Comparative audit of intravenous lorazepam and diazepam in the emergency treatment of convulsive status epilepticus in children

Why won't it stop? The dynamics of benzodiazepine resistance in status epilepticus

Status epilepticus is a life-threatening neurological emergency that affects both adults and children. Approximately 36% of episodes of status epilepticus do not respond to the current preferred first-line treatment, benzodiazepines. The proportion of episodes that are refractory to benzodiazepines is higher in low-income and middle-income countries (LMICs) than in high-income countries (HICs). Evidence suggests that longer episodes of status epilepticus alter brain physiology, thereby contributing to the emergence of benzodiazepine resistance. Such changes include alterations in GABA_A receptor function and in the transmembrane gradient for chloride, both of which erode the ability of benzodiazepines to enhance inhibitory synaptic signalling. Often, current management guidelines for status epilepticus do not account for these duration-related changes in pathophysiology, which might differentially impact individuals in LMICs, where the average time taken to reach medical attention is longer than in HICs. In this Perspective article, we aim to combine clinical insights and the latest evidence from basic science to inspire a new, context-specific approach to efficiently managing status epilepticus.

Benzodiazepines in the Management of Seizures and Status Epilepticus: A Review of Routes of Delivery, Pharmacokinetics, Efficacy, and Tolerability

Status epilepticus (SE) is an acute, life-threatening medical condition that requires immediate, effective therapy. Therefore, the acute care of prolonged seizures and SE is a constant challenge for healthcare professionals, in both the pre-hospital and the in-hospital settings. Benzodiazepines (BZDs) are the first-line treatment for SE worldwide due to their efficacy, tolerability, and rapid onset of action. Although all BZDs act as allosteric modulators at the inhibitory gamma-aminobutyric acid (GABA)_A receptor, the individual agents have different efficacy profiles and pharmacokinetic and pharmacodynamic properties, some of which differ significantly. The conventional BZDs clonazepam, diazepam, lorazepam and midazolam differ mainly in their durations of action and available routes of administration. In addition to the common intravenous, intramuscular and rectal administrations that have long been established in the acute treatment of SE, other administration routes for BZDs-such as intranasal administration-have been developed in recent years, with some preparations already commercially available. Most recently, the intrapulmonary administration of BZDs via an inhaler has been investigated. This narrative review provides an overview of the current knowledge on the efficacy and tolerability of different BZDs, with a focus on different routes of administration and therapeutic specificities for different patient groups, and offers an outlook on potential future drug developments for the treatment of prolonged seizures and SE.

Drug management for acute tonic-clonic convulsions including convulsive status epilepticus in children

BACKGROUND

Tonic-clonic convulsions and convulsive status epilepticus (currently defined as a tonic-clonic convulsion lasting at least 30 minutes) are medical emergencies and require urgent and appropriate anticonvulsant treatment. International consensus is that an anticonvulsant drug should be administered for any tonic-clonic convulsion that has been continuing for at least five minutes. Benzodiazepines (diazepam, lorazepam, midazolam) are traditionally regarded as first-line drugs and phenobarbital, phenytoin and paraldehyde as second-line drugs. This is an update of a Cochrane Review first published in 2002 and updated in 2008.

OBJECTIVES

To evaluate the effectiveness and safety of anticonvulsant drugs used to treat any acute tonic-clonic convulsion of any duration, including established convulsive (tonic-clonic) status epilepticus in children who present to a hospital or emergency medical department.

SEARCH METHODS

For the latest update we searched the Cochrane Epilepsy Group's Specialised Register (23 May 2017), the Cochrane Central Register of Controlled Trials (CENTRAL) via the Cochrane Register of Studies Online (CRSO, 23 May 2017), MEDLINE (Ovid, 1946 to 23 May 2017), ClinicalTrials.gov (23 May 2017), and the WHO International Clinical Trials Registry Platform (ICTRP, 23 May 2017).

SELECTION CRITERIA

Randomised and quasi-randomised trials comparing any anticonvulsant drugs used for the treatment of an acute tonic-clonic convulsion including convulsive status epilepticus in children.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion and extracted data. We contacted study authors for additional information.

MAIN RESULTS

The review includes 18 randomised trials involving 2199 participants, and a range of drug treatment options, doses and routes of administration (rectal, buccal, nasal, intramuscular and intravenous). The studies vary by design, setting and population, both in terms of their ages and also in their clinical situation. We have made many comparisons of drugs and of routes of administration of drugs in this review; our key findings are as follows:(1) This review provides only low- to very low-quality evidence comparing buccal midazolam with rectal diazepam for the treatment of acute tonic-clonic convulsions (risk ratio (RR) for seizure cessation 1.25, 95% confidence interval (CI) 1.13 to 1.38; 4 trials; 690 children). However, there is uncertainty about the effect and therefore insufficient evidence to support its use. There were no included studies which compare intranasal and buccal midazolam.(2) Buccal and intranasal anticonvulsants were shown to lead to similar rates of seizure cessation as intravenous anticonvulsants, e.g. intranasal lorazepam appears to be as effective as intravenous lorazepam (RR 0.96, 95% CI 0.82 to 1.13; 1 trial; 141 children; high-quality evidence) and intranasal midazolam was equivalent to intravenous diazepam (RR 0.98, 95% CI 0.91 to 1.06; 2 trials; 122 children; moderate-quality evidence).(3) Intramuscular midazolam also showed a similar rate of seizure cessation to intravenous diazepam (RR 0.97, 95% CI 0.87 to 1.09; 2 trials; 105 children; low-quality evidence).(4) For intravenous routes of administration, lorazepam appears to be as effective as diazepam in stopping acute tonic clonic convulsions: RR 1.04, 95% CI 0.94 to 1.16; 3 trials; 414 children; low-quality evidence. Furthermore, we found no statistically significant or clinically important differences between intravenous midazolam and diazepam (RR for seizure cessation 1.08, 95% CI 0.97 to 1.21; 1 trial; 80 children; moderate-quality evidence) or intravenous midazolam and lorazepam (RR for seizure cessation 0.98, 95% CI 0.91 to 1.04; 1 trial; 80 children; moderate-quality evidence). In general, intravenously-administered anticonvulsants led to more rapid seizure cessation but this was usually compromised by the time taken to establish intravenous access.(5) There is limited evidence from a single trial to suggest that intranasal lorazepam may be more effective than intramuscular paraldehyde in stopping acute tonic-clonic convulsions (RR 1.22, 95% CI 0.99 to 1.52; 160 children; moderate-quality evidence).(6) Adverse side effects were observed and reported very infrequently in the included studies. Respiratory depression was the most common and most clinically relevant side effect and, where reported, the frequency of this adverse event was observed in 0% to up to 18% of children. None of the studies individually demonstrated any difference in the rates of respiratory depression between the different anticonvulsants or their different routes of administration; but when pooled, three studies (439 children) provided moderate-quality evidence that lorazepam was significantly associated with fewer occurrences of respiratory depression than diazepam (RR 0.72, 95% CI 0.55 to 0.93).Much of the evidence provided in this review is of mostly moderate to high quality. However, the quality of the evidence provided for some important outcomes is low to very low, particularly for comparisons of non-intravenous routes of drug administration. Low- to very low-quality evidence was provided where limited data and imprecise results were available for analysis, methodological inadequacies were present in some studies which may have introduced bias into the results, study settings were not applicable to wider clinical practice, and where inconsistency was present in some pooled analyses.

AUTHORS' CONCLUSIONS

We have not identified any new high-quality evidence on the efficacy or safety of an anticonvulsant in stopping an acute tonic-clonic convulsion that would inform clinical practice. There appears to be a very low risk of adverse events, specifically respiratory depression. Intravenous lorazepam and diazepam appear to be associated with similar rates of seizure cessation and respiratory depression. Although intravenous lorazepam and intravenous diazepam lead to more rapid seizure cessation, the time taken to obtain intravenous access may undermine this effect. In the absence of intravenous access, buccal midazolam or rectal diazepam are therefore acceptable first-line anticonvulsants for the treatment of an acute tonic-clonic convulsion that has lasted at least five minutes. There is no evidence provided by this review to support the use of intranasal midazolam or lorazepam as alternatives to buccal midazolam or rectal diazepam.

Is intravenous lorazepam really more effective and safe than intravenous diazepam as first-line treatment for convulsive status epilepticus? A systematic review with meta-analysis of randomized controlled trials

BACKGROUND

Some guidelines or expert consensus indicate that intravenous (IV) lorazepam (LZP) is preferable to IV diazepam (DZP) for initial treatment of convulsive status epilepticus (SE). We aimed to critically assess all the available data on efficacy and tolerability of IV LZP compared with IV DZP as first-line treatment of convulsive SE.

METHODS

Systematic search of the literature (MEDLINE, CENTRAL, EMBASE, ClinicalTrials.gov) to identify randomized controlled trials (RCTs) comparing IV LZP versus IV DZP used as first-line treatment for convulsive SE (generalized or focal). Inverse variance, Mantel-Haenszel meta-analysis to obtain risk ratio (RR) with 95% confidence intervals (CI) of following outcomes: seizure cessation after drug administration; continuation of SE requiring a different drug; seizure cessation after a single dose of medication; need for ventilator support; clinically relevant hypotension.

RESULTS

Five RCTs were included, with a total of 656 patients, 320 randomly allocated to IV LZP and 336 to IV DZP. No statistically significant differences were found between IV LZP and IV DZP for clinical seizure cessation (RR 1.09; 95% CI 1.00 to 1.20), continuation of SE requiring a different drug (RR 0.76; 95% CI 0.57 to 1.02), seizure cessation after a single dose of medication (RR 0.96; 95% CI 0.85 to 1.08), need for ventilator support RR 0.93; 95% CI 0.61 to 1.43, and clinically relevant hypotension.

CONCLUSION

Despite its favorable pharmacokinetic profile, a systematic appraisal of the literature does not provide evidence to strongly support the preferential use of IV LZP as first-line treatment of convulsive SE over IV DZP.

Lorazepam or diazepam for convulsive status epilepticus: A meta-analysis

Convulsive status epilepticus (CSE) is a neurological emergency in adults and children. However, whether a particular benzodiazepine is of superior efficacy and safety in management of CSE is controversial. We performed a meta-analysis to compare the outcome of lorazepam and diazepam for treating CSE. We searched the PubMed, Medline, Embase, Cochrane Central Register of Controlled Trials, and Google Scholar databases from 1966 to February 2014. No language restriction was applied. Reference lists of all the selected articles were hand-searched for any additional trials. Trial quality was assessed using the modified Jadad scale and the Consolidated Standards Of Reporting Trials (CONSORT) checklist. Two authors independently extracted data from all eligible studies, including study design, participants, interventions, and outcomes. The data was analyzed using fixed-effects or random-effects models with mean differences and risk ratios for continuous and dichotomous variables, respectively. A total of six studies involving 970 patients were included in this analysis. The majority of patients were children (n=574) and 396 patients were adults. Meta-analysis showed no significant difference between the two treatment groups regarding seizure control and adverse effects regardless of patient age. This meta-analysis demonstrates that diazepam and lorazepam have equal efficacy and side effects for treating CSE in adults and children, and either can be chosen as a reasonable first-line therapy. More high quality randomized controlled trials are needed to support this finding.

Therapeutic choices in convulsive status epilepticus

INTRODUCTION

Convulsive status epilepticus (SE) is one of the most frequent and severe neurological emergencies in both adults and children. A timely administration of appropriate antiepileptic drugs (AEDs) can stop seizures early and markedly improve outcome.

AREAS COVERED

The main treatment strategies for SE are reviewed with an emphasis on initial treatments. The established first-line treatment consists of benzodiazepines, most frequently intravenous lorazepam. Benzodiazepines that do not require intravenous administration like intranasal midazolam or intramuscular midazolam are becoming more popular because of easier administration in the field. Other benzodiazepines may also be effective. After treatment with benzodiazepines, treatment with fosphenytoin and phenobarbital is usually recommended. Other intravenously available AEDs, such as valproate and levetiracetam, may be as effective and safe as fosphenytoin and phenobarbital, have a faster infusion time and better pharmacokinetic profile. The rationale behind the need for an early treatment of SE is discussed. The real-time delays of AED administration in clinical practice are described.

EXPERT OPINION

There is limited evidence to support what the best initial benzodiazepine or the best non-benzodiazepine AED is. Recent and developing multicenter trials are evaluating the best treatment options and will likely modify the recommended treatment choices in SE in the near future. Additionally, more research is needed to understand how different treatment options modify prognosis in SE. Timely implementation of care protocols to minimize treatment delays is crucial.

The relative effectiveness of five antiepileptic drugs in treatment of benzodiazepine-resistant convulsive status epilepticus: a meta-analysis of published studies

PURPOSE

Systematic evaluation of published evidence-base of the efficacy of five antiepileptic drugs - lacosamide, levetiracetam, valproate, phenytoin and phenobarbital - in convulsive benzodiazepine-resistant status epilepticus.

METHODS

Data sources included electronic databases, personal communication, and back tracing of references in pertinent studies. These were prospective and retrospective human studies presenting original data for participants with convulsive benzodiazepine-resistant status epilepticus. Interventions were intravenous lacosamide, levetiracetam, phenobarbital, phenytoin and valproate. Outcome measured is clinically detectable cessation of seizure activity. Level-of-evidence was assessed according to Oxford Centre of Evidence-Based Medicine and The Cochrane Collaboration's Tool for Assessment of Risk. Twenty seven studies (798 cases of convulsive status epilepticus) were identified and 22 included in a meta-analysis. Random-effects analysis of dichotomous outcome of a single group estimate (proportion), with inverse variance weighting, was implemented. Several sources of clinical and methodological heterogeneity were identified.

RESULTS

Efficacy of levetiracetam was 68.5% (95% CI: 56.2-78.7%), phenobarbital 73.6% (95% CI: 58.3-84.8%), phenytoin 50.2% (95% CI: 34.2-66.1%) and valproate 75.7% (95% CI: 63.7-84.8%). Lacosamide studies were excluded from the meta-analysis due to insufficient data.

CONCLUSION

Valproate, levetiracetam and phenobarbital can all be used as first line therapy in benzodiazepine-resistant status epilepticus. The evidence does not support the first-line use of phenytoin. There is not enough evidence to support the routine use of lacosamide. Randomized controlled trials are urgently needed.

Gaps and opportunities in refractory status epilepticus research in children: a multi-center approach by the Pediatric Status Epilepticus Research Group (pSERG)

PURPOSE

Status epilepticus (SE) is a life-threatening condition that can be refractory to initial treatment. Randomized controlled studies to guide treatment choices, especially beyond first-line drugs, are not available. This report summarizes the evidence that guides the management of refractory convulsive SE (RCSE) in children, defines gaps in our clinical knowledge and describes the development and works of the 'pediatric Status Epilepticus Research Group' (pSERG).

METHODS

A literature review was performed to evaluate current gaps in the pediatric SE and RCSE literature. In person and online meetings helped to develop and expand the pSERG network.

RESULTS

The care of pediatric RCSE is largely based on extrapolations of limited evidence derived from adult literature and supplemented with case reports and case series in children. No comparative effectiveness trials have been performed in the pediatric population. Gaps in knowledge include risk factors for SE, biomarkers of SE and RCSE, second- and third-line treatment options, and long-term outcome.

CONCLUSION

The care of children with RCSE is based on limited evidence. In order to address these knowledge gaps, the multicenter pSERG was established to facilitate prospective collection, analysis, and sharing of de-identified data and biological specimens from children with RCSE. These data will allow identification of treatment strategies associated with better outcomes and delineate evidence-based interventions to improve the care of children with SE.

Guidelines for the evaluation and management of status epilepticus

Status epilepticus (SE) treatment strategies vary substantially from one institution to another due to the lack of data to support one treatment over another. To provide guidance for the acute treatment of SE in critically ill patients, the Neurocritical Care Society organized a writing committee to evaluate the literature and develop an evidence-based and expert consensus practice guideline. Literature searches were conducted using PubMed and studies meeting the criteria established by the writing committee were evaluated. Recommendations were developed based on the literature using standardized assessment methods from the American Heart Association and Grading of Recommendations Assessment, Development, and Evaluation systems, as well as expert opinion when sufficient data were lacking.

Pharmacokinetics of intravenous lorazepam in pediatric patients with and without status epilepticus

OBJECTIVE

To evaluate the single dose pharmacokinetics of an intravenous dose of lorazepam in pediatric patients treated for status epilepticus (SE) or with a history of SE.

STUDY DESIGN

Ten hospitals in the Pediatric Emergency Care Applied Research Network enlisted patients 3 months to 17 years with convulsive SE (status cohort) or for a traditional pharmacokinetics study (elective cohort). Sparse sampling was used for the status cohort, and intensive sampling was used for the elective cohort. Non-compartmental analyses were performed on the elective cohort, and served to nest compartmental population pharmacokinetics analysis for both cohorts.

RESULTS

A total of 48 patients in the status cohort and 15 patients in the elective cohort were enrolled. Median age was 7 years, 2 months. The population pharmacokinetics parameters were: clearance, 1.2 mL/min/kg; half-life, 16.8 hours; and volume of distribution, 1.5 L/kg. On the basis of the pharmacokinetics model, a 0.1 mg/kg dose is expected to achieve concentrations of approximately 100 ng/mL and maintain concentrations >30 to 50 ng/mL for 6 to 12 hours. A second dose of 0.05 mg/kg would achieve desired therapeutic serum levels for approximately 12 hours without excessive sedation. Age-dependent dosing is not necessary beyond using a maximum initial dose of 4 mg.

CONCLUSIONS

Lorazepam pharmacokinetics in convulsive SE is similar to earlier pharmacokinetics measured in pediatric patients with cancer, except for longer half-life, and similar to adult pharmacokinetics parameters except for increased clearance.

Intravenous diazepam, midazolam and lorazepam in acute seizure control

OBJECTIVE

To evaluate the safety and efficacy of three benzodiazepine drugs: Lorazepam, Midazolam and Diazepam, when given parenterally in the control of acute seizure.

METHODS

One hundred and twenty children of either sex in the age group 6 month to 14 years brought convulsing to the pediatric emergency services, were enrolled in the study. These were randomised to three equal groups of 40 patients each; Group A-received diazepam, Group B-received midazolam, Group C-received lorazepam. End of seizure episode (clinically) was defined as cessation of visible epileptic phenomenon or return of purposeful response to external stimuli within 15 min of drug administration. A stopwatch was used to measure various time intervals accurately. The patient's vitals were monitored and recorded in a predesigned performa. The primary outcome was the time to seizure cessation and secondary outcome was the side effects of the drugs. Data obtained was analysed statistically using student's t-test and chi-square test.

RESULTS

Mean duration to clinical seizure cessation was comparable among the three groups. For diazepam group it was 84.94 ± 38.56 s, for midazolam group it was 92.69 ± 25.97 s, for lorazepam group it was 91.12 ± 23.58 s. Number of patients with any abnormality in seizure cessation were significantly higher in diazepam group [11/40 (27.5%)] when compared to the midazolam [4/40 (10%)] and lorazepam group [2/40 (5%)]. Number of patients requiring 2nd dose to control seizures was significantly higher [4/40 (10%)] in diazepam group when compared to lorazepam group [0/40 (0%)] but diazepam and midazolam and midazolam and lorazepam were comparable in this aspect.All the three drugs were comparable in terms of side effects except excessive somnolence which was significantly higher in diazepam group.

CONCLUSIONS

All the three groups were comparable in terms of time to clinical seizure cessation, seizure recurrence and uncontrolled seizures after drug administration. However, number of patients requiring second dose to control seizures were significantly higher in diazepam group when compared to lorazepam group. Excessive somnolence and sedation occurred more frequently with diazepam.

Challenges in the design and analysis of non-inferiority trials: a case study

BACKGROUND

The literature on the design, conduct, and analysis of non-inferiority trials is continuously evolving. Several design issues continue to be researched including the choice of active control, choice of non-inferiority margin, and optimal analytic approaches. To date, there has been relatively little in the literature documenting actual experiences with implementing available methodology for non-inferiority trials.

PURPOSE

This article serves as a case study and highlights some of the challenges encountered in the design of a Phase III non-inferiority trial in status epilepticus that is being conducted under a Food and Drug Administration Investigational New Drug Application (IND).

METHODS

The IND application was put on clinical hold by the Food Drug and Administration due to concerns with the design. Specifically, support for the active control, non-inferiority margin, and overall interpretability of trial results were questioned, and a recommendation was made to consider a superiority design. The authors describe their interactions with the Food Drug and Administration and their application of available methods and approaches to address these concerns.

RESULTS

The investigators' response to the clinical hold provided detailed information to support the conduct of a non-inferiority trial. The study team received Food Drug and Administration approval to initiate the trial in October 2008. The trial enrollment began in June 2009 and is being conducted by roughly 800 paramedic units in over 40 Emergency Medicine Service systems across the United States.

LIMITATIONS

There is still a great deal of methodological research needed to fully understand the application and impact of the non-inferiority trial design.

CONCLUSIONS

It is evident that non-inferiority trials have an important place in clinical trial design and analysis. These trials may be the only way and only opportunity to answer certain questions; so, they must be designed and conducted with rigor. This case study is an attempt to share our experiences in implementation.

Intranasal versus intravenous lorazepam for control of acute seizures in children: a randomized open-label study

PURPOSE

Intravenous lorazepam is considered the drug of first choice for control of acute convulsive seizures. However, resource or personnel constraints necessitate the study of alternative routes and medications. This study compared the efficacy and adverse effects of intranasal versus intravenous lorazepam in children aged 6-14 years who presented with acute seizures.

METHODS

This was a randomized open-label study conducted at an Indian hospital from August 2008 to April 2009. One hundred forty-one consecutive children aged 6-14 years who presented convulsing to the emergency room were included. After stabilization, the children were randomized to receive either intravenous or intranasal lorazepam (0.1 mg/kg, maximum 4 mg). The primary outcome measure was clinical seizure remission within 10 min of drug administration. The study was registered with clinicaltrials.gov (NCT00735527).

KEY FINDINGS

Seventy patients were randomized to receive intravenous and 71 to receive intranasal lorazepam. The patients in the two groups were comparable at baseline. Clinical seizure remission within 10 min of drug administration was found in 80% of the intravenous group as compared to 83.1% of intranasal group. The lower limit of 95% confidence interval for effect size was approximately -9.7%, with an a priori cutoff for noninferiority of -10%.

SIGNIFICANCE

Intranasal administration of lorazepam is not found to be inferior to intravenous administration for termination of acute convulsive seizures in children.

[Use of injectable lorazepam in status epilepticus: a comparative study in French-speaking hospitals]

BACKGROUND

Injectable lorazepam (IL) is marketed in many countries but in France is only available within the framework of a compassionate use program for refractory status epilepticus. This study aims to evaluate the differences of pediatric use and status of IL in the hospitals of the Mother-Child French-speaking Network (Réseau mère-enfant de la francophonie, i.e., RMEF).

METHODS

Inclusion criteria are: firstly, RMEF member; secondly, one site per town; thirdly, all the Assistance publique-Hôpitaux de Paris hospitals. After a phone-recruitment in each selected hospital, a survey was sent by e-mail. The data collected concerned the number of beds in the hospital, the official status of IL, its place in the therapeutic strategy, in hospital consumption in 2008 (in milligram) and the therapeutic alternatives.

RESULTS

Among the 18 hospitals selected, 17 were contacted and 12 (70%) replied. IL is not marketed in Tunisia and Lebanon. In Switzerland, Canada and Belgium, IL is marketed and used in all the polled hospitals (6.2 to 48.0mg per bed). In France, only the Robert Debré Hospital uses it (3.2mg per bed). In the countries where it is marketed, IL was firstly prescribed for the studied indication. In the other countries, injectable diazepam was the first line treatment (six out of eight hospitals).

DISCUSSION/CONCLUSION

France is the only country where IL is available though not marketed. The pharmacokinetic data favor use of IL instead of its principal therapeutic alternative (injectable diazepam) but no currently available evidence concludes that IL is superior to diazepam in the management of pediatric status epilepticus. The official indication of IL in France (last intention) is in contradiction with its use in the countries where it is marketed and with the data of the literature in favor of the first intention. This works presents the first evaluation on the use of IL in pediatric status epilepticus in the RMEF hospitals. It highlights the discrepancies in the management of status epilepticus in comparable pediatric hospitals.

Response to diazepam in children with malaria-induced seizures

Malaria infection reduces the binding capacity of benzodiazepine receptors in mice. We studied the efficacy of diazepam terminating seizures in children with falciparum malaria. Diazepam stopped seizures in fewer patients with malaria parasitaemia (χ² = 3.93, P = 0.047) and those with clinical diagnosis of malaria (χ² = 9.84, P = 0.002) compared to those without. However malaria was not identified as an independent risk factor for diazepam's failure to stop seizures in children.

Benzodiazepines in epilepsy: pharmacology and pharmacokinetics

Benzodiazepines (BZDs) remain important agents in the management of epilepsy. They are drugs of first choice for status epilepticus and seizures associated with post-anoxic insult and are also frequently used in the treatment of febrile, acute repetitive and alcohol withdrawal seizures. Clinical advantages of these drugs include rapid onset of action, high efficacy rates and minimal toxicity. Benzodiazepines are used in a variety of clinical situations because they have a broad spectrum of clinical activity and can be administered via several routes. Potential shortcomings of BZDs include tolerance, withdrawal symptoms, adverse events, such as cognitive impairment and sedation, and drug interactions. Benzodiazepines differ in their pharmacologic effects and pharmacokinetic profiles, which dictate how the drugs are used. Among the approximately 35 BZDs available, a select few are used for the management of seizures and epilepsy: clobazam, clonazepam, clorazepate, diazepam, lorazepam and midazolam. Among these BZDs, clorazepate has a unique profile that includes a long half-life of its active metabolite and slow onset of tolerance. Additionally, the pharmacokinetic characteristics of clorazepate (particularly the sustained-release formulation) could theoretically help minimize adverse events. However, larger, controlled studies of clorazepate are needed to further examine its role in the treatment of patients with epilepsy.

Pharmacokinetics and clinical efficacy of lorazepam in children with severe malaria and convulsions

AIM

To investigate the pharmacokinetics and clinical efficacy of intravenous (i.v.) and intramuscular (i.m.) lorazepam (LZP) in children with severe malaria and convulsions.

METHODS

Twenty-six children with severe malaria and convulsions lasting > or =5 min were studied. Fifteen children were given a single dose (0.1 mg kg(-1)) of i.v. LZP and 11 received a similar i.m. dose. Blood samples were collected over 72 h for determination of plasma LZP concentrations. Plasma LZP concentration-time data were fitted using compartmental models.

RESULTS

Median [95% confidence interval (CI)] LZP concentrations of 65.1 ng ml(-1) (50.2, 107.0) and 41.4 ng ml(-1) (22.0, 103.0) were attained within median (95% CI) times of 30 min (10, 40) and 25 min (20, 60) following i.v. and i.m. administration, respectively. Concentrations were maintained above the reported therapeutic concentration (30 ng ml(-1)) for at least 8 h after dosing via either route. The relative bioavailability of i.m. LZP was 89%. A single dose of LZP was effective for rapid termination of convulsions in all children and prevention of seizure recurrence for >72 h in 11 of 15 children (73%, i.v.) and 10 of 11 children (91%, i.m), without any clinically apparent respiratory depression or hypotension. Three children (12%) died.

CONCLUSION

Administration of LZP (0.1 mg kg(-1)) resulted in rapid achievement of plasma LZP concentrations within the reported effective therapeutic range without significant cardiorespiratory effects. I.m administration of LZP may be more practical in rural healthcare facilities in Africa, where venous access may not be feasible.

Safety and efficacy of buccal midazolam versus rectal diazepam for emergency treatment of seizures in children: a randomised controlled trial

BACKGROUND

Rectal diazepam and buccal midazolam are used for emergency treatment of acute febrile and afebrile (epileptic) seizures in children. We aimed to compare the safety and efficacy of these drugs.

METHODS

A multicentre, randomised controlled trial was undertaken to compare buccal midazolam with rectal diazepam for emergency-room treatment of children aged 6 months and older presenting to hospital with active seizures and without intravenous access. The dose varied according to age from 2.5 to 10 mg. The primary endpoint was therapeutic success: cessation of seizures within 10 min and for at least 1 hour, without respiratory depression requiring intervention. Analysis was per protocol.

FINDINGS

Consent was obtained for 219 separate episodes involving 177 patients, who had a median age of 3 years (IQR 1-5) at initial episode. Therapeutic success was 56% (61 of 109) for buccal midazolam and 27% (30 of 110) for rectal diazepam (percentage difference 29%, 95% CI 16-41). Analysing only initial episodes revealed a similar result. The rate of respiratory depression did not differ between groups. When centre, age, known diagnosis of epilepsy, use of antiepileptic drugs, prior treatment, and length of seizure before treatment were adjusted for with logistic regression, buccal midazolam was more effective than rectal diazepam.

INTERPRETATION

Buccal midazolam was more effective than rectal diazepam for children presenting to hospital with acute seizures and was not associated with an increased incidence of respiratory depression.