Phenobarbital Research Articles

Hepatic enzyme induction and its potential effect on thyroid hormone metabolism in the metamorphosing tadpole of Xenopus laevis (African clawed frog).

Hepatic enzyme induction, an inherent defense system against xenobiotics, is known to simultaneously affect endocrine system functions in mammals under specific conditions, particularly thyroid hormone (TH) regulation. While this phenomenon has been studied extensively, the pathway leading to this indirect thyroid effect in mammals has unclear applicability to amphibians, despite the importance of amphibian species in assessing thyroid-disruptive chemicals. Here, we investigated the effects of three well-known mammalian enzyme inducers-β-naphthoflavone (BNF), pregnenolone carbonitrile (PCN), and sodium phenobarbital (NaPB)-on the gene expression of phase-I and phase-II metabolizing enzymes in Xenopus laevis tadpoles. Waterborne exposure to BNF and PCN significantly induced the expression of both phase-I (cytochrome P450, CYP) and phase-II enzymes (UDP-glucuronosyltransferase, UGT and sulfotransferase, SULT), but in different patterns, while NaPB exposure induced CYP2B expression without affecting phase-II enzymes in tadpoles, in contrast to mammals. Furthermore, an ex vivo hepatic enzyme activity assay confirmed that BNF treatment significantly increased phase-II metabolic activity (glucuronidation and sulfation) toward TH. These results suggest the potential for certain mammalian enzyme inducers to influence TH clearance in X. laevis tadpoles. Our findings provide insights into the profiles of xenosensing activity and enzyme induction in amphibians, which can facilitate a better understanding of the mechanisms of indirect effects on the thyroid system via hepatic enzyme induction in nonmammalian species.

Long-term phenobarbital treatment is effective in working-age patients with epilepsy in rural Northeast China: a 10-year follow-up study.

Effective management of epilepsy in working-age patients is essential to reduce the burden on individuals, families, and communities. This study aimed to assess the long-term efficacy of phenobarbital (PB) in working-age patients with epilepsy in rural Northeast China and identify the risk factors for seizures during treatment. Patients aged 18-65 years diagnosed with convulsive epilepsy in rural areas of Jilin Province between 2010 and 2024 were included, and demographic and clinical data were recorded. Seizure frequency, self-efficacy, adherence, and adverse events (AEs) were assessed monthly. Of the 3,568 participants, 288 (8.1%) withdrew from the study and 159 (4.5%) died. During the first year of treatment, 75.2% of patients experienced a ≥50% reduction in seizure frequency compared with baseline (considered as treatment effectiveness); 53.7% of patients were seizure-free. By the tenth year, 97.7% of patients showed treatment effectiveness, and 89.6% were seizure-free. Self-efficacy was improved in 37.8% of patients in the first year and in 72% of patients by the tenth year. The independent risk factors for seizures during treatment were higher baseline seizure frequency [odds ratio (OR) = 1.431, 95% confidence interval (CI): 1.122-1.824], presence of multiple seizure types (OR = 1.367, 95% CI: 1.023-1.826), and poor adherence (OR = 14.806, 95% CI: 3.495-62.725), with significant differences observed in the first, third, and fifth years. The most commonly reported AEs were drowsiness (43.3%), dizziness (25.0%), and headaches (17.0%), most of which were mild and decreased over time. Age at enrollment was the only factor influencing withdrawal (hazard ratio = 0.984, 95% CI: 0.973-0.996, p = 0.010), with a substantial number of patients who withdrew (32.6%) relocating for work. Cardiovascular disease was the primary cause of death, and age at enrollment was the only risk factor (hazard ratio = 1.026, 95% CI: 1.009-1.043, p = 0.002). Working-age adults with epilepsy demonstrated a favorable response and tolerability to PB monotherapy. Baseline seizure frequency, seizure type, and adherence consistently predicted prognosis throughout the treatment period. Withdrawal was mainly explained by work-related pressures in this age group. Therefore, it is essential to implement interventions that support patient adherence to therapy and maintain stable regimens.

Decompensated MASH-Cirrhosis Model by Acute and Toxic Effects of Phenobarbital.

Metabolic dysfunction-associated Steatohepatitis (MASH), is a prominent cause for liver cirrhosis. MASH-cirrhosis is responsible for liver complications and there is no specific treatment. To develop new therapeutic approaches, animal models are needed. The aim of this study was to develop a fast animal model of MASH-cirrhosis in rats reflecting the human disease. Carbon tetrachloride (CCl4) injections in combination with a high-fat Western diet (WD) were used to induce MASH-cirrhosis. To accelerate liver injury, animals received phenobarbital (PB) in their drinking water using two different regimens. Rats developed advanced MASH-cirrhosis characterized by portal hypertension, blood biochemistry, hepatic ballooning, steatosis, inflammation and fibrosis. Importantly, rats receiving low-dose PB for the long term (LT) showed ascites after 6 weeks, whereas rats with high-dose short-term (ST) PB developed ascites after 8 weeks. ST- and LT-treated rats showed increased portal pressure (PP) and decreased mean arterial pressure (MAP). Of note, hepatocyte ballooning was only observed in the LT group. The LT administration of low-dose PB with CCl4 intoxication and WD represents a fast and reproducible rat model mimicking decompensated MASH-cirrhosis in humans. Thus, CCl4 + WD with LT low-dose phenobarbital treatment might be the preferred rat animal model for drug development in MASH-cirrhosis.

Artificial intelligence driven image analysis identifies phenobarbital induced hepatocyte hypertrophy in liver microtissues across species

In vivo treatment of rats with phenobarbital (PB) induces liver enzyme induction associated with hepatocyte hypertrophy. In the present study we used a novel microTMA technology coupled with artificial intelligence (AI) driven image analysis and proteomics analysis to test the hypothesis that PB treatment of rat and human liver microtissues could recapitulate hepatocyte hypertrophy in vitro. Human and rat liver microtissues were treated with PB over a range of concentrations (500 uM - 2000 uM). Fixed liver microtissues were embedded in paraffin in a microTMA mold, sectioned and stained on parallel microTMA sections with H&E and cell type specific markers, respectively. An AI algorithm was trained to identify and measure changes in hepatocyte cytoplasmic area on images of H&E stained microtissue sections. Image analysis with this algorithm showed that treatment of human and rat liver microtissues with PB (500 uM) for 96 h caused significant increases (p ≤ 0.08- p < 0.01) in hepatocyte cytoplasmic area, a hallmark of hypertrophy. Proteomics analysis of control and PB treated liver microtissue samples confirmed this treatment also caused phase1 and phase 2 enzyme induction in both human and rat samples. In conclusion AI driven image analysis of H&E stained liver microtissue FFPE sections shows that this model can recapitulate a PB-induced hypertrophy response.

Padsevonil suppresses seizures without inducing cell death in neonatal rats.

Padsevonil (PSL) is a rationally designed anti-seizure medication (ASM) which has overlapping mechanisms of action with the two most common ASMs used for neonatal seizures, phenobarbital (PB) and levetiracetam (LEV). Here we evaluated the anti-seizure properties of PSL across the neonatal and adolescent period in rats in the pentlyenetetrazole (PTZ) induced seizures model. Postnatal day (P)7, P14 and P21 Sprague-Dawley rat pups were pre-treated with PSL (1-30mg/kg), and assessed for seizure latency and severity 30min later following injection of PTZ. A separate cohort of P7 pups were treated with neonatal ASMs and euthanized 24h later (on P8) to assess induction of cell death, a feature common to many ASMs when given to P7 rodents. This effect has been extensively reported with PB, but not with LEV. Cell death was assessed by PathoGreen staining. PSL suppressed PTZ-evoked seizures across multiple age groups, particularly at higher doses, without producing increased cell death compared to vehicle. The effects of PSL were particularly notable at suppressing tonic-clonic seizure manifestations (82% of P7 and 100% of P14 and P21 animals were protected from tonic-clonic seizures with the 30mg/kg dose). PSL displayed dose-dependent anti-seizure effects in immature rodents in the PTZ model of seizures in immature rats. While many ASMs, including PB, induce cell death in neonatal rats, PSL does not. This suggests that PSL may offer therapeutic benefit and a favorable safety profile for the treatment of neonatal seizures.

Pharmacokinetic and pharmacodynamic data from the NEOLEV1 and NEOLEV2 studies

ObjectivesTo confirm that levetiracetam (LEV) demonstrates predictable pharmacokinetics(PK) at higher doses and to study the pharmacodynamics(PD) of LEV.DesignPharmacokinetic data from the NEOLEV1 and NEOLEV2 trials were analysed using a non-linear...

Thromboelastography in dogs with idiopathic epilepsy treated with phenobarbital monotherapy

AbstractBackgroundThromboelastography (TEG) is an effective technique to assess the efficiency of coagulation. Phenobarbital (PB) can induce hematological and coagulation disorders in both animals and humans, but its effects on hemostasis have been little investigated and are poorly understood in dogs.ObjectivesThe aim of this article was to assess coagulation using TEG in a population of dogs with idiopathic epilepsy treated with PB.Material and MethodsProspective observational study. TEG was performed in blood samples from dogs with idiopathic epilepsy that were divided in three groups: Two groups of treated dogs that were on phenobarbital treatment for less or more than 6 months, and a control group of healthy dogs. Duration of treatment, dose, phenobarbital serum concentration and selected hematological and biochemical parameters were evaluated and correlated with the TEG results.ResultsNo statistically significant differences were found between groups. None of the animals appeared to be in a hypo‐ or hypercoagulable state, however 9/19 (47,4%) dogs were classified as hyper‐fibrinolytic. A statistically significant negative relationship between MA and G values and increased fibrinolytic activity (LY30) were found. No statistically significant relationship was found between PB dose or PB blood levels and TEG parameters in either group. No bleeding complications were observed.DiscussionThe rise in fibrinolysis might be due to hepatic damage from PB, as indicated by elevated liver enzymes in many dogs with abnormal fibrinolytic patterns. Although TEG showed hyperfibrinolysis in some dogs, the presence of primary or secondary hyperfibrinolysis could not be confirmed due to the lack of D‐dimer measurements and liver biopsy. TEG’s sensitivity compared to other fibrinolysis biomarkers like PAP might also affect results.ConclusionsTThe cause of hyperfibrinolysis in epileptic dogs treated with phenobarbital remains unclear, with potential links to hepatic effects or handling, and further research is needed to assess its clinical significance.

Phenobarbital Versus Benzodiazepines for Alcohol Withdrawal in the Medical Intensive Care Unit (ICU): A Retrospective Cohort Study.

Background: Phenobarbital (PHB) is a safe and efficacious alternative to benzodiazepines (BZD) for treating severe alcohol withdrawal (AWS). However, the safety of utilizing PHB for patients initially treated with BZD is unknown. Objective: To evaluate the safety and efficacy of PBH compared to BZDs in severe AWS in the medical intensive care unit (ICU). Methods: This was a retrospective cohort study comparing critically ill patients admitted for AWS who received BZDs or PHB. The primary outcome was time to persistent resolution of altered mentation. Secondary outcomes included development and duration of delirium, need for mechanical ventilation, development of withdrawal seizures, and ICU and hospital length of stay. Results: Ninety-five patients were evaluated (53 in PHB group, 42 in BZD group). Before study medication, less BZD patients demonstrated abnormal mentation compared with PHB patients (RASS < -2: 2.39% vsvs. 28.12%, respectively, and RASS > +2: 9.9% vsvs. 48.76%; P <0.001 for both). No difference was seen between groups for the primary outcome (1.8 hours for BZD cohort vsvs. 13.81 hours for PHB cohort; P =0.22). More patients in the BZD cohort developed a seizure after study medication administration (5.67% vs 0%, respectively; P =0.02). No significant difference was seen in other secondary outcomes. Conclusions: This study provides support for use of PHB after BZD if patients remain in uncontrolled withdrawal. Despite significant doses of BZDs before PHB, patients in the PHB cohort demonstrated similar clinical and safety outcomes compared to BZD alone.

Physiologically based in vitro – in vivo correlation of modified release oral formulations with non-linear intestinal absorption: A case study using mirabegron

Establishing an in vitro – in vivo correlation (IVIVC) for oral modified release (MR) formulations would make it possible to substitute an in vitro dissolution test for human bioequivalence (BE) studies when changing the formulation or manufacturing methods. However, the number of IVIVC applications and approvals are reportedly low. One of the main reasons for failure to obtain IVIVCs using conventional methodologies may be the lack of consideration of the dissolution and absorption mechanisms of drugs in the physiological environment. In particular, it is difficult to obtain IVIVC using conventional methodologies for drugs with non-linear absorption processes. Therefore, the aim of the present study was to develop a physiologically based biopharmaceutics model (PBBM) that enables Level A IVIVCs for mirabegron MR formulations with non-linear absorption characteristics.Using human pharmacokinetic (PK) data for immediate-release formulations of mirabegron, the luminal drug concentration-dependent membrane permeation coefficient was calculated through curve fitting. The membrane permeation coefficient data were then applied to the human PK data of the MR formulations to estimate the in vivo dissolution rate by curve fitting. It was assumed that in vivo dissolution could be described using a zero-order rate equation. Furthermore, a Levy plot was generated using the estimated in vivo dissolution rate and the in vitro dissolution rate obtained from the literature. Finally, the dissolution rate of the MR formulations from the Levy plot was applied to the PBBM to predict the oral PK of the mirabegron MR formulations.This PB-IVIVC approach successfully generated linear Levy plots with slopes of almost 1.0 for MR formulations with different dose strengths and dissolution rates. The Cmax values of the MR formulations were accurately predicted using this approach, whereas the prediction errors for AUC exceeded the Level A IVIVC criteria. This can be attributed to the incomplete description of colonic absorption in the current PBBM.

Safety of Phenobarbital Versus Benzodiazepines for Alcohol Withdrawal in Critically Ill Patients With Primary Neurologic Injuries.

Alcohol withdrawal syndrome (AWS) is a complication of alcohol use disorder that manifests as a range of symptoms. Symptom-triggered benzodiazepines (BZDs) are often used as first-line treatment of AWS. However, recent literature suggests phenobarbital (PHB) may be safer and more efficacious, but studies are limited by exclusion of patients with neurological injuries. We aimed to evaluate the safety of PHB compared to BZDs for the management of AWS among patients with primary neurologic injuries. Retrospective cohort study of patients with primary neurologic injuries admitted to an ICU who received PHB or symptom-triggered BZD for AWS between December 2013 and February 2020. The primary outcome was incidence of oversedation, defined as Richmond Agitation Sedation Scale (RASS) scores from -5 to -3 within 24 hours of initial PHB or BZD dose. Secondary outcomes included largest decrease in RASS, need for mechanical ventilation, and additional sedative use within 24 hours of initial PHB or BZD dose. A multivariable analysis was performed to evaluate the association of PHB administration with the primary outcome. Among 600 patients treated for AWS, 84 patients were included in our analysis (PHB, n = 56; BZD, n = 28). In the unadjusted analysis, there were no differences between the PHB and BZD groups for the primary outcome of oversedation (21.4 vs. 7.1%, P = 0.13), or secondary outcomes of decrease in RASS (P = 0.34), or new ventilator requirement (P = 0.55). Patients who received PHB had higher rates of additional sedative use (P < 0.01). Multivariable regression revealed an increase in oversedation among intubated patients (P = 0.014), while PHB administration was not independently associated with oversedation (P = 0.516). Phenobarbital did not independently increase the risk of oversedation compared to BZD for AWS in patients with primary neurologic injuries. Future studies should determine optimal dosing of PHB in this population.

A case of recurrent convulsions caused by acute sulfuryl fluoride gas poisoning

Sulfuryl fluoride is a kind of pesticide with strong permeability, convenient use at low temperature, non-corrosive and other characteristics, which can kill food pests and has strong lethality to termites. In acute sulfuryl fluoride poisoning, patients can see recurrent convulsions, epileptic electroencephalogram abnormalities such as matrix spikes or high amplitude spikes. In this paper, a patient with sulfuryl fluoride poisoning with convulsion-based mental system symptoms was reported, and after clinical treatment with dexamethasone and phenobarbital sodium, the patient was cured and discharged.

Physically-Based Descriptors of the Nitrogen Reduction Reaction on Transition Metal Nitrides

Due to the high energy intensity and consequent carbon footprint of the Haber-Bosch process for ammonia production, researchers have been intensely studying the electrochemical nitrogen reduction reaction (NRR) as a means to directly produce ammonia using clean energy with lower emissions of carbon by-products. One exciting class of materials for NRR catalysis are transition metal nitrides (TMNs), as they have been shown to have good stability, flexible electronic structures, and decent electrochemical activity [1]. Previous studies using density functional theory (DFT) have explored the energetics of known NRR pathways (associative, dissociative, and Mars-van Krevelen) on the mononitrides of all naturally occurring d-block metals in rock salt and zincblende structures [2]. The most favorable NRR mechanism (determined to be the pathway that contains the smallest maximum potential change across all steps of the reaction) on these materials was shown to be the Mars-van Krevelen mechanism. Uncovering electronic, structural, and dynamic descriptors that correlate well with the energetics of this favorable NRR mechanism on TMNs will be useful in mitigating the need to run full DFT calculations when expanding the search space of potential catalyst candidates, such as ternary transition metal nitrides (TTMNs) and perovskite transition metal oxynitrides (TMONs). Previous literature has shown that the proton adsorption energy is a good descriptor for catalytic NRR activity on TMNs [3], oxygen vacancy content [4] and the oxygen p-band center of bulk perovskites [5] are good descriptors for catalytic oxygen evolution reaction performance, and the metal d-band center of pure transition metal catalysts is a good descriptor for reactivity and adsorption energies [6]. Inspired by these results, this work uses DFT on a set of TMNs to calculate a variety of potential physics-based descriptors, including: metal d and nitrogen p-band centers, hybridization between nitrogen p and metal d orbitals, nitrogen vacancy content, surface Bader charges, and phonon band centers. Since the energetics of the NRR can be modulated by the properties of either the atoms in the bulk or in the top surface layers, we calculate all of our descriptors from atoms in the TMN bulk form as well as from surface and subsurface atoms in the TMN slab form.Our results reveal several correlations between the descriptors and material attributes (such as adsorption energies and vacancy formation energies), which in turn govern the energetics of the NRR on the TMNs. We find that the N2 adsorption energy is negatively correlated with the metal d-band center, the N adsorption energy is positively correlated with the nitrogen p-band center, and both the proton adsorption energy and nitrogen vacancy formation energy are negatively correlated with nitrogen p and metal d orbital hybridization. Interestingly, we also find that for some attributes, the subsurface layer atoms dictate the attribute values and not the surface layer atoms. This suggests that heterogeneous catalysis reactivity may be modulated by atomic properties not purely from the bulk or purely from the surface, but rather from multiple subsurface layers as well.Overall, the insights gained from our descriptor analysis can be used to constrain the search and design space of future potential NRR catalysts, such as TTMNs and TMONs. In doing so, the descriptors can be used in future works in either a high-throughput screening or machine learning framework to allow for the inverse material design of optimal NRR catalysts. These optimal catalysts can in turn lead to the emergence of electrochemical ammonia synthesis in industrial production.References Qiao Z, Johnson D and Djire A. Cell Rep Phys Sci 2021; 2.Abghoui Y and Skúlason E. Catal Today 2017; 286: 69-77.Abghoui Y, Garden AL, Hlynsson VF, Björgvinsdóttir S, Ólafsdóttir H and Skúlason E. Physical Chemistry Chemical Physics 2015; 17: 4909-4918.Marelli E, Gazquez J, Poghosyan E, Müller E, Gawryluk DJ, Pomjakushina E, Sheptyakov D, Piamonteze C, Aegerter D, Schmidt TJ, Medarde M and Fabbri E. Angewandte Chemie - International Edition 2021; 60: 14609-14619.Jacobs R, Hwang J, Shao-Horn Y and Morgan D. Chemistry of Materials 2019; 31: 785-797.Nørskov JK, Abild-Pedersen F, Studt F and Bligaard T. Proc Natl Acad Sci U S A 2011; 108: 937-943.

Environmental fate of phenobarbital in water: Homogeneous and non-homogeneous environment

In aqueous environments, phenobarbital (PB) undergoes degradation mediated by hydroxyl radicals (HO·) and sulfate radicals (SO4·−). In this study, a theoretical approach was used to investigate the oxidation of phenobarbital triggered by HO·/SO4·− in different dissociated forms of PB at different pH values, as well as the adsorption mechanism of phenobarbital on the silica surface and the non-homogeneous reaction with HO·. Our study confirms three primary reaction models for PB degradation: radical addition, hydrogen abstraction, and single electron transfer reactions. Thermodynamic and kinetic calculations show that the reaction of PB with HO· is the main degradation pathway compared to the reaction of SO4−. At the C5 and C6 positions, HO·-addition and H-abstraction from H6 and H7 are competitive mechanisms. However, in non-homogeneous environments, HO·-addition at C5 becomes the dominant pathway. Our work identifies the primary products of these degradation reactions. At a temperature of 298 K, the total rate constants for the degradation reactions of HO· with PB neutral molecules and anions were determined to be 2.06 M−1 s−1 and 4.11 × 107 M−1 s−1, respectively. In a non-homogeneous reaction with HO·, the total rate constant is 4.47 × 1010 M−1 s−1. Despite degradation, the majority of these products retain their potential to impact aquatic organisms. In particular, compounds such as 5-ethyl-5-hydroxypyrimidine-2,4,6(1H,3H,5H)-trione, 5-(1-hydroxyethyl)-5-phenylpyrimidine-2,4,6(1H,3H,5H)-trione, and 5-acetyl-5-phenylpyrimidine-2,4,6(1H,3H,5H)-trione have a greater toxic effect on green algae. The findings underscore the need for future research to consider the environmental implications and ecotoxicity of PB. Such consideration is crucial for a comprehensive understanding of the long-term environmental impact of pharmaceutical residues in aquatic ecosystems.

Effects of species of origin and mode of induction of microsomes on carbamazepine-induced cell toxicity

Standardization and validation of in vitro drug metabolism is essential for pre-clinical drug development as well as for in vitro toxicity assays including the lymphocyte toxicity assay (LTA) and the in vitro platelet toxicity assay (iPTA). Use of isolated liver microsomes (MIC) in in vitro testing has been utilized for a long time; however, the effect of species of origin and induction agents on the metabolic capacities of MIC is not adequately evaluated. In this study we investigated the impact of species of origin and induction agent on the capacity of MICs to bioactivate carbamazepine (CBZ) using cytotoxicity as a gross endpoint to measure the levels of cytotoxic metabolites generated by each type of MICs. Jurkat E6.1 cell line was used and MICs from human, rat, mouse, minipig and rabbit origin as well as rat MICs that is either non-induced or induced by phenobarbitone (PHB), dexamethasone (DEXA), 3-methylcholanthrene (3MC), clofibrate (CLOF) and isoniazid (INH) were investigated. MICs from minipig and rat MICs induced with 3MC exhibited the highest capacity to produce cytotoxic metabolites of CBZ. These findings will help optimize and standardize in vitro toxicity assays and provide guidance to pre-clinical investigation of drugs.

Drug Disposition in Neonatal Göttingen Minipigs: Exploring Effects of Perinatal Asphyxia and Therapeutic Hypothermia.

Asphyxiated neonates often undergo therapeutic hypothermia (TH) to reduce morbidity and mortality. Since both perinatal asphyxia (PA) and TH influence physiology, altered pharmacokinetics (PK) and pharmacodynamics (PD) are expected. Given that TH is the standard of care for PA with moderate to severe hypoxic-ischemic encephalopathy, disentangling the effect of PA versus TH on PK/PD is not possible in clinical settings. However, animal models can provide insights into this matter. The (neonatal) Göttingen Minipig, the recommended strain for nonclinical drug development, was selected as translational model. Four drugs-midazolam (MDZ), fentanyl (FNT), phenobarbital (PHB), and topiramate (TPM)-were intravenously administered under four conditions: control (C), therapeutic hypothermia (TH), hypoxia (H), and hypoxia plus TH (H+TH). Each group included six healthy male neonatal Göttingen Minipigs anesthetized for 24 hours. Blood samples were drawn at 0 (predose) and 0.5, 2, 2.5, 3, 4, 4.5, 6, 8, 12, and 24 hours post drug administration. Drug plasma concentrations were determined using validated bioanalytical assays. The PK parameters were estimated through compartmental and noncompartmental PK analysis. The study showed a statistically significant decrease in FNT clearance (CL; 66% decrease), with an approximately threefold longer half-life (t1/2) in the TH group. The H+TH group showed a 17% reduction in FNT CL, with a 62% longer t1/2 compared with the C group; however, it was not statistically significant. Although not statistically significant, trends toward lower CL and longer t1/2 were observed in the TH and H+TH groups for MDZ and PHB. Additionally, TPM demonstrated a 28% decrease in CL in the H group compared with controls. SIGNIFICANCE STATEMENT: The overarching goal of this study using the neonatal Göttingen Minipig model was to disentangle the effects of systemic hypoxia and TH on PK using four model drugs. Such insights can subsequently be used to inform and develop a physiologically based pharmacokinetic model, which is useful for drug exposure prediction in human neonates.

The effect of oral zonisamide treatment on serum phenobarbital concentrations in epileptic dogs.

Zonisamide is used in dogs for the treatment of epileptic seizures. It is predominantly metabolised by CYP450 hepatic enzymes. When used concurrently with phenobarbital (PB), zonisamide clearance is increased and its elimination half-life decreases. However, the effect that zonisamide may have on serum PB concentrations in dogs has not been previously described. Eight dogs diagnosed with idiopathic epilepsy and two dogs with structural epilepsy commenced zonisamide at 8.0 mg/kg/12 h [7.4-10 mg/kg/12 h] following an increase in the frequency of epileptic seizures. Nine dogs were receiving PB every 12 h (4.2 mg/kg/12 h [3.8-6 mg/kg/12 h]), and one dog was receiving PB every 8 h (6 mg/kg/8 h). Following the addition of zonisamide and despite no increase in PB dosage, an increase in phenobarbital serum PB concentration was observed in 9 out of 10 dogs in subsequent measurements. In five dogs, phenobarbital serum concentrations were raised to concentrations higher than the reported hepatotoxic concentrations (trough>35 mg/L). This required a reduction in daily doses of PB. This case series suggests that zonisamide affects the metabolism of PB and causes an increase in PB serum concentrations over time.

Mode of action analysis for fluxapyroxad-induced rat liver tumour formation: evidence for activation of the constitutive androstane receptor and assessment of human relevance

The fungicide fluxapyroxad (BAS 700 F) has been shown to significantly increase the incidence of liver tumours in male Wistar rats at dietary levels of 1500 and 3000 ppm and in female rats at a dietary level of 3000 ppm via a non-genotoxic mechanism. In order to elucidate the mode of action (MOA) for fluxapyroxad-induced rat liver tumour formation a series of in vivo and in vitro investigative studies were undertaken. The treatment of male and female Wistar rats with diets containing 0 (control), 50, 250, 1500 and 3000 ppm fluxapyroxad for 1, 3, 7 and 14 days resulted in a dose-dependent increases in relative weight at 1500 and 3000 ppm from day 3 onwards in both sexes, with an increase in relative liver weight being also observed in male rats given 250 ppm fluxapyroxad for 14 days. Examination of liver sections revealed a centrilobular hepatocyte hypertrophy in some fluxapyroxad treated male and female rats. Hepatocyte replicative DNA synthesis (RDS) was significantly increased in male rats given 1500 and 3000 ppm fluxapyroxad for 3 and 7 days and in female rats given 50–3000 ppm fluxapyroxad for 7 days and 250–3000 ppm fluxapyroxad for 3 and 14 days; the maximal increases in RDS in both sexes being observed after 7 days treatment. The treatment of male and female Wistar rats with 250–3000 ppm fluxapyroxad for 14 days resulted in significant increases in hepatic microsomal total cytochrome P450 (CYP) content and CYP2B subfamily-dependent enzyme activities. Male Wistar rat hepatocytes were treated with control medium and medium containing 1–100 μM fluxapyroxad or 500 μM sodium phenobarbital (NaPB) for 4 days. Treatment with fluxapyroxad and NaPB increased CYP2B and CYP3A enzyme activities and mRNA levels but had little effect on markers of CYP1A and CYP4A subfamily enzymes and of the peroxisomal fatty acid β-oxidation cycle. Hepatocyte RDS was significantly increased by treatment with fluxapyroxad, NaPB and 25 ng/ml epidermal growth factor (EGF). The treatment of hepatocytes from two male human donors with 1–100 μM fluxapyroxad or 500 μM NaPB for 4 days resulted in some increases in CYP2B and CYP3A enzyme activities and CYP mRNA levels but had no effect on hepatocyte RDS, whereas treatment with EGF resulted in significant increase in RDS in both human hepatocyte preparations. Hepatocytes from male Sprague-Dawley wild type (WT) and constitutive androstane receptor (CAR) knockout (CAR KO) rats were treated with control medium and medium containing 1–16 μM fluxapyroxad or 500 μM NaPB for 4 days. While both fluxapyroxad and NaPB increased CYP2B enzyme activities and mRNA levels in WT hepatocytes, only minor effects were observed in CAR KO rat hepatocytes. Treatment with both fluxapyroxad and NaPB only increased RDS in WT and not in CAR KO rat hepatocytes, whereas treatment with EGF increased RDS in both WT and CAR KO rat hepatocytes. In conclusion, a series of in vivo and in vitro investigative studies have demonstrated that fluxapyroxad is a CAR activator in rat liver, with similar properties to the prototypical CAR activator phenobarbital. A robust MOA for fluxapyroxad-induced rat liver tumour formation has been established. Based on the lack of effect of fluxapyroxad on RDS in human hepatocytes, it is considered that the MOA for fluxapyroxad-induced liver tumour formation is qualitatively not plausible for humans.

Thyroid Hormone Status in Children Taking Antiepileptic Drugs (AEDs): An Experience in a Tertiary Care Hospital of Bangladesh.

Introduction: Antiepileptic drugs (AEDs) may alter thyroid hormone homeostasis at the level of biosynthesis, release, transport, metabolism and excretion of thyroid hormones. The purpose of the study was to see the thyroid hormone status in children with epilepsy treating with common antiepileptic drugs. Materials &amp; Method: The cross-sectional study was carried out in department of pediatric neurology, National Institute of Neurosciences and Hospital (NINS), Dhaka. One hundred and sixty epileptic children aged 1 year to 14 years who were on monotherapy or polytherapy with the most commonly used Antiepileptic drugs (AEDs) for at least 6 months or more were enrolled. Serum TSH and FT4 were measured in all selected patients with early morning serum sample. Result: Nearly one third of study subjects had thyroid dysfunction, most of which were Subclinical hypothyroidism (SCH). The frequency of SCH was 29.2% in carbamazepine(CBZ), 50% in oxcabazepine (OXC), 28.6% in phenobarbitone(PHB) and 13% in valproic acid (VPA) treated epileptic children. No child was found to have subclinical hypothyroidism with topiramate and ethosuximide monotherapy. Antiepileptic drugs (AEDs) monotherapy or polytherapy had no significant difference in alteration on thyroid hormone level. Use of CBZ for long duration significantly altered thyroid function. Doses of Antiepileptic drugs (AEDs) didn’t show any significant thyroid dysfunction. Conclusion: Commonly used Antiepileptic drugs (AEDs) in children with epilepsy were associated with alteration of thyroid hormones, most commonly subclinical hypothyroidism. BANGLADESH J CHILD HEALTH 2022; VOL 46 (2) : 58-64

Load and go: Assessing safety outcomes of patients discharged from the emergency department after receiving phenobarbital for alcohol withdrawal.

Phenobarbital (PB) is a long-acting GABA A-agonist with favorable pharmacokinetics (long half-life and duration of effect) that allows effective treatment of alcohol withdrawal (AW) after administration of a single loading dose. Current evidence suggests that in the setting of AW, PB administration may be associated with decreased hospital admissions and hospital length of stay. The aim of this study was to evaluate the safety outcomes of AW patients who were treated and discharged from the emergency department (ED) after receiving PB for AW. This retrospective chart review included a convenience sample of 33 AW patients who presented to four EDs within an 18-month span. Descriptive statistics (frequencies and percentages) were used to describe demographics, distribution of resources and referrals, and the safety outcomes of PB administration for low-risk AW patients. Patients were selected for inclusion in consultation with a medical toxicologist, treated with PB, and discharged from the ED. Electronic medical records were utilized to gather information on the patient cohort. All patients were treated with at least a single loading dose of 5‒10mg/kg (ideal body weight) of intravenous or per os PB during their ED stay. Only one patient had an unanticipated event after discharge, which was related to driving against advice. Two additional patients had ED revisits for recurrent alcohol use within 72h, and 16 patients had recurrent alcohol use within 30 days. All 33 patients were provided with resources for linkage to treatment. None required hospital admission. ED PB "load and go" may be a safe, effective AW treatment that could help treat AW, facilitate linkage to specific rehabilitation treatments, and decrease hospital admissions.

Synaptic vesicle protein 2A mitigates parthanatos via apoptosis-inducing factor in a rat model of pharmacoresistant epilepsy.

Synaptic vesicle protein 2A (SV2A) is a unique therapeutic target for pharmacoresistant epilepsy (PRE). As seizure-induced neuronal programmed death, parthanatos was rarely reported in PRE. Apoptosis-inducing factor (AIF), which has been implicated in parthanatos, shares a common cytoprotective function with SV2A. We aimed to investigate whether parthanatos participates in PRE and is mitigated by SV2A via AIF. An intraperitoneal injection of lithium chloride-pilocarpine was used to establish an epileptic rat model, and phenytoin and phenobarbital sodium were utilized to select PRE and pharmacosensitive rats. The expression of SV2A was manipulated via lentivirus delivery into the hippocampus. Video surveillance was used to assess epileptic ethology. Biochemical tests were employed to test hippocampal tissues following a successful SV2A infection. Molecular dynamic calculations were used to simulate the interaction between SV2A and AIF. Parthanatos core index, PARP1, PAR, nuclear AIF and MIF, γ-H2AX, and TUNEL staining were all increased in PRE. SV2A is bound to AIF to form a stable complex, successfully inhibiting AIF and MIF nuclear translocation and parthanatos and consequently mitigating spontaneous recurrent seizures in PRE. Moreover, parthanatos deteriorated after the SV2A reduction. SV2A protected hippocampal neurons and mitigated epileptic seizures by inhibiting parthanatos via binding to AIF in PRE.