The impact of the COVID-19 pandemic on a cohort of adults with epilepsy

OBJECTIVES

The aim of this study was to assess the direct and indirect impacts of the COVID-19 pandemic on adults with epilepsy in Glasgow.

METHODS

We used routinely collected data for a previously identified cohort of patients with epilepsy to evaluate access to scheduled and unscheduled care with quarterly rates of inpatient admissions, outpatient attendance and accident & emergency attendance calculated. Anti-seizure medication prescribing and persistence, incidence of anxiety and depression and deaths for a cohort of patients with epilepsy was evaluated prior to the pandemic in comparison to during the pandemic, from 2015 to 2021.

RESULTS

All-cause mortality and epilepsy related mortality showed a statistically significant reduction during the pandemic. Although overall rates of out-patient hospital attendance dropped during the early stages of the pandemic (and had not returned to pre-pandemic levels by the end of 2021) epilepsy-related services saw maintenance of patient contact as a result of a rapid adoption of telephone clinics. A significant decrease in overall mortality was observed in PWE during the pandemic compared to the pre-pandemic period. COVID-19 was the single commonest cause of death in PWE during the pandemic (61/453) and 160 patients (3.7%) had at least 1 admission to hospital for COVID-19. Anti-seizure medication (ASM) prescribing remained rates remained stable during the pandemic. During the pandemic an average of 38.8% of cohort patients were treated for depression and 16.3% for anxiety per quarter, 8.2% and 12.4% of whom had not been previously treated for these conditions respectively.

CONCLUSION

We have shown that during a national lockdown, in the context of a pandemic, mortality in patients with epilepsy has reduced, while out-patient services were delivered remotely, primarily via the telephone. The reasons for this remain unclear but suggest that some of the excess mortality in people with epilepsy may be potentially avoidable by changes in lifestyle.

Winning hearts and minds: ECG reporting in the first seizure clinic

BACKGROUND AND AIMS

An electrocardiogram (ECG) is a mandatory test for anyone presenting with loss of consciousness. Many referrals to the first seizure clinic (FSC) are caused by syncope. We assessed the sensitivity of neurologists' ECG reporting in detecting rhythm abnormalities including some potentially life-threatening cardiac conditions.

METHODS

We audited patients referred to a FSC in Glasgow over 4 years. All ECGs were interpreted by the attending neurologist as standard practice. Subsequently, two cardiologists reviewed the ECGs independently.

RESULTS

Of 160 consecutive patients, 92 patients (58%) were diagnosed as having seizures, 43 (27%) as syncope, and 25 (16%) were unclassified. Twenty eight ECGs thought to be normal by the neurologist were considered abnormal by the cardiologist, including three with long corrected QT interval. The proportion of abnormal ECGs and disparity in reporting between neurologists and cardiologists persisted independent of the underlying diagnosis.

CONCLUSION

Reporting of ECGs by non-cardiologists may not be adequately sensitive in picking up potentially life threatening cardiac conditions. Cardiologist input into FSCs is recommended to enhance the diagnostic yield.

Viva la VOSCE?

BACKGROUND

The COVID-19 pandemic lockdown precluded face-to-face final Objective Structured Clinical Examinations (OSCE) in the UK.

RESULTS

In response, we rapidly developed and then successfully implemented a novel Virtual Objective Structured Clinical Examination (VOSCE).

CONCLUSIONS

In this article we both describe and reflect on our experience as well as discuss the implications for future undergraduate assessment as the situation evolves.

Epilepsy and Pregnancy: For healthy pregnancies and happy outcomes. Suggestions for service improvements from the Multispecialty UK Epilepsy Mortality Group

Between 2009 and 2012 there were 26 epilepsy-related deaths in the UK of women who were pregnant or in the first post-partum year. The number of pregnancy-related deaths in women with epilepsy (WWE) has been increasing. Expert assessment suggests that most epilepsy-related deaths in pregnancy were preventable and attributable to poor seizure control. While prevention of seizures during pregnancy is important, a balance must be struck between seizure control and the teratogenic potential of antiepileptic drugs (AEDs). A range of professional guidance on the management of epilepsy in pregnancy has previously been issued, but little attention has been paid to how optimal care can be delivered to WWE by a range of healthcare professionals. We summarise the findings of a multidisciplinary meeting with representation from a wide group of professional bodies. This focussed on the implementation of optimal pregnancy epilepsy care aiming to reduce mortality of epilepsy in mothers and reduce morbidity in babies exposed to AEDs in utero. We identify in particular -What stage to intervene - Golden Moments of opportunities for improving outcomes -Which Key Groups have a role in making change -When - 2020 vision of what these improvements aim to achieve. -How to monitor the success in this field We believe that the service improvement ideas developed for the UK may provide a template for similar initiatives in other countries.

Neurology liaison services in the acute medical receiving unit

INTRODUCTION

Guidelines from the Association of British Neurologists and National Health Service Quality Improvement Scotland suggest that neurologists should be involved in the early management of patients presenting to hospital with acute neurological illness.

AIM

We chose to evaluate whether regular neurology review in an acute medical receiving unit in a busy city hospital was feasible, and whether it would have an impact on patient care.

METHODS

Over a 5-week period from Monday to Friday, all neurology patients admitted to an acute medical receiving unit were identified and all headaches and blackouts were reviewed.

RESULTS

Fourteen (24%) were headache patients, 37 (63%) presumed seizure and 8 (13%) had another neurological illness. Diagnosis was made by the admitting physician in six headache patients (43%). The remaining eight headache patients were diagnosed by the visiting neurologist and two physician diagnoses were revised. The diagnosis made by the admitting physician was clarified by the visiting neurologist in 13 blackout patients (35%) and nine other diagnoses were revised (24%). Appropriate outpatient follow-up or transfer was arranged.

CONCLUSION

These results suggest that a daily neurology review service is useful in medical receiving units by clarifying diagnoses, directing tests and limiting inappropriate follow-up.

Modern management of epilepsy

The expected quality of care for epilepsy has increased sharply in the last two decades, informed and directed by published guidance. Meeting these demands has become possible only by providing adequate numbers of consultants and nurses with the relevant expertise, alongside improvements in investigative facilities. The increasing choice of AEDs has been helpful in improving treatment options. Both primary and secondary care have an important role to play in easing diagnosis of new cases and highlighting cases where improvement in control are needed.

Asymptomatic pontine myelinolysis

A 43-year-old lady presented with bilateral foot drop due to alcohol-related peripheral neuropathy. There was no history of electrolyte disturbance or altered consciousness. Cranial nerve, bulbar and pyramidal symptoms and signs were absent. Nerve conduction studies confirmed the neuropathy. Inadvertently requested neuroimaging of brain demonstrated signal change typical of central pontine myelinolysis. Asymptomatic pontine myelinolysis occurs rarely in alcoholics in the absence of bulbar dysfunction. It is important for physicians to be aware of the clinical entity of asymptomatic pontine myelinolysis to avoid misinterpretation of abnormalities detected on cerebral imaging in alcoholic individuals.

Which electroencephalography (EEG) for epilepsy? The relative usefulness of different EEG protocols in patients with possible epilepsy

BACKGROUND AND AIMS

Electroencephalography (EEG) is an essential investigative tool for use in young people with epilepsy. This study assesses the effects of different EEG protocols on the yield of EEG abnormalities in young people with possible new epilepsy.

METHODS

85 patients presenting to the unit underwent three EEGs with differing protocols: routine EEG (r-EEG), sleep-deprived EEG (SD-EEG), EEG carried out during drug-induced sleep (DI-EEG). The yield of EEG abnormalities was compared using each EEG protocol.

RESULTS

98 patients were recruited to the study. Of the 85 patients who completed the study, 33 (39%) showed no discernible abnormality on any of their EEG recordings. 36 patients (43%) showed generalised spike and wave during at least one EEG recording, whereas 15 (18%) had a focal discharge evident at some stage. SD-EEG had a sensitivity of 92% among these patients, whereas the sensitivity of DI-EEG and r-EEG was 58% and 44%, respectively. The difference between the yield from SD-EEG was significantly higher than that from other protocols (p < 0.001). Among the 15 patients showing focal discharges, SD-EEG provoked abnormalities in 11 (73%). r-EEG and DI-EEG each produced abnormalities in 40% and 27%, respectively. 7 patients (47%) had changes seen only after sleep deprivation. In 2 (13%), the only abnormalities were seen on r-EEG. In only 1 patient with focal discharges (7%) was the focal change noted solely after drug-induced sleep. These differences did not reach significance.

CONCLUSION

EEG has an important role in the classification of epilepsies. SD-EEG is an easy and inexpensive way of increasing the yield of EEG abnormalities. Using this as the preferred protocol may help reduce the numbers of EEGs carried out in young patients presenting with epilepsy.

Epilepsy in the UK: Misdiagnosis, mistreatment, and undertreatment?

OBJECTIVE

To assess the diagnostic and therapeutic difficulties in patients with epilepsy who had never come into contact with specialist services.

METHODS

Assessment was offered to 676 patients diagnosed as having epilepsy and receiving anti-epileptic drug therapy (AED), who had no previous contact with the local epilepsy services. Two hundred and seventy-five patients gave consent and attended for reassessment. We identified the proportion of patients (a) who had previously seen a neurologist, (b) in whom the diagnosis of epilepsy was not secure, (c) in whom planned AED withdrawal could be considered (d) in whom seizure control could be improved.

RESULTS

53/275 (19.3%) of those attending for review had previously been seen by a neurologist. 87/275 (31.6%) patients ultimately received continued specialist care. Diagnostic doubt was expressed in 3/53 (5.6%) and 42/222 (18.9%) of patients diagnosed by neurologist and non-specialist, respectively. Of 133/219 (60.7%) of patients whose epilepsy was in remission, only 6 elected to withdraw or change medication. Of 18 patients with diagnostic doubt who accepted follow-up, 12 successfully stopped treatment. 17/55 (30.9%) patients with active epilepsy (10 partial, 7 generalised) achieved at least a 1 year remission consequent upon treatment in this clinic. In 15 cases this was a first ever remission.

CONCLUSION

Approximately 55% of the population of adults receiving treatment for epilepsy have never received specialist advice. Reassessment of these patients uncovers diagnostic uncertainty, failure to classify (leading to sub-optimal therapy) and lack of information and advice about all aspects of epilepsy care. The development of integrated services for people with epilepsy (PWE) must take account of this hidden need. The new General Medical Services contract for general practitioners will bring this need to our attention, and our experience will help predict the measures required to deal with the under-treatent and mistreatment of this group. The majority of PWE, not currently receiving shared care, merit reassessment and approximately one-third will require continued specialist care. Existing services do not have the capacity to process a marked increase in rate of referral. This project informs prioritisation of referrals and service reorganisation.

The legacy of vigabatrin in a regional epilepsy clinic

OBJECTIVES

To review all patients who had received vigabatrin at the Walton Centre to determine the incidence of visual field defect, seizure outcome if vigabatrin had been stopped, and adherence to guidelines on the use of vigabatrin in clinical practice.

METHODS

Retrospective review of 583 patients prescribed vigabatrin at any time between 1989 and 2001 from a regional and satellite epilepsy clinic. Data were collected on dose and duration of treatment, results of quantitative perimetry, and reasons for, and outcome of, discontinuation.

RESULTS

The visual fields were abnormal with no alternative cause in 42 of the 98 tested (43%). There was no clear relation between the cumulative dose of vigabatrin received and the occurrence of a visual field abnormality. Fifty patients continued taking vigabatrin, and a further 84 were lost to follow up while taking vigabatrin. In 75 patients who had stopped vigabatrin due to a visual field abnormality or concern over this potential adverse effect, the seizure control was no different or had improved in 66 (88%), while it had deteriorated in only 7 (9%).

CONCLUSIONS

This study confirms the previously reported high incidence of asymptomatic visual field defects associated with vigabatrin. Many patients taking vigabatrin may not have been counselled about the risks, and there are significant cost implications in tracing and assessing those patients lost to follow up. Switching over to another antiepileptic drug usually does not result in deterioration in seizure control, but in clinical practice an individual risk to benefit ratio needs to be taken into consideration.

Neurological presentation of Fabry's disease in a 52 year old man

Fabry's disease is an X linked inborn error of metabolism due to deficient activity of the lysosomal enzyme alpha galactosidase A. Previously unrecognised Fabry's disease presenting in a 52 year old man being investigated for progressive dysarthria and ataxia is discussed. Brain magnetic resonance imaging suggested the presence of small vessel disease but skin biopsy (done to exclude cerebral autosomal dominant arteriopathy with subcortical infarcts and leucencephalopathy) showed typical changes of Fabry's disease. This diagnosis was confirmed by subsequent enzyme assays. The authors contend that Fabry's disease should be excluded, at least on clinical grounds, in patients with otherwise unexplained cerebrovascular disease.

Future prospects for the drug treatment of epilepsy

Great progress has been made in the last 150 years in the pharmacological management of epilepsy, and, despite the increasing number of technological advances available, antiepileptic drugs (AEDs) remain the mainstay of treatment for the vast majority of patients with epilepsy. This review looks at possible avenues of development in the drug treatment of epilepsy. The strengths and weaknesses of those AEDs which are currently licensed are examined, and ways in which their use may be improved are discussed (e.g. rational combinations, use of new formulations). Potentially new targets that may allow the development of effective treatments are highlighted (neuroimmunological manipulation, decreasing inherent drug resistance mechanisms, and modification of adenosine neurotransmission), and a summary of the most promising AEDs currently in development is provided [e.g. carabersat, ganaxolone, harkoseride, MDL 27192, safinamide (NW 1015), pregabalin, retigabine, talampanel, valrocemide, losigamone and BIA 2093].

Remacemide for drug-resistant localization related epilepsy

BACKGROUND

Epilepsy is a common neurological condition, affecting 0.5 to 1% of the population. Nearly 30 per cent of people with epilepsy have seizures that are refractory to currently available drugs. In response to this problem, potential new drugs are being developed. Remacemide is one of these.

OBJECTIVES

To evaluate the effects of add-on treatment with remacemide upon seizures, adverse effects, cognition and quality of life for people with drug-resistant localization related epilepsy.

SEARCH STRATEGY

We searched the Cochrane Epilepsy Group trials register (4 July 2002), the Cochrane Controlled Trials Register (The Cochrane Library Issue 2, 2002) and MEDLINE (28 May 2002). In addition, we contacted AstraZeneca (makers of remacemide) and colleagues in the field to see if they were aware of any trials that we had missed.

SELECTION CRITERIA

Randomized placebo controlled add-on trials of people of any age with localization related seizures, in which an adequate method of concealment of randomization was used. The studies could be blinded or unblinded and be of parallel or crossover design. They had to have a minimum treatment period of eight weeks.

DATA COLLECTION AND ANALYSIS

Two reviewers independently selected trials for inclusion and extracted data. Any disagreements were resolved by discussion. Outcomes investigated included 50 per cent or greater reduction in seizure frequency, treatment withdrawal, adverse effects, effects on cognition and quality of life. The primary analyses were by intention-to-treat. Dose response was evaluated in regression models.

MAIN RESULTS

Two parallel group trials were included representing 514 individuals. Daily doses of 300, 600, 800 and 1200mg of remacemide were tested. The overall relative risk (RR) for remacemide versus placebo with 95% confidence intervals(CI) for a 50 per cent or greater reduction in seizure frequency was 1.59(95% CI 0.91 to 2.79). Due to differences in response rates among trials, regression models were unable to provide reliable estimates of responses to individual doses. Regression models did however suggest a significant effect for 800-1200mg remacemide per day. Remacemide was more likely to be withdrawn than placebo, the RR for treatment withdrawal was 1.90(95% CI 1.00 to 3.60). The RR for dizziness indicates that it is significantly associated with remacemide 3.08(99% CI 1.37 to 6.95). Effects on cognition and quality of life were not reported.

REVIEWER'S CONCLUSIONS

Given the modest effect on seizure frequency and significant withdrawal rate it is unlikely that remacemide will be further developed as an antiepileptic drug.

Levetiracetam, oxcarbazepine, remacemide and zonisamide for drug resistant localization-related epilepsy: a systematic review

OBJECTIVE

To undertake a systematic review and meta-analysis of placebo controlled add-on trials of levetiracetam, oxcarbazepine, remacemide and zonisamide for patients with drug resistant localization related epilepsy.

METHODS

We searched Medline, The Cochrane Library and contacted the relevant pharmaceutical companies. Outcomes were 50% or greater reduction in seizure frequency and treatment withdrawal for any reason. Data were synthesised in a meta-analysis. The effect of dose was explored in regression models for levetiracetam and remacemide.

RESULTS

We found four trials (1023 patients) of levetiracetam, two (961) of oxcarbazepine, two (388) of remacemide and three (499) of zonisamide. Ignoring dose, the relative risks (95% CI) for a 50% response were 3.78 (2.62-5.44), 2.51 (1.88-3.33), 1.59 (0.91-2.97) and 2.46 (1.61-3.79), respectively. There was evidence for increasing effect with increasing dose for levetiracetam, oxcarbazepine and remacemide. The relative risks for treatment withdrawal were 1.21 (0.88-1.66), 1.72 (1.35-2.18), 1.90 (1.00-3.60) and 1.64 (1.02-2.62), respectively.

CONCLUSIONS

These data suggest a useful effect for levetiracetam, oxcarbazepine and zonisamide. Levetiracetam has the more favourable 'responder-withdrawal ratio' followed by zonisamide and oxcarbazepine.

Concentration-effect studies with topiramate on selected enzymes and intermediates of the GABA shunt

PURPOSE

Topiramate (TPM) is a new antiepileptic agent with a multifactorial mechanism of action. The drug potentiates responses to gamma-aminobutyric acid (GABA) at the GABA(A) receptor and has inhibitory effects on neuronal sodium channels, the AMPA/kainate subtype of glutamate receptor, and carbonic anhydrase. Recent evidence has, however, suggested that the drug also increases brain GABA concentrations in humans. These studies were designed to investigate the neurochemical basis of this observation.

METHODS

Adult male mice were randomised into two groups and administered TPM (0-1,000 mg/kg) intraperitoneally either as a single dose or daily for 8 days. At 4 h after the final dose, brain tissues were analysed for concentrations of GABA, glutamate, and glutamine and for the activities of GABA-transaminase and glutamic acid decarboxylase. TPM levels in brain also were determined.

RESULTS

Single-dose and repeated TPM treatments were without effect on all of the parameters investigated, although the drug was detectable in the brain at doses of > or =10 mg/kg.

CONCLUSIONS

These results contradict the reported increase in brain GABA concentrations with TPM. More detailed studies are required to determine the basis of this clinical observation and the extent to which it contributes to the antiepileptic activity of the drug.

Serial perfusion brain tomographic scans detect reversible focal ischaemia in Rasmussen's encephalitis

A 39-year-old man with advanced adult-onset Rasmussen's encephalitis was treated with prednisolone and long-term, high-dose, human intravenous immunoglobulin. A pretreatment, semiquantitative interictal brain perfusion single photon emission computed tomography (SPECT) scan using (99)Tc(m) HMPAO (hexamethylene propylene amine oxime) showed hypoperfusion in the clinically affected right frontal, parietal and temporal lobes and contralateral perfusion defects. A second scan 8 months later revealed significant improvements (more than two standard deviations) in perfusion of the right frontal and temporal lobes despite serial magnetic resonance imaging evidence of permanent brain damage. This was associated with useful recovery of the patient's physical and cognitive function. We conclude that serial perfusion brain SPECT scanning is a useful method to demonstrate improvement in patients with Rasmussen's encephalitis in response to therapy.

Improvement in adult-onset Rasmussen's encephalitis with long-term immunomodulatory therapy

OBJECTIVE

To study the immediate and chronic effects of high-dose, long-term human i.v. immunoglobulin (h i.v.Ig) therapy in two patients with advanced adult-onset Rasmussen's encephalitis (RE).

BACKGROUND

Despite advances in our understanding of the autoimmune pathogenesis of RE, medical options for chronic treatment are limited.

METHODS

In an open-label treatment trial, treatment started with monthly cycles of high-dose h i.v.Ig (0.4 g/kg/d for 5 days) followed by maintenance therapy (0.4 g/kg 1 day each month) after the patients' conditions began to improve. Outcome measures included clinical, psychological, functional, and laboratory assessments before and at relevant intervals throughout 1 year of treatment.

RESULTS

In both patients, unrelenting pretreatment deterioration halted, and after this they displayed striking improvements in seizure control, hemiparesis, and cognition that produced useful recovery of function. Improvements were delayed until after 2 to 4 monthly cycles of high-dose h i.v.Ig and continued when patients switched to maintenance treatment. Their recoveries were accompanied by increased cerebral perfusion on interictal SPECT and suppression of inflammatory markers in CSF.

CONCLUSIONS

h i.v.Ig can be a useful, possibly disease-modifying, long-term therapy for adult-onset RE that should be considered before radical surgery is performed. Because improvements can be delayed, we propose guidelines for intensive and prolonged trials of immunomodulatory therapy in adults with this syndrome.

Neurochemical actions of the desglycinyl metabolite of remacemide hydrochloride (ARL 12495AA) in mouse brain

1. Remacemide hydrochloride, a recently developed antiepileptic drug, is believed to exert its effects, at least in part, via its desglycinyl metabolite, ARL 12495AA. 2. We have investigated the effects of ARL 12495AA on several neurochemical parameters in mouse brain. Adult male ICR mice were randomized into two groups and administered ARL 12495AA (0-75 mg kg-1) intraperitoneally, either as a single dose or once daily for 5 days. 3. Six hours after the final dose, animals were killed and their brains removed. Brain tissues were analysed for concentrations of gamma-aminobutyric acid (GABA), glutamine and glutamate and for the activities of GABA-transaminase (GABA-T) and glutamic acid decarboxylase (GAD). 4. Single dose ARL 12495AA was without effect on any of the parameters investigated. 5. Repeated ARL 12495AA treatment did not alter brain concentrations of GABA and glutamine, but at a high dose there was a trend toward reduced brain glutamate concentrations (P = 0.10). 6. Repeated administration of ARL 12495AA at a high dose significantly increased GABA-T activity (P < 0.05) and decreased that of GAD (P < 0.05). 7. These findings may have relevance to the clinical use of remacemide hydrochloride in human epilepsy.

Neurochemical actions of gabapentin in mouse brain

Gabapentin (GBP) is a recently licensed antiepileptic, drug whose mode of action remains to be fully elucidated. The following studies were designed to investigate the effects of GBP on several gamma-aminobutyric acid (GABA) related neurochemical parameters in mouse brain. GBP (0-75 mg/kg) was administered by intraperitoneal injection either as a single dose or twice daily for 8 days. Animals were sacrificed 4 h after the final administration and their brains removed and analysed for concentrations of GABA, glutamate and glutamine and the activities of GABA-transaminase (GABA-T) and glutamic acid decarboxylase (GAD). Single dose GBP increased brain GABA-T activity and glutamine concentration but was without effect on GAD activity or the concentrations of GABA and glutamate. Following repeated treatment with GBP, brain GABA-T activity was consistently decreased and there was also a decrease in brain glutamate concentration. Repeated drug treatment was without effect on the activity of GAD or on the concentrations of GABA and glutamine. These results suggest that GBP has effects on the GABAergic system which may contribute to its antiepileptic and/or neuroprotective actions.

Lack of pharmacokinetic interaction between remacemide hydrochloride and sodium valproate in epileptic patients

A randomized, double-blind, placebo-controlled cross-over study of adjuvant treatment with remacemide hydrochloride was carried out in 17 patients taking sodium valproate (VPA) as monotherapy. Plasma concentration profiles of VPA, remacemide, and its active desglycinyl metabolite (ARL12495XX) were determined following single (300 mg) and multiple dosing (150 or 300 mg twice daily) of remacemide hydrochloride for 14 days with a 300-mg final dose. Central nervous system side-effects were more common at the higher dose, which prompted dosage reduction to 150 mg twice daily for subsequent patients partway through the study. The mean area under the concentration-time curve, peak concentration and pre-dose concentration of VPA were unchanged by remacemide hydrochloride in three patients on the higher and in 10 patients on the lower dose of remacemide. The pharmacokinetic parameters of remacemide and its active metabolite in the VPA-treated patients were similar to those described previously in healthy volunteers. Thus, remacemide hydrochloride does not interfere with the pharmacokinetics of VPA and vice versa.

Neurochemical actions of vigabatrin and tiagabine alone and in combination in mouse cortex

1. The effects of repeated administration of the anticonvulsant compounds, vigabatrin (VGB) and tiagabine (TGB), on gamma-aminobutyric acid (GABA) concentration and the activities of GABA-transaminase (GABA-T) and glutamic acid decarboxylase (GAD) were investigated in mouse cortex. 2. VGB alone increased GABA levels and decreased GABA-T and GAD activities. 3. TGB alone was essentially without effect. 4. Low doses of VGB and TGB in combination increased GABA levels when neither drug had such an effect alone. 5. Despite this observation, this study failed to establish any conclusive evidence for an interaction between VGB and TGB that might help to explain their reported clinical synergism.

Neurochemical studies with the novel anticonvulsant levetiracetam in mouse brain

Levetiracetam is a novel antiepileptic agent with a wide spectrum of activity against experimental and clinical seizures. The mechanism of its anticonvulsant action remains to be determined. We have investigated the effects of levetiracetam on several gamma-aminobutyric acid (GABA)-related neurochemical parameters in mouse brain. Adult male mice were randomised into two groups and administered levetiracetam (0-300 mg/kg) intraperitoneally either as a single dose or twice daily for 5 days. Four hours after the final dose, animals were killed and their brains removed. Brain tissues were analysed for concentrations of GABA, glutamate and glutamine and for the activities of GABA-transaminase and glutamic acid decarboxylase. Single dose and repeated levetiracetam treatments were without effect on all of the parameters investigated. The anticonvulsant action of levetiracetam is unlikely to be mediated via an action on the GABAergic system.

Gabapentin and cognition: a double blind, dose ranging, placebo controlled study in refractory epilepsy

OBJECTIVE

To assess the effect of different doses of gabapentin (GBP) on cognitive function in treated epileptic patients.

METHODS

Twenty seven patients with refractory partial seizures commenced a double blind, dose ranging, placebo controlled, crossover study of adjuvant GBP. Each treatment phase lasted three months, during which the dose of GBP or matched placebo was increased stepwise at intervals of four weeks (1200 mg/day, 1800 mg/day, and 2400 mg/day in three daily doses). Psychomotor and memory testing was carried out at the end of each four week period, at which time the patient also completed subjective measures of cognition, fatigue, worry, temper, and dysphoria. A visual analogue scale was used to assess drowsiness and a questionnaire was employed to gauge the severity of side effects.

RESULTS

In the 21 patients completing the study, GBP produced a significant reduction in median monthly seizure frequency from 7 to 4.3 (P = 0.02), the decrease being most pronounced for secondarily generalised seizures (from 1.0 to 0.3, P = 0.01). Forty three per cent of patients reported a reduction in seizure frequency of at least 50% throughout all GBP doses. Mean (SD) plasma concentrations of GBP at 1200, 1800, and 2400 mg/day were 4.7 (2.6), 6.8 (3.8), and 8.6 (3.3) mg/l respectively. The drug had no effect on composite psychomotor and memory scores; nor was there alteration in any self assessment subscore. The mean drowsiness (P = 0.03) score was higher during treatment with 2400 mg GBP daily compared with matched placebo. Composite psychomotor (r = -0.47, P < 0.01), tiredness (r = 0.42, P < 0.01), and side effect (r = 0.61, P < 0.001) scores correlated significantly with seizure frequency but not with GBP dose.

CONCLUSION

GBP is a well tolerated and effective antiepileptic drug which had no measurable effect on cognition but did produce sedation at the highest dose. This study also supports the suggestion that seizures can cause cognitive impairment.

Mutual interaction between remacemide hydrochloride and phenytoin

A randomised, double-blind, placebo-controlled crossover study of add-on remacemide hydrochloride was carried out in epilepsy patients being treated with phenytoin (PHT) monotherapy. Eleven patients were recruited, ten of whom completed the study. Plasma concentration profiles of PHT, remacemide, and its active desglycinyl metabolite (ARL12495XX) were determined following single and multiple dosing with remacemide hydrochloride. Following 14 days' treatment with remacemide hydrochloride 300 mg twice daily, the mean AUC of PHT was increased by 11.5% (P = 0.33), Cmax by 13.7% (P = 0.32) and Cmin by 22.2% (P = 0.12) over placebo. There was an increase in trough concentrations of PHT averaging 20% during active treatment compared with placebo (P = 0.01). No symptoms of PHT toxicity were reported by any patient. There was no evidence of autoinduction of remacemide metabolism. However, average concentrations of remacemide and its active metabolite in PHT-treated patients were around 40 and 30% lower, respectively than in healthy volunteers previously receiving the same dose of remacemide hydrochloride. Thus, remacemide hydrochloride has a small inhibitory effect on PHT metabolism, which itself induces that of remacemide and its active metabolite. This mutual interaction is predictable and modest and should not present a barrier to their clinical use in combination.

Mutual interaction between remacemide hydrochloride and carbamazepine: two drugs with active metabolites

PURPOSE

We wished to determine mutual interaction of two drugs with active metabolism: remacemide, hydrochloride and carbamazepine (CBZ).

METHODS

A randomized, double-blind, placebo-controlled cross-over study of add-on remacemide hydrochloride was performed in 10 of 14 recruited patients being treated with CBZ monotherapy. Forty-eight-hour concentration profiles of CBZ, its active epoxide metabolite (CBZ-E), remacemide, and its desglycinyl metabolite (ARL12495XX) were assayed after single and multiple dosing.

RESULTS

After patients were treated with 300 mg remacemide hydrochloride twice daily for 14 days, the mean area under the concentration-time curve (AUC) of CBZ was increased by 22% (p = 0.12), Cmax was increased by 27% (p = 0.07), and Cmin was increased by 22% (p = 0.29). Trough concentrations of CBZ were higher (p = 0.0037) during active treatment as compared with placebo treatment. CBZ-E levels were unaffected. No symptoms of CBZ toxicity were reported. There was no evidence of autoinduction of remacemide metabolism. However, in CBZ-treated patients, the AUC of remacemide and its active metabolite was 60 and 30%, respectively, of values observed in healthy volunteers treated previously with the same dose.

CONCLUSIONS

Remacemide hydrochloride inhibits CBZ metabolism, which itself induces that of remacemide hydrochloride and its active metabolite. This mutual interaction between remacemide hydrochloride and CBZ is predictable and modest and should not present a barrier to their clinical use in combination.

Effects of tiagabine and vigabatrin on GABA uptake into primary cultures of rat cortical astrocytes

Tiagabine (TGB) and vigabatrin (VGB) are two novel anticonvulsant compounds reported to exert their pharmacological effects via an action on the gamma-aminobutyric acid (GABA) system. We have investigated the effects of acute exposure of these drugs on the uptake of GABA into rat cortical astrocytes in primary culture. Astrocytes were prepared from the cerebral cortices of one day-old rat pups by a mechanical dissociation technique and were assayed for GABA uptake activity after 21 days in culture. Tiagabine (100-300 nM) and VGB (100 microM) reduced GABA uptake when compared to control at four hours post-exposure. GABA uptake was also reduced following eight and 24 hour exposures to 200 nM TGB. A combination of TGB (200 nM) and VGB (100 microM) treatments reduced GABA uptake when compared to both control and VGB treated cultures. These results support the efficacy of TGB as a GABA uptake inhibitor and suggest that VGB may also exert an effect by this mechanism.

Determination of gabapentin in plasma by high-performance liquid chromatography

A rapid and simple method for determination of the novel antiepileptic compound gabapentin [1-(aminomethyl)cyclohexaneacetic acid] in plasma is described. Blank human plasma was spiked with gabapentin (1.0-10.0 micrograms/ml) and internal standard [1-(aminomethyl)-cycloheptaneacetic acid; 5.0 micrograms/ml]. Individual samples were treated with 2 M perchloric acid, centrifuged and then derivatised with o-phthalaldehyde-3-mercaptopropionic acid. Separation was achieved on a Beckman Ultrasphere 5 microns reversed-phase column with mobile phase consisting of 0.33 M acetate buffer (pH 3.7; containing 100 mg/l EDTA)-methanol-acetonitrile (40:30:30, v/v). Eluents were monitored by fluorescence spectroscopy with excitation and emission wavelengths of 330 and 440 nm, respectively. The calibration curve for gabapentin in plasma was linear (r = 0.9997) over the concentration range 1.0-10.0 micrograms/ml. Recovery was seen to be > or = 90%. The inter- and intra-assay variations for three different gabapentin concentrations were < or = 10% throughout. The lower limit of quantitation was found to be 0.5 microgram/ml. Chromatography was unaffected by a range of commonly employed antiepileptic drugs or selected amino acids.

Deliberate overdose with the novel anticonvulsant tiagabine

Tiagabine is a novel antiepileptic drug which acts by decreasing gamma aminobutyric acid uptake in astrocytes and neurones. Here the first case of deliberate overdose with this compound in a patient on concomitant phenytoin is reported. On admission to hospital his conscious level deteriorated to grade III coma. No changes in the electrocardiogram were noted. Recovery from the initial effects was rapid, and there were no sequelae. Plasma levels of tiagabine (3.1 micrograms/ml) 4 hours after ingestion were 30 times higher than at typical steady state during therapeutic dosing. The effects of poisoning with current first-line antiepileptic drugs are reviewed. The newer agents, particularly those with greater biochemical specificity, may be safer in overdose than the more established anticonvulsants.

New antiepileptic drugs--an explosion of activity

The low therapeutic index of established antiepileptic drugs coupled with a better understanding of the pathophysiology of seizure production has led to the development of a range of new therapeutic agents for the treatment of epilepsy. In this review, the three drugs recently licensed in the UK (vigabatrin, lamotrigine and gabapentin) are profiled, together with several of the more promising up-and-coming compounds (oxcarbazepine, felbamate, tiagabine, stiripentol, remacemide and topiramate). Future avenues for clinical research in the pharmacological management of the epilepsies involve their rational use both singly and in combination.

Plasma endothelinlike immunoreactivity levels in IDDM patients with microalbuminuria

OBJECTIVE

To determine whether plasma endothelin, a potent vasoconstrictor and growth factor for vascular smooth muscle, is elevated in microalbuminuric insulin-dependent diabetes mellitus patients.

RESEARCH DESIGN AND METHODS

Plasma endothelinlike immunoreactivity was measured by radioimmunoassay in 15 microalbuminuric diabetic patients, 12 normoalbuminuric diabetic patients, and 12 control subjects.

RESULTS

The mean levels of plasma endothelinlike immunoreactivity were raised in the normoalbuminuric patients (8.4 pM [range 4.8-12.7 pM]; P less than 0.01) and the microalbuminuric patients (10.2 pM [range 5.6-31.1 pM]; P less than 0.001) compared with control subjects (6.1 pM [range 4.5-7.6 pM]). Plasma endothelinlike immunoreactivity was also higher in the microalbuminuric patients compared with the normoalbuminuric patients (P less than 0.05).

CONCLUSIONS

The increase in plasma endothelinlike immunoreactivity further confirms endothelial dysfunction in diabetes and this increase in plasma endothelin may contribute to the vascular disease prevalent in diabetes.

Free radical activity and hemostatic factors in NIDDM patients with and without microalbuminuria

In non-insulin-dependent diabetes mellitus (NIDDM) patients, microalbuminuria predicts early mortality, predominantly from cardiovascular disease. Increased free radical activity and abnormalities in hemostasis have been implicated in the development of vascular disease. Therefore, we measured markers of free radical activity (nonperoxide-conjugated diene isomer of linoleic acid [PL-9,11-LA'] and lipid peroxides expressed as malondialdehyde [MDA]) along with the hemostatic variables: fibrinogen, von Willebrand factor (vWf), plasminogen activator inhibitor (PAI-1), tissue plasminogen activator (t-PA), and plasmin activity (B beta 15-42) in 24 NIDDM patients (12 patients with microalbuminuria and 12 without microalbuminuria) and in 12 age-matched control subjects. There were no differences in linoleic acid (PL-9,12-LA) concentrations between the three groups. PL-9,11-LA' was elevated in the microalbuminuric patients compared with control subjects (P less than 0.05), but there was no difference between the two diabetic groups. MDA was elevated in the microalbuminuric diabetic patients compared with those patients without microalbuminuria (P less than 0.05) and control subjects (P less than 0.001). MDA was also increased in the patients without microalbuminuria compared with control subjects (P less than 0.01). Except for B beta 15-42, all the hemostatic variables were increased (P less than 0.05) in the diabetic patients compared with control subjects. The microalbuminuric diabetic patients had further increases in vWf (P less than 0.03) and t-PA (P less than 0.03) compared with patients with microalbuminuria. Our study suggests that there is an increase in free radical activity and abnormalities in hemostatic variables favoring a hypercoagulable state in NIDDM, especially in those with microalbuminuria.(ABSTRACT TRUNCATED AT 250 WORDS)