Drug treatment of epilepsy in elderly people: focus on valproic Acid

Joint use of population pharmacokinetics and machine learning for prediction of valproic acid plasma concentration in elderly epileptic patients

BACKGROUND

Valproic acid (VPA) is a commonly used broad-spectrum antiepileptic drug. For elderly epileptic patients, VPA plasma concentrations have a considerable variation. We aim to establish a prediction model via a combination of machine learning and population pharmacokinetics (PPK) for VPA plasma concentration.

METHODS

A retrospective study was performed incorporating 43 variables, including PPK parameters. Recursive Feature Elimination with Cross-Validation was used for feature selection. Multiple algorithms were employed for ensemble model, and the model was interpreted by Shapley Additive exPlanations.

RESULTS

The inclusion of PPK parameters significantly enhances the performance of individual algorithm model. The composition of categorical boosting, light gradient boosting machine, and random forest (7:2:1) with the highest R2 (0.74) was determined as the ensemble model. The model included 11 variables after feature selection, of which the predictive performance was comparable to the model that incorporated all variables.

CONCLUSIONS

Our model was specifically tailored for elderly epileptic patients, providing an efficient and cost-effective approach to predict VPA plasma concentration. The model combined classical PPK with machine learning, and underwent optimization through feature selection and algorithm integration. Our model can serve as a fundamental tool for clinicians in determining VPA plasma concentration and individualized dosing regimens accordingly.

Ethnic Aspects of Valproic Acid P-Oxidation

The safety of the use of psychotropic drugs, widely used in neurological and psychiatric practice, is an urgent problem in personalized medicine. This narrative review demonstrated the variability in allelic frequencies of low-functioning and non-functional single nucleotide variants in genes encoding key isoenzymes of valproic acid P-oxidation in the liver across different ethnic/racial groups. The sensitivity and specificity of pharmacogenetic testing panels for predicting the rate of metabolism of valproic acid by P-oxidation can be increased by prioritizing the inclusion of the most common risk allele characteristic of a particular population (country).

Episodic Migraine and Older Adults

PURPOSE OF REVIEW

Migraine is and continues to be a significant medical issue in older adults. Migraine can have different characteristics in older adults and specific diagnostic and treatment considerations need to be applied when managing headache and migraine in this population, which is increasing in both size and diversity. Contrary to widely held beliefs, migraine may not improve in older women following menopause and can have new onset in older age. The purpose of this review is to give an update on the diagnosis and treatment of episodic migraine in older adults.

RECENT FINDINGS

As the population ages, migraine in older adults will become a more significant public health issue. Migraine in older adults can present with different clinical symptoms than in a younger population and is primarily a diagnosis of exclusion in older adults. Migraine treatment considerations for older adults should include comorbidities and medication interactions. Recent findings suggest there are medications that should be avoided when treating seniors with migraine. The purpose of this review is to give an update on the most important aspects regarding the diagnosis and treatment of headache and migraine in older adults. In addition, recommendations will be made concerning medications that need careful consideration when prescribing to seniors.

Antiepileptic drugs for the primary and secondary prevention of seizures after stroke

BACKGROUND

Seizures after stroke are an important clinical problem and may result in poor outcomes. The indications of antiepileptic drugs (AEDs) for seizure prophylaxis after stroke remain unclear. This is an updated version of the Cochrane Review previously published in 2014.

OBJECTIVES

To assess the effects of AEDs for the primary and secondary prevention of seizures after stroke. For primary prevention, we aimed to assess whether AEDs reduce the likelihood of seizures in people who have a stroke but do not have a seizure. For secondary prevention, we aimed to assess whether AEDs reduce the likelihood of further seizures in people who have a stroke and at least one post-stroke seizure.

SEARCH METHODS

We searched the following databases on 9 March 2021: Cochrane Register of Studies (CRS Web), MEDLINE (Ovid, 1946 to March 08, 2021). CRS Web includes randomised or quasi-randomised controlled trials from PubMed, Embase, ClinicalTrials.gov, the World Health Organisation International Clinical Trials Registry Platform (ICTRP), the Cochrane Central Register of Controlled Trials (CENTRAL), and the Specialised Registers of Cochrane Review Groups including Epilepsy and Stroke. We also checked the reference lists of articles retrieved from these searches.

SELECTION CRITERIA

We selected randomised and quasi-randomised controlled studies that recruited participants with a clinical diagnosis of stroke, either ischaemic or haemorrhagic. We excluded studies that only recruited participants with subarachnoid haemorrhage, subdural haemorrhage, extradural haemorrhage, or other non-stroke diagnoses such as tumour- or infection-related infarction or haemorrhage. We also excluded studies that recruited only participants who had undergone neurosurgery. We included participants of all ages suffering any seizure type who were assigned to AEDs or placebo groups.

DATA COLLECTION AND ANALYSIS

In accordance with standard methodological procedures expected by The Cochrane Collaboration, two review authors independently assessed trials for inclusion before evaluating trial risk of bias and extracting relevant data. The primary outcome assessed was the proportion of participants who experienced seizures in the follow-up period. We presented results as summary risk ratios (RRs) with 95% confidence intervals (CIs) for dichotomous outcomes and mean differences (MDs) with 95% CIs for continuous outcomes. Where we had sufficient data, we calculated random-effects (Mantel-Haenszel) meta-analyses for dichotomous outcomes; otherwise, we reported results narratively. We used the I2 statistic to analyse statistical heterogeneity. We planned to use funnel plots to assess publication bias in meta-analyses with at least 10 included studies. We used the GRADE approach to assess the certainty of the evidence.

MAIN RESULTS

Two studies with a total of 856 subjects were included. AEDs were not shown to be effective in primary prophylaxis of post-stroke seizure (RR 0.65, 95% CI 0.34 to 1.26; 2 studies, 856 participants; moderate-certainty evidence). The first study was a randomised double-blind study comparing valproic acid with placebo for primary seizure prevention up to one year after stroke. The study included 72 adults with intracerebral haemorrhage. There was no difference in the risk of post-stroke seizures (RR 0.88, 95% CI 0.35 to 2.16) or of death (RR 1.20, 95% CI 0.40 to 3.58). The second study was a substudy on the use of diazepam in acute stroke. It was a randomised double-blind study, comparing a three-day diazepam treatment versus placebo for primary seizure prevention up to three months after stroke in 784 adults with acute stroke. There was no evidence of a difference in the risk of post-stroke seizures for all stroke or subgroups of haemorrhagic or ischaemic stroke (RR for all stroke 0.47, 95% CI 0.18 to 1.22). In a subgroup analysis of anterior circulation cortical infarcts, primary prophylaxis with diazepam was associated with a reduced risk of post-stroke seizures (RR 0.21, 95% CI 0.05 to 0.95). Risks of mortality did not differ between the diazepam and the placebo group at two weeks (RR 0.84, 95% CI 0.56 to 1.26) and three months follow-up (RR 0.95, 95% CI 0.72 to 1.26). We assessed both studies to be at a low overall risk of bias. Using the GRADE approach, we assessed the overall certainty of the evidence as low to moderate.

AUTHORS' CONCLUSIONS

There is insufficient evidence to support the routine use of AEDs on the primary and secondary prevention of seizures after stroke. Further well-conducted studies are warranted for this important clinical problem.

Prescription patterns and dosages of antiepileptic drugs in prevalent patients with epilepsy in Taiwan: A nationwide retrospective cross-sectional study

OBJECTIVE

To evaluate the prescription patterns and prescribed daily dose (PDD)/defined daily dose (DDD) ratios of antiepileptic drugs (AEDs) in prevalent patients with epilepsy in Taiwan.

MATERIALS AND METHODS

A nationwide retrospective cross-sectional study was conducted for prevalent patients with epilepsy in 2016 using the Taiwanese National Health Insurance Research Database. The prescription records of AEDs of all prevalent patients with epilepsy were retrieved. The mean PDDs and PDD/DDD ratios of AEDs in adult patients were obtained to evaluate dosing adequacy. A chi-square test and two-sample t test were used to analyze the differences in AED prescription patterns and dosages, respectively, among patients with different ages, sexes, comorbidities, and therapeutic approaches.

RESULTS

A total of 118,937 prevalent patients with epilepsy were enrolled. The predominant therapeutic approach was monotherapy, especially in the elder adults, accounting for 82.9% of elder adult patients with epilepsy. The proportion of AED monotherapy was higher in patients with dementia (78.9%) and stroke (80.6%). The top three antiepileptic monotherapies were valproic acid (28.7%), levetiracetam (19.1%), and phenytoin (16.9%); however, oxcarbazepine (22.8%) was substituted for carbamazepine (3.9%) as monotherapy for patients aged 0-17 years. Among adult patients with epilepsy, the PDD/DDD ratio of each AED in monotherapy was less than 1.00. The mean PDD of each AED was higher in polytherapy than in monotherapy (p < 0.01), except for lacosamide. The mean PDDs of all evaluated AEDs in monotherapy were lower in elder adult patients than in younger adult patients, most of which reached statistical significance (p < 0.001).

CONCLUSIONS

In Taiwan, valproic acid was the most prescribed AED for prevalent patients with epilepsy. The mean PDDs of most AEDs were lower than the DDDs developed by the World Health Organization.

Treatment with the combination of clavulanic acid and valproic acid led to recovery of neuronal and behavioral deficits in an epilepsy rat model

Epilepsy, which is caused by abnormal neuronal firing in the brain, is a common neurological disease and affects motor and cognitive functions. Excessive levels of glutamate and insufficient levels of inhibitory GABA are involved in its pathophysiology. Valproic acid (Val), a GABAergic agonist, is one of the first-line antiepileptic drugs, but it shows many adverse side effects at the clinical dose. Clavulanic acid (CA), a β-lactamase inhibitor, has been demonstrated to increase glutamate transporter-1 expression. This study evaluated the effects of CA and Val in an epilepsy rat model. Male Wistar rats received intraperitoneal injections of pentylenetetrazol (PTZ, 35 mg/kg, every other day, IP, for 13 days) to induce kindling epilepsy. After four times of PTZ injection, rats received daily treatment with CA (1 or 10 mg/kg, IP), Val (50 or 100 mg/kg, IP), or the combination of CA (1 mg/kg) and Val (50 mg/kg) for 7 consecutive days. Motor, learning, and memory functions were measured. Rats with PTZ-induced kindling exhibited seizures, motor dysfunction, cognitive impairment, and cell loss and reduction of neurogenesis in the hippocampus. Neither 1 mg/kg CA nor 50 mg/kg Val treatment was effective in alleviating behavioral and neuronal deficits. However, treatment with 10 mg/kg CA, 100 mg/kg Val, and the combination of 1 mg/kg CA and 50 mg/kg Val improved these behavioral and neuronal deficits. Particularly, the combination of CA and Val showed synergistic effects on seizure suppression, suggesting the potential for treating epilepsy and related neuronal damage and motor and cognitive deficits.

Evaluation of sodium valproate low dose efficacy in radicular pain management and it's relation with pharmacokinetics parameters

BACKGROUND

Radiculopathy due to lumbar or cervical disc disease is the most common chronic neuropathic pain in adults. The aim of present study was evaluation of low dose of sodium valproate (VPA) on radicular pain and determining VPA pharmacokinetics.

MATERIALS AND METHODS

In this double blind randomized placebo control clinical study, 80 patients with established lumbar or cervical radicular pain, have been randomly allocated into two study groups: 40 have received sodium valproate 200 mg/day and Celecoxib 100 mg/day and acetaminophen 500 mg PRN as rescue medication, and second group has received placebo, Celecoxib and acetaminophen. Quantitative assessment of pain was done by visual analogue scale (VAS) prior to perform the intervention and after ten days (treatment duration). Blood sample has been taken for determining mean through concentration after five half-lives. Evaluation of plasma concentration of VPA and that of efficacy on pain score relationship by comparing VAS before and after the therapy was done.

RESULTS

Group A and B have demonstrated significant alleviation in mean VAS score; -21.97 ± 25.41, -14.39 ± 23.03 respectively (P < 0.001). The mean plasma concentration of VPA in group A was: 26.9 ± 13.5 mg/L. Moreover, no significant correlation was seen between pain score with age, gender, and weight (p > 0.05).

CONCLUSION

Low dose of sodium valproate especially together with NSAIDs demonstrated good efficacy in lumbar and cervical radicular pain management.

Why we urgently need improved epilepsy therapies for adult patients

PURPOSE

Up to a third of patients with epilepsy suffer from recurrent seizures despite therapeutic advances.

RESULTS

Current epilepsy treatments are limited by experiential data from treating different types of epilepsy. For example, we lack evidence-based approaches to efficacious multi-drug therapies or identifying potentially serious or disabling adverse events before medications are initiated. Despite advances in neuroscience and genetics, our understanding of epilepsy pathogenesis and mechanisms of treatment-resistance remains limited. For most patients with epilepsy, precision medicine for improved seizure control and reduced toxicity remains a future goal.

CONCLUSION

A third of epilepsy patients suffer from ongoing seizures and even more suffer from adverse effects of treatment. There is a critical need for more effective and safer therapies for epilepsy patients with frequent comorbitidies, including depression, anxiety, migraine, and cognitive impairments, as well as special populations (e.g., women, elderly). Advances from genomic sequencing techniques may identify new genes and regulatory elements that influence both the depth of the epilepsies' roots within brain circuitry as well as ASD resistance. Improved understanding of epilepsy mechanisms, identification of potential new therapeutic targets, and their assessment in randomized controlled trials are needed to reduce the burden of refractory epilepsy. This article is part of the special issue entitled 'New Epilepsy Therapies for the 21st Century - From Antiseizure Drugs to Prevention, Modification and Cure of Epilepsy'.

Current translational potential and underlying molecular mechanisms of necroptosis

Cell death has a fundamental impact on the evolution of degenerative disorders, autoimmune processes, inflammatory diseases, tumor formation and immune surveillance. Over the past couple of decades extensive studies have uncovered novel cell death pathways, which are independent of apoptosis. Among these is necroptosis, a tightly regulated, inflammatory form of cell death. Necroptosis contribute to the pathogenesis of many diseases and in this review, we will focus exclusively on necroptosis in humans. Necroptosis is considered a backup mechanism of apoptosis, but the in vivo appearance of necroptosis indicates that both caspase-mediated and caspase-independent mechanisms control necroptosis. Necroptosis is regulated on multiple levels, from the transcription, to the stability and posttranslational modifications of the necrosome components, to the availability of molecular interaction partners and the localization of receptor-interacting serine/threonine-protein kinase 1 (RIPK1), receptor-interacting serine/threonine-protein kinase 3 (RIPK3) and mixed lineage kinase domain-like protein (MLKL). Accordingly, we classified the role of more than seventy molecules in necroptotic signaling based on consistent in vitro or in vivo evidence to understand the molecular background of necroptosis and to find opportunities where regulating the intensity and the modality of cell death could be exploited in clinical interventions. Necroptosis specific inhibitors are under development, but >20 drugs, already used in the treatment of various diseases, have the potential to regulate necroptosis. By listing necroptosis-modulated human diseases and cataloging the currently available drug-repertoire to modify necroptosis intensity, we hope to kick-start approaches with immediate translational potential. We also indicate where necroptosis regulating capacity should be considered in the current applications of these drugs.

Population Pharmacokinetic Analysis of Phenytoin After Intravenous Administration of Fosphenytoin in Adult and Elderly Epileptic Patients

BACKGROUND

Fosphenytoin, the diphosphate ester salt of phenytoin, is widely used to treat status epilepticus. The aim of this study was to develop a population pharmacokinetic (PPK) model to describe serum phenytoin concentrations after the intravenous administration of fosphenytoin in adult and elderly epileptic patients.

METHODS

Patient backgrounds, laboratory tests, and prescribed drugs were retrospectively collected from electronic medical records. Patients who received fosphenytoin were enrolled. The PPK analysis was performed using NONMEM 7.3.0 with the first-order conditional estimation method with interaction. Age, sex, laboratory tests, and coadministered drugs were selected as candidates for covariates. Significance levels for forward inclusion and backward elimination were set at 0.05 and 0.01, respectively. The study protocol was approved by the Fukuoka Tokushukai Ethics Committee.

RESULTS

A total of 340 serum phenytoin concentrations from 200 patients treated with fosphenytoin were available. The median age and body weight of the population were 71 years and 53.4 kg, respectively. A linear 1-compartment model with the conversion rate of fosphenytoin to phenytoin clearly described the pharmacokinetics of phenytoin after the intravenous administration of fosphenytoin. Age was detected as a covariate of clearance (CL): CL (L/h) = 1.99 × (body weight/53.4) × (age/71). Goodness-of-fit plots revealed the high-predictive performance of the final PPK model, and systematic deviations were not observed. The final model was validated by a prediction-corrected visual predictive check and bootstrap analysis.

CONCLUSIONS

We herein developed a PPK model to describe phenytoin concentrations after the intravenous administration of fosphenytoin. Age was identified as a significant covariate for CL.

The critical interaction between valproate sodium and warfarin: case report and review

BACKGROUND

Valproic acid (VPA) and warfarin are commonly prescribed for patients with epilepsy and concomitant atrial fibrillation (AF). When VPA and warfarin are prescribed together, clinically important interactions may occur. VPA may replace warfarin from the protein binding sites and result in an abnormally increased anticoagulation effect. This is commonly underrecognized.

CASE PRESENTATION

In our case, we report a 78-year-old woman with a glioma who presented with status epilepticus. The patient was on warfarin to prevent cardiogenic embolism secondary to AF. Intravenous loading dose of VPA was administered, but international normalized ratio (INR) increased significantly to 8.26. Intravenous vitamin K1 was then given and the patient developed no overt bleeding during the hospitalization.

CONCLUSION

By reviewing the literature and discussing the critical interaction between valproate sodium and warfarin, we conclude that intravenous VPA and the co-administrated warfarin may develop critical but underrecognized complications due to effects on the function of hepatic enzymes and displacement of protein binding sites.

Severe recurrent hypothermia in an elderly patient with refractory mania associated with atypical antipsychotic, valproic acid and oxcarbazepine therapy

Hypothermia is a rare but serious condition that has been associated with various psychiatric medications. We present a 76-year-old woman with refractory mania who developed multiple episodes of severe hypothermia associated with several psychiatric medications including olanzapine, quetiapine, valproic acid and oxcarbazepine. These episodes resolved following discontinuation of the agents. The patient had never experienced hypothermia before, despite having been on these or similar agents for many years. With traditional treatments for mania not feasible, other medications were used to treat her including lithium, clonazepam, gabapentin and the novel protein kinase c inhibitor tamoxifen. The regimen resulted in some success and importantly, without triggering hypothermia. This case alerts clinicians to the rare side effect of hypothermia in response to various psychiatric medications, the fact that patients can suddenly develop this intolerance and suggests possible medications that may be used safely without triggering hypothermia.

Co-morbidity and clinically significant interactions between antiepileptic drugs and other drugs in elderly patients with newly diagnosed epilepsy

PURPOSE

A study was conducted to investigate the frequency of potential pharmacokinetic drug-to-drug interactions in elderly patients with newly diagnosed epilepsy. We also investigated co-morbid conditions associated with epilepsy.

METHOD

From the register of Kuopio University Hospital (KUH) we identified community-dwelling patients aged 65 or above with newly diagnosed epilepsy and in whom use of the first individual antiepileptic drug (AED) began in 2000-2013 (n=529). Furthermore, register data of the Social Insurance Institution of Finland were used for assessing potential interactions in a nationwide cohort of elderly subjects with newly diagnosed epilepsy. We extracted all patients aged 65 or above who had received special reimbursement for the cost of AEDs prescribed on account of epilepsy in 2012 where their first AED was recorded in 2011-2012 as monotherapy (n=1081). Clinically relevant drug interactions (of class C or D) at the time of starting of the first AED, as assessed via the SFINX-PHARAO database, were analysed.

RESULTS

Hypertension (67%), dyslipidemia (45%), and ischaemic stroke (32%) were the most common co-morbid conditions in the hospital cohort of patients. In these patients, excessive polypharmacy (more than 10 concomitant drugs) was identified in 27% of cases. Of the patients started on carbamazepine, 52 subjects (32%) had one class-C or class-D drug interaction and 51 (31%) had two or more C- or D-class interactions. Only 2% of the subjects started on valproate exhibited a class-C interaction. None of the subjects using oxcarbazepine displayed class-C or class-D interactions. Patients with 3-5 (OR 4.22; p=0.05) or over six (OR 8.86; p=0.003) other drugs were more likely to have C- or D-class interaction. The most common drugs with potential interactions with carbamazepine were dihydropyridine calcium-blockers, statins, warfarin, and psychotropic drugs.

CONCLUSIONS

Elderly patients with newly diagnosed epilepsy are at high risk of clinically relevant pharmacokinetic interactions with other drugs, especially if exposed to carbamazepine, but these interactions can be controlled via rational drug choices and with prediction of the possible drug-to-drug interactions. Patients on dihydropyridine calcium-channel blockers, statins, warfarin, and risperidone face the highest risk of interactions.

Lacosamide and concomitant use of antiepileptic and other medications in a US population - A retrospective cohort study

Information on the use of lacosamide and concomitant antiepileptic and non-antiepileptic drugs (non-AEDs) is available from clinical trials and observational studies with small sample sizes. This retrospective cohort study was conducted to gain insight into the use of lacosamide in a large number of patients with epilepsy in real-life clinical practice with less restrictive selection criteria compared with clinical trial participants. The Truven Health MarketScan (Commercial Claims and Medicare Supplemental) database was used to identify patients with a prior diagnosis of epilepsy with at least one prescription claim for lacosamide between June 2009 and September 2013 and continuous health insurance enrolment with medical and pharmacy coverage during the 1-year pre-index baseline period. A total of 8859 eligible patients were identified, of whom, at index (lacosamide initiation), 16.8% received lacosamide as monotherapy and 54.0% as polytherapy. The median prescription duration was 196days (Interquartile range 69-476days). Levetiracetam was the most frequently prescribed concomitant AED across all age groups, followed by phenytoin among older (>65years) and lamotrigine among younger patients. Older patients who had LCM monotherapy at initiation, were prescribed fewer concomitant AEDs, but more non-AEDs. The most common non-AED medications were prescribed for pain, psychiatric conditions, hyperlipidemia and gastrointestinal diseases across all age groups. Overall, results suggest that the lacosamide use is driven predominantly by age and that there is substantial use of lacosamide monotherapy (16.8%), despite lack of indication at the time of the study. Results also reveal substantial use of concomitant non-AEDs; 90.4% among patients >65years of age and 54.3% among those ≤17years, confirming the high prevalence of comorbidities among patients with epilepsy across all ages. Despite the availability of numerous newer AEDs, older AEDs are still being frequently prescribed, especially for elderly patients, notably phenytoin. This warrants careful consideration, given the strong propensity of enzyme-inducing AEDs to interact with other drugs, producing unwanted side effects. These results highlight the value of real-life prescription patterns and the potential in informing treatment decisions to ensure patients receive appropriate treatment.

Analysis of the Variables Influencing Valproic Acid Concentration in the Serum and Cerebrospinal Fluid of Chinese Patients After Craniotomy

BACKGROUND

Valproic acid (VPA) has been widely used in Chinese patients after craniotomy. Many studies have focused on the influencing factors of VPA serum concentration, but conclusions are sometimes paradoxical. Furthermore, the concentration of VPA in the cerebrospinal fluid (CSF) has been rarely reported. In the present study, VPA CSF concentrations were measured, and the potential factors influencing serum concentration and CSF distribution of VPA were investigated. In addition, the functional relationship between serum and CSF concentration was explored.

METHODS

Subjects were patients who underwent craniotomy and were administrated with VPA and had a lumbar puncture. Serum and CSF VPA concentrations were measured by use of the Abbott i1000 system. CYP2C9 (430 C>T, 1075 A>C, 1076 T>C, 1080 C>G), UGT1A6 (541 A>G, 552 A>C), UGT2B7 (211 G>T, 802 C>T), and ABCB1 (1236 C>T, 2677 G>T/A, 3435 C>T) genotypes were determined by direct sequencing. Information, such as age, gender, and height, was collected, and their effect on serum and CSF VPA concentrations was investigated by univariate analysis and multiple linear regression analysis.

RESULTS

First, the concomitant use of carbapenems (β' = -0.422) and UGT1A6 (552 AA → AC) (β' = -0.249) had a significant negative correlation with the weight-adjusted VPA serum concentration (C:W ratio), whereas CYP2C9 (1075 AA → AC) (β' = 0.186) and gender (female compared with male) (β' = 0.322) showed a positive correlation with VPA serum C:W ratio. The coefficient of determination (R) was only 0.348. Second, the relationship between the serum concentration and the CSF square root of the concentration (R = 0.705) had a better linear fit. Third, serum VPA concentration (β' = 0.810), concomitant use of glycerol fructose (β' = 0.160), and age (≥65 compared with <65) (β' = 0.118) showed a positive correlation (R = 0.748) with the variability of square root of the concentration of the CSF.

CONCLUSIONS

In Chinese patients, after craniotomy, female patients with 1 or more of CYP2C9 (1075 AC) and UGT1A6 (552 AA) genotypes required a lower VPA dosage compared with male patient. There was a better-fitted linear relationship between VPA serum and the square root of CSF concentrations. CSF VPA concentrations were relatively stable, with only age and the use of glycerol fructose having a small influence.

Epilepsy management in older people: Lessons from National Audit of Seizure management in Hospitals (NASH)

PURPOSE

Epilepsy is the third most common diagnosis in older people, however management in this group remains variable. National Audit of Seizure management in Hospitals (NASH) set out to assess care provided to patients attending hospitals in England following a seizure.

METHOD

154 Emergency Departments (EDs) across the UK took part. 1256 patients aged 60 years or over were included for analysis (median age 74 years, 54% men). 51% were known to have epilepsy, 17% had history of previous seizure or blackout and 32% presented with a suspected first seizure.

RESULTS

14% of older patients with epilepsy were not on treatment, 59% were on monotherapy. Sodium valproate was the most commonly used antiepileptic, 28%. 35% of patients with epilepsy, aged 60 and over, had a CT during admission compared to only 17% of those under 60. 80% of patients aged 60 and over presenting with a likely first seizure were admitted to hospital, compared to 65% of those under 60. 34% of those with suspected first seizure were referred to a neurologist on discharge compared to 68% of patients under the age of 60. 52% of 60-69year olds with a suspected first seizure were referred to neurology compared to 25% of patients aged 80-89.

CONCLUSIONS

Older patients presenting with seizures are more likely to be admitted to hospital and have imaging. They are less likely to be referred to specialist services on discharge. There appears to be significant disparity in patient age and rate of referral.

Comparative effectiveness of levetiracetam, valproate and carbamazepine among elderly patients with newly diagnosed epilepsy: subgroup analysis of the randomized, unblinded KOMET study

Background

Few clinical trials have evaluated the efficacy and tolerability of antiepileptic drugs (AEDs) as initial monotherapy for elderly patients.

Methods

This post-hoc subgroup analysis of data from an unblinded, randomized, 52-week superiority study (KOMET) compared the effectiveness of levetiracetam (LEV) with extended-release sodium valproate (VPA-ER) and controlled-release carbamazepine (CBZ-CR) as monotherapy in patients aged ≥ 60 years with newly diagnosed epilepsy. The physician chose VPA or CBZ as preferred standard treatment; patients were randomized to standard AEDs or LEV. The primary endpoint was time to treatment withdrawal. Results are exploratory, since KOMET was not powered for a subgroup analysis by age.

Results

Patients (n = 308) were randomized to LEV (n = 48) or VPA-ER (n = 53) in the VPE-ER stratum or to LEV (n = 104) or CBZ-CR (n = 103) in the CBZ-CR stratum. Mean age was 69.6 years, range 60.2–89.9 years (intention-to-treat population n = 307). Time to treatment withdrawal hazard ratio [HR] (95 % confidence interval [CI]) for LEV vs. standard AEDs was 0.44 (0.28–0.67); LEV vs. VPA-ER: 0.46 (0.16–1.33); LEV vs. CBZ-CR: 0.45 (0.28–0.72). Twelve-month withdrawal rates were: LEV vs. standard AEDs, 20.4 vs. 38.7 %; LEV vs. VPA-ER, 10.4 vs. 23.1 %; LEV vs. CBZ-CR, 25.0 vs. 46.6 %. Time to first seizure was similar between LEV and standard AEDs (HR: 0.92, 95 % CI: 0.63–1.35), LEV and VPA-ER (0.77, 0.38–1.56), and LEV and CBZ-CR (1.02, 0.64–1.63). Adverse events were reported by 76.2, 67.3, and 82.5 % of patients for LEV, VPA-ER, and CBZ-CR, respectively. Discontinuation rates due to AEs were 11.3, 10.2, and 35.0 % for LEV, VPA-ER, and CBZ-CR, respectively.

Conclusions

Time to treatment withdrawal was longer with LEV compared with standard AEDs. This finding was driven primarly by the result in the CBZ-CR stratum, which in turn was likely due to the more favorable tolerability profile of LEV. Results of this post-hoc analysis suggest that LEV may be a suitable option for initial monotherapy for patients aged ≥ 60 years with newly diagnosed epilepsy.

Trial registration

ClinicalTrials.gov: NCT00175903; September 9, 2005.

Electronic supplementary material

The online version of this article (doi:10.1186/s12883-016-0663-7) contains supplementary material, which is available to authorized users.

Seizure Outcomes and Predictors of Recurrent Post-Stroke Seizure: A Retrospective Observational Cohort Study

Background

Seizure is a common complication after stroke (termed “post-stroke seizure,” PSS). Although many studies have assessed outcomes and risk factors of PSS, no reliable predictors are currently available to determine PSS recurrence. We compared baseline clinical characteristics and post-stroke treatment regimens between recurrent and non-recurrent PSS patients to identify factors predictive of recurrence.

Methods

Consecutive PSS patients admitted to our stroke center between January 2011 and July 2013 were monitored until February 2014 (median 357 days; IQR, 160–552) and retrospectively evaluated for baseline clinical characteristics and PSS recurrence. Cumulative recurrence rates at 90, 180, and 360 days post-stroke were estimated by Kaplan—Meier analysis. Independent predictors of recurrent PSS were identified by Cox proportional-hazards analysis.

Results

A total of 104 patients (71 men; mean age, 72.1 ± 11.2 years) were analyzed. PSS recurred in 31 patients (30%) during the follow-up. Factors significantly associated with PSS recurrence by log-rank analysis included previous PSS, valproic acid (VPA) monotherapy, polytherapy with antiepileptic drugs (AEDs), frontal cortical lesion, and higher modified Rankin Scale score at discharge (all p < 0.05). Independent predictors of recurrent PSS were age <74 years (HR 2.38, 95% CI 1.02–5.90), VPA monotherapy (HR 3.86, 95% CI 1.30–12.62), and convulsions on admission (HR 3.87, 95% CI 1.35–12.76).

Conclusions

Approximately one-third of PSS patients experienced seizure recurrence within one year. The predictors of recurrent PSS were younger age, presence of convulsions and VPA monotherapy. Our findings should be interpreted cautiously in countries where monotherapy with second-generation AEDs has been approved because this study was conducted while second-generation AEDs had not been officially approved for monotherapy in Japan.

Interaction of valproic acid and the antidepressant drugs doxepin and venlafaxine: analysis of therapeutic drug monitoring data under naturalistic conditions

Valproic acid and the antidepressants doxepin and venlafaxine are frequently used psychotropic drugs. In the literature, an influence of valproic acid on serum levels of antidepressants has been described, although studies have focused on amitriptyline. The authors assessed their therapeutic drug monitoring (TDM) database for patients receiving a combination of doxepin or venlafaxine and valproic acid and compared these samples with matched controls without valproic acid comedication in terms of the serum concentration of antidepressants. The mean dose-corrected serum concentration of doxepin+N-doxepin in 16 patients who received valproic acid comedication was higher (2.171±1.482 ng/ml/mg) than that in the matched controls (0.971±0.857 ng/ml/mg, P<0.003). We also found a significant correlation between valproic acid serum level and dose-corrected doxepin+N-doxepin serum level (Spearman's ρ r=0.602, P<0.014). The mean dose-corrected serum level of venlafaxine+O-desmethylvenlafaxine in 41 patients who received valproic acid comedication did not differ significantly from that of the matched controls (P<0.089), but there was a significant difference between both groups in the dose-corrected serum level of O-desmethylvenlafaxine (1.403±0.665 vs. 1.102±0.444, P<0.017). As a consequence, if a combination of valproic acid with doxepin or venlafaxine is administered, cautious dosing is advisable and TDM should be performed.

Antiepileptic drugs for the primary and secondary prevention of seizures after stroke

BACKGROUND

This is an updated version of the original Cochrane review published in 2010, Issue 1. Seizures after stroke are an important clinical problem, and they may be associated with poor outcome. The effects of antiepileptic drugs for the primary and secondary prevention of seizures after stroke remain unclear.

OBJECTIVES

We aimed to assess the effects of antiepileptic drugs for the primary and secondary prevention of seizures after stroke.

SEARCH METHODS

We searched the Specialised Registers of the Cochrane Epilepsy Group (12 August 2013) and the Cochrane Stroke Group (12 August 2013), the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library 2013, Issue 7), and MEDLINE (OVID, 1946 to 12 August 2013). We also checked the reference lists of articles retrieved from these searches.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials in which participants were assigned to treatment or control group (placebo or no drug).

DATA COLLECTION AND ANALYSIS

Two review authors independently screened all the titles, abstracts, and keywords of publications identified by the searches to assess their eligibility, and both review authors assessed their suitability for inclusion according to prespecified selection criteria. We included only one study for data collection and analysis.

MAIN RESULTS

We found only one trial that fulfilled the study inclusion criteria of comparison of the effects of an antiepileptic drug with placebo (or no drug) for the primary or secondary prevention of seizures after stroke. This was a prospective randomised, double-blind, placebo-controlled trial comparing valproic acid with placebo for primary prevention of seizures in 72 adults (over 18 years of age) with spontaneous non-aneurysmal, non-traumatic intracerebral haemorrhage; no statistically significant difference in outcome (seizure occurrence at one year) was demonstrated between groups.

AUTHORS' CONCLUSIONS

Currently, there is insufficient evidence to support the routine use of antiepileptic drugs for the primary or secondary prevention of seizures after stroke. Further well-conducted research is needed for this important clinical problem.

Valproic acid causes proteasomal degradation of DICER and influences miRNA expression

Valproic acid (VPA) is a commonly used drug to treat epilepsy and bipolar disorders. Known properties of VPA are inhibitions of histone deacetylases and activation of extracellular signal regulated kinases (ERK), which cannot fully explain VPA's clinical features. We found that VPA induces the proteasomal degradation of DICER, a key protein in the generation of micro RNAs. Unexpectedly, the concentration of several micro RNAs increases after VPA treatment, which is caused by the upregulation of their hosting genes prior to DICER degradation. The data suggest that a loss of DICER protein and changes in micro RNA concentration contributes to the clinical properties of VPA. VPA can be used experimentally to down regulate DICER protein levels, which likely reflects a natural regulation of DICER.

Interaction of valproic acid and amitriptyline: analysis of therapeutic drug monitoring data under naturalistic conditions

Amitriptyline (AMI) and valproic acid (VPA) are common psychotropic drugs which are frequently used in psychiatry and also administered in neurology or anesthesia in the absence of a psychiatric indication. On the basis of the case of a 73-year-old man with therapy-resistant major depressive episode who experienced anticholinergic delirium after adding VPA to AMI, we retrospectively analyzed therapeutic drug monitoring data of the years 2008 to 2010. We assessed cases receiving a combination of AMI and VPA, and obtained a control sample of AMI patients without VPA which were matched for sex, age, daily dose, and comedication. Both samples were compared regarding the serum levels of AMI and nortriptyline (NOR) as well as the ratio of NOR and AMI with the Mann-Whitney U test. The combination of AMI and VPA led to a remarkable increase of AMI and NOR serum levels. When comparing 33 patients who received comedication with VPA versus 33 matched controls, the total concentration by combining mean AMI and NOR serum levels (237.1 [119.9] vs 126.4 [52.8] ng/mL) and NOR/AMI ratio (1.300 [0.905] vs 0.865 [0.455]) was significantly higher. Both AMI and VPA are widely prescribed drugs. A combination of both is common for psychiatric or neurologic patients. A cautious dosing of AMI with VPA comedication is advisable, and therapeutic drug monitoring should be performed because this combination may lead to a remarkable increase of AMI and NOR serum levels.

Lack of effect of lacosamide on the pharmacokinetic and pharmacodynamic profiles of warfarin

PURPOSE

The aim of this study was to evaluate the effect of the antiepileptic drug lacosamide on the pharmacokinetics and pharmacodynamics of the anticoagulant warfarin.

METHODS

In this open-label, two-treatment crossover study, 16 healthy adult male volunteers were randomized to receive a single 25-mg dose of warfarin alone in one period and lacosamide 200 mg twice daily on days 1-9 with a single 25 mg dose of warfarin coadministered on day 3 in the other period. There was a 2-week washout between treatments. Pharmacokinetic end points were area under the plasma concentration-time curve (AUC(0,last) and AUC(0,∞) ) and maximum plasma concentration (Cmax ) for S- and R-warfarin. Pharmacodynamic end points were area under the international normalized ratio (INR)-time curve (AUCINR ), maximum INR (INRmax ), maximum prothrombin time (PTmax ) and area under the PT-time curve (AUCPT ).

KEY FINDINGS

Following warfarin and lacosamide coadministration, Cmax and AUC of S- and R-warfarin, as well as peak value and AUC of PT and INR, were equivalent to those after warfarin alone. In particular, the AUC(0,∞) ratio (90% confidence interval) for coadministration of warfarin and lacosamide versus warfarin alone was 0.97 (0.94-1.00) for S-warfarin and 1.05 (1.02-1.09) for R-warfarin, and the AUCINR ratio was 1.04 (1.01-1.06). All participants completed the study.

SIGNIFICANCE

Coadministration of lacosamide 400 mg/day did not alter the pharmacokinetics of warfarin 25 mg or the anticoagulation level. These results suggest that there is no need for dose adjustment of warfarin when coadministered with lacosamide.

Valproic acid induces astrocyte-dependent neurite outgrowth from cultured rat primary cortical neuron via modulation of tPA/PAI-1 activity

Tissue plasminogen activator (tPA) is expressed in several regions of brain and plays regulatory roles such as neurite outgrowth, synaptic plasticity and long term potentiation. The activity of tPA is regulated by an endogenous inhibitor plasminogen activator inhibitor-1 (PAI-1), which is expressed mainly in astrocytes. Valproic acid (VPA), a histone deacetylase inhibitor that is used for the treatment of epilepsy and bipolar disorders, promotes neurite extension, neuronal growth and has neuroprotective effect in neurodegenerative diseases. In this study, we examined whether the neurite extension effects of VPA is mediated by modulating tPA/PAI-1 system. VPA dose-dependently increased tPA activity and decreased PAI-1 activity in rat primary astrocytes but not in neurons. PAI-1 protein level secreted into the culture medium but not tPA per se was decreased by VPA. In co-culture system or in neuronal culture stimulated with astrocyte conditioned media but not in pure neuronal cell culture, VPA induced neurite outgrowth via increased tPA activity due to the decreased PAI-1 activity in astrocytes. The decrease in PAI-1 activity and increased neurite extension was regulated via JNK mediated post-transcriptional pathway. The essential role of tPA/PAI-1 system in the regulation of VPA-mediated neurite extension was further demonstrated by experiments using astrocyte conditioned media obtained from tPA or PAI-1 knockout mice. Regulation of PAI-1 activity in astrocyte by VPA may affect both physiological and pathological processes in brain by upregulating tPA activity.

Levetiracetam versus carbamazepine in patients with late poststroke seizures: a multicenter prospective randomized open-label study (EpIC Project)

BACKGROUND

Strokes are the leading cause of epileptic seizures in adults and account for 50% of seizures in those over the age of 65 years. The use of antiepileptic drugs to prevent recurrent poststroke seizures is recommended.

METHODS

One hundred and twenty-eight patients with poststroke seizures were randomly allocated to treatment with either levetiracetam (LEV) or sustained-release carbamazepine (CBZ) in a multicenter randomized open-label study. After a titration study phase (2 weeks), the optimal individual dose of trial medication was determined and treatment was continued for another 52 weeks. The primary endpoint was defined as the proportion of seizure-free patients; the secondary endpoints were: evaluation of time recurrence to the first seizure, EEG tracings, cognitive functions and side effects.

RESULTS

Of 128 patients, 22 discontinued the trial prematurely; thus a total of 106 patients (52 treated with LEV and 54 treated with CBZ) were included in the analysis. The results of the study were as follows: no significant difference in number of seizure-free patients between LEV and CBZ (p = 0.08); time to the first recurrence tended to be longer among patients on LEV; there was no correlation between the therapeutic effect and the EEG findings in either treatment group; LEV caused significantly fewer (p = 0.02) side effects than CBZ; attention deficit, frontal executive functions and functional scales (Activities of Daily Living and Instrumental Activities of Daily Living indices) were significantly worse in the CBZ group.

CONCLUSIONS

This trial suggests that LEV may be a valid alternative to CBZ in poststroke seizures, particularly in terms of efficacy and safety. In addition, our results show that LEV has significant advantages over CBZ on cognitive functions. This trial also indicates that LEV in monotherapy is a safe and effective therapeutic option in elderly patients who have suffered epileptic seizures following a stroke.

Antiepileptic drug monotherapy versus polytherapy: pursuing seizure freedom and tolerability in adults

PURPOSE OF REVIEW

Despite the availability of many new antiepileptic drugs (AEDs), only around 50% of people with epilepsy will become seizure free on their first drug. This article explores treatment options and issues influencing whether AEDs should be substituted or combined in the remainder of the patient population.

RECENT FINDINGS

Prior to the introduction of novel AEDs, it was generally opined that combining traditional agents did not necessarily lead to an improvement in seizure control and might increase the propensity for side effects. Newer AEDs, many with different mechanisms of action, have increased the potential for polytherapy regimens, although robust data to support or refute this therapeutic strategy are sparse. It seems sensible to substitute rather than combine when the first AED produces an idiosyncratic reaction, is poorly tolerated at a low/moderate dose or shows no efficacy. Polytherapy may be preferred if the patient tolerates their first or second AED well, but with a suboptimal response, particularly when there is an identifiable anatomical substrate for the seizures. AED selection requires consideration of many factors some of which are discussed in this study.

SUMMARY

There are no definitive answers on whether to combine or substitute AEDs. Different strategies are required for different scenarios in different patients.

Antiepileptic drug interactions - principles and clinical implications

Antiepileptic drugs (AEDs) are widely used as long-term adjunctive therapy or as monotherapy in epilepsy and other indications and consist of a group of drugs that are highly susceptible to drug interactions. The purpose of the present review is to focus upon clinically relevant interactions where AEDs are involved and especially on pharmacokinetic interactions. The older AEDs are susceptible to cause induction (carbamazepine, phenobarbital, phenytoin, primidone) or inhibition (valproic acid), resulting in a decrease or increase, respectively, in the serum concentration of other AEDs, as well as other drug classes (anticoagulants, oral contraceptives, antidepressants, antipsychotics, antimicrobal drugs, antineoplastic drugs, and immunosupressants). Conversely, the serum concentrations of AEDs may be increased by enzyme inhibitors among antidepressants and antipsychotics, antimicrobal drugs (as macrolides or isoniazid) and decreased by other mechanisms as induction, reduced absorption or excretion (as oral contraceptives, cimetidine, probenicid and antacides). Pharmacokinetic interactions involving newer AEDs include the enzyme inhibitors felbamate, rufinamide, and stiripentol and the inducers oxcarbazepine and topiramate. Lamotrigine is affected by these drugs, older AEDs and other drug classes as oral contraceptives. Individual AED interactions may be divided into three levels depending on the clinical consequences of alterations in serum concentrations. This approach may point to interactions of specific importance, although it should be implemented with caution, as it is not meant to oversimplify fact matters. Level 1 involves serious clinical consequences, and the combination should be avoided. Level 2 usually implies cautiousness and possible dosage adjustments, as the combination may not be possible to avoid. Level 3 refers to interactions where dosage adjustments are usually not necessary. Updated knowledge regarding drug interactions is important to predict the potential for harmful or lacking effects involving AEDs.

Elderly and drugs: risks and necessity of rational use

In recent decades, the world has undergone a demographic transformation with a rapid growth of the elderly population, resulting in an increased demand for funds to maintain their health and drug consumption. Pharmacokinetic and pharmacodynamic changes occurring in the elderly can interfere directly in the adverse effects of drugs and increase the risk of intoxication. In addition, there are external factors interfering with the pharmacotherapy of the elderly, such as inappropriate use and the lack of access to information. Many therapeutic classes of drugs should be used with caution or avoided in the elderly population, such as anti-inflammatory and some anti-hypertensive drugs, diuretics and digitalis. If not managed carefully, these medicines can affect the safety and quality of life in the elderly. Thus, the aim of this review was to identify drugs that should be used with caution in elderly patients in order to avoid intoxication and/or adverse drug events.

Antiepileptic drugs for the primary and secondary prevention of seizures after stroke

BACKGROUND

Seizures after stroke are an important clinical problem, and they may be associated with poor outcome. The effects of antiepileptic drugs for the primary and secondary prevention of seizures after stroke remain unclear.

OBJECTIVES

We aimed to assess the effects of antiepileptic drugs for the primary and secondary prevention of seizures after stroke.

SEARCH STRATEGY

We searched the Specialised Registers of the Cochrane Epilepsy Group and the Cochrane Stroke Group (2 July 2009), the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library Issue 2, 2009), and MEDLINE (1950 to June, week 4, 2009). We also checked the reference lists of articles retrieved from these searches.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials in which patients were assigned to treatment or control group (placebo or no drug).

DATA COLLECTION AND ANALYSIS

Both review authors independently screened all the titles, abstracts, and keywords of publications identified by the searches to assess their eligibility, and both review authors assessed their suitability for inclusion according to pre-specified selection criteria. No study was included, hence no data analysis was performed.

MAIN RESULTS

We did not find any randomised controlled trials that have compared the effects of antiepileptic drugs with placebo (or no drug) for the primary or secondary prevention of seizures after stroke. We did, however, find three randomised controlled trials that have assessed the effects of several different antiepileptic drugs for the secondary prevention of post-stroke seizures. The first study was performed in older adults (mean age 72 years) with a mixture of diagnoses including stroke (comparing carbamazepine, lamotrigine and gabapentin); the second study was performed in children and younger adults (mean age 38 years) with a mixture of diagnoses including stroke (comparing carbamazepine, oxcarbazepine, lamotrigine, gabapentin and topiramate); and the third study was performed in stroke patients only (comparing carbamazepine and lamotrigine).

AUTHORS' CONCLUSIONS

Currently, there is insufficient evidence to support the routine use of antiepileptic drugs for the primary or secondary prevention of seizures after stroke. Further well-conducted research is needed for this important clinical problem.

[Seizures and epilepsies after stroke]

Epilepsies after stroke represent 20% of all adult-onset epilepsies and exhibit special characteristics with respect to diagnosis, treatment, and prognosis. Patients are frequently amnestic for their seizures the signs of which can be very subtle. Postictal pareses and confusional states can last for days, which further complicate diagnosis. Single seizures after stroke were reported in 2% to 10% of cases, and community-based studies found epilepsies in 3% to 4% of stroke patients. Analyses of subgroups identified epilepsy risks of 3% after ischemic infarction, 6% to 10% after intracerebral hemorrhage, and 9% after subarachnoid hemorrhage. Status epilepticus developed in less than 1% of stroke patients. Besides etiology, further risk factors for epilepsy comprise: remote seizures (latency >2 weeks, risk of recurrence >50%) more than early seizures (latency <2 weeks, risk of recurrence <50%), extent of stroke, cortical involvement, and degree of neurological deficit. The first appearance of seizures in patients older than 60 years represents a risk factor for future stroke with a hazard ratio of 2.89.There is currently no sufficient evidence for starting AED treatment before seizures occur. The benefit is still unclear of starting AED after a single early post-stroke seizure. Most authors recommend AED treatment after the second seizure but also after a first remote seizure because of the high risk of seizure recurrence in these situations. Possible pharmacokinetic interactions should be considered when choosing AED. Especially the first-generation AED carry the potential to interact with comedication, which is usually seen in stroke patients receiving substances such warfarin and salicylates. Only very few studies investigate specific AED exclusively in stroke patients. Lamotrigine and gabapentin have been successfully tested in these patients.

Antiepileptic drug interactions

INTRODUCTION

Antiepileptics are drugs used in the long-term treatment of epilepsy and other conditions such as pain or psychiatric diseases. They are often administered as polytherapy or in combination with other treatments. It is therefore important to know their potential interactions (with each other and with other substances) in order to avoid altering their efficacy or potentiating their side effects.

OBJECTIVE

The purpose of this article is to review these aspects and stress the most important interactions in day-to-day clinical practice.

RESULTS

Older antiepileptic drugs (AEDs) such as phenytoin, carbamazepine, phenobarbital and valproic acid can significantly interfere not only with each other and other AEDs, but also with other treatments. Although newer AEDs have a more favourable pharmacokinetic profile, they are not entirely exempt from interactions and they are also commonly administered in combination with older AEDs. Another aspect that should be considered is the existence of any clinically important pharmacokinetic and pharmacodynamic interactions in patients requiring the continuous administration of other treatments.

CONCLUSION

We must be aware of the pharmacokinetic and pharmacodynamic interactions of AEDs. Because of a lack of significant interactions, drugs such as levetiracetam, gabapentin or pregabalin can be recommended in particular groups such as patients with cancer, transplants, anticoagulant treatments or HIV infection. In all cases, it is important to ensure AED efficacy and prevent serious complications.

Epilepsy and dementia in the elderly

Epilepsy is a frequent condition in the elderly; however, it remains a relatively understudied condition in older adults with dementia. The diagnosis of a seizure is particularly difficult and is most often based on questions to the caregiver. Epilepsy in dementia has significant consequences on the prognosis of the underlying dementia: it can result in a worsening of cognitive performance, particularly in language, as well as a reduction in autonomy, a greater risk of injury and a higher mortality rate. In this review, management strategies are recommended for the clinician. The presence of pre-existing Alzheimer's disease does not exempt the clinician from ruling out other symptomatic causes of seizures. Anti-epileptic drugs (AED) should be started only after the diagnosis has been clearly established, when the risk of recurrence is high, and with monotherapy whenever possible. Although few data are available, the more recent AED offer significant advantages over the older medications in this context.

Is valproate encephalopathy under-recognised in older people? A case series

BACKGROUND

Valproate (VPA) is an antiepileptic drug with a broad spectrum of efficacy. Although usually well-tolerated, it may have side-effects of which encephalopathy is one of the most serious.

OBJECTIVE

To describe the clinical characteristics of valproate encephalopathy (VE) in five older patients with remote symptomatic seizures treated with rapid VPA loading.

DESIGN

Case series.

SETTING

Teaching hospital

PATIENTS

Five patients (71-89 years old) with underlying cerebrovascular disease or dementia and symptomatic seizures.

RESULTS

VE was characterised by decline in conscious level and (in some cases) increase in seizure frequency. Three of the five patients had elevated ammonia levels. EEG showed generalised slow activity, in some cases accompanied by additional epileptic discharges. The condition was reversible in four patients after VPA discontinuation. One patient died.

CONCLUSIONS

Older people may be at particular risk of VE because of co-morbid pathology, age-related metabolic changes and co-medication.

Idiosyncratic toxicity: a convergence of risk factors

The therapeutic margin for any drug is based on both toxicity and efficacy. Generally, toxicity is dose-dependent and is driven either by the therapeutic target or by an untoward target. However, idiosyncratic toxicities are usually not observed until a drug has been on the market and has gained broad exposure. Except in the case of pharmacokinetic interactions, these toxicities are not driven solely by drug exposure but rather depend on several drug- and patient-related risk factors. Drug-related risk factors include metabolism, bioactivation and covalent binding, and the inhibition of key cell functions. Patient-related risk factors include underlying disease, age, gender, comedications, nutritional status, activation of the innate immune system, physical activity, and genetic predispositions. Idiosyncratic toxicity can occur when a convergence of risk factors, including drug exposure, tips the risk-benefit balance away from benefit and toward risk.

Case report: valproic Acid and risperidone treatment leading to development of hyperammonemia and mania

This case report describes two children who developed hyperammonemia together with frank manic behavior during treatment with a combination of valproic acid and risperidone. One child had been maintained on valproic acid for years and risperidone was added. In the second case, valproic acid was introduced to a child who had been treated with risperidone for years. In both cases, discontinuing the valproic acid resulted in normalization of ammonia levels and cessation of the manic behavior. This case report alerts physicians to the importance of obtaining serum ammonia levels in children treated with valproic acid and risperidone who present with manic behavior.

Pharmacokinetics and interactions of headache medications, part II: prophylactic treatments

The present part II review highlights pharmacokinetic drug-drug interactions (excluding those of minor severity) of medications used in prophylactic treatment of the main primary headaches (migraine, tension-type and cluster headache). The principles of pharmacokinetics and metabolism, and the interactions of medications for acute treatment are examined in part I. The overall goal of this series of two reviews is to increase the awareness of physicians, primary care providers and specialists regarding pharmacokinetic drug-drug interactions (DDIs) of headache medications. The aim of prophylactic treatment is to reduce the frequency of headache attacks using beta-blockers, calcium-channel blockers, antidepressants, antiepileptics, lithium, serotonin antagonists, corticosteroids and muscle relaxants, which must be taken daily for long periods. During treatment the patient often continues to take symptomatic drugs for the attack, and may need other medications for associated or new-onset illnesses. DDIs can, therefore, occur. As a whole, DDIs of clinical relevance concerning prophylactic drugs are a limited number. Their effects can be prevented by starting the treatment with low dosages, which should be gradually increased depending on response and side effects, while frequently monitoring the patient and plasma levels of other possible coadministered drugs with a narrow therapeutic range. Most headache medications are substrates of CYP2D6 (e.g., beta-blockers, antidepressants) or CYP3A4 (e.g., calcium-channel blockers, selective serotonin re-uptake inhibitors, corticosteroids). The inducers and, especially, the inhibitors of these isoenzymes should be carefully coadministered.

Outcomes in Elderly Patients With Newly Diagnosed and Treated Epilepsy

Epilepsy develops most commonly in the elderly. Seizures can severely affect a senior citizen's quality of life, and despite a growing elderly population with epilepsy, there is a paucity of good clinical data in this age group. To address some of the issues encountered by elderly patients with epilepsy, prospective information from elderly patients attending the Epilepsy Unit at the Western Infirmary in Glasgow, Scotland, was analyzed. Ninety patients, aged 65-93 years, were diagnosed with epilepsy and started on antiepileptic drug (AED) treatment. Neuroimaging was performed in 84 patients (93%), with 69 evaluated via computerized tomography and 15 via magnetic resonance imaging; abnormalities were found in 45 patients (54%). Sixty-eight patients underwent interictal electroencephalography, which revealed epileptiform discharges in 18 patients (26%). Fifty-eight of 90 patients (64%) became seizure free for at least 12 months on modest doses of the first prescribed AED. Seizures remained uncontrolled in 21 patients (23%), and the first AED was withdrawn in 11 patients (12%) because of adverse events. Following pharmacological manipulation, a total of 76 patients (84%) achieved seizure freedom. Patients starting treatment > or =2 years after their first seizure were less likely to achieve seizure control than patients who initiated treatment earlier. Newly diagnosed elderly patients were more likely to remain seizure free on AED treatment than newly diagnosed younger populations (p < 0.001). The majority of patients evaluated had partial-onset seizures, and underlying cerebral atrophy and infarcts were common. Treating an older person with initial AED therapy can be complicated; taking adequate time and communicating clearly are paramount. Although most of the patients evaluated had a positive outcome, all AEDs have some disadvantages in this population. Choice of drug may depend on comorbidity and comedication, among other factors. Initial dosing should be low with a slow titration schedule. A holistic approach to care helps optimize the outcome for elderly people with epilepsy.

Clinically relevant drug interactions with antiepileptic drugs

Some patients with difficult-to-treat epilepsy benefit from combination therapy with two or more antiepileptic drugs (AEDs). Additionally, virtually all epilepsy patients will receive, at some time in their lives, other medications for the management of associated conditions. In these situations, clinically important drug interactions may occur. Carbamazepine, phenytoin, phenobarbital and primidone induce many cytochrome P450 (CYP) and glucuronyl transferase (GT) enzymes, and can reduce drastically the serum concentration of associated drugs which are substrates of the same enzymes. Examples of agents whose serum levels are decreased markedly by enzyme-inducing AEDs, include lamotrigine, tiagabine, several steroidal drugs, cyclosporin A, oral anticoagulants and many cardiovascular, antineoplastic and psychotropic drugs. Valproic acid is not enzyme inducer, but it may cause clinically relevant drug interactions by inhibiting the metabolism of selected substrates, most notably phenobarbital and lamotrigine. Compared with older generation agents, most of the recently developed AEDs are less likely to induce or inhibit the activity of CYP or GT enzymes. However, they may be a target for metabolically mediated drug interactions, and oxcarbazepine, lamotrigine, felbamate and, at high dosages, topiramate may stimulate the metabolism of oral contraceptive steroids. Levetiracetam, gabapentin and pregabalin have not been reported to cause or be a target for clinically relevant pharmacokinetic drug interactions. Pharmacodynamic interactions involving AEDs have not been well characterized, but their understanding is important for a more rational approach to combination therapy. In particular, neurotoxic effects appear to be more likely with coprescription of AEDs sharing the same primary mechanism of action.