A high-performance liquid chromatography-tandem mass spectrometry method for quantification of perampanel in human plasma: Effect of concomitant anti-seizure medications on perampanel concentration in patients with epilepsy.

Perampanel is a first-in-class α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor antagonist and a novel anti-seizure medication. It is currently used as adjunctive treatment for partial seizures in patients over 12 years of age. With the increasing clinical application of perampanel, monitoring its concentration under certain clinical conditions is important. This study developed a rapid and sensitive high-performance liquid chromatography-tandem mass spectrometry method to quantify perampanel in human plasma. Protein precipitation with acetonitrile was performed for sample preparation. Perampanel and perampanel-d5 (internal standard) were analyzed under gradient conditions using a C18 column. The mobile phase was composed of 0.1% (v/v) formic acid in water (solvent A) and 0.1% (v/v) formic acid in acetonitrile (solvent B) at a flow rate of 0.4 mL/min. Mass detection was performed using multiple reaction monitoring in the positive ionization mode. The proposed method was validated over a range of 0.5-500 ng/mL for perampanel. The linearity (r2 value) was higher than 0.999, and the linear equation was y = 0.00116x + 0.0116. The accuracy of the low-, middle-, and high-quality control samples was between 103% and 113%, and the intra- and inter-day precisions were below 6.81%. The quality of the proposed method was evaluated in accordance with the US Food and Drug Administration Bioanalytical Method Validation Guidance for Industry. The plasma concentrations of perampanel in 25 patients were successfully determined to be 38.7-577.7 ng/mL using the validated method.

Association between PK/PD-involved gene polymorphisms and carbamazepine-individualized therapy.

AIM: To evaluate the association between the major genetic variants involved in the pharmacokinetic/pharmacodynamic (PK/PD) properties of carbamazepine (CBZ) and its maintenance doses and concentrations. PATIENTS & METHODS: The genotypes of 166 patients receiving CBZ monotherapy were detected using high-resolution melting curve (HRM) and TaqMan methods. RESULTS: Both univariate and multiple regression analyses revealed that carriers of the SCN1A IVS5-91G>A or EPHX1 c.337T>C allele tended to require a higher CBZ dose and a lower CBZ natural logarithmic concentration-dose ratio (lnCDR) than noncarriers (p < 0.05). Furthermore, two interactions between these genes were associated with the lnCDR and the maintenance dosage of CBZ, respectively. CONCLUSION: SCN1A IVS5-91G>A gene polymorphism is potential genetic biomarker associated with the PK of CBZ.

eEF-2 Phosphorylation Down-Regulates P-Glycoprotein Over-Expression in Rat Brain Microvessel Endothelial Cells.

OBJECTIVE: We investigated whether glutamate, NMDA receptors, and eukaryote elongation factor-2 kinase (eEF-2K)/eEF-2 regulate P-glycoprotein expression, and the effects of the eEF-2K inhibitor NH125 on the expression of P-glycoprotein in rat brain microvessel endothelial cells (RBMECs). METHODS: Cortex was obtained from newborn Wistar rat brains. After surface vessels and meninges were removed, the pellet containing microvessels was resuspended and incubated at 37°C in culture medium. Cell viability was assessed by the MTT assay. RBMECs were identified by immunohistochemistry with anti-vWF. P-glycoprotein, phospho-eEF-2, and eEF-2 expression were determined by western blot analysis. Mdr1a gene expression was analyzed by RT-PCR. RESULTS: Mdr1a mRNA, P-glycoprotein and phospho-eEF-2 expression increased in L-glutamate stimulated RBMECs. P-glycoprotein and phospho-eEF-2 expression were down-regulated after NH125 treatment in L-glutamate stimulated RBMECs. CONCLUSIONS: eEF-2K/eEF-2 should have played an important role in the regulation of P-glycoprotein expression in RBMECs. eEF-2K inhibitor NH125 could serve as an efficacious anti-multidrug resistant agent.

SCN1A, ABCC2 and UGT2B7 gene polymorphisms in association with individualized oxcarbazepine therapy.

AIM: Associations between the effects of SCN1A, SCN2A, ABCC2 and UGT2B7 genetic polymorphisms and oxcarbazepine (OXC) maintenance doses in Han Chinese epileptic patients were investigated. PATIENTS & METHODS: Genetic polymorphisms were detected in 184 epileptic patients receiving OXC monotherapy by high-resolution melting curve and TaqMan method. RESULTS: Carriers of the SCN1A IVS5-91G>A, UGT2B7 c.802T>C and ABCC2 c.1249G>A variant alleles required significantly higher OXC maintenance doses than noncarriers (p < 0.05). Corresponding relative ln (concentration-dose ratios) values for SCN1A IVS5-91 variants differed by the genotypic order GG > GA > AA. CONCLUSION: SCN1A, UGT2B7 and ABCC2 genetic polymorphisms are associated with OXC maintenance doses and may be useful for the personalization of OXC therapy in epileptic patients. Further studies are needed. Original submitted 6 June 2014; Revision submitted 5 September 2014.

MicroRNA-181c negatively regulates the inflammatory response in oxygen-glucose-deprived microglia by targeting Toll-like receptor 4.

Cerebral hypoxia/ischemia rapidly induces inflammation in the brain, which is characterized by microglial activation and the release of inflammatory cytokines. We have previously demonstrated that miR-181c can directly regulate tumor necrosis factor (TNF)-α production post-transcriptionally. Here, we determined that hypoxia up-regulated TLR4 expression but down-regulated miR-181c expression in primary microglia. We also demonstrated that miR-181c suppresses TLR4 by directly binding its 3'-untranslated region. In addition, miR-181c inhibited NF-κB activation and the downstream production of proinflammatory mediators, such as TNF-α, IL-1ß, and iNOS. Knocking down TLR4 in microglia significantly decreased TLR4 expression and inhibited NF-κB activation and the downstream production of proinflammatory mediators, whereas ectopic TLR4 expression significantly abrogated the suppressed inflammatory response induced by miR-181c. Therefore, our study identified an important role for the miR-181c-TLR4 pathway in hypoxic microglial activation and neuroinflammation. This pathway could represent a potential therapeutic target for cerebral hypoxic diseases associated with microglial activation and the inflammatory response. Cerebral hypoxia/ischemia induces microglial activation and the release of inflammatory cytokines. We found that hypoxia down-regulated miR-181c in primary microglia. In addition, miR-181c inhibited TLR4 expression through binding to its 3'UTR, thus inhibiting NF-kB activation and the production of downstream proinflammatory mediators. Therefore, the miR-181c-TLR4 pathway may be a potential therapeutic target for the treatment of cerebral hypoxic diseases.

Enhanced brain delivery of lamotrigine with Pluronic(®) P123-based nanocarrier.

BACKGROUND: P-glycoprotein (P-gp) mediated drug efflux across the blood-brain barrier (BBB) is an important mechanism underlying poor brain penetration of certain antiepileptic drugs (AEDs). Nanomaterials, as drug carriers, can overcome P-gp activity and improve the targeted delivery of AEDs. However, their applications in the delivery of AEDs have not been adequately investigated. The objective of this study was to develop a nano-scale delivery system to improve the solubility and brain penetration of the antiepileptic drug lamotrigine (LTG). METHODS: LTG-loaded Pluronic(®) P123 (P123) polymeric micelles (P123/LTG) were prepared by thin-film hydration, and brain penetration capability of the nanocarrier was evaluated. RESULTS: The mean encapsulating efficiency for the optimized formulation was 98.07%; drug-loading was 5.63%, and particle size was 18.73 nm. The solubility of LTG in P123/LTG can increase to 2.17 mg/mL, making it available as a solution. The in vitro release of LTG from P123LTG presented a sustained-release property. Compared with free LTG, the LTG-incorporated micelles accumulated more in the brain at 0.5, 1, and 4 hours after intravenous administration in rats. Pretreatment with systemic verapamil increased the rapid brain penetration of free LTG but not P123/LTG. Incorporating another P-gp substrate (Rhodamine 123) into P123 micelles also showed higher efficiency in penetrating the BBB in vitro and in vivo. CONCLUSION: These results indicated that P123 micelles have the potential to overcome the activity of P-gp expressed on the BBB and therefore show potential for the targeted delivery of AEDs. Future studies are necessary to further evaluate the appropriateness of the nanocarrier to enhance the efficacy of AEDs.

Association of SCN1A, SCN2A and ABCC2 gene polymorphisms with the response to antiepileptic drugs in Chinese Han patients with epilepsy.

AIM: The purpose of this study was to investigate the potential impact of SCN1A, SCN2A and ABCC2 gene polymorphisms on the response to antiepileptic drugs in Chinese Han patients with epilepsy. PATIENTS & METHODS: Genetic polymorphisms in the candidate genes were detected in 453 Chinese epileptic patients by high-resolution melting curve and TaqMan methods. RESULTS: The SCN1A IVS5-91G>A AA genotype and the ABCC2 c.1249G>A GA genotype were significantly associated with carbamazepine/oxcarbamazepine (CBZ/OXC)-resistant epilepsy (p =0.002 and p = 0.036, respectively). The frequencies of haplotypes AA (SCN1A gene) and AC (ABCC2 gene) in drug-resistant patients were significantly higher than those in responsive patients (p = 0.002 and p = 0.005, respectively). CONCLUSION: This study suggested that SCN1A and ABCC2 polymorphisms may be associated with the response to CBZ/OXC in the Chinese Han population, indicating that they could serve as predictors of drug response. Original submitted 29 January 2014; Revision submitted 30 May 2014.

Tenidap is neuroprotective in a pilocarpine rat model of temporal lobe epilepsy.

BACKGROUND: Tenidap is a liposoluble non-steroidal anti-inflammatory drug that is easily distributed in the central nervous system and also inhibits the production and activity of cyclooxygenase-2 (COX-2) and cytokines in vitro. This study aimed to evaluate the neuroprotective effect of tenidap in a pilocarpine rat model of temporal lobe epilepsy (TLE). METHODS: Tenidap was administered daily at 10 mg/kg for 10 days following pilocarpine-induced status epilepticus (SE) in male Wistar rats after which prolonged generalized seizures resulted in TLE. After tenidap treatment, spontaneous recurrent seizures (SRSs) were recorded by video monitoring (for 7 hours per day for 14 days). The frequency and severity of the SRSs were observed. Histological and immunocytochemical analyses were used to evaluate the neuroprotective effect of tenidap and detect COX-2 expression, which may be associated with neuronal death. RESULTS: There were 46.88 ± 10.70 survival neurons in tenidap-SE group, while there were 27.60 ± 5.18 survival neurons in saline-SE group at -2.4 mm field in the CA3 area. There were 37.75 ± 8.78 survival neurons in tenidap-SE group, while there were 33.40 ± 8.14 survival neurons in saline-SE group at -2.4 mm field in the CA1 area. Tenidap treatment significantly reduced neuronal damage in the CA3 area (P < 0.05) and slightly reduced damage in the CA1 area. Tenidap markedly inhibited COX-2 expression in the hippocampus, especially in the CA3 area. CONCLUSION: Tenidap conferred neuroprotection to the CA3 area in a pilocarpine-induced rat model of TLE by inhibiting COX-2 expression.

Determinants of quality of life in people with epilepsy and their gender differences.

Improving the patient's quality of life (QOL) is the most important goal of epilepsy management. We performed this study to determine the factors associated with QOL in people with epilepsy and to assess whether there are gender differences in these determinants. Patients were interviewed using the Quality of Life in Epilepsy Inventory-31(QOLIE-31), the Adverse Event Profile (AEP), the Self-Rating Anxiety Scale (SAS), and the Hamilton Depression Rating Scale (HAMD). Two hundred forty-seven patients (152 men, 95 women) were included in the analysis. Among all patients, regressive analyses showed that AEP score was the strongest predictor of the QOLIE-31 overall score, accounting for 10.4% of the variance. The next strongest predictors were the number of currently used antiepileptic drugs (AEDs) (3.6%), the HAMD score (2.5%), and the SAS score (1.2%). Importantly, there were gender differences in these predictors of QOL. The strongest predictors of the QOLIE-31 overall score in women were the AEP score and the number of AEDs. In contrast, the strongest predictors in men were the SAS score, the AEP score and the frequency of seizures. These results indicate that perceived adverse effects of treatments and number of AEDs exerted greater effects on QOL in women, whereas anxiety and seizure-related variables had a stronger impact on QOL among men. Accordingly, it may be necessary to individualize interventions to improve the QOL of people with epilepsy.

A 6-month prospective study on efficacy safety and QOL profiles of extended-release formulation of valproate in patients with epilepsy.

The goals of this study were to evaluate the efficacy, safety, and quality of life profiles of ER formulation of valproate in patients with epilepsy. This was a prospective, multicentre, open-lable study. Patients with a definite diagnosis of epilepsy were included and prescribed the ER formulation of valproate as initial or add-on therapy for 6 months. Efficacy and safety re-evaluation procedures were performed at 1 (V1), 3 (V2), and 6 months (V3) after enrollment. A QOLIE-31 inventory was used to assess the quality of life before and after the 6-month treatment. Nine hundred and fifty-eight patients with diagnosis of epilepsy were included in the analysis. The mean of seizure frequency at baseline was 8.56 per month. The median maintenance dose of the ER valproate was 750 mg per day. The number of seizure attacks per month was significantly decreased at the last visit compared to baseline by 88.3%. Patients improved quality of life in the fields of 'seizure worry' (P=0.000), 'overall quality of life' (P=0.000), 'social function' (P<0.01), and 'Question 31' (P=0.000), but showed decreased 'energy' (P=0.000). In the early phase of treatment, the main adverse effects included drowsiness, dizziness, and anorexia. By 6 months of treatment, weight gain, alopecia, and tremor were most frequently reported. The results of the present study demonstrated that patients receiving ER valproate as add-on or mono-therapy for 6 months exhibited significantly greater median percent reductions from baseline in seizure frequency for all seizure types, and significantly higher responder rates and higher seizure freedom rates, with good tolerance and improved quality of life.

[Factors associated with quality of life in epileptics and the variations between men and women, younger and older people].

OBJECTIVE: To determine factors associated with quality of life (QOL) in epileptics and the variations between men and women, younger and older people. METHODS: A total of 204 patients (160 younger, 49 older; 125 men, 79 women) were interviewed by the quality of life in epilepsy-31 (QOLIE-31), side effect profile (SEP), self-rating anxiety scale (SAS) and Hamilton depression scale (HAMD). Medical and socio-demographic data were acquired from patient records. Multivariate linear regressive analyses were used to determine the set of best predictors of composite QOLIE-31 score. RESULTS: No statistical difference was revealed in QOLIE-31 overall score either between younger and older patients or between men and women. Among all patients, regressive analyses revealed that SEP (beta = - 0.395, P = 0.000) and SAS (beta = -0.152, P = 0.016) were two strong predictors of QOLIE-31 overall score. Grouped by gender, among men, epilepsy duration (beta = -0.165, P = 0.028) and seizure frequency (beta = -0.284, P = 0.001) respectively associated with QOLIE-31 overall score and "social function" score while the number of AEDs (antiepileptic drugs) substantially correlated with QOLIE-31 overall score among women (beta= -0.238, P = 0.006). Grouped by ages, seizure frequency (beta = -0.284, P = 0.000) and education level (beta = 0.203, P = 0.005) predicted QOLIE-31 "social function" score only among younger patients; among older patients, a significant association were found between the number of AEDs and QOLIE-31 overall score (beta = - 0.363, P = 0.004). CONCLUSION: Side effects of AEDs and number of AEDs exert greater effect on QOL in women and older patients. And such seizure-related variables as epileptic duration and seizure frequency influence QOL only among men and younger patients.

Multicenter double-blind, randomized, placebo-controlled trial of levetiracetam as add-on therapy in Chinese patients with refractory partial-onset seizures.

PURPOSE: To evaluate efficacy and tolerability of levetiracetam (LEV; Keppra) as add-on therapy in Chinese patients with refractory partial-onset seizures. METHODS: In this multicenter, double-blind, randomized, placebo-controlled trial, 206 patients aged 16-70 years with uncontrolled partial-onset seizures were randomized to receive LEV (n =103) or placebo (n =103); 202 patients (LEV, n =102; placebo, n = 100) comprised the intent-to-treat population. An 8-week historical baseline period confirmed eligibility according to seizure count. The 16-week treatment period consisted of a 4-week up-titration period (LEV, 1,000-3,000 mg/day in two equal divided doses) followed by a 12-week maintenance period. Efficacy assessments were based on weekly frequency of partial-onset seizures during the 16-week treatment period. RESULTS: LEV significantly decreased weekly partial-onset seizure frequency over placebo by 26.8% (p < 0.001). Median percentage reductions in weekly partial-onset seizure frequency from historical baseline were 55.9% for LEV and 13.7% for placebo (p < 0.001). The >or=50% responder rates were 55.9% for LEV, compared with 26.0% for placebo (p < 0.001). Freedom from partial-onset seizures during treatment period was achieved by 11 LEV patients (10.8%) and 2 placebo patients (2.0%) (p = 0.012). Adverse events were reported by 65 LEV-treated patients (63.1%) and 62 placebo-treated patients (60.2%); most were of mild-to-moderate intensity. The most common adverse events were somnolence (LEV, 17.5%; placebo, 17.5%), decreased platelet count (LEV, 9.7%; placebo, 9.7%), and dizziness (LEV, 7.8%; placebo, 13.6%). DISCUSSION: Add-on LEV was effective and well-tolerated in Chinese patients with refractory partial-onset seizures.

[Effect of dizocilpine on P-glycoprotein expression in hippocampus in limbic seizure: experiment with rats].

OBJECTIVE: To observe the effect of dizocilpine (MK801), a noncompetitive antagonist of N-methyl-D-aspartic acid (NMDA) receptor, on P-glycoprotein (P-gp) expression after limbic seizure, and to explore whether NMDA receptor play a role in the regulation of P-gp expression during limbic seizure. METHODS: 120 Wistar rats were randomly divided into 2 equal sets. 50 rats in Set 1 underwent intraperitoneal injection of lithium chloride, scopolamine, and pilocarpine so as to cause status epilepticus (SE) for 90 min. Then diazepam was given to terminate the SE. The rats were killed 0, 3, 6, 14, and 72 h after the SE respectively. The hippocampus was isolated. Realtime fluorescent quantitative RT-PCR (qRT-PCR) was used to detect the expression of multidrug resistance gene 1a (mdr1a) and mdr1b. Immunohistochemistry was used to detect the P-gp. The rats were used as controls. Another 60 rats (Set 2) were randomly divided into 3 equal groups: control group, given with normal saline (NS) only, SE group, given with NS 20 min before administration of pilocarpine, and MK801 group, given with MK801 20 min before administration of pilocarpine. The 3 groups in Set 2 were further divided into 2 equal subgroups of 10 rats to be killed 6 or 24 h after SE. RESULTS: The mdr1a expression in hippocampus within 72 h after seizure was much higher at each time point: the level of mdr1a expression instantly after the seizure was terminated was [5.6 (2.9) x 10(5) mRNA copies/40 ng total RNA], significantly higher than that of the controls [2.4 (1.1) x 10(5) mRNA copies/40 ng total RNA, P < 0.05], increased to the level of [7.6 (6.3) x 10(5), P < 0.01] 3 h after, and kept at such level till 72 h after. The msr1b expression transiently increased 2.2 and 2.4 times that of the controls respectively 3 h and 6 h after the seizure was terminated [(3.3 +/- 0.4) x 10(4), and (3.6 +/- 1.0) x 10(4), both P < 0.01)]. The expression level of mdr1a 6 h after the seizure was terminated of the MK801 group was (4.3 +/- 0.8) x 10(5) and the expression level of mdr1b 6 h after the seizure was terminated of the MK801 group was (2.0 +/- 0.7) x 10(4), both significantly lower than those of the SE group (both P < 0.01). The P-gp expression level 24 h after the seizure was terminated of the MK801 group was 26.6 +/- 5.0 pieces of microvessels/400 times field, significantly lower than that of the SE group (39.0 +/- 4.1, P < 0.01). CONCLUSION: MK801 down-regulates the overexpression of P-gp after seizure, which indicates that NMDA receptor may be involved in the regulation of P-gp expression during seizure. Therefore, it is possible to prevent the overexpression of P-gp after seizure by inhibiting NMDA receptor's overactivation effectively.