Effect of antiepileptic drug monotherapy on urinary pH in children and young adults

Objects Since alkaline urine is a risk factor for urolithiasis, the relationship between antiepileptic drugs and urinary pH was retrospectively studied in epilepsy patients treated with antiepileptic drug monotherapy for more than 1 month.Methods A total of 913 urinary samples from antiepileptic drug-treated patients were compared with 780 age-matched control samples, and with 112 samples from epilepsy patients who had not been treated with antiepileptic drugs. The antiepileptic drugs administered were carbamazepine, valproate, phenobarbital, zonisamide, sulthiame, and phenytoin.Conclusions The proportion of the acid urine in the valproate-treated patients was lower than that in controls. The proportion of the alkaline urine in the valproate-treated patients was higher than that in controls. This effect was independent of age, sex, and the serum valproate concentration. There was no significant difference in urinary pH among the epilepsy patients treated with other antiepileptic drugs, the epilepsy patients who had not been treated with antiepileptic drugs, and the controls.     

The teratogenic risk of antiepileptic drug polytherapy

Purpose: To compare the risks of fetal malformation during pregnancy associated with antiepileptic drug (AED) polytherapy and monotherapy. Methods: Statistical analysis of malformation rate and antiepileptic drug exposure data from the Australian Register of Antiepileptic Drugs in Pregnancy, and from the literature. Results: The calculated relative risk (RR) value for AED polytherapy compared with monotherapy was below 1.0 in only 3 of 14 literature publications. In the register, at 1 year postnatally there were fetal malformations in 5.32% of 282 AED polytherapy pregnancies, and in 7.84% of 791 AED monotherapy pregnancies, an RR of 0.68 [95% confidence interval (CI) 0.39–1.17). For pregnancies exposed to valproate, the RR of fetal malformation (0.39, 95% CI 0.20–0.89) was lower in polytherapy (7.26%) than in monotherapy (17.9%); the difference did not depend on valproate dosage. The RR values for fetal malformation were not significantly different for AED polytherapy and monotherapy when valproate was not involved. Logistic regression suggested that coadministration of lamotrigine may have reduced the malformation risk from valproate. Discussion: The fetal hazard of AED polytherapy relative to monotherapy may depend more on the degree of exposure to valproate than on the fact of polytherapy per se. Coadministration with lamotrigine may lower the fetal risk of valproate therapy.     

Selection of antiepileptic drug polytherapy based on mechanisms of action: the evidence reviewed

PURPOSE: When monotherapy with antiepileptic drugs (AEDs) fails, combination therapy is tried in an attempt to improve effectiveness by improving efficacy, tolerability, or both. We reviewed the available studies (both animal and human) on AED polytherapy to determine whether AEDs can be selected for combination therapy based on their mechanisms of action, and if so, which combinations are associated with increased effectiveness. Because various designs and methods of analysis were used in these studies, it was also necessary to evaluate the appropriateness of these approaches. METHODS: Published papers reporting on AED polytherapy in animals or humans were identified by Medline search and by checking references cited in these papers. RESULTS: Thirty-nine papers were identified reporting on two-drug AED combinations. Several combinations were reported to offer improved effectiveness, but no uniform approach was used in either animal or human studies for the evaluation of pharmacodynamic drug interactions; efficacy was often the only end point. CONCLUSIONS: There is evidence that AED polytherapy based on mechanisms of action may enhance effectiveness. In particular, combining a sodium channel blocker with a drug enhancing GABAergic inhibition appears to be advantageous. Combining two GABA mimetic drugs or combining an AMPA antagonist with an NMDA antagonist may enhance efficacy, but tolerability is sometimes reduced. Combining two sodium channel blockers seems less promising. However, given the incomplete knowledge of the pathophysiology of seizures and indeed of the exact mechanisms of action of AEDs, an empirical but rational approach for evaluating AED combinations is of fundamental importance. This would involve appropriate testing of all possible combinations in animal models and subsequent evaluation of advantageous combinations in clinical trials. Testing procedures in animals should include the isobologram method, and the concept of drug load should be the basis of studies in patients with epilepsy.     

Comparison of antiepileptic drug prescribing in children in three European countries

Purpose: Antiepileptic drug (AED) use in young people is increasing. However, evidence of its use at a multinational level is limited. This study aims to characterize AED prescribing in the young in three European countries and to assess the capacity of drug safety surveillance. Methods: A retrospective cohort study was conducted in 2001–2005 using primary care databases: PEDIANET (Italy, 0–11 years), IPCI (The Netherlands, 0–18 years), and IMS Disease Analyzer (United Kingdom, 0–18 years). Prescribing prevalence was calculated by country, patient age, and drug type. Results: In 2005, AED prevalence in children (0–11 years) was highest in Italy [3.9 subjects/1,000 person‐years (PY)] followed by the United Kingdom (3.0 subjects/1,000 PY) and The Netherlands (2.2 subjects/1,000 PY). Over the study period, prescribing prevalence in 0–11 year olds was stable in all countries. In contrast, a steady rise of AED prevalence was observed in adolescents (12–18 years) in the United Kingdom (p = 0.0003) but not in The Netherlands (p = 0.88). All countries showed a slight increase in prevalence for newer AEDs. Simultaneously, the prevalence of conventional AEDs decreased in The Netherlands and Italy, but not in the United Kingdom. In 2005, lamotrigine use was highest in The Netherlands and the United Kingdom, whereas topiramate was favored in Italy. Discussion: In Europe, conventional AEDs are still the main treatment choice for children with epilepsy, and the use of newer AEDs remains low. Our study highlights a lack of research capacity to conduct multinational AED safety studies in children. Further work should explore large databases and other health care settings to meet these research needs.     

Metabolic and hormonal disturbances in women with epilepsy on antiepileptic drug monotherapy

PURPOSE: Women with epilepsy (WWE) tend to have hormonal and metabolic abnormalities, raising concerns about an increased risk of cardiovascular disorders. This study was performed to determine whether epilepsy itself and/or antiepileptic drug (AED) medication cause metabolic abnormalities. METHODS: WWE in premenopausal state aged 18 to 45 years old, currently on AED monotherapy for more than six months, were recruited for this study. The subjects checked their oral temperature each morning, and tested serum levels for lipid profiles, insulin, glucose, and leptin. A HOMA-index was used as a marker for insulin resistance. RESULTS: Of the 54 total patients, 18 women were diagnosed with primary generalized epilepsy (PGE) and the other 36 were diagnosed with localization-related epilepsy (LRE). Among the subjects, 19 women were on carbamazepine (CBZ), 12 on valproate (VPA), 12 on lamotrigine (LTG), and 11 on topiramate (TPM). Body mass index increased and HDL-cholesterol decreased in patients on VPA monotherapy compared with CBZ, LTG, or TPM (p=0.046 and 0.002). Metabolic syndrome was more frequently associated with VPA-treated patients (41.7%) than CBZ (5.3%), LTG (0%), or TPM group (0%) (p=0.005). There were no differences in hormonal and metabolic indices between PGE and LRE groups. CONCLUSIONS: WWE on VPA monotherapy are more obese and more frequently suffer from metabolic syndrome. LTG or TPM may be safer when prescribed to the patients with high risk of cardiovascular disease.     

The importance of drug interactions in epilepsy therapy

Long-term antiepileptic drug (AED) therapy is the reality for the majority of patients diagnosed with epilepsy. One AED will usually be sufficient to control seizures effectively, but a significant proportion of patients will need to receive a multiple AED regimen. Furthermore, polytherapy may be necessary for the treatment of concomitant disease. The fact that over-the-counter drugs and nutritional supplements are increasingly being self-administered by patients also must be considered. Therefore the probability of patients with epilepsy experiencing drug interactions is high, particularly with the traditional AEDs, which are highly prone to drug interactions. Physicians prescribing AEDs to patients with epilepsy must, therefore, be aware of the potential for drug interactions and the effects (pharmacokinetic and pharmacodynamic) that can occur both during combination therapy and on drug discontinuation. Although pharmacokinetic interactions are numerous and well described, pharmacodynamic interactions are few and usually concluded by default. Perhaps the most clinically significant pharmacodynamic interaction is that of lamotrigine (LTG) and valproic acid (VPA); these drugs exhibit synergistic efficacy when coadministered in patients with refractory partial and generalised seizures. Hepatic metabolism is often the target for pharmacokinetic drug interactions, and enzyme-inducing drugs such as phenytoin (PHT), phenobarbitone (PB), and carbamazepine (CBZ) will readily enhance the metabolism of other AEDs [e.g., LTG, topiramate (TPM), and tiagabine (TGB)]. The enzyme-inducing AEDs also enhance the metabolism of many other drugs (e.g., oral contraceptives, antidepressants, and warfarin) so that therapeutic efficacy of coadministered drugs is lost unless the dosage is increased. VPA inhibits the metabolism of PB and LTG, resulting in an elevation in the plasma concentrations of the inhibited drugs and consequently an increased risk of toxicity. The inhibition of the metabolism of CBZ by VPA results in an elevation of the metabolite CBZ-epoxide, which also increases the risk of toxicity. Other examples include the inhibition of PHT and CBZ metabolism by cimetidine and CBZ metabolism by erythromycin. In recent years, a more rational approach has been taken with regard to metabolic drug interactions because of our enhanced understanding of the cytochrome P450 system that is responsible for the metabolism of many drugs, including AEDs. The review briefly discusses the mechanisms of drug interactions and then proceeds to highlight some of the more clinically relevant drug interactions between AEDs and between AEDs and non-AEDs. Understanding the fundamental principles that contribute to a drug interaction may help the physician to better anticipate a drug interaction and allow a graded and planned therapeutic response and, therefore, help to enhance the management of patients with epilepsy who may require treatment with polytherapy regimens.     

Efficacy and tolerability of the first antiepileptic drug in children with newly diagnosed idiopathic epilepsy

PurposeLimited data are available for the effectiveness of the antiepileptic drugs in children in daily clinical practice. The aim of this study was to investigate the efficacy and tolerability of the first prescribed old and new antiepileptic drugs in children with newly diagnosed idiopathic epilepsy during a 12-month period.MethodA total of 289 children (141 females and 148 males) who received phenobarbital (n = 33), valproate (n = 142), carbamazepine (n = 42), oxcarbazepine (n = 38), or levetiracetam (n = 34) as the first-line treatment, were enrolled in the study. Seizure control and the occurrence of adverse events were assessed during a treatment period of 12 months.ResultsOverall, 245 (84.8%) patients remained seizure-free during the study period. The rate of seizure control did not differ significantly between the drug groups (p = 0.099). Forty-four (15.2%) patients including 1 (3.0%) treated with phenobarbital, 22 (15.5%) with valproate, 7 (16.7%) with carbamazepine, 10 (26.3%) with oxcarbazepine, and 4 (11.8%) with levetiracetam had treatment failure. There was no significant difference between seizure-free and failure groups in terms of age, gender, seizure type, and drugs used. Overall, 80 (27.7%) patients had adverse events, of those the most common ones were behavioral problems, nausea and/or vomiting, weight gain, and learning difficulties. The reasons for treatment failures were lack of seizure control in 29 (10.0%) patients and intolerable adverse events in 15 (5.2%) patients.ConclusionIt appears that old (phenobarbital, valproate and carbamazepine) and new antiepileptic drugs (oxcarbazepine and levetiracetam) have similar efficacy and tolerability profiles.Institutional ethic number is 28.3.2013/14.     

儿童癫痫及抗癫痫治疗对血脂水平影响的研究

对１１４例儿童癫痫患者的血脂水平进行监测。结果发现癫痫本身对血脂水平无影响，抗癫痫药物治疗后总胆固醇和甘油三产高，且随治疗时间的延长差异更为明显，高密度脂蛋白无变化。丙戊酸钠对血脂无影响，而苯舀英钠，苯巴比舀，卡马西平可使ＴＣ，ＴＧ明显升高。     

The effect of antiepileptic drugs on thyroid function in children

BackgroundLimited and conflicting data exist for the influence of antiepileptic drugs on thyroid function in children.ObjectiveThe aim of this study was to investigate the effects of phenobarbital, valproate, carbamazepine, oxcarbazepine, and levetiracetam monotherapy on thyroid function in daily clinical practice during a 12-month treatment period.MethodA total of 223 children (103 females and 120 males) with new onset and controlled epilepsy treated with valproate (n = 129), phenobarbital (n = 33), carbamazepine (n = 36), oxcarbazepine (n = 14), levetiracetam (n = 11) were enrolled in the study. Serum free thyroxine (fT4) and thyroid-stimulating hormone (TSH) levels were measured before and at first, sixth and twelfth months of therapy.ResultsAt baseline, average fT4 and TSH concentrations were not different between the drug groups. Valproate-treated patients had decreased fT4 and increased TSH levels at months 1, 6, and 12. Carbamazepine-treated patients had decreased fT4 levels at months 1, 6, and 12 and increased TSH levels at months 1, and 6. Phenobarbital-treated patients had decreased fT4 levels at months 1, and 6, and increased TSH levels at months 6 and 12. Oxcarbazepine-treated patients had decreased fT4 levels at month 1. Levetiracetam-treated patients showed no significant change of fT4 and TSH at any times. The frequency of subclinical hypothyroidism at month 12 was 28% in valproate, 21.4% in oxcarbazepine, 18.2% in phenobarbital, 13.9% in carbamazepine, and 0% in levetiracetam groups.ConclusionOur data suggest that all antiepileptic drugs studied except levetiracetam had varying degrees of deleterious effects on thyroid function.     

传统抗癫痫药物和妥泰对成年癫痫患者生活质量的影响

目的 评价传统抗癫痫药物和妥泰对成年癫痫患者生活质量的影响。方法 102例临床新确诊的成年癫痫患者被随机分为两组：一组予以传统抗癫痫药物单药系统治疗(AEDs组)，另一组予以妥泰单药治疗(TPM组)。1个月后比较两组的发作频率和不良反应。并用QOLIE-30表对这102例癫痫患者进行生活质量评定。结果 TPM组的发作频率和不良反应均明显低于AEDs组，而生活质量总分明显高于AEDs组，尤其在前五项的评分中更加明显。结论 TPM能提高癫痫患者的生活质量，其改善生活质量的作用主要是通过控制发作和减轻不良反应实现的。     

Effect of antiepileptic drugs on short-latency somatosensory evoked potentials

Short-latency somato sensory evoked potentials (SEPs) were recorded in 45 freshly diagnosed cases of epilepsy before starting treatment. Follow-up recordings were made 6 weeks and 3 months after diphenylhydantoin, carbamazipine and phenobarbitone monotherapy were started. Serum drug levels were monitored. Both amplitude and latency of the initial component (N20) remained unchanged and were identical to a group of 30 age- and sex-matched normal individuals in whom SEPs were recorded during the period of study.     

Bone mineral density in children, adolescents, and young adults with epilepsy

Purpose:   The aim of this study was to assess bone mineral density (BMD) in a large population of children, adolescents, and young adults with epilepsy alone or in association with cerebral palsy and/or mental retardation.
Methods:   Ninety-six patients were enrolled in the study. The group comprised 50 males and 46 females, aged between 3 and 25 years (mean age 11 years). The control group consisted of 63 healthy children and adolescents (23 males, 40 females), aged between 3 and 25 years (mean age 12.1 years). Patients underwent a dual-energy x-ray absorptiometry (DEXA) scan of the lumbar spine (L1–L4) and the z scores were calculated for each patient; the t score was considered for patients 18 years of age or older.
Results:   Abnormal BMD was found in 56 patients (58.3%), with values documenting osteopenia in 42 (75%) and osteoporosis in 14 (25%). A significant difference emerged between epileptic patients and the control group in BMD, z score, and body mass index (BMI) (p = <0.001). Lack of autonomous gait, severe mental retardation, long duration of antiepileptic treatment, topiramate adjunctive therapy, and less physical activity significantly correlated with abnormal BMD.
Discussion:   This study detected abnormal BMD in more than half of a large pediatric population with epilepsy with or without cerebral palsy and/or mental retardation. The clinical significance of these findings has yet to be clarified.     

Cost-effectiveness of first-line antiepileptic drug treatments in the developing world: a population-level analysis

PURPOSE: To establish the population-level costs and cost-effectiveness of first-line antiepileptic drug (AED) treatments for reducing the treatment gap in developing countries. METHODS: A population model was applied to nine World Health Organization (WHO) developing subregions to estimate the impact of four first-line AEDs in the primary care management of (ICD-10 defined) idiopathic epilepsy and epileptic syndromes: phenobarbitone (PB), phenytoin (PHT), carbamazepine (CBZ), and valproic acid (VPA). The efficacy of treatment was gauged in terms of improvements to both disability and recovery, subsequently adjusted for treatment coverage, response, and adherence. Total population-level treatment effects (measured in disability-adjusted life years or DALYs averted) and treatment costs (measured in international dollars; IUS dollars) were combined to form ratios of cost-effectiveness. RESULTS: Across nine developing WHO subregions, extending AED treatment coverage to 50% of primary epilepsy cases would avert between 150 and 650 DALYs per one million population (equivalent to 13-40% of the current burden), at an annual cost per capita of IUS dollars 0.20-1.33. Older first-line AEDs (PB, PHT) were most cost-effective on account of their similar efficacy but lower acquisition cost (IUS dollars 800-2,000 for each DALY averted). CONCLUSIONS: A significant proportion of the current burden of epilepsy in developing countries is avertable by scaling-up the routine availability of low-cost AEDs. Critical factors in the successful implementation of such a scaled-up level of service delivery, apart from renewed political support and investment, relate to appropriate training and continuity of drug supply.     

Effects of long-term antiepileptic drug monotherapy on vascular risk factors and atherosclerosis

Purpose: Long‐term therapy with antiepileptic drugs (AEDs) has been associated with metabolic consequences that lead to an increase in risk of atherosclerosis in patients with epilepsy. We compared the long‐term effects of monotherapy using different categories of AEDs on markers of vascular risk and the atherosclerotic process. Methods: One hundred sixty adult patients who were receiving AED monotherapy, including two enzyme‐inducers (carbamazepine, CBZ; and phenytoin, PHT), an enzyme‐inhibitor (valproic acid, VPA), and a noninducer (lamotrigine, LTG) for more than 2 years, and 60 controls were enrolled in this study. All study participants received measurement of common carotid artery (CCA) intima media thickness (IMT) by B‐mode ultrasonography to assess the extent of atherosclerosis. Other measurements included body mass index, and serum lipid profile or levels of total homocysteine (tHcy), folate, uric acid, fasting blood sugar, high sensitivity C‐reactive protein (hs‐CRP), or thiobarbituric acid reactive substances (TBARS). Key Findings: Long‐term monotherapy with older‐generation AEDs, including CBZ, PHT, and VPA, caused significantly increased CCA IMT in patients with epilepsy. After adjustment for the confounding effects of age and gender, the CCA IMT was found to be positively correlated with the duration of AED therapy. Patients with epilepsy who were taking enzyme‐inducing AED monotherapy (CBZ, PHT) manifested disturbances of cholesterol, tHcy or folate metabolism, and elevation of the inflammation marker, hs‐CRP. On the other hand, patients on enzyme‐inhibiting AED monotherapy (VPA) exhibited an increase in the levels of uric acid and tHcy, and elevation of the oxidative marker, TBARS. However, no significant alterations in the markers of vascular risk or CCA IMT were observed in patients who received long‐term LTG monotherapy. Significance: Patients with epilepsy who were receiving long‐term monotherapy with CBZ, PHT, or VPA exhibited altered circulatory markers of vascular risk that may contribute to the acceleration of the atherosclerotic process, which is significantly associated the duration of AED monotherapy. This information offers a guide for the choice of drug in patients with epilepsy who require long‐term AED therapy, particularly in aged and high‐risk individuals.     

Balance impairment in chronic antiepileptic drug users: A twin and sibling study

Purpose: Patients taking antiepileptic drugs (AEDs) have an increased incidence of fractures. This study investigated chronic AED use and physical contributors to falls risk using an AED‐discordant, twin and sibling matched‐pair approach, and assessed clinically relevant subgroups: AED polytherapy; longer‐duration AED; and falls history. Methods: Twenty‐nine same‐sex (mean age 44.9 years, 59% female), ambulatory, community‐dwelling twin and sibling pairs, discordant for AED exposure (and AED‐indication), were recruited. Validated clinical and laboratory tests of strength, gait, and balance were performed. Relevant AED levels, and fasting serum samples for 25‐hydroxyvitamin D (25OHD), 1,25‐dihydroxyvitamin D [1,25(OH)₂D], and immunoreactive parathyroid hormone (iPTH) levels were taken. Results: There were significant mean within‐pair differences in tests of static and dynamic balance, with the AED user having poorer balance function than the AED nonuser. No difference was seen in lower limb strength or gait measures. Increased duration of AED therapy and AED polytherapy were independent predictors of increased sway. No significant within‐pair differences were seen in fasting serum levels of 1,25(OH)₂D, 25OHD and iPTH after Bonferroni correction. Discussion: Balance performance is impaired in AED users compared to their matched nonuser siblings. Pairs where the AED users took AED polytherapy, or had a longer duration of AED use, had more impaired balance performance. These balance deficits may contribute to the increased rate of fractures in this population.     

Elevated plasma concentrations of homocysteine in antiepileptic drug treatment

PURPOSE: Homocysteine is an experimental convulsant and an established risk factor in atherosclerosis. A nutritional deficiency of vitamin B6, vitamin B12, or folate leads to increased homocysteine plasma concentrations. During treatment with carbamazepine (CBZ), phenytoin, or phenobarbital, a deficiency in these vitamins is common. The objective of the study was to test the hypothesis that antiepileptic drug (AED) treatment is associated with increased homocysteine plasma concentrations. METHODS: A total of 51 consecutive outpatients of our epilepsy clinic receiving stable, individually adjusted AED treatment and 51 sex- and age-matched controls were enrolled in the study. Concentrations of total homocysteine and vitamin B6 were measured in plasma; vitamin B12 and folate were measured in the serum of fasted subjects. RESULTS: Patients and controls differed significantly in concentrations of folate ( 13.5+/-1.0 vs. 17.4+/-0.8 nM and vitamin B6 (39.7+/-3.4 vs. 66.2+/-7.5 nM), whereas serum concentrations of vitamin B12 were similar. The homocysteine plasma concentration was significantly increased to 14.7+/-3.0 microM in patients compared with controls (9.5+/-0.5 microM; p < 0.05, Wilcoxon rank-sum test). The number of patients with concentrations of >15 microM was significantly higher in the patient group than among controls. The same result was obtained if only patients with CBZ monotherapy were included. Patients with increased homocysteine plasma concentrations had lower folate concentrations. CONCLUSIONS: These data support the hypothesis that prolonged AED treatment may increase plasma concentrations of homocysteine, although the alternative explanation that increased homocysteine plasma concentrations are associated with the disease and not the treatment cannot be completely excluded at the moment.