Action Of Carbamazepine Research Articles

Anticonvulsant effect of (±) citronellal possibly through the GABAergic and voltage-gated sodium channel receptor interaction pathways: In vivo and in silico studies

This study aimed to investigate the anticonvulsant effects of citronellal (CIT) and possible underlying mechanisms through an isoniazid (INH)-induced seizure (convulsion) via in vivo and in silico studies. For this, convulsions were induced by the oral administration of INH (300 mg/kg) to the mice. The animals were treated orally with different doses of CIT (50, 100, and 200 mg/kg). Vehicle served as a negative control (NC), while diazepam (DZP) (2 mg/kg) and carbamazepine (CAR) (80 mg/kg) were provided (p.o.) as positive controls (PC). A combination therapy of CIT (middle dose) with DZP and CAR was also given to two separate groups of animals to estimate the synergistic or antagonistic effects. Molecular docking and visualization of ligand-receptor interactions are also estimated through different computational tools. The results of the in vivo study showed that CIT dose-dependently significantly (p < 0.05) exhibited a higher onset of seizures while reducing the frequency and duration of seizures in mice compared to the NC group. Besides these, in combination therapy, CIT significantly antagonized the activity of CAR and DZP, leading to a reduction in the onset of seizures and an increase in their frequency and duration compared to treatment with CAR and DZP alone. Additionally, molecular docking revealed that the CIT exhibited a moderate binding affinity (−5.8 kcal/mol) towards the GABAA receptor and a relative binding affinity (−5.3 kcal/mol) towards the voltage-gated sodium channel receptor by forming several bonds. In conclusion, CIT showed moderate anticonvulsant activity in INH-induced convulsion animals, possibly by enhancing GABAA receptor activity and inhibiting the voltage-gated sodium channel receptor.

Toxicometabolomics and Biotransformation Product Elucidation in Single Zebrafish Embryos Exposed to Carbamazepine from Environmentally-Relevant to Morphologically Altering Doses.

Toxicometabolomics and biotransformation product (bioTP) elucidation were carried out in single zebrafish (ZF) embryos exposed to carbamazepine (CBZ). Exposures were conducted in 96-well plates containing six CBZ concentrations ranging from 0.5 μg/L to 50 mg/L (n = 12 embryos per dose). In the 50 mg/L dose group, 33% of embryos developed edema during the exposure (120 hpf), while hatching was significantly delayed in three of the lower-dose groups (0.46, 3.85, and 445 μg/L) compared to the control at 48 hpf. Toxicometabolomic analysis together with random forest modeling revealed a total of 80 significantly affected metabolites (22 identified via targeted lipidomics and 58 via nontarget analysis). The wide range of doses enabled the observation of both monotonic and nonmonotonic dose responses in the metabolome, which ultimately produced a unique and comprehensive biochemical picture that aligns with existing knowledge on the mode of action of CBZ. The combination of high dose exposures and apical endpoint assessment in single embryos also enabled hypothesis generation regarding the target organ for the morphologically altering insult. In addition, two CBZ bioTPs were identified without additional exposure experiments. Overall, this work showcases the potential of toxicometabolomics and bioTP determination in single ZF embryos for rapid and comprehensive chemical hazard assessment.

Development and Molecular Investigation into the Effects of Carbamazepine Exposure in the Zebrafish (Danio rerio)

Concerns regarding environmental exposures and the impacts of pharmaceuticals on non-target aquatic organisms continue to increase. The antiepileptic drug carbamazepine (CBZ) is often detected as an aquatic contaminant and can disrupt various behaviors of fishes. However, there are few reports which investigate the mechanism of CBZ action in fish. The aim of the current study was to evaluate the effects of CBZ on embryonic development (i.e., hatching rate, heart rate, and body length) and early spontaneous movement. Moreover, we sought to investigate potential mechanisms by focusing on the gamma-aminobutyric acid (GABA) neurotransmitter system in zebrafish 6 days after of exposure. The results show that CBZ exposure did not cause significant effects on embryo development (hatching rate, heart rate, nor body length) at the test concentrations. However, the early spontaneous movement of embryos was inhibited following 10 μg/L CBZ exposure at 28–29 h post-fertilization (hpf). In addition, acetylcholinesterase (AChE) activity and GABA concentrations were increased with exposure, whereas glutamate (Glu) concentrations were decreased in larval zebrafish. Gene expression analysis revealed that GABA and glutamate metabolic pathways in zebrafish larvae were altered following exposure to CBZ. GABA transaminase (abat) and glutamic acid decarboxylase (gad1b) decreased to 100 µg/L, and glutamate receptor, ionotropic, N-methyl D-aspartate 1b (grin1b) as well as the glutamate receptor, ionotropic, α-amino-3hydroxy-5methylisoxazole-4propionic 2b (gria2b) were down-regulated with exposure to 1 µg/L CBZ. Our study suggests that CBZ, which can act as an agonist of the GABAA receptor in humans, can also induce alterations in the GABAergic system in fish. Overall, this study improves understanding of the neurotoxicity and behavioral toxicity of zebrafish exposed to CBZ and generates data to be used to understand mechanisms of action that may underlie antiepileptic drug exposures.

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Nebivolol attenuates the anticonvulsant action of carbamazepine and phenobarbital against the maximal electroshock-induced seizures in mice

BackgroundDue to co-occurrence of seizures and cardiovascular disorders, nebivolol, a widely used selective β1-blocker with vasodilatory properties, may be co-administered with antiepileptic drugs. Therefore, we wanted to assess interactions between nebivolol and four conventional antiepileptic drugs: carbamazepine, valproate, phenytoin and phenobarbital in the screening model of tonic–clonic convulsions.MethodsSeizure experiments were conducted in the electroconvulsive threshold and maximal electroshock tests in mice. The chimney test served as a method of assessing motor coordination, whereas long-term memory was evaluated in the computerized step-through passive-avoidance task. To exclude or confirm pharmacokinetic interactions, we measured brain concentrations of antiepileptic drugs using the fluorescence polarization immunoassay.ResultsIt was shown that nebivolol applied at doses 0.5–15 mg/kg did not raise the threshold for electroconvulsions. However, nebivolol at the dose of 15 mg/kg reduced the anti-electroshock properties of carbamazepine. The effect of valproate, phenytoin, and phenobarbital remained unchanged by combination with the β-blocker. Nebivolol significantly decreased the brain concentration of valproate, but did not affect concentrations of remaining antiepileptic drugs. Therefore, contribution of pharmacokinetic interactions to the final effect of the nebivolol/carbamazepine combination seems not probable. Nebivolol alone and in combinations with antiepileptic drugs did not impair motor performance in mice. Nebivolol alone did not affect long-term memory of animals, and did not potentiate memory impairment induced by valproate and carbamazepine.ConclusionsThis study indicates that nebivolol attenuated effectiveness of some antiepileptic drugs. In case the results are confirmed in clinical settings, this β-blocker should be used with caution in epileptic patients.

Carbamazepine Attenuates Astroglial L-Glutamate Release Induced by Pro-Inflammatory Cytokines via Chronically Activation of Adenosine A2A Receptor

Carbamazepine (CBZ) binds adenosine receptors, but detailed effects of CBZ on astroglial transmission associated with adenosine receptor still need to be clarified. To clarify adenosinergic action of CBZ on astroglial transmission, primary cultured astrocytes were acutely or chronically treated with CBZ, proinflammatory cytokines (interferon γ (IFNγ) and tumor necrosis factor α (TNFα)), and adenosine A2A receptor (A2AR) agonist (CGS21680). IFNγ and TNFα increased basal, adenophostin-A (AdA)-evoked, and 2-amino-3-(3-hydroxy-5-methyl-isoxazol-4-yl)propanoic acid (AMPA)-evoked astroglial L-glutamate releases. In physiological condition, CGS21680 increased basal astroglial L-glutamate release but glutamate transporter inhibition prevented this CGS21680 action. CBZ did not affect basal release, whereas glutamate transporter inhibition generated CBZ-induced glutamate release. Furthermore, AdA-evoked and AMPA-evoked releases were inhibited by CBZ but were unaffected by CGS21680. Contrary to physiological condition, chronic administrations of IFNγ and TNFα enhanced basal, AdA-, and AMPA-evoked releases, whereas IFNγ and TNFα decreased and increased CGS21680-evoked releases via modulation A2AR expression. Both chronic administration of CGS21680 and CBZ suppressed astroglial L-glutamate release responses induced by chronic cytokine exposer. Especifically, chronic administration of CBZ and CGS21680 prevented the reduction and elevation of A2AR expression by respective IFNγ and TNFα. These findings suggest that A2AR agonistic effects of CBZ contribute to chronic prevention of pathomechanisms developments of several neuropsychiatric disorders associated with proinflammatory cytokines.

Sublethal psychotropic pharmaceutical effects on the model organism Danio rerio: Oxidative stress and metal dishomeostasis

Contaminants of emerging concern have become an important environmental problem, especially pharmaceutically active compounds (PhACs), since, after use, these drugs return to the environment, contaminating aquatic ecosystems. Some may display the ability to bioaccumulate and biomagnify throughout the food chain, leading to potential environmental and human deleterious effects which are, however, still largely unknown. In this context, the aim of the present study was to evaluate the effect of two psychotropic drugs commonly found in the environment, carbamazepine (CBZ) and clonazepam (CZP), both isolated and co-administrated, on oxidative stress biomarkers and essential metal homeostasis in Danio rerio fish specimens. No studies are available to data in this regard concerning CZP effects on fish. Reduced Glutathione (GSH), Metallothionein (MT), Catalase (CAT) and Glutathione S-Transferase (GST) were determined, as well as essential metals in fish liver, kidney and brains. Significant oxidative stress effects were observed for several biomarkers, where brain GST activity was the most affected, mainly with regard to CBZ exposure, while GST and CAT activity in the liver were downregulated in the co-administration mixture. In addition, dishomeostasis of several essential elements was detected in all analyzed organs, with a synergistic action of CBZ and CZP in brain, decreasing basal Mg, Al, K, Fe, Co, Ni and Cu levels in this organ, the target site for these drugs in humans. The brain organ was the most affected as observed by altered GST activity and metal dyshomeostasis concerning exposure to both compounds. These compounds, thus, present health risks to the aquatic biota, due to the evidenced deleterious effects and their constant release into the environment due to widespread use. Steps are needed to implement adequate legislation for risk analysis and decision-making in order to mitigate the effects of these emerging contaminants on aquatic ecosystem health.

Carbamazepine disrupts molting hormone signaling and inhibits molting and growth of Eriocheir sinensis at environmentally relevant concentrations

Carbamazepine (CBZ), one of the most frequently detected pharmaceutical compounds in aquatic environments, has recently been shown to cause chronic toxicity and endocrine disruption in a variety of non-target aquatic organisms. However, neither the effects nor the specific mechanism of CBZ action on the molting of crustaceans is well understood. The aim of this study was to investigate the effects of CBZ on the molting and growth of the Chinese mitten crab Eriocheir sinensis, a native and economically important species in China, and to elucidate the specific mechanisms through which molt inhibition occurs. Juvenile E. sinensis were treated with four nominal environmentally relevant concentrations (0.01, 0.1, 1, or 10 μg/L) of CBZ for acute (4 days) and chronic (40 days) exposures. After acute exposure, chitinase activity in the epidermis and 20-hydroxyecdysone (20-HE) concentration in the hemolymph were significantly decreased (p < 0.05) following treatment with 10 μg/L CBZ, whereas epidermal chitobiase activity significantly decreased (p < 0.05) in response to both 1 and 10 μg/L CBZ treatments. Transcript levels of the genes encoding crustacean hyperglycemic hormone (chh) and molt-inhibiting hormone (mih) in the eyestalks were also markedly induced after 1 or 10 μg/L CBZ treatment (p < 0.05), whereas the expression of genes encoding ecdysone receptor (ecr) and crustacean retinoid X receptor (rxr) in the hepatopancreas were significantly suppressed (p < 0.05) after acute exposure. Moreover, under chronic exposure, CBZ inhibited the molting and growth of E. sinensis, resulting in a longer time before molting was completed (TBM), as well as a lower molting increment (MI) with 1 or 10 μg/L treatment (p < 0.05). Collectively, these data indicate that CBZ can inhibit the molting process of E. sinensis by interfering with the activity of chitinolytic enzymes and molting hormone signaling, suggestive that carbamazepine may have long-term effects on crab development. We also confirmed that CBZ may function as an endocrine disruptor in decapod crustaceans, a phenomenon that has previously been reported in vertebrates.

Sotalol enhances the anticonvulsant action of valproate and diphenylhydantoin in the mouse maximal electroshock model.

Sotalol as a drug blocking β-receptors and potassium KCNH2 channels may interact with different substances that affect seizures. Herein, we present interactions between sotalol and four conventional antiepileptic drugs: carbamazepine, valproate, phenytoin and phenobarbital. Effects of sotalol and antiepileptics alone on seizures were determined in the electroconvulsive threshold test, while interactions between sotalol and antiepileptic drugs were estimated in the maximal electroshock test in mice. Motor coordination and long-term memory were evaluated, respectively, in the chimney test and passive-avoidance task. Brain concentrations of antiepileptics were determined by fluorescence polarization immunoassay. Sotalol at doses up to 100mg/kg did not affect the electroconvulsive threshold. Applied at doses 60-100mg/kg, sotalol potentiated the antielectroshock action of valproate, while at doses 80-100mg/kg that of phenytoin. Sotalol (up to 100mg/kg) did not affect the action of carbamazepine or phenobarbital in the maximal electroshock. Sotalol alone and in combinations with antiepileptics impaired neither motor performance nor long-term memory in mice. Finally, sotalol did not change brain concentration of valproate and phenytoin, so pharmacokinetic interactions between the drugs are not probable. As far as obtained data may be extrapolated into clinical conditions, sotalol may be considered as an arrhythmic drug that does not reduce the action of classical antiepileptic drugs and thereby can be used in epileptic patients with cardiac arrhythmias.

Activity Clamp Provides Insights into Paradoxical Effects of the Anti-Seizure Drug Carbamazepine.

A major challenge in experimental epilepsy research is to reconcile the effects of anti-epileptic drugs (AEDs) on individual neurons with their network-level actions. Highlighting this difficulty, it is unclear why carbamazepine (CBZ), a frontline AED with a known molecular mechanism, has been reported to increase epileptiform activity in several clinical and experimental studies. We confirmed in an in vitro mouse model (in both sexes) that the frequency of interictal bursts increased after CBZ perfusion. To address the underlying mechanisms, we developed a method, activity clamp, to distinguish the response of individual neurons from network-level actions of CBZ. We first recorded barrages of synaptic conductances from neurons during epileptiform activity and then replayed them in pharmacologically isolated neurons under control conditions and in the presence of CBZ. CBZ consistently decreased the reliability of the second action potential in each burst of activity. Conventional current-clamp recordings using excitatory ramp or square-step current injections failed to reveal this effect. Network modeling showed that a CBZ-induced decrease of neuron recruitment during epileptic bursts can lead to an increase in burst frequency at the network level by reducing the refractoriness of excitatory transmission. By combining activity clamp with computer simulations, the present study provides a potential explanation for the paradoxical effects of CBZ on epileptiform activity.SIGNIFICANCE STATEMENT The effects of anti-epileptic drugs on individual neurons are difficult to separate from their network-level actions. Although carbamazepine (CBZ) has a known anti-epileptic mechanism, paradoxically, it has also been reported to increase epileptiform activity in clinical and experimental studies. To investigate this paradox during realistic neuronal epileptiform activity, we developed a method, activity clamp, to distinguish the effects of CBZ on individual neurons from network-level actions. We demonstrate that CBZ consistently decreases the reliability of the second action potential in each burst of epileptiform activity. Network modeling shows that this effect on individual neuronal responses could explain the paradoxical effect of CBZ at the network level.

The effects of cimetidine chronic treatment on conventional antiepileptic drugs in mice

The aim of this study was to evaluate the effects of 1-day, 7-day and 14-day administrations of cimetidine on the anticonvulsant activity of conventional antiepileptic drugs (AEDs; valproate, carbamazepine, phenytoin and phenobarbital) against maximal electroshock (MES)-induced convulsions in mice. Electroconvulsions were evoked in Albino Swiss mice by a current delivered via ear-clip electrodes. In addition, the effects of cimetidine, AEDs alone and their combinations were studied on performance and long-term memory tests. Pharmacokinetic changes in plasma and brain concentrations of AEDs after cimetidine administration were evaluated with immunofluorescence. Cimetidine (up to 100mg/kg) after 1-day administration did not affect the electroconvulsive threshold in animals. Moreover, in the 14-day treatment, cimetidine administered at a dose of 40mg/kg did not significantly change the electroconvulsive threshold in the MES-test, cimetidine administered 14-day (at 20mg/kg) significantly increased the anticonvulsant activity of carbamazepine, staying without effects after a 1-day and 7-day studies. In contrast, both the 7-day and 14-day administrations of cimetidine resulted in significant reductions of protective efficacy of the phenobarbital. Only valproate and phenytoin were not affected by cimetidine (20mg/kg) in all experimental period. Cimetidine administered 1-day, did not alter total brain concentrations and free plasma levels of all AEDs tested, whilst the 14-day study elevated carbamazepine plasma and brain concentration and reduced phenobarbital brain concentration. Cimetidine co-applied with AEDs did not impair performance of mice evaluated in the chimney test however, it worsened long-term memory in animals. Based on this preclinical study, a special caution is advised when treating epileptic patients with combinations of phenobarbital or carbamazepine with cimetidine.

Ellagic acid enhances the antinociceptive action of carbamazepine in the acetic acid writhing test with mice

Context: Ellagic acid (EA) produced antinociceptive and anti-inflammatory effects through the central and peripheral sites of action.Objective: The objective of the current study was to examine the functional interaction between ellagic acid and carbamazepine (CBZ) on pain.Materials and methods: Fourteen groups of mice (8–10 each) were used in this study. Pain was induced by intraperitoneal acetic acid in mice (writhing test) and the functional interaction was analyzed using the isobolographic method. EA at doses 0.3, 1, 3, and 10 mg/kg and carbamazepine at doses 3, 10, 20, and 30 mg/kg, alone and also in combination (1/2, 1/4, and 1/8 of the drug’s ED50) were intraperitoneally administered 30 min before acetic acid (0.6% v/v). Then, the abdominal writhes were counted during a 25-min period.Results: EA (0.3–10 mg/kg, i.p.) and CBZ (3–30 mg/kg, i.p.) inhibited the writhing response evoked by acetic acid. Fifty percent effective dose (ED50) values against this tonic pain were 1.02 mg/kg and 6.40 mg/kg for EA and CBZ, respectively. The antinociception induced by EA showed higher potency than that of carbamazepine. Co-administration of increasing fractional increments of ED50 values of EA and CBZ produced additive interaction against writhing responses, as revealed by isobolographic analysis.Discussion and conclusion: These results suggest that a combination of carbamazepine and ellagic acid may be a new strategy for the management of neuropathic pain such as what occurs in trigeminal neuralgia, since the use of carbamazepine is often limited by its adverse effects and by reduction of its analgesic effect through microsomal enzyme induction.

The antidepressant drug Carbamazepine induces differential transcriptome expression in the brain of Atlantic salmon, Salmo salar

Concerns are being expressed recently over possible environmental effects of human pharmaceuticals. Although the likelihood of acute toxicity is low, the continuous discharge of pharmaceuticals into the aquatic environment means that sublethal effects on non-target organisms need to be seriously considered. One-year-old Atlantic salmon parr were exposed to 7.85±0.13μgL−1 of the antidepressant drug Carbamazepine (CBZ) for five days to investigate changes of mRNA expression in the brain by means of a custom 17k Atlantic salmon cDNA microarray. The selected concentration is similar to upper levels that can be found in hospital and sewage treatment plant effluents. After treatment, 373 features were differently expressed with 26 showing up- or down-regulation of ≥2-fold (p≤0.05). Among the mRNAs showing the highest change were the pituitary hormones encoding features somatolactin, prolactin and somatotropin, or growth hormone. Functional enrichment and network analyses of up- and down-regulated genes showed that CBZ induced a highly different gene expression profile in comparison to untreated organisms. CBZ induced expression of essential genes of the focal adhesion and extracellular matrix – receptor interaction pathways most likely through integrin alpha-6 (itga6) activation. Negative regulation of apoptotic process, extracellular matrix organization and heme biosynthesis were the most enriched biological process related GO-terms, with the simultaneous enrichment of collagen and extracellular region related cellular component GO-terms, and extracellular matrix structural constituent, hormone activity and chromatin binding molecular function related GO-terms. These results show that relatively low doses of CBZ may affect brain physiology in exposed salmon parr, targeting similar processes as in human, indicating a high degree of conservation of targets of CBZ action. However, and since the mRNAs showing most changes in expression are critical for adaptation to different stressors and life history transitions in Atlantic salmon, more research should be undertaken to assess CBZ effects to avoid impairment of normal development and maintenance of natural populations.

The effect of propafenone on the anticonvulsant action of carbamazepine and valproate in the mouse model of maximal electroshock

The effect of propafenone on the anticonvulsant action of carbamazepine and valproate in the mouse model of maximal electroshock

Действие антиконвульсантов на систему оксида азота

The effect of phenobarbital, carbamazepine, valproate sodium, depakine, topiramate and lamotrigine on the content of NO and NO-synthase activity in white rat brain tissues has been studied. It was established that the action of carbamazepine, valproate sodium, topiramate and lamotrigine decreases the activity of NO-synthase and the level of NO in the brain tissues. The amount of NO does not change while NO-synthase activity increases with the introduction of phenobarbital. The involvement of nitric oxide in the mechanism of action of the studied anticonvulsant drugs is discussed.

Protective Effect of Carbamazepine on Kainic Acid-induced Neuronal Cell Death Through Activation of Signal Transducer and Activator of Transcription-3

Studies have shown that the protective effect of carbamazepine (CBZ) on seizure-induced neuronal injury. However, its precise mechanisms remain unknown. Here, to investigate the neuroprotective mechanism of CBZ against seizure-induced neuronal cell death, we identified the change of gene expressions by CBZ in the hippocampus of kainic acid (KA)-treated mice using microarray method, and studied the involvement of candidate gene in neuroprotective action of CBZ. KA (15mg/kg) and/or CBZ (30mg/kg, 0.5h after KA exposure) were injected intraperitoneally into mice. Through microarray analysis, we found that signal transducer and activator of transcription-3 (Stat3) gene expression was upregulated in the hippocampal CA3 region, 24h after KA injection (15mg/kg), and that CBZ further elevated Stat3 expression in KA-treated mice. KA also increased the protein level and phosphorylation of Stat3, and CBZ further increased the Stat3 phosphorylation, without changing Stat3 protein level in KA-treated mice. In particular, phospho-Stat3 immunoreactivity (IR) by KA was shown in astrocytes rather than in neurons; whereas phospho-Stat3 IR by CBZ in KA-treated mice was observed predominantly in neurons, and also in neuroprotective protein Bcl-xL-expression cells. These results indicate that Stat3 may play an important role in neuroprotective action of CBZ on seizure-induced neuronal injury.

Carbamazepine affects water and electrolyte homoeostasis in rat--similarities and differences to vasopressin antagonism

Carbamazepine (CBZ) is a drug widely used in the therapy of epilepsy and mood disorders. One frequently observed side effect is hyponatraemia. The role of vasopressin in hyponatraemic action of CBZ is discussed controversially. In this study, we tested the influence of CBZ on water and salt homoeostasis in rat under different hydration states and under vasopressin 2 receptor (V2R) antagonism by satavaptan to elucidate the renal and vasopressin independent action of CBZ. CBZ-treated rats were investigated on metabolic cages after (i) 6 day with ad libitum fluid intake, (ii) moderate water load and (iii) water restriction. The effect of satavaptan was tested in clearance experiments under continuous saline infusion in anaesthetized rats after CBZ pretreatment. Compared to controls, CBZ induced a higher urinary flow rate which was most pronounced (20-fold) after water load and significantly elevated (2-fold) after 10-h water restriction. In addition, CBZ consistently increased renal sodium loss but failed to decrease plasma sodium concentration. In the presence of satavaptan, urinary flow and natriuresis were further increased by CBZ, while there was no differential effect on urea excretion and anion gap. At the investigated dose (50 mg/kg body weight), CBZ did not induce hyponatraemia or antidiuresis in the rat. However, depending on the hydration state, it induced an increased water and electrolyte loss. Its enhanced influence on urinary flow and natriuresis in the presence of satavaptan suggests additional renal targets for CBZ, independent of vasopressin signalling.

Carbamazepine Mucoadhesive Nanoemulgel (MNEG) as brain targeting delivery system via the olfactory mucosa

Carbamazepine (CBZ) is an antiepileptic orally administered drug, but due to its low solubility in water, its gastrointestinal absorption is slow and irregular, leading to delayed brain uptake with consequent peripheral side actions. The objective of this study was the brain targeting of CBZ via the olfactory mucosa in form of an intranasal mucoadhesive o/w nanoemulgel (MNEG). CBZ was formulated in a nanoemulgel system containing oleic acid/labrasol in a ratio of 1:5 as oil/surfactant and 0.1% xanthan gum as anionic mucoadhesive polymer. The prepared MNEG was characterized with respect to oil droplet size, mucoadhesion, in-vitro release of the drug and CBZ uptake by phosphatidylcoline liposomes as an in-vitro model for olfactory cells. The anticonvulsant action of nasal MNEG was studied on chemically and electrically induced convulsive Swiss Albino mice. The in-vitro release of CBZ from MNEG was very low, however CBZ uptake via liposomal membrane reached 65% within 1 hr. Treatment of animals with MNEG significantly prolonged the onset times for convulsion of chemically convulsive mice and protected the animals from two electric shocks. One can thus spire and hope for the emergence of a new intranasal treatment of epilepsy with consequent decrease in the peripheral side actions of CBZ.

Ionizing Irradiation Protection and Mitigation by Carbamazepine Is p53 and Autophagy Independent,

Abstract 3400 Introduction:Carbamazepine (CBZ), an established sodium channel blocker, used in treatment of epilepsy and trigeminal neuralgia, induces autophagy. CBZ has recently been demonstrated to be an ionizing radiation mitigator and protector (Kim,H.et. al IJRB-in press). CBZ protected C57BL/6NHsd female mice from irradiation if given 24 hr before total body irradiation (TBI) and mitigated if given 12 hours after irradiation.Materials and Methods: To elucidate the mechanism of CBZ action, autophagy incompetent (ATG5−/−) and competent (ATG5+/+) mouse embryo fibroblasts (MEF), p53−/− and p53+/+ bone marrow stromal cells and 32D cl 3 murine IL-3 dependent hematopoietic progenitor cells were tested for CBZ mediated radiation protection and mitigation in clonagenic irradiation survival curves. We also measured CBZ effect on irradiation-induced apoptosis, and depletion of antioxidant stores in vitro and after (TBI) in vivo in control mice and in hind limb irradiated mice with orthotopic tumors. Results:CBZ was a significant radiation protector and mitigator for both ATG5−/− and ATG5 +/+ cell lines by an increased ñ (a measurement of the shoulder on the clonogenic survival curve). CBZ treated ATG5 +/+ cells has an increased ñ of 11.1 +/− 0.2 or 8.8 +/− 0.2 for CBZ added before or after irradiation respectively compared to 5.4 +/− 0.9 for irradiation control cells (p = 0.0287 or 0.0119,respectively). ATG −/− cells were also protected and mitigated by CBZ (ñ of 16.1 +/− 2.6 as a radioprotector or 9.8 +/− 1.5 as a mitigator compared to 4.6 +/− 0.7 for irradiated control cells (p = 0.0002 or 0.0037, respectively). Thus, CBZ functions independent of autophagy. Incubation of p53 +/+ and p53−/− cell lines in 10 μM CBZ for one hour before irradiation protected (ñ of 5.6 +/− 0.9 compared to 1.9 +/− 0.5 for control irradiated p53 +/+ cells (p = 0.0126) and 3.7 +/− 1.9 compared to 1.8 +/− 0.4 for irradiated control p53 −/− cells (p = 0.0018). Thus, CBZ functions in a p53 independent manner. Other pro-autophagy drugs, Valproic Acid and Lithium Carbonate, were ineffective radiation protectors or mitigators. CBZ treatment of 32D cl 3 cells for one hour before or immediately following irradiation had no effect on mitochondrial membrane depolarization, apoptosis or viability but was protective and mitigative in clonagenic survival curve assays. Irradiation initially decreased antioxidant stores in both ATG5+/+ and ATG5−/− cells 10 to 30 min following irradiation. However, cells treated with CBZ had a faster recovery of antioxidant stores to pre-irradiation levels by 90 min compared to 120 min for control irradiated cells. To determine if CBZ protected both normal tissues and tumors in vivo mice with 3LL Lewis Lung carcinoma hind limb xenografts were treated with 10 mg/kg CBZ before or after 20 Gy limb irradiation. There was no significant difference in tumor growth inhibition by 20 Gy in mice treated with CBZ before or after irradiation (p = 0.2431 or 0.5439, respectively). Conclusion:Thus, CBZ is an effective radiation protector and mitigator of normal but not tumor tissues by a novel mechanism independent of autophagy, p53 and apoptosis. Acknowledgments:This project was supported by U191A168021–06. Disclosures:No relevant conflicts of interest to declare.

Intracellular CICR -associated pharmacological mechanism of action of antiepileptic drugs

Carbamazepine (CBZ) and zonisamide (ZNS) are antiepileptic drugs (AEDs) with multiple mechanisms of action, including inhibition of voltage-dependent sodium and calcium channels, enhancement of inhibitory events mediated by GABAergic neurotransmission, and blockade of the glutamatergic neurotransmission in the brain. Recently, the intracellular signaling pathways have been implicated as the new targets of AEDs. Especially, we have investigated the functional importance of Ca2+ mobilization, composed of influx through Ca2+ channels and output through ryanodine receptor (RyR)- and inositol-triphosphate receptor (IP3R)-sensitive intracellular Ca2+-induced Ca2+ releasing systems (CICRs), in the pathogenesis of epilepsy and the pharmacological mechanism of AEDs. In this review, we discuss the actions of CBZ and ZNS on neurotransmitter exocytosis associated with RyR-sensitive CICR. Further studies on the mechanisms of action of AEDs may help to understand the clinical benefits of AEDs in the treatment of epilepsy disorders.