Phenytoin Research Articles

A comprehensive overview on phytomedicines as an upcoming/emerging candidate for the management of epilepsy

Background: The word "epilepsy" refers to a category of chronic CNS illnesses characterised by spontaneous occurrence of seizures, which are typically accompanied by loss of consciousness and uncontrollable shaking of the body (convulsions). Epilepsy is one of the most commonly occurring non-communicable neurological disorder that affects people of all age groups. By preventing discharge and inducing hypnosis, anticonvulsant medications are used to manage convulsions. The medication used for the therapy includes phenytoin (PHT), diazepam, valproate (VPA), levetiracetam, etc. These medications have brand-new effectiveness ranges and brand-new side effects. They also represent a significant cost increase. Herbal medicine, which has its roots in ancient civilizations, involves the use of medicinal plants to treat diseases and promote overall well-being. Although the widespread use of herbal medicine as an antiepileptic, there is little solid data supporting the effectiveness and safety of the majority of herbs. Additionally, the herbal remedy needs to pass a rigorous, evidence-based review. As herbal drugs are derived from natural sources, they are often considered safer than synthetic drugs. Therefore, there is a growing interest in exploring the potential of herbal medicine for treating neurodegenerative diseases such as Parkinson's disease. Due to their lower adverse effects, herbal medications are becoming more and more popular for the adjuvant treatment of epilepsy.
 Objective: The objective of this article is to investigate whether herbal medications have potential as a treatment option for Parkinsonism, and to provide a clear understanding of the current state of research on this topic.
 Keywords: Convulsion, epilepsy, herbal treatment, seizures, phytoconstituents, herbal medicine, GABA.

Pluronic P85 decreases the delivery of phenytoin to the brain in drug-resistant rats with P-glycoprotein overexpressed chronic mesial temporal lobe epilepsy

P-glycoprotein (Pgp) overexpressed in blood brain barrier (BBB) is hypothesized to lower brain drug concentrations and thus inhibit anticonvulsant effects in drug-resistant epilepsy. Pluronic P85 (P85) was proved to enhance the delivery of drugs into the brain by inhibition of Pgp. To determine whether the surfactant P85 [versus Pgp inhibitor tariquidar (TQD)] enhance phenytoin (PHT) into the brain in drug-resistant rats with chronic mesial temporal lobe epilepsy (MTLE) induced by lithium-pilocarpine, in brain of which Pgp were overexpressed, then direct verification of PHT transport via measurement of PHT concentration in brain using microdialysis. The drug-resistant model rats were randomly divided into three groups, which were treated with PHT, 1%P85 + PHT, or PHT+TQD, respectively. 1%P85 + PHT treatment displayed a lower ratio of the area under the curve (AUC) of the PHT concentration in the brain/plasma even than that of the PHT treatment in model rats (p < 0.05), while PHT+TQD showed the highest ratio of the AUC of all treatments. However, the ratio of the PHT concentration in the liver/plasma was similar in three model groups (p > 0.05). For the ratio of the kidney/plasma, PHT+TQD treatment model group had the highest ratio of the other treatments in model rats. Thus, P85 oppositely decreased PHT concentration in brain in drug-resistant model rats with Pgp overexpressed MTLE while TQD could increase PHT distribution in brain.

Antibacterial Properties of Mesoporous Silica Nanoparticles Modified with Fluoroquinolones and Copper or Silver Species.

Antibiotic resistance is a global problem and bacterial biofilms contribute to its development. In this context, this study aimed to perform the synthesis and characterization of seven materials based on silica mesoporous nanoparticles functionalized with three types of fluoroquinolones, along with Cu2+ or Ag+ species to evaluate the antibacterial properties against Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, and Pseudomonas aeruginosa, including clinical and multi-drug-resistant strains of S. aureus and P. aeruginosa. In addition, in order to obtain an effective material to promote wound healing, a well-known proliferative agent, phenytoin sodium, was adsorbed onto one of the silver-functionalized materials. Furthermore, biofilm studies and the generation of reactive oxygen species (ROS) were also carried out to determine the antibacterial potential of the synthesized materials. In this sense, the Cu2+ materials showed antibacterial activity against S. aureus and E. coli, potentially due to increased ROS generation (up to 3 times), whereas the Ag+ materials exhibited a broader spectrum of activity, even inhibiting clinical strains of MRSA and P. aeruginosa. In particular, the Ag+ material with phenytoin sodium showed the ability to reduce biofilm development by up to 55% and inhibit bacterial growth in a "wound-like medium" by up to 89.33%.

Association of epilepsy, anti-epileptic drugs (AEDs), and type 2 diabetes mellitus (T2DM): a population-based cohort retrospective study, impact of AEDs on T2DM-related molecular pathway, and via peroxisome proliferator-activated receptor γ transactivation.

A potential association between epilepsy and subsequent type 2 diabetes mellitus (T2DM) has emerged in recent studies. However, the association between epilepsy, anti-epileptic drugs (AEDs), and the risk of T2DM development remains controversial. We aimed to conduct a nationwide, population-based, retrospective, cohort study to evaluate this relationship. We extracted data from the Taiwan Longitudinal Generation Tracking Database of patients with new-onset epilepsy and compared it with that of a comparison cohort of patients without epilepsy. A Cox proportional hazards regression model was used to analyze the difference in the risk of developing T2DM between the two cohorts. Next-generation RNA sequencing was used to characterize T2DM-related molecularchanges induced by AEDs and the T2DM-associated pathways they alter. The potential of AEDs to induce peroxisome proliferator-activated receptor γ (PPARγ) transactivation was also evaluated. After adjusting for comorbidities and confounding factors, the case group (N = 14,089) had a higher risk for T2DM than the control group (N = 14,089) [adjusted hazards ratio (aHR), 1.27]. Patients with epilepsy not treated with AEDs exhibited a significantly higher risk of T2DM (aHR, 1.70) than non-epileptic controls. In those treated with AEDs, the risk of developing T2DM was significantly lower than in those not treated (all aHR ≤ 0.60). However, an increase in the defined daily dose of phenytoin (PHE), but not of valproate (VPA), increased the risk of T2DM development (aHR, 2.28). Functional enrichment analysis of differentially expressed genes showed that compared to PHE, VPA induced multiple beneficial genes associated with glucose homeostasis. Among AEDs, VPA induced the specific transactivation of PPARγ. Our study shows epilepsy increases the risk of T2DM development, however, some AEDs such as VPA might yield a protective effect against it. Thus, screening blood glucose levels in patients with epilepsy is required to explore the specific role and impact of AEDs in the development of T2DM. Future in depth research on the possibility to repurpose VPA for the treatment of T2DM, will offer valuable insight regarding the relationship between epilepsy and T2DM.

Novel Collagen Surgical Patches for Local Delivery of Multiple Drugs.

Effective control of post-operative inflammation after tissue repair remains a clinical challenge. A tissue repair patch that could appropriately integrate into the surrounding tissue and control inflammatory responses would improve tissue healing. A collagen-based hybrid tissue repair patch has been developed in this work for the local delivery of an anti-inflammatory drug. Dexamethasone (DEX) was encapsulated into PLGA microspheres and then co-electrocompacted into a collagen membrane. Using a simple process, multiple drugs can be loaded into and released from this hybrid composite material simultaneously, and the ratio between each drug is controllable. Anti-inflammatory DEX and the anti-epileptic phenytoin (PHT) were co-encapsulated and released to validate the dual drug delivery ability of this versatile composite material. Furthermore, the Young's modulus of this drug-loaded collagen patch was increased to 20 KPa using a biocompatible riboflavin (vitamin B2)-induced UV light cross-linking strategy. This versatile composite material has a wide range of potential applications which deserve exploration in further research.

A real-life pilot study of the clinical application of pharmacogenomics testing on saliva in epilepsy.

Response to antiseizure medications (ASMs) can be influenced by several gene polymorphisms, causing either lower efficacy or higher occurrence of adverse drug reactions (ADRs). We investigated the clinical utility of salivary pharmacogenomic testing on epilepsy patients. A commercialized pharmacogenomic salivary test was performed in a cohort of epileptic patients. Genetic variants on five genes (i.e., CYP1A2, CYP2C9, CYP2C19, EPHX1, and ABCB1) involved in common ASMs metabolism were selected. Twenty-one individuals (median age [Q1 -Q3 ]: 15 [6.5-28] years) were enrolled. Six patients harboring the homozygous *1F allele in CYP1A2 could have reduced chance of response to stiripentol due to fast metabolism. CYP2C9 had reduced activity in 10 patients (alleles *2 and *3), potentially affecting phenytoin (PHT), phenobarbital (PB), primidone, lacosamide (LCM), and valproic acid metabolism. Seven patients, carrying the *2 allele of CYP2C19, had an increased risk of ADRs with clobazam (CLB), PB, PHT, LCM, brivaracetam; while one individual with the *17 allele in heterozygosity reported a CLB fast metabolism. Six patients showed a CC polymorphism of EPHX1 associated with the impaired efficacy of carbamazepine. ABCB1 polymorphisms related to drug-resistance (3435 CC) or drug-sensitive phenotype (CT or TT) were found in 6 out of 7 patients. Pharmacogenomic testing on saliva proved easy and safe in clinical practice to convey information for the management of epileptic patients, especially those resistant to treatment or sensitive to severe ADRs.

SYNTHESIS AND ANTICONVULSANT ACTIVITY OF NEWER BENZOTHIAZINYL / BENZOXAZINYL INDOLES

3-Acetyl-2-methyl-indole (1) was synthesized by acetylation of 2-methyl indole with acetyl chloride. Facile condensation of compound (1) with various aromatic aldehydes yielded 1-(2’ -methylindolyl) arylidenyl chalcones (2-7), which on treating with 2-aminothiophenol and 2-aminophenol afforded 2-substitutedphenyl-2,3-dihydro-4-(2’ -methylindolyl)-1,5-benzthiazepines (8-13) and 2-substitutedphenyl-2,3-dihydro-4-(2’ -methylindolyl)-1,5-benzoxazepines (14-19), respectively. The structures of all the compounds were delineated by elemental analysis, IR and proton magnetic resonance. The newly synthesized compounds were evaluated for their anticonvulsant activity and were compared with standard drug phenytoin sodium. These compounds were also tested for acute toxicity. Compound 12 was found to be the most potent compound of the series, exhibiting activity of 90 % more potent than standard drug. Compounds 13 and 18 also showed promising activity of 80 %, equipotent to standard drug.

ROS/Electro Dual-Reactive Nanogel for Targeting Epileptic Foci to Remodel Aberrant Circuits and Inflammatory Microenvironment.

Medicinal treatment against epilepsy is faced with intractable problems, especially epileptogenesis that cannot be blocked by clinical antiepileptic drugs (AEDs) during the latency of epilepsy. Abnormal circuits of neurons interact with the inflammatory microenvironment of glial cells in epileptic foci, resulting in recurrent seizures and refractory epilepsy. Herein, we have selected phenytoin (PHT) as a model drug to derive a ROS-responsive and consuming prodrug, which is combined with an electro-responsive group (sulfonate sodium, SS) and an epileptic focus-recognizing group (α-methyl-l-tryptophan, AMT) to form hydrogel nanoparticles (i.e., a nanogel). The nanogel will target epileptic foci, release PHT in response to a high concentration of reactive oxygen species (ROS) in the microenvironment, and inhibit overexcited circuits. Meanwhile, with the clearance of ROS, the nanogel can also reduce oxidative stress and alleviate microenvironment inflammation. Thus, a synergistic regulation of epileptic lesions will be achieved. Our nanogel is expected to provide a more comprehensive strategy for antiepileptic treatment.

Calcium Phosphate-Based Nanoformulation Selectively Abolishes Phenytoin Resistance in Epileptic Neurons for Ceasing Seizures.

Phenytoin (PHT) is a first-line antiepileptic drug in clinics, which could decrease neuronal bioelectric activity by blocking the voltage-operated sodium channels. However, the intrinsically low blood-brain-barrier (BBB)-crossing capability of PHT and upregulated expression level of the efflux transporter p-glycoprotein (P-gp) coded by the gene Abcb1 in epileptic neurons limit its efficacy in vivo. Herein, a nanointegrated strategy to overcome PHT resistance mechanisms for enhanced antiepileptic efficacy is reported. Specifically, PHT is first incorporated into calcium phosphate (CaP) nanoparticles through biomineralization, followed by the surface modification of the PEGylated BBB-penetrating TAT peptide. The CaP@PHT-PEG-TAT nanoformulation could effectively cross the BBB to be taken in by epileptic neurons. Afterward, the acidic lysosomal environment would trigger their complete degradation to release Ca2+ and PHT into the cytosol. Ca2+ ions would inhibit mitochondrial oxidative phosphorylation to reverse cellular hypoxia to block hypoxia-inducible factor-1α (Hif1α)-Abcb1-axis, as well as disrupt adenosine triphosphate generation, leading to simultaneous suppression of the expression and drug efflux capacity of P-gp to enhance PHT retention. This study offers an approach for effective therapeutic intervention against drug-resistant epilepsy.

Evaluation of the Effect of Pheophytin A on Electroshock- Induced Seizures in Experimental Animals

Abstract: Background: An epileptic seizure is a transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain. Approximately, 5–10% of the people have at least one kind of seizure, with more chance of occurrence in early childhood and late adulthood. There are many drugs used in seizures such as phenytoin and valproate sodium, so the main objective of current study was evaluated the efficacy of Pheophytin A compared to Valproate sodium on electroshock-induced seizures in experimental mice. Materials and Methods: The total number of 18 mice were used after divided into 3 groups in which each group was 6 mice. The first group, which is control, was received injection with distilled water. The second group was standard reference which received valproate sodium at dose of 300 mg/kg. The third group was test group which received 20 mg /kg of pheophytin A. Maximum electrical shocker was used to induce seizures. Results: The present study showed that pheophytin-A group had significantly reduced duration of seizures after 30 min of injection as compared to valproate sodium group. Valproate sodium produced more reduction in duration of seizures than pheophytin-A. Conclusion: The Pheophytin A showed antiseizure effect using maximal electrical shocker, so that it may be used in the future for treatment of seizures after further investigations. Keywords: Seizures, Pheophytin A, Valproate sodium, Maximal electroshock seizure, In vivo.

Attenuation of Strychnine-Induced Epilepsy Employing Amaranthus viridis L. Leaves Extract in Experimental Rats.

Epilepsy is one of the most prevalent neurological illnesses defined by periodic seizures with or without loss of consciousness caused by aberrant neural activity. There are many allopathic medications available for the treatment of epilepsy such as phenytoin (PHY), but the side effects are a major concern. Therefore, the present study involved the evaluation of the pharmacological significance of Amaranthus viridis L. extract (EAV) in the management of strychnine (STR)-induced epilepsy. STR (3.5 mg/kg, i.p.) was injected into male rats 30 minutes after the pre-treatment of a standard drug (PHY: 20 mg/kg) and the two doses of EAV (EAV-200 and EAV-400 mg/kg, p.o.) to the respective groups to cause the convulsions. The anti-convulsant effect of EAV-200 and EAV-400 against STR-induced convulsion in rats was investigated in terms of convulsion onset, duration of convulsions, number of convulsions, and convulsion score. Furthermore, the mitochondrial function and integrity in the brain's prefrontal cortex (PFC) were also estimated. EAV-400 significantly increased the onset of convulsion from 61.67 ± 3.051 to 119.2 ± 2.738 and reduced the STR-induced duration of convulsions from 144.8 ± 3.582 to 69.17 ± 3.736, number of convulsions from 4.000 ± 0.1592 to 1.533 ± 0.1542, and convulsion score from 5.000 ± 0.3651 to 2.833 ± 0.3073 in rats. EAV-400 significantly attenuated the STR-induced decrease in the mitochondrial function and integrity of the rat PFC. In rats, EAV-400 significantly accelerated the onset of convulsions while decreasing the STR-induced duration, frequency, and score. Based on investigational findings, EAV-400 could be inferred to be a possible anti-epileptic option for the treatment of epilepsy of this plan in preclinical research.

Transcranial focused ultrasound-mediated unbinding of phenytoin from plasma proteins for suppression of chronic temporal lobe epilepsy in a rodent model

The efficacy of many anti-epileptic drugs, including phenytoin (PHT), is reduced by plasma protein binding (PPB) that sequesters therapeutically active drug molecules within the bloodstream. An increase in systemic dose elevates the risk of drug side effects, which demands an alternative technique to increase the unbound concentration of PHT in a region-specific manner. We present a low-intensity focused ultrasound (FUS) technique that locally enhances the efficacy of PHT by transiently disrupting its binding to albumin. We first identified the acoustic parameters that yielded the highest PHT unbinding from albumin among evaluated parameter sets using equilibrium dialysis. Then, rats with chronic mesial temporal lobe epilepsy (mTLE) received four sessions of PHT injection, each followed by 30 min of FUS delivered to the ictal region, across 2 weeks. Two additional groups of mTLE rats underwent the same procedure, but without receiving PHT or FUS. Assessment of electrographic seizure activities revealed that FUS accompanying administration of PHT effectively reduced the number and mean duration of ictal events compared to other conditions, without damaging brain tissue or the blood–brain barrier. Our results demonstrated that the FUS technique enhanced the anti-epileptic efficacy of PHT in a chronic mTLE rodent model by region-specific PPB disruption.

A Survey of Therapeutic Drug Monitoring Status in China.

To understand the status of therapeutic drug monitoring (TDM) in China Mainland, and thus lay down the foundation for further improvement in TDM. In the present study, a nationwide questionnaire survey was conducted, which was distributed and collected using a mobile-based application. Clinicians, pharmacists, and clinical laboratory physicians belonging to different levels of public hospitals were involved as subjects/objects. The contents of the survey included TDM implementation in their hospital and information regarding their opinions and suggestions on TDM work. Mann-Whitney test was used to compare the difference between top tertiary hospitals and non-top tertiary hospitals. A total of 475 questionnaires were collected, 383 from top tertiary hospitals (3A hospitals) and 92 from non-top tertiary hospitals (other than 3A hospitals). A total of 240 clinicians, TDM pharmacists, and clinical laboratory physicians were involved, with an effective rate of 50.5%. Top tertiary hospitals were associated with certain advantages, such as the number of TDM testing facilities, annual sample size, number of monitoring varieties, and interpretation rate of monitoring reports, compared with non-top tertiary hospitals. In particular, β-lactamase inhibitor, olanzapine, carbamazepine, and glucocorticoids seemed to be the main projects that clinicians wanted to assess. The drugs for which TDM was commonly performed included vancomycin, valproic acid, carbamazepine, phenytoin sodium, and methotrexate. The most commonly used detection methods include high-performance liquid chromatography, immunization, 2D-LC, and LC-MS. The monitoring concentration range was found to be inconsistent for most of the drugs. Currently, no unified regulation exists for TDM charges in China, which is no more than ¥200 in general. Clinicians rely on pharmacists for professional guidance. Importantly, improvement in the interpretation of monitoring reports, proficiency testing, and cooperation with clinical departments may aid in improving the level of TDM service. This survey objectively reflected the current status of TDM work in hospitals in China, and provided a strong reference base for devising strategies for improvement and effective execution of TDM work.

Teratogenic Effects of Carissa spinarum and Azadirachta indica Aqueous Extracts in Mice

Carissa spinarum (mũkawa in Kikuyu, lamuriak in Maasai) and Azadirachta indica (neem, mwarubaini in Kiswahili) are widely used in African communities. C. spinarum is used as food and as treatment for gonorrhoea, cancer, and abnormal pain in pregnancy. A. indica is used as a mosquito-repellent and as treatment for malaria and dental carries. Both plants have broad biological activities including anticancer, hypoglycaemic, antinociceptive, and anti-inflammatory activity. However, data on their safety for use during pregnancy is scarce. This study aimed to determine the teratogenic effects of C. spinarum and A. indica in mice. FDA guidelines for reproduction studies were used. Pregnant mice were randomly divided into 8 groups (n=5) for the assay. Plant extracts were prepared in the doses 100, 250, and 500mg/kg body weight. Phenytoin sodium 100mg/kg body weight was used as the positive control and distilled water was used as the negative control. Treatments were administered orally and began from gestation day 6 and ended on gestation day 15. On gestation day 18, the mice were weighed and euthanized and the pups were recovered. Weights of the gravid uteri, number of pups and their body measurements, and incidences of foetal resorption were also recorded. Data were expressed as means and their standard errors and analysed using one-way ANOVA/Dunnett’s post hoc test. The significance level was set at p&lt;0.05. Heavy metal concentrations in the plant samples were determined using flame photometry and atomic absorption spectrophotometry. All doses of C. spinarum and A. indica caused significant (p&lt;0.001) weight loss and foetal resorption in the gravid mice. Reduced head sizes (microcephaly) and elongated limbs were observed in the C. spinarum 100mg/kg and A. indica 500mg/kg groups. Premature birth and high birth weights were also observed in the latter group. The plant samples were found to have high concentrations of lead, cadmium, iron, chromium, manganese, and zinc and this may have added to the teratogenicity observed. C. spinarum and A. indica exhibited significant teratogenicity and should be used with caution during pregnancy. In addition, the level of heavy metal contamination in Kenya should be assessed.

Investigation on the potential application of some metal oxide nanoclusters in the detection of phenytoin in gas and solvent phases through density functional theory calculations

To explore an appropriate sensor for the phenytoin (PHT) drug, metal oxide nanoclusters (Zn12O12, Mg12O12, and Be12O12) were used to adsorb the PHT utilizing the density functional theory calculations. After the interaction of PHT with nanoclusters, the adsorption energies were obtained to be − 60.17, −45.57, and –32.75 kcal mol−1, respectively. Thermodynamic parameters indicated that the adsorption of PHT on the nanoclusters is exothermic and spontaneous. After the adsorption process, electrical conductivity changed to 1.18, −8.68 %, and − 26.65 % in the Zn12O12, Mg12O12, and Be12O12, respectively. Thus, the electrical conductivity values indicated that the Be12O12 nanocluster has changed after adsorption, and this change can be considered the signal for the detection of PHT. Furthermore, Be12O12 indicated an ideal recovery time for PHT desorption from the nanocluster. Solvent phase calculations indicated that the nanoclusters also could be used in biological samples. UV–vis calculation showed that after the adsorption of PHT on the Be12O12, the spectrum shifted to a higher wavelength (red shift). Thus, it can be concluded that the Be12O12 nanocluster is an appropriate candidate for PHT detection.

Treatment of benzodiazepine-refractory status epilepticus: A retrospective, cohort study

IntroductionStatus epilepticus (SE) is a frequent neurological emergency, derived from the failure of mechanisms responsible for seizure termination. The present study aims to compare the efficacy of the most common antiseizure medications (ASMs) employed for the treatment of benzodiazepine-refractory SE. MethodsWe performed a retrospective cohort study of all SE episodes treated in our hospital between January 2016 and December 2020. Inclusion criteria were: age ≥ 18 years; a diagnosis of status epilepticus. Exclusion criteria were: status epilepticus resolved by initial therapy with benzodiazepines; impossibility to retrieve medical records. We considered as effective the ASM that was the last drug introduced or increased in dose before termination of SE and without changes in the co-medication. ResultsA total of 244 episodes in 219 patients were included in the study. The mean age of the final study cohort was 63.6 ± 19.2, with 108 (49%) men. In the total cohort, phenytoin (PHT) showed the highest response rate (57.6%), followed by lacosamide (LCM) (40.7%) and valproate (VPA) (39.8%). The comparative efficacy among the different drugs was significantly different (p < 0.001). In the pairwise comparisons, VPA was superior to levetiracetam (LEV) (response rate: 39.75% vs 24.71%; p = 0.004), but not to LCM. Phenytoin had a significantly higher resolution rate compared to VPA (response rate: 57.63% vs 39.75%; p = 0.02) and LEV (response rate: 57.63% vs 24.71; p < 0.001). The clinical predictors of anaesthetics administration were a disorder of consciousness upon clinical presentation, previous diagnosis of epilepsy, and younger age. ConclusionIn our cohort of SE, PHT showed higher effectiveness in terminating established SE, as well as refractory SE in the subgroup of patients treated with anaesthetics.

Functional characterization and identification of a therapeutic for a novel SCN5A-F1760C variant causing type 3 long QT syndrome refractory to all guideline-directed therapies

Pathogenic variants in the SCN5A-encoded Nav1.5 sodium channel cause type 3 long QT syndrome (LQT3). We present the case of an infant with severe LQT3 who was refractory to multiple pharmacologic therapies as well as bilateral stellate ganglionectomy. The patient's novel variant, p.F1760C-SCN5A, involves a critical residue of the Nav1.5's local anesthetic binding domain. The purpose of this study was to characterize functionally the p.F1760C-SCN5A variant using TSA-201 and patient-specific induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs). Whole-cell patch clamp was used to assess p.F1760C-SCN5A associated sodium currents with/without lidocaine (Lido), flecainide, and phenytoin (PHT) in TSA-201 cells. p.F1760C-SCN5A and CRISPR-Cas9 variant-corrected isogenic control (IC) iPSC-CMs were generated. FluoVolt voltage dye was used to measure the action potential duration (APD) with/without mexiletine or PHT. V1/2 of inactivation was right-shifted significantly in F1760C cells (-72.2 ± 0.7 mV) compared to wild-type (WT) cells (-86.3 ± 0.9 mV; P <.0001) resulting in a marked increase in windowcurrent. F1760C increased sodium late current 2-fold from 0.18% ± 0.04% of peak in WT to 0.49% ± 0.07% of peak in F1760C (P = .0005). Baseline APD to 90% repolarization (APD90) was increased markedly in F1760C iPSC-CMs (601 ± 4 ms) compared to IC iPSC-CMs (423 ± 15 ms; P <.0001). However, 4-hour treatment with 10 μM mexiletine failed to shorten APD90, and treatment with 5μM PHT significantly decreased APD90 of F1760C iPSC-CMs (453 ± 6 ms; P <.0001). PHT rescued electrophysiological phenotype and APD of a novel p.F1760C-SCN5A variant. The antiepileptic drug PHT may be an effective alternative therapeutic for the treatment of LQT3, especially for variants that disrupt the Lido/mexiletine binding site.

Interaction of Varenicline with Classic Antiseizure Medications in the Mouse Maximal Electroshock-Induced Seizure Model.

Varenicline (VAR) is a partial agonist of brain α4β2 nicotinic acetylcholine receptors recommended as a first line pharmacotherapy for smoking cessation. The aim of this study was to examine whether VAR affects the protective activity of four classic antiseizure medications, i.e., carbamazepine (CBZ), phenobarbital (PB), phenytoin (PHT), and valproate (VPA) on maximal electroshock (MES)-induced seizures, which may serve as an experimental model of human-generalized tonic-clonic seizures in mice. VAR administered intraperitoneally (i.p.) at a subthreshold dose of 0.5 mg/kg decreased the protective activity of CBZ against MES-induced convulsions, increasing its median effective dose (ED50) from 10.92 ± 1.0 to 18.15 ± 1.73 mg/kg (p < 0.01). The effect of VAR was dose-dependent because a lower dose of VAR (0.25 mg/kg) failed to antagonize the protective activity of CBZ. VAR administered at the subthreshold dose of 0.5 mg/kg had no impact on the protective activity of PB, PHT, and VPA in the mouse MES model. The inhibitory effect of VAR on the protective activity of CBZ against tonic-clonic convulsions most likely resulted from the pharmacodynamic mechanism(s) and was not associated with the changes in total brain concentrations of CBZ. VAR-evoked alterations in the anticonvulsive activity of CBZ may be of serious concern for epileptic tobacco smokers.

Development of a useful single-reference HPLC method for therapeutic drug monitoring of phenytoin and carbamazepine in human plasma.

A single reference high-performance liquid chromatographic (SR-HPLC) method was developed and validated for the therapeutic drug monitoring (TDM) of phenytoin (PHT) and carbamazepine (CBZ) in plasma from patients. The analytical parameters evaluated were linearity, limit of quantification (LOQ), selectivity, accuracy, and stability according to the US Food and Drug Administration (FDA) guideline. The developed method shows good linearity (r2 > 0.999; LOQ-50µg/mL), and LOQ values were 1.56µg/mL for PHT and 0.40µg/mL for CBZ at 254nm. For the development of SR-HPLC method, we evaluated to improve the detection wavelength, stirred retention time, and stability for SR, and selected 5-(p-methylphenyl)-5-phenylhydantoin for PHT (relative molar sensitivity, RMS = 0.848) and 10-methoxyiminostilbene for CBZ (RMS = 0.263). The established differential definite quantities of PHT and CBZ in plasma samples were similar using the RMS and absolute calibration methods based on RSD < 5.10%. A preliminary application was performed using chemiluminescent immunoassay and SR-HPLC method, in which the detectable values of the correlation coefficient and the slope of the intercept were PHT: 0.964 and 0.992647, and CBZ: 0.969 and 1.072089, respectively. Based on these results, we propose that the SR-HPLC method with RMS would be offered to the useful and accurate TDM of various medicines in plasma/serum samples.

Thiosemicarbazide Induces Partial Myoclonic, Generalized Tonic-Clonic and Status Epilepticus Seizures Depending on the Dose in the Rat

The present study aimed to characterize the seizures produced by injections of Thiosemicarbazide (TSC), a glutamic acid decarboxylase inhibitor. It aimed also to evaluate the anticonvulsant effect of the antiseizure medications Phenobarbital (PHB), Valproate (VPA), and Phenytoin (PNT) and of the antipsychotics Chlorpromazine (CPZ) and Haloperidol (HAL) as well as the antidepressant SSRI, Fluoxetine (FXT). Male Wistar rats received TSC i.p. injections of 2.5, 5, 7.5, 10, and 20 mg/kg. The rat's changes in behavior and the onset latencies of seizures were recorded and compared using an ANOVA test whereas the incidences of seizures were compared using a c2 test. Seizure severity was categorized as Partial Myoclonic Seizures (PMS), Generalized Tonic-Clonic Seizures (GTCS), and Status Epilepticus (SE). At low doses, TSC induced a significant change in behavior indicating an anxiety-inducing effect. The threshold dose for PMS was 7.5 mg/kg and when the dose increased to 10 mg/kg, PMS progressed to GTCS. TSC 7.5 mg/kg dose also induced susceptibility to audiogenic seizure (p<0.005) while 10 and 20 mg/kg doses caused SE in a dose-dependent manner (p<0.05). PHB (30 mg/kg), VPA (200 mg/kg), PNT (30 mg/kg), and VPA + PNT (100+15 mg/kg) prevented SE and significantly reduced the incidence of TSC 10 mg/kg-induced PMS (p<0.05) and GTCS (p<0.001). These treatments also increased the onset latencies of seizures (p<0.001). HAL (1 mg/kg), CPZ (1 and 2 mg/kg), and FXT (1 and 2 mg/kg) significantly reduced the incidence of PMS (p<0.05) and GTCS (p<0.01). The occurrence of SE was completely inhibited by FXT (p<0.001). All doses of HAL, CPZ, and FXT increased onset latencies of GTCS (p<0.01) while HAL (1.5 mg/kg), CPZ (2 mg/kg), and FXT (1 and 2 mg/kg) also increased onset latencies of PMS (p<0.05). Our study validated TSC-induced seizures in rats as a dose-dependent model of PMS, GTCS, and SE.