearly 85% of patients achieving a complete or partial response to therapy. Adverse effects were generally mild and uncommon.

CONCLUSIONS

The continuous-infusion protocol permitted rapid intravenous loading of VPA in pediatric patients while minimizing adverse events and achieving concentrations in the upper region of the therapeutic range.

Generalised convulsive status epilepticus: an overview

Generalised convulsive status epilepticus is one of the most common emergencies encountered in clinical practice. This review discusses the recent understanding of this life-threatening condition with reference to the definition, pathophysiology, evaluation, complications, refractory status and prognosis. Besides epilepsy, other neurological and medical illnesses could be associated with status epilepticus. The goals of management and pharmacological approach are outlined, considering the available evidence. Prompt recognition and timely intervention, including pre-hospital treatment, are therapeutically beneficial. Refractory status should be managed in intensive care units under close monitoring. More evidence is needed for evolving the optimal treatment. A suitable treatment protocol would guide in avoiding the pitfalls at various points along the management pathway.

EFNS guideline on the management of status epilepticus

The objective of the current paper was to review the literature and discuss the degree of evidence for various treatment strategies for status epilepticus (SE) in adults. We searched MEDLINE and EMBASE for relevant literature from 1966 to January 2005. Furthermore, the Cochrane Central Register of Controlled Trials (CENTRAL) was sought. Recommendations are based on this literature and on our judgement of the relevance of the references to the subject. Recommendations were reached by informative consensus approach. Where there was a lack of evidence but consensus was clear we have stated our opinion as good practice points. The preferred treatment pathway for generalised convulsive status epilepticus (GCSE) is intravenous (i.v.) administration of 4 mg of lorazepam or 10 mg of diazepam directly followed by 15-18 mg/kg of phenytoin or equivalent fosphenytoin. If seizures continue for more than 10 min after first injection another 4 mg of lorazepam or 10 mg of diazepam is recommended. Refractory GCSE is treated by anaesthetic doses of midazolam, propofol or barbiturates; the anaesthetics are titrated against an electroencephalogram burst suppression pattern for at least 24 h. The initial therapy of non-convulsive SE depends on the type and the cause. In most cases of absence SE, a small i.v. dose of lorazepam or diazepam will terminate the attack. Complex partial SE is initially treated such as GCSE, however, when refractory further non-anaesthetising substances should be given instead of anaesthetics. In subtle SE i.v. anaesthesia is required.

Management of Seizures in the Critically Ill

Seizures in a critically ill patient are not infrequent phenomena. Physicians are perplexed by the wide range of possible cranial or extracranial etiologies, alerted by the risk for further crucial organ compromise if seizures recur, and confused about the treatment options in an environment rich in complex drug interactions and multiple organ dysfunction. The advent of an armamentarium containing multiple new antiepileptic medications complicates the situation further, since several of them have less known mechanisms of action, side effects, or interactions with other intensive care unit (ICU) medications. This review contains useful information regarding the most common etiologies and treatment options for intensivists, consulting neurologists, neurosurgeons, or other specialized physicians treating ICU patients with seizures.

Chemically Induced Seizures

Drug- and toxin-associated seizures (DTS) may result from exposure to a wide variety of agents. Most DTS can be managed with supportive care. First-line anticonvulsant therapy should include benzodiazepines, unless agents require a specific antidote. Phenytoin is generally not expected to be useful for DTS and in some instances may be harmful. In this article the authors discuss the pathophysiology of DTS, the potential differential diagnosis, and the clinical presentation. They also review selected agents that cause DTS and provide an overview of how the clinician should approach the management of patients who have DTS.

Animal models for the development of new neuropharmacological therapeutics in the status epilepticus

Status epilepticus (SE) is a major medical emergency associated with significant morbidity and mortality. SE is best defined as a continuous, generalized, convulsive seizure lasting > 5 min, or two or more seizures during which the patient does not return to baseline consciousness. The relative efficacy and safety of different drugs in the treatment of human SE should be determined in a prospective, randomized, blinded study. However, complementary animal models of SE are required to answer important questions concerning the treatment of SE because of the obvious difficulties of setting up such studies in clinical emergency conditions. This review offers an overview of the implementation and characteristics of some of the most prevalent animal models of SE currently in use. A description is also provide about how animal models of SE may facilitate the use of neurobiological techniques to successfully address critical questions in the drug treatment of SE. In particular, the experience with recently introduced drugs such as intravenous valproate will be addressed. Finally, the importance of some animal models and pharmacological approaches is explained and we discuss their impact in the development of therapeutic strategies to improve pharmacological treatment for SE is discussed.

Refractory generalised convulsive status epilepticus : a guide to treatment

The patient with status epilepticus has continuous or rapidly repeating seizures. Generalised convulsive status epilepticus (GCSE) is the most common form of the disorder and is a life-threatening condition that requires prompt medical management. Status epilepticus that does not respond to first-line benzodiazepines (lorazepam or diazepam) or to second-line antiepileptic drugs (phenytoin/fosphenytoin, phenobarbital or valproate) is usually considered refractory and requires more aggressive treatment. The optimal treatment of refractory GCSE has not been defined, but patients should be treated in an intensive care unit, as artificial ventilation and haemodynamic support are required. Invasive haemodynamic monitoring is often necessary and EEG monitoring is essential. The drug treatment of refractory GCSE involves general anaesthesia with continuous intravenous anaesthetics given in doses that abolish all clinical and electrographic epileptic activity, often requiring sedation to the point of burst suppression on the EEG. Barbiturate anaesthetics, pentobarbital in the US and thiopental sodium in Europe and Australia, are the most frequently used agents and are highly effective for refractory GCSE both in children and adults. Indeed, they remain the only way to stop seizure activity with certainty in severely refractory cases. Other options are midazolam for adults and children and propofol for adults only.Regardless of the drug selected, intravenous fluids and vasopressors are usually required to treat hypotension. Once seizures have been controlled for 12-24 hours, continuous intravenous therapy should be gradually tapered off if the drug being administered is midazolam or propofol. Gradual tapering is probably not necessary with pentobarbital or thiopental sodium. Continuous EEG monitoring is required during high-dose treatment and while therapy is gradually withdrawn. During withdrawal of anaesthetic therapy, intravenous phenytoin/fosphenytoin or valproate should be continued (these agents having been administered during earlier phases of GCSE) to ensure an adequate baseline of antiepileptic medication so as to prevent the recurrence of status epilepticus. If additional medication is needed, the most appropriate antiepileptic drugs are gabapentin for focal seizures and levetiracetam and topiramate for all seizure types, as these drugs can be started at high doses with a low risk of idiosyncratic reactions. Even with current best practice, mortality in patients who experience refractory GCSE is about 50% and only the minority return to their premorbid functional baseline. Therefore, new treatment options are urgently needed. The ideal new drug for refractory GCSE would be one that has the ability to stop seizures more effectively and safely than current drugs, and that has neuroprotective properties to prevent the brain damage and neurological morbidity caused by GCSE.

Drug- and toxin-associated seizures

Drug- and toxin-associated seizures may result from exposure to a wide variety of agents. Obtaining a comprehensive history behind the exposure is generally more helpful than diagnostic testing. Most DTS may be managed with supportive care, including benzodiazepines, except in the case of agents that require a specific intervention or antidote.

Valproate suppresses status epilepticus induced by 4-aminopyridine in CA1 hippocampus region

PURPOSE

We investigated the effects of valproate (VPA) on an in vivo model of status epilepticus (SE) induced by intrahippocampal application of 4-aminopyridine (4-AP).

METHODS

To induce continuous epileptiform activity without a clinical component, 4-AP (100 mM) was slowly injected in the hippocampus of adult rats. Extracellular field potential from the CA1 region of the rat hippocampus was recorded to assess abnormal epileptiform activity. Once the SE seizures were induced by 4-AP, the test drug was injected. In some experiments to test the ability of a drug to prevent the induction of SE, the drug was administered before 4-AP injection.

RESULTS

Intrahippocampal injection of 4-AP induced continuous epileptic activity without a clinical component that lasted >60 min. The intravenous injection of 400-600 mg/kg VPA rapidly (approximately 100 s) abolished the SE, and this effect persisted for >/=4 h in our experimental model. The intravenous injection of 100-300 mg/kg VPA did not abolish previously induced SE, but prevented the appearance of SE when applied before the induction of SE. The intravenous injection of 80 mg/kg phenytoin or carbamazepine did not abolish or prevent SE.

CONCLUSIONS

We conclude that 4-AP-induced SE was suppressed by VPA at 400-600 mg/kg, whereas minor doses (100-300 mg/kg) only prevent the 4-AP-induced SE. Present results suggest the revisiting of VPA as a useful drug for the treatment of SE.

Status epilepticus: a review of different syndromes, their current evaluation, and treatment

BACKGROUND

Status epilepticus (SE) encompasses a wide range of seizure types with different clinical presentations, pathophysiologies, treatment imperatives, and outcomes. The most dramatic and life-threatening form, generalized convulsive status epilepticus, has been reviewed in all of these aspects, but other less common types of SE have been described less extensively.

REVIEW SUMMARY

Definitions of generalized convulsive SE and its pathophysiology are reviewed briefly. Defining SE by a specific duration of seizures is controversial and has implications for studies and for clinical management. Several types of SE are different in their causes, presentations, and outcomes. Many are underdiagnosed. This article focuses on the pharmacology and clinical studies of several anticonvulsant medications used to treat SE. A protocol approach is not detailed. Rather, the clinical evaluation begins with meticulous diagnosis of the type of SE. Establishing the SE syndrome diagnosis and use of anticonvulsants with demonstrated effectiveness facilitate an appropriate treatment plan for individual patients. Recent developments in the basic science of SE raise the possibility of better treatments in the future.

CONCLUSIONS

As there are many types of seizures, there are also many types of SE. Each has unique presentations and treatment considerations. Review of actual clinical data from SE treatment studies should be helpful in devising the best treatment for an individual patient.

Diagnosis and Treatment of Nonconvulsive Status Epilepticus in an Intensive Care Unit Setting

Nonconvulsive status epilepticus (NCSE) in adults is a heterogeneous epileptic emergency and includes absence status (AS), complex-partial status epilepticus (CPSE), and the status epilepticus of epileptic encephalopathy (SEEE). The latter seems to be strikingly frequent among patients in intensive care units (ICU). Diagnosis of NCSE is difficult, but has to be made quickly. It relies on clinical signs and a confirmation electroencephalography (EEG). According to the different etiologies and outcomes of AS, CPSE, and SEEE, treatment has to be individually adapted, but needs to follow some basic principles--treatment should take place in the ICU and be monitored by continuous EEG. With a few exceptions, the first drug is an intravenous benzodiazepine, mainly lorazepam. Intravenous fosphenytoin or phenytoin or valproate may follow next. If some forms of NCSE are resistant to first- and second-line treatments, single or combinations of anesthetics and enteral antiepileptic drugs (AEDs) may be added. This opinion is not evidence-based, and randomized controlled prospective trials to evaluate optimal treatment of NCSE are of first priority.