Serum Concentrations Of Antiepileptic Drugs Research Articles

Diagnosis and prognosis of serum Fut8 for epilepsy and refractory epilepsy in children.

With adequate serum concentration of antiepileptic drugs, the epilepsy symptoms in many patients still cannot be controlled well. The alteration of glycosyltransferase has obvious influence on the pathogenesis of epilepsy. In this study, we focus on the diagnostic and prognostic value of fucosyltransferase 8 (Fut8) on epilepsy and refractory epilepsy. Serum samples of 199 patients with epilepsy, 59 patients with refractory epilepsy and 22 healthy controls who were diagnosed in Shenzhen Children's hospital from August 2018 to August 2019 were collected. The level of lectins was further analyzed by lectin chip and enzyme linked immunosorbent assay (ELISA). The diagnostic value of serum Fut8 for epilepsy and refractory epilepsy was evaluated by receiver operating characteristic curve. Finally, the difference in the recurrence rate of convulsion in patients with epilepsy or refractory epilepsy within 2 years were observed in different Fut8 expression patients. The concentration of valproic acid (VPA) were significant different between epilepsy and refractory epilepsy group. The expression of α1, 6-fucosylation and Fut8 was significantly increased in the refractory epilepsy group compared with healthy controls. The area under the curve of Fut8 as a biomarker for predicting epilepsy or refractory epilepsy was 0.620 and 0.856, respectively. There was a significant difference in the recurrence rate of convulsion within 2 years in the children with refractory epilepsy (p = 0.0493) not epilepsy (p = 0.1865) between the high and low Fut8 expression groups. Fut8 was one of the effective indicators for the diagnosis and prognosis of refractory epilepsy.

Therapeutic Drug Monitoring of Lamotrigine, Lacosamide, and Levetiracetam in Dried Capillary Blood-Determination of Conversion Factors for Serum-Based Reference Ranges.

Drug concentrations of antiepileptic drugs (AEDs) are routinely determined from blood serum or plasma at trough levels (before intake of morning dose). In capillary blood collection, blood is taken from the fingertip with the aid of a disposable tool and dried on absorbent material. The volumetric absorptive microsampling technique offers several advantages over the use of filter paper cards. The aim of this study was to determine conversion factors for the estimation of AED serum concentrations from capillary blood concentrations. Venous and capillary blood samples were collected from adult inpatients with epilepsy who were treated with lacosamide (LCM, n = 30), lamotrigine (LTG, n = 40), and/or levetiracetam (LEV, n = 36). A validated liquid chromatography-mass spectrometry (LC-MS) method for dried blood samples for these AEDs was compared with routine serum laboratory methods. Method agreement was evaluated using different regression techniques, and the conversion factors were calculated. Regression analyses revealed a linear relationship between serum and capillary blood concentrations for all 3 AEDs (r ≥ 0.95). For LTG, the regression intercept was significantly different from 0, indicating that the relationship was linear, but not necessarily proportional. Although LEV and LCM concentrations tended to be lower in capillary blood than in serum (mean ratio of serum concentration to capillary blood concentration: 1.14 and 1.22, respectively), LTG concentrations were higher in capillary blood (mean ratio = 0.85). The estimation of serum concentrations from measured capillary blood concentrations is feasible for LCM, LTG, and LEV. A simple ratio approach using the mean ratio and Passing-Bablok regression showed the best results for all 3 AEDs. The volumetric absorptive microsampling technique facilitates the quantitative sample collection of capillary blood and overcomes the drawbacks associated with the classical dried blood spot technique.

Metabolic syndrome and obstructive sleep apnea syndrome among patients with epilepsy on monotherapy

ObjectivesThe study aimed to determine the frequency of metabolic syndrome (MetS) and obstructive sleep apnea syndrome (OSAS) in patients with epilepsy receiving monotherapy and the relationship between these syndromes and antiepileptic drugs (AEDs). MethodsTwo hundred and ninety-seven patients with epilepsy between the ages of 18–65 years receiving monotherapy for at least one year and 50 healthy participants were enrolled. Body mass indices and waist circumferences were measured. Serum fasting glucose levels, high-density lipoprotein (HDL), low density lipoprotein (LDL), total cholesterol (TC), triglyceride, and serum AED concentrations were noted. The frequency of MetS in patients with epilepsy was calculated. The snoring, tiredness, observed apnea, high blood pressure, body mass index, age, neck circumference, and male gender (STOP-Bang) questionnaire was used to determine the risk of OSAS. The relationship between these two syndromes and seizure type, disease duration, AED dosage, and treatment duration was analyzed. ResultsMetabolic syndrome was more frequent in patients with epilepsy compared with healthy participants (32.6% vs. 12.0%), and it was diagnosed in 37.8% of patients receiving valproic acid (VPA), 36.1% of patients receiving carbamazepine (CBZ), 34.9% of patients receiving oxcarbazepine (OXC), and 30.5% of patients on levetiracetam (LEV). There was a positive correlation between VPA treatment duration and MetS existence (p < 0.05). However, MetS frequency did not change because of seizure type, disease duration, or AED dosages in patients with epilepsy receiving monotherapy. The risk for OSAS was higher in patients with epilepsy compared with healthy participants (24.6% vs. 12%), and it was calculated high in 27.7% of patients receiving CBZ, 32.2% of patients receiving LEV, and 30.2% of patients receiving OXC. The OSAS risk was higher in patients who have focal seizures than generalized seizures (p = 0.044). There was no relationship between OSAS risk and duration of epilepsy, duration of treatment, drug doses, and serum drug levels (p > 0.05). ConclusionHigher frequency of MetS and OSAS risk should be kept in mind on clinical follow-up of patients with epilepsy receiving monotherapy.

Pharmacological monitoring of antiepileptic drugs in epilepsy patients on haemodialysis.

To retrospectively evaluate the pharmacological profiles of antiepileptic drugs (AEDs) in epilepsy patients during haemodialysis using therapeutic drug monitoring data. The serum concentration of AEDs was collected before and after haemodialysis, and the clearance rate and concentration-to-dose ratio were calculated as pharmacological parameters. Thirty-six patients were enrolled in the study (25 males, 11 females; age: 65.3 ± 14.8 years). In 24 of the 36 patients, epilepsy was associated with cerebrovascular disorders, and diabetes was the most common reason for haemodialysis in 16 patients. With regards to seizure type, focal aware seizures were less frequent than focal impaired awareness seizures and focal-to-bilateral tonic-clonic seizures. Interictal EEG showed intermittent rhythmic slow waves and intermittent slow waves more often than spikes or sharp waves. Levetiracetam was the most commonly used AED and led to the highest percentage of responders (80%; 16/20 patients). However, the clearance rate of levetiracetam during dialysis was highest among the antiepileptic drugs used, requiring supplementary doses after haemodialysis in all 20 patients. Valproic acid was not effective for focal epilepsy for patients on haemodialysis, and non-responders to phenytoin had low serum concentration of phenytoin both before and after haemodialysis. The pre-haemodialysis concentration of levetiracetam tended to be higher than the reference range, suggesting a potential risk of overdosing before haemodialysis. The pre- and post-haemodialysis concentrations of valproic acid tended to be lower than the reference range, suggesting a potential risk of underdosing. The concentration-to-dose ratios for levetiracetam, valproic acid, phenytoin, and carbamazepine were significantly lower after than before haemodialysis. The majority of patients with epilepsy on haemodialysis had cerebrovascular diseases, and therapeutic drug monitoring for levetiracetam, valproic acid, and phenytoin, before and after haemodialysis, is needed to ensure proper dosing.

Pharmacokinetic interaction between modified Atkins diet and antiepileptic drugs in adults with drug-resistant epilepsy.

The aim was to examine the influence of modified Atkins diet on serum concentration of antiepileptic drugs (AEDs). Prospective data from 63 adult patients with either focal or generalized drug-resistant epilepsy recruited to 12-week dietary treatment as add-on to AEDs are analyzed. AED serum concentrations, ketones, glucose, and hemoglobin A1c were measured before and after the dietary intervention. Paired t test was used and Spearman correlation coefficient, r, was estimated. Mean age was 37years (range 16-65years). Mean serum concentrations of carbamazepine, clobazam, and valproate were significantly reduced after 4 and 12weeks of the diet period (<.001≤P≤.02). Levels of lacosamide, lamotrigine, and topiramate were less reduced (.02≤P≤.08), whereas the serum concentrations of oxcarbazepine, zonisamide, and levetiracetam were unchanged (.06≤P≤.90). The largest reduction in serum concentration was found for clobazam: mean reduction after 12weeks was 1.5μmol/L (34%). Percent change in serum concentration after 4 and 12weeks of all drugs analyzed was -10.5% (95% confidence interval [CI] -14.1 to -6.8; n=60; P<.001) and -13.5% (95% CI -18.8 to -8.3; n=56; P<.001), respectively. Percent change in serum concentration of AEDs was not significantly correlated to percent change in seizure frequency after 12weeks of dietary treatment (r=.14, P=.33, n=53) but negatively correlated to urine ketosis (r=-.43; P=.003; n=46). A reduction in AED serum concentrations may counteract a seizure-reducing effect of the diet, and in patients without such an effect, it may cause seizure aggravation. Thus, we recommend that clinicians who are treating patients with ketogenic diets monitor serum concentrations of the concomitant AEDs.

Effect of modified Atkins diet in adults with drug-resistant focal epilepsy: A randomized clinical trial.

Ketogenic diets reduce seizures in children with drug-resistant epilepsy. Whether adults benefit from similar treatment has not been clarified. We therefore examined the efficacy of the modified Atkins diet in adults with drug-resistant focal epilepsy. We performed a randomized clinical trial (RCT) with patients >16years who had at least 3 seizures per month despite having tried at least 3 antiepileptic drugs. They were randomized to either 12weeks on the modified Atkins diet (diet group) or habitual diet (control group). Primary endpoint was a change in seizure frequency from baseline to the intervention period, comparing those on diet with controls. We assigned 37 patients to the diet group and 38 to the control group. Nine of the patients in the diet group and 4 controls were excluded. Of those who completed the dietary intervention (n=24), median seizure change was -1.0 (interquartile range [IQR] -13.7-8.8), while in the control group (n=32) the median change was 4.5 (IQR -4.8-33.5). The median difference between the groups was -7.0 (95% confidence interval [CI] -37.0-3.0; P=.21). In the intention-to-treat analysis, the relative risk (RR) for achieving >50% seizure reduction was 1.8 (95% CI 0.3-10.2; P=.65), while for achieving >25% seizure reduction RR was 2.43 (95% CI 0.94-6.28; P=.06). We observed no serious adverse events. In this RCT investigating the effect of an adjunctive modified Atkins diet on seizure frequency in adults with difficult-to-treat focal epilepsy, we found a significant reduction in seizure frequency in the diet group compared to the controls, but only for moderate benefit (>25% seizure reduction) among those who completed the intervention. However, seizure response varied considerably between individuals, perhaps negatively influenced by a drop in serum concentrations of antiepileptic drugs.

Evaluation of the Effects of Extracorporeal Membrane Oxygenation on Antiepileptic Drug Serum Concentrations in Pediatric Patients.

Patients supported on extracorporeal membrane oxygenation (ECMO) have an increased incidence of seizures. Phenobarbital (PB) and fosphenytoin (fos-PHT) are common antiepileptic drugs (AEDs) used to manage seizures in the pediatric population; however, it is unknown what effect ECMO has on the serum concentrations of AEDs. The purpose of this study is to evaluate the effect of ECMO on AED serum concentrations. A retrospective, matched-cohort study was performed in patients younger than 18 years who received ECMO and were treated with intravenous (IV) PB or fos-PHT at Texas Children's Hospital between 2004 and 2014. Patients receiving IV AED therapy and ECMO were matched, based on age, sex, and weight, with patients receiving IV AED therapy without ECMO. The 24-hour cumulative AED dose, serum concentrations, number of doses per serum concentration drawn ratio, volume of distribution, therapeutic serum concentrations, and time to therapeutic serum concentration were compared between both groups. The fos-PHT and PB groups were analyzed in all patients and in neonates only. Fourteen patients met inclusion criteria. The fos-PHT neonatal (20.1 vs 11.3 mg/kg/day, p = 0.044), PB composite (33.9 vs 21.6 mg/kg/day, p = 0.012), and PB neonatal (40.3 vs 20 mg/kg/day, p = 0.04) had larger 24-hour cumulative doses compared with non-ECMO patients. Lower serum concentrations were observed in the PB composite ECMO group (19.1 vs 35.4 mg/L, p < 0.001) and the PB neonatal ECMO group (20.5 vs 27.8 mg/L, p = 0.01) compared with non-ECMO patients. Pediatric patients receiving PB on ECMO and neonatal patients receiving fos-PHT on ECMO required larger doses, and in pediatric patients achieved lower serum concentrations, suggesting the necessity for alternative dosing strategies in these populations.

Effect of ketogenic diet and other dietary therapies on anti-epileptic drug concentrations in patients with epilepsy.

The ketogenic diet (KD) is an effective high-fat, adequate-protein, low-carbohydrate diet for patients with refractory epilepsy. The aim of this study was to investigate the potential effects of the KD and other dietary therapies on the concentrations of anticonvulsants in patients with epilepsy. Patients with epilepsy who were treated with the KD and other dietary therapies for more than 30days with at least one measurement performed both before and during the diet were evaluated. The mean serum concentrations and the mean serum concentrations per weight per daily dose per bioavailability (F) of anti-epileptic drugs (AEDs) before and during the treatment were assessed. We also compared the rates of events out of reference ranges of the AEDs between before and during the KD and other dietary therapies. We compared the serum albumin, alanine transaminase and aspartate transaminase data of patients with valproic acid before and during the KD. One-hundred thirty-nine patients including 81 male patients were enrolled. The median age of the patients was 2.91 (0.15-15.46) years. The median duration of the dietary therapies was 153 (35-2307) days. After the dietary therapies, the serum concentrations of carbamazepine, lamotrigine, levetiracetam, topiramate and valproic acid decreased, whereas that of phenobarbital slightly increased. However, statistical significance was found only with valproic acid (67.07±25.89μg/mL vs 51.00±20.19μg/mL, P<.05). The serum concentrations per weight per daily dose per drug F significantly decreased for valproic acid (1.38±1.39×10-2 vs 0.82±0.82×10-2 μgdmL-1 F-1 ) and phenobarbital (6.66±7.20×10-2 vs 4.75±4.07×10-2 μgdmL-1 F-1 , P<.05). The rate of occurrence of events out of reference ranges significantly increased with valproic acid (36.08% vs 57.23%, P<.05). Most anti-epileptic drug serum concentrations remained stable during the KD and other related dietary therapies except those of valproic acid. Therefore, serum concentrations of valproic acid should be monitored when the KD and other dietary therapies are concomitantly administered.

Impact of generic substitution on levetiracetam serum concentration—A prospective study in an outpatient setting

BackgroundSwitching patients from a branded antiepileptic drug (AED) to a generic is often challenging. Several studies have shown that considerable proportions of patients report deteriorated seizure control or increased adverse effects, enforcing a switchback to the original drug. Since tolerability and seizure control usually correlate with AED serum concentrations, we examined the fluctuation of levetiracetam (LEV) serum concentrations in patients with epilepsy before and after generic substitution. MethodsThis was an 18-week, naturalistic, open, prospective, two-center study. After a baseline period of 10 weeks, 33 outpatients on stable treatment with branded LEV (Keppra®) either continued with this product or were switched overnight to a generic LEV preparation (1A Pharma) for an eight-week study period. Throughout the study, patients were monitored with bi-weekly LEV serum concentration measurements and seizure diaries. Results16 out of 33 patients were switched to a generic LEV product. No switchbacks were seen. LEV dose, LEV serum concentrations, fluctuation index and concentration/dose-ratio (C/D-ratio) were not significantly different within-group (baseline vs. study period) or between-group. Large within-subject variability in serum concentrations was seen in both groups. None of the patients that were seizure-free before inclusion experienced seizures while on the generic LEV product. ConclusionsOur results show equal fluctuation of LEV serum concentrations with branded LEV and the generic LEV. Most importantly, within-subject variability was much larger than the small, non-significant differences between brands.

Association of UGT2B7 and UGT1A4 Polymorphisms with Serum Concentration of Antiepileptic Drugs in Children.

BackgroundThis study aimed to analyze the relationship of UGT2B7 and UGT1A4 polymorphisms with metabolism of valproic acid (VPA) and lamotrigine (LTG) in epileptic children.Material/MethodsWe administered VPA (102) and LTG (102) to 204 children with epilepsy. Blood samples were collected before the morning dose. Serum concentration of LTG was measured by high-performance liquid chromatography (HPLC). Serum VPA concentration was tested by fluorescence polarization immunoassay. UGT2B7 A268G, C802T, and G211T polymorphisms, as well as UGT1A4 L48V polymorphism, were assayed by direct automated DNA sequencing after PCR. Evaluation of efficacy was conducted using the Engel method.ResultsThe adjusted serum concentration of VPA was 4.26 μg/mL per mg/kg and LTG was 1.56 μg/mL per mg/kg. Multiple linear regression analysis revealed that VPA or LTG adjusted concentration showed a good linear relation with sex and age. UGT2B7 A268G and C802T polymorphisms were demonstrated to affect the serum concentration of VPA (F=3.147, P=0.047; F=22.754, P=0.000). UGT1A4 L48V polymorphism was not related with the serum concentration of LTG (F=5.328, P=0.006). In the efficacy analysis, we found that C802T polymorphism exerted strong effects on efficacy of VPA (χ2=9.265, P=0.010). L48V polymorphism also showed effects on efficacy of LTG (χ2=17.397, P=0.001).ConclusionsUGT2B7, UGT1A4 polymorphisms play crucial roles in metabolism of VPA and LTG.

Nonadherence to treatment causing acute hospitalizations in people with epilepsy: an observational, prospective study.

The aim was to assess the clinical relevance of antiepileptic drug (AED) nonadherence by means of therapeutic drug concentration monitoring (TDM). Two hundred eighty-two consecutive patients with epilepsy acutely admitted to hospital for seizures were included. Nonadherence was defined as having a serum concentration/dose ratio at admission of <75% of the patient's own control value (probable nonadherence: 50-75%; definite: <50%). Nonadherence was identified in 39% of patients (definite 24%; probable 15%). It was significantly more common in patients with generalized seizures compared to those with focal onset seizures, and in patients <30years compared to older patients. When specifically asked, 44% of nonadherent patients claimed regular intake. Nonadherence is a major cause of seizure breakthrough in patients with epilepsy, particularly in young adults. Many patients seem to be unaware of missed drug intake. Prompt measurements of AED serum concentrations should be available as part of the emergency care for patients acutely hospitalized for seizures to permit this issue to be thoroughly addressed prior to discharge.

Current anti‐epileptic treatment in women of childbearing age

AbstractThe treatment of epilepsy in women of childbearing age requires special considerations. Pregnancies should ideally be planned allowing for appropriate treatment adjustments before conception. The prescribing physician therefore needs to be aware of the pharmacokinetic interactions between enzyme‐inducing anti‐epileptic drugs (AED) and oral contraceptives, and also of the effect of estradiol‐containing contraceptives on lamotrigine. The pharmacological treatment of epilepsy during pregnancy aims at controlling generalized tonic–clonic seizures with minimized exposure to potentially teratogenic drugs. Research has shown differences between AED in their teratogenic potential. Whereas, valproate has been associated with greater risks for malformations and adverse effects on cognition than carbamazepine and lamotrgine, the teratogenic risks with the latter two AED appears to be limited. Risks appear to increase with the dose. Our knowledge of the safety of other newer AED is still insufficient. The teratogenic risks should be balanced against the need for seizure control, which can be challenging, as serum concentrations of AED might be affected by pregnancy. This is most pronounced for lamotrigine, but is also relevant for other AED. The general strategy is to select the most appropriate AED for the individual woman taking efficacy as well as teratogenic potential into account and to try out, before conception, the lowest effective dose. Once this has been established, it is recommended to measure the serum concentration of the drug that will serve as a reference for drug concentrations obtained during pregnancy. After delivery, breast‐feeding can usually be recommended.

Antiepileptic drug clearance and seizure frequency during pregnancy in women with epilepsy

The aims of the study were to characterize the magnitude of clearance changes during pregnancy for multiple antiepileptic drugs (AEDs) and to assess seizure frequency and factors increasing seizure risk in pregnant women with epilepsy. A retrospective analysis was performed for 115 pregnancies in 95 women with epilepsy followed at the Emory Epilepsy Center between 1999 and 2012. Antiepileptic drug blood levels (ABLs) obtained during routine clinical practice were used to calculate AED clearance at multiple points during pregnancy. Antiepileptic drug doses and seizure activity were also recorded. The data were analyzed for changes in clearance and dose across pregnancy and for an association between ABL and changes in seizure frequency. Significant changes in clearance during pregnancy were observed for lamotrigine (p<0.001) and levetiracetam (p<0.006). Average peak clearance increased by 191% for lamotrigine and 207% for levetiracetam from nonpregnant baseline. Marked variance was present across individual women and also across repeat pregnancies in individual women. Despite increased AED dose across most AEDs, seizures increased in 38.4% of patients during pregnancy. Seizure deterioration was significantly more likely in patients with seizures in the 12months prior to conception (p<0.001) and those with localization-related epilepsy (p=0.005). When ABL fell >35% from preconception baseline, seizures worsened significantly during the second trimester when controlling for seizure occurrence in the year prior to conception. Substantial pharmacokinetic changes during pregnancy occur with multiple AEDs and may increase seizure risk. Monitoring of AED serum concentrations with dose adjustment is recommended in pregnant women with epilepsy. Further studies are needed for many AEDs.

Antiepileptic drug treatment in pregnancy: Changes in drug disposition and their clinical implications

Pregnancy is a state where pharmacokinetic changes are more pronounced and more rapid than during any other period of life. The consequences of such changes can be far reaching, not least in the management of epilepsy where the risks with uncontrolled seizures during pregnancy need to be balanced against potential teratogenic effects of antiepileptic drugs (AEDs). This article aims to review the literature on gestational effects on the pharmacokinetics of older and newer generation AEDs and discuss the implications for the treatment of epilepsy in women during pregnancy. Pregnancy can affect the pharmacokinetics of AEDs at any level from absorption, distribution, metabolism, to elimination. The effect varies depending on the type of AED. The most pronounced decline in serum concentrations is seen for AEDs that are eliminated by glucuronidation (UGT), in particular lamotrigine where the effect may be profound. Serum concentrations of AEDs that are cleared mainly through the kidneys, for example, levetiracetam, can also decline significantly. Some AEDs, such as carbamazepine seem to be affected only marginally by pregnancy. Data on pharmacokinetics during pregnancy are lacking completely for some of the newer generation AEDs: pregabalin, lacosamide, retigabine, and eslicarbazepine acetate. Where data are available, the effects of pregnancy on serum concentrations seem to vary considerably individually and are thus difficult to predict. Although large-scale systematic studies of the clinical relevance of the pharmacokinetic alterations are lacking, prospective and retrospective case series have reported an association between declining serum concentrations and deterioration in seizures control. The usefulness of routine monitoring of AED serum concentrations in pregnancy and of dose adjustments based on falling levels, are discussed in this review. We suggest that monitoring could be important, in particular when women have been titrated to the lowest effective AED dose and serum concentration before pregnancy, and when that individual optimal concentration can be used as reference.

Association betweenABCB1 Genotype and Seizure Outcome in Collies with Epilepsy

Medically refractory seizures are an important problem in both humans and dogs with epilepsy. Altered expression of ABCB1, the gene encoding for p-glycoprotein (PGP), has been proposed to play a role in drug-resistant epilepsy. Heterogeneity of the ABCB1 gene is associated with seizure outcome in dogs with epilepsy. Twenty-nine Collies with epilepsy being treated with antiepileptic drugs (AEDs). Prospective and retrospective cohort study. Dogs were classified as having a good outcome (≤ 1 seizure/month, no cluster seizures) or a poor outcome (>1 seizure/month, with or without cluster seizures) based on owner-completed questionnaire. Serum AED concentrations were measured, and ABCB1 genotyping was performed on buccal tissue samples. Association analyses were performed for genotype and seizure outcome, number of AEDs administered, serum AED concentrations, and incidence of adverse effects. Fourteen dogs of 29 (48%) were homozygous for the ABCB1-1∆ mutation (M/M), 11 dogs (38%) were heterozygous (M/N), and 4 dogs (14%) had the wild-type genotype (N/N). Dogs with the M/M genotype were significantly more likely to have fewer seizures and have less AED-related sedation than M/N or N/N dogs (P = .003 and P = .001, respectively). Serum phenobarbital and bromide concentrations did not differ between groups, but the M/N and N/N groups received a larger number of AEDs than the M/M group (P = .014). ABCB1 genotype is associated with seizure outcome in Collies with epilepsy. This cannot be attributed to differences in PGP function, but might be because of intrinsic variations in seizure severity among phenotypes.

Utilization patterns of antiepileptic drugs among adult epileptic patients at a tertiary hospital in Oman

To describe utilization patterns of antiepileptic drugs (AEDs) among adult epileptic patients at a tertiary hospital in Oman. Data were collected retrospectively from January 2006 to December 2009. The study included all adult (>18 years) epileptic patients on AEDs and followed up at a neurology clinic at Sultan Qaboos University Hospital in Oman. All reported therapeutic drug monitoring (TDM) requests for serum AED concentrations were also collected. Institutional ethical approval was sought and obtained. The study included a total of 372 patients with a mean age of 34 ± 15 years. Monotherapy AEDs accounted for 53% of the prescriptions, whereas polytherapy with two or three AED combinations accounted for 27% and 20% respectively. The most frequently prescribed AED was sodium valproate (27%) followed by carbamazepine (23%). The commonly prescribed AED combinations were sodium valproate with clonazepam (12%) followed by sodium valproate with lamotrigine (12%). Evaluation of 574 TDM requests for three AEDs showed that 57% of carbamazepine, 78% of phenytoin and 54% of valproic acid requests were either above or below the recommended therapeutic threshold. Most of these requests were ordered from the hospital's emergency department for suspected insufficient serum concentrations. Antiepileptic drug monotherapy is still the most frequently employed therapeutic strategy in adult patients with epilepsy in keeping with the standard therapeutic guidelines. Sodium valproate is commonly used for different types of seizures reflecting its wide spectrum of anticonvulsant potential. Newer AED utilizations are becoming increasingly popular in our subjects particularly as add-on with other standard AEDs.

A Systematic Review of the Pharmacokinetics of Antiepileptic Drugs in Neonates With Refractory Seizures

Neonatal seizures are associated with neurological sequelae and an increased risk of epilepsy later in life. Phenobarbital and phenytoin remain the antiepileptic drugs (AEDs) most commonly used to treat neonatal seizures, despite their suboptimal effectiveness and safety. As a result, other AEDs, such as levetiracetam and topiramate, are often used in neonates with refractory seizures, despite limited data and off-label use. To systematically review published pharmacokinetic data for second-line AEDs used in neonates with seizures and to provide dosing recommendations for these agents in the neonatal population. A literature search was conducted in PubMed (1949-May 2012), Medline (1950-May 2012), and Embase (1980-May 2012). Each study was ranked according to the quality of evidence it provided, based on the classification system developed by the US Preventive Services Task Force. Information extracted from each study included study design, number of subjects, gestational and postnatal age, AED dosage regimen, pharmacokinetic parameters, pharmacokinetic model, AED serum concentrations, and sampling times. Nineteen relevant pharmacokinetic studies involving a total of 8 different drugs were identified. No prospective, randomized, controlled studies (level I evidence) or nonrandomized controlled studies (level II-I evidence) were identified; 2 studies were prospective, nonrandomized, uncontrolled (cohort) studies (level II-2 evidence), 11 studies obtained evidence from multiple time series (level II-3 evidence), and 6 studies were case reports or descriptive studies (level III evidence). There are limited pharmacokinetic data for the use of carbamazepine, levetiracetam, lidocaine, paraldehyde, topiramate, valproic acid, and vigabatrin for neonates with seizures refractory to treatment with first-line antiepileptic agents. Further research is needed to elucidate target AED serum concentrations (if any) required to optimize effectiveness and minimize dose-related adverse effects in neonates.

Evaluation of Levetiracetam as Adjunctive Treatment for Refractory Canine Epilepsy: A Randomized, Placebo‐Controlled, Crossover Trial

There is little evidence-based information available to guide treatment of refractory epilepsy in dogs. The antiepileptic drug levetiracetam (LEV) is administered to dogs, although its safety and efficacy are unknown. To evaluate the safety and efficacy of LEV as adjunctive therapy for refractory epilepsy in dogs. Thirty-four client-owned dogs with idiopathic epilepsy. Randomized, blinded trial involving dogs resistant to phenobarbital and bromide. Dogs received LEV (20 mg/kg PO q8h) or placebo for 16 weeks, and after a 4-week washout were crossed over to the alternate treatment for 16 weeks. Owners kept records on seizure frequency and adverse events. Hemogram, chemistry profile, urinalysis, and serum antiepileptic drug concentrations were evaluated at established intervals. Twenty-two (65%) dogs completed the study. Weekly seizure frequency during the 1st treatment period decreased significantly during LEV administration relative to baseline (1.9 ± 1.9 to 1.1 ± 1.3, P = .015). The reduction in seizures with LEV was not significant when compared to placebo (1.1 ± 1.3 versus 1.5 ± 1.7, P = .310). The most common adverse event was ataxia, with no difference in incidence between LEV and placebo (45 versus 18%, P = .090). No changes in laboratory parameters were identified and owners reported an improved quality of life (QOL) with LEV compared to placebo (QOL score 32.7 ± 4.3 versus 29.4 ± 4.5, P = .028). Adjunctive treatment with LEV appears safe in epileptic dogs. Efficacy of LEV over placebo was not demonstrated, although the power of the study was limited. Further evaluation of LEV as treatment for epilepsy in dogs is warranted.

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.

Fetal valproate syndrome in a 2-month-old male infant

Fetal valproate syndrome (FVS) results from prenatal exposure to valproic acid. It is characterized by a distinctive facial appearance, a cluster of minor and major anomalies and central nervous system dysfunction. We describe a 2-month-old male infant with the typical dysmorphic features characteristic of FVS. He had a persistent left superior vena cava draining into a dilated coronary sinus and mild pulmonary hypertension. There was a history of maternal intake of sodium valproate during pregnancy.