Mouse Maximal Electroshock Seizure Research Articles

Stereoselective Analysis of the Antiseizure Activity of Fenfluramine and Norfenfluramine in Mice: Is l-Norfenfluramine a Better Follow-Up Compound to Racemic-Fenfluramine?

The aim of this study was to investigate the comparative antiseizure activity of the l-enantiomers of d,l-fenfluramine and d,l-norfenfluramine and to evaluate the relationship between their concentration in plasma and brain and anticonvulsant activity. d,l-Fenfluramine, d,l-norfenfluramine and their individual enantiomers were evaluated in the mouse maximal electroshock seizure (MES) test. d,l-Fenfluramine, d,l-norfenfluramine and their individual l-enantiomers were also assessed in the DBA/2 mouse audiogenic seizure model. All compounds were administered intraperitoneally. Brain and plasma concentrations of the test compounds in DBA/2 mice were quantified and correlated with anticonvulsant activity. In the MES test, fenfluramine, norfenfluramine and their enantiomers showed comparable anticonvulsant activity, with ED50 values between 5.1 and 14.8 mg/kg. In the audiogenic seizure model, l-norfenfluramine was 9 times more potent than d,l-fenfluramine and 15 times more potent than l-fenfluramine based on ED50 (1.2 vs. 10.2 and 17.7 mg/kg, respectively). Brain concentrations of all compounds were about 20-fold higher than in plasma. Based on brain EC50 values, l-norfenfluramine was 7 times more potent than d,l-fenfluramine and 13 times more potent than l-fenfluramine (1940 vs. 13,200 and 25,400 ng/g, respectively). EC50 values for metabolically formed d,l-norfenfluramine and l-norfenfluramine were similar to brain EC50 values of the same compounds administered as such, suggesting that, in the audiogenic seizure model, the metabolites were responsible for the antiseizure activity of the parent compounds. Because of the evidence linking d-norfenfluramine to d,l-fenfluramine to cardiovascular and metabolic adverse effects, their l-enantiomers could potentially be safer follow-up compounds to d,l-fenfluramine. We found that, in the models tested, the activity of l-fenfluramine and l-norfenfluramine was comparable to that of the corresponding racemates. Based on the results in DBA/2 mice and other considerations, l-norfenfluramine appears to be a particularly attractive candidate for further evaluation as a novel, enantiomerically pure antiseizure medication.

PRAX-562-102: A Phase 1 Trial Evaluating the Safety, Tolerability, Pharmacokinetics and Pharmacodynamics of PRAX-562 in Healthy Volunteers (P4-9.011)

<h3>Objective:</h3> We report findings from a Phase 1 clinical trial characterizing the safety, tolerability, pharmacokinetics (PK) and pharmacodynamics (PD) of PRAX-562 in healthy adults. <h3>Background:</h3> PRAX-562 is a next-generation sodium channel blocker with a unique profile expected to translate to a wider therapeutic window compared to current standard-of-care for severe DEE. <h3>Design/Methods:</h3> PRAX-562-102 was a randomized, placebo-controlled trial in healthy adults (18–55 years). Part A evaluated 90mg PRAX-562 over 28 days (QD) vs. placebo. Part B evaluated oxcarbazepine (OXC) in combination with 120mg PRAX-562 (QD) over 28 days vs. OXC alone. PD effects were examined on quantitative EEG (qEEG) and stimulated EEG (auditory steady state response, ASSR). <h3>Results:</h3> 48 participants were enrolled (Part A, n=18 PRAX-562, n=12 placebo; Part B, n=14 OXC+PRAX-562, n=4 OXC+placebo). PRAX-562 concentrations exceeded the EC₅₀ in the mouse maximal electroshock seizure (MES) model by 13-fold and was unaltered with OXC coadministration. PRAX-562 was generally well tolerated in Part A. TEAEs were mostly mild or moderate (100% Part A; 96% Part B). Part B was stopped early after 5 participants receiving OXC+PRAX-562 developed TEAEs; one of whom experienced 3 study drug-related SAEs leading to study drug discontinuation. Exposure-depended PD changes were observed on qEEG (all frequencies) and ASSR. Significant differences between placebo and PRAX-562 were observed in Part A on qEEG (Delta, <i>P</i>=0.0013; Theta, <i>P</i>&lt;0.0001) and ASSR (phase-locking-factor, <i>P</i>=0.028; Evoked power, <i>P</i>=0.016), and in Part B participants receiving OXC+PRAX-562 vs. OXC alone on qEEG (Delta, <i>P</i>=0.012; Theta, <i>P</i>=0.018). <h3>Conclusions:</h3> PRAX-562 was well tolerated in healthy adults at 90mg (Part A). Most AEs including SAEs in Part B were considered due to coadministration of projected supratherapeutic doses of PRAX-562 with OXC. Our PK and tolerability findings are consistent with a wide therapeutic window for PRAX-562, while PD findings indicate qEEG may be a sensitive translational biomarker of sodium channel blockade. <b>Disclosure:</b> Dr. Mahalingam has nothing to disclose. Dr. Oldham has received personal compensation for serving as an employee of Praxis Precision Medicines. Dr. Puryear has received personal compensation for serving as an employee of Praxis Precision Medicine. Dr. Puryear has stock in Praxis Precision Medicines. Dr. Bansal has received personal compensation for serving as an employee of Praxis precision medicines . Dr. Bansal has stock in Praxis Precision medicines . Dr. Sriram has received personal compensation for serving as an employee of Praxis Precision Medicines. Dr. Sriram has stock in Praxis Precision Medicines. Dr. Sriram has stock in Biogen Inc. Dr. Patel has received personal compensation for serving as an employee of Praxis Precision Medicines, Inc.. Dr. Patel has received personal compensation for serving as an employee of Noven Pharmaceuticals. Dr. Patel has stock in Praxis Precision Medicines, Inc.. Dr. Jacotin has received personal compensation for serving as an employee of Praxis Precision Medicines. Dr. Jacotin has received personal compensation for serving as an employee of Takeda. Dr. Jacotin has stock in Takeda. Dr. Jacotin has stock in Certara. Dr. Jacotin has stock in Clover Health. Dr. Jacotin has stock in Coinbase. Marjie Hard has nothing to disclose. Dr. Arefayene has nothing to disclose. Dr. Ravina has received personal compensation for serving as an employee of Praxis Precision Medicines. Dr. Ravina has stock in Praxis. Dr. Souza has received personal compensation for serving as an employee of Praxis Precision Medicines. Dr. Souza has stock in Praxis Precision Medicines. Steven Petrou has received personal compensation in the range of $100,000-$499,999 for serving as a Consultant for Praxis Precision Medicines. Steven Petrou has stock in Praxis Precision Medicines. The institution of Steven Petrou has received research support from Praxis Precision Medicines. The institution of Steven Petrou has received research support from Medical Research Future Fund. Steven Petrou has received intellectual property interests from a discovery or technology relating to health care. Steven Petrou has received intellectual property interests from a discovery or technology relating to health care.

The effects of cannabidiol and Δ9-tetrahydrocannabinol, alone and in combination, in the maximal electroshock seizure model

In the present study, cannabidiol (CBD), Δ9-tetrahydrocannabinol (THC), and combinations of CBD and THC, were evaluated in the mouse maximal electroshock (MES) seizure test – an animal model of generalized-onset seizures. Male CF-1 mice were injected intraperitoneally (i.p.) with either CBD, THC or a combination of CBD and THC. The MES test was conducted 2 h after the injection of CBD and 1 h after the injection of THC. A wide range of doses was tested to allow the construction of dose-response curves. Toxicity was assessed using a behavioral rating scale. It was found that: 1) the ED50 for THC alone was 52 mg/kg and its therapeutic index (TI) was 1.7; 2) the ED50 for CBD alone was 190 mg/kg and its TI was 2.4; and 3) the ED50 for a 15:1 combination of CBD+THC was 130 mg/kg + 8.6 mg/kg (CBD + THC). Thus, CBD and THC were both effective in the MES model, and CBD was somewhat more effective in the presence of low (non-therapeutic) doses of THC. The improvement in CBD’s effect, however, was less dramatic than that seen in past experiments with the amygdala-kindling model (Fallah et al., 2021). Both CBD alone and CBD+THC in combination might be useful in the treatment of generalized-onset seizures. The advantage of adding THC to CBD, however, might be less than in the treatment of focal-onset seizures.

Pharmacodynamic synergism contributes to the antiseizure action of cannabidiol and clobazam

The management of refractory epilepsy involves treatment with more than one antiseizure medication (ASM). Combination of ASMs with distinct mechanisms of action are hypothesized to improve overall treatment effectiveness. In clinical trials, concomitant use of cannabidiol (CBD) and clobazam (CLB) was associated with increased seizure reduction and bidirectional elevation in levels of their active metabolites, 7-hydroxy-cannabidiol (7-OH-CBD) and nor-clobazam (n-CLB). Using isobolographic analysis, we investigated whether CBD and CLB interacted pharmacodynamically. In the mouse maximal electroshock seizure (MES) test, brain tissue levels of CBD and CLB corresponding to seizure prevention in 50% of animals (brain Effective Exposure, bEE50) were 7.9 μM and 1.6 μM, respectively. In the 6 Hz psychomotor seizure model, 7-OH-CBD displayed a 5-fold greater potency than CBD (b-EE50, 8.7 μM vs 47.3 μM). Isobolographic analysis performed on combination of CBD/CLB at 1:1, 3:1, and 1:3 ratios based on equi-effective bEE50 values revealed synergism at all doses with combination indices (CI) of 0.43, 0.62 and 0.75 respectively. These outcomes were independent of pharmacokinetic interaction between CBD and CLB. These findings identify pharmacodynamic synergism as an important factor underlying enhanced antiseizure effect during concomitant CBD and CLB use.

Influence of methadone on the anticonvulsant efficacy of valproate sodium gabapentin against maximal electroshock seizure in mice by regulation of brain MDA TNF-α.

Methadone is the most frequently used opioid therapy worldwide, with controversial effects on oxidative stress homeostasis. This study investigated the effects of intraperitoneal (i.p.) co-administration of methadone (0.1, 0.3, 1, and 3 mg/kg) and valproate sodium (300 mg/kg) or gabapentin (50 mg/kg) in the mice maximal electroshock (MES)-induced seizure model. The adverse effect of drugs was assessed using the chimney test. The levels of tumor necrosis factor-alpha (TNF-α) and malondialdehyde (MDA) contents were measured in mice brains after a single seizure. Administration of methadone alone resulted in a significant reduction in the duration of hind limb extension (HLE) than that in the control group. Methadone pretreatment at doses of 0.1 and 0.3 mg/kg i.p. decreased, and at doses of 1 and 3 mg/kg i.p. had an increasing effect on anticonvulsant efficacy of gabapentin. Pretreatment with all doses of methadone significantly decreased the valproate anticonvulsive efficacy. At doses of 1 and 3 mg/kg i.p. methadone per se increased brain MDA levels after MES-induced seizure. Administration of methadone (0.3 mg/kg i.p.) enhanced and at 3 mg/kg decreased gabapentin effect on brain MDA level, but their co-treatment did not lead to further increase in MDA. Methadone at 0.3–3 mg/kg enhanced the effect of sodium valproate on MDA levels in the brain, but at all doses significantly potentiated its effect on brain TNF-α levels. The drugs did not produce any side effects on motor coordination in experimental animals. In conclusion, methadone showed different effects on anticonvulsant actions of gabapentin and valproate through regulation of brain levels of MDA and TNF-α.

Effect of acute and chronic exposure to lovastatin on the anticonvulsant action of classical antiepileptic drugs in the mouse maximal electroshock-induced seizure model

Numerous studies indicate neuroprotective activity of statins, commonly used cholesterol lowering drugs in epilepsy and several other neurological diseases. Promising anti-convulsant and neuroprotective effects of statins, attributed to their anti-excitotoxic and anti-inflammatory action were reported in several animals’ seizure models.To determine the effects of acute (single) and chronic (once daily for 7 consecutive days) administration of lovastatin on the protective activity of four classical antiepileptic drugs such as carbamazepine, phenobarbital, phenytoin and valproate in the mouse maximal electroshock seizure model.Seizure activity (maximal electroconvulsions) in mice were generated by alternating current delivered via ear-clip electrodes. Adverse-effect profile of lovastatin combinations with the tested antiepileptic drugs was assessed in the chimney test (motor performance). Total brain concentrations of antiepileptic drugs were evaluated with the fluorescence polarization immunoassay technique as a measure of the pharmacokinetic interaction between drugs.Lovastatin administered acutely or chronically (5–20 mg/kg) did not significantly affect the threshold for electroconvulsions in mice. Acute lovastatin (10 mg/kg) significantly enhanced the anticonvulsant effect of valproate, which was accompanied with a 34% significant increase in total brain concentration of valproate. Acute lovastatin in combination with phenytoin impaired motor performance by notably decreasing the TD50 value of phenytoin. Chronic lovastatin (10 mg/kg) markedly enhanced the anticonvulsant potential of phenytoin.Acute lovastatin increased anticonvulsant action of valproate but also significantly raised level of valproate in brain after combined administration suggesting pharmacokinetic nature of interaction. The combinations of chronic lovastatin combined with phenytoin can potentially enhance the anticonvulsant potency of phenytoin.

Antiallodynic and antihyperalgesic activity of new 3,3-diphenyl-propionamides with anticonvulsant activity in models of pain in mice

Anticonvulsant drugs are used to treat a wide range of non-epileptic conditions, including chronic pain. The aim of the present experiments was to examine analgesic activity of three new 3,3-diphenyl-propionamides, which had previously demonstrated anticonvulsant activity in the MES (maximal electroshock seizure), scPTZ (subcutaneous pentylenetetrazole) and/or 6Hz (psychomotor seizure) tests in mice. Antinociceptive activity was examined in mouse models of acute pain (the hot plate test) and tonic pain (the formalin test) in mice. Antiallodynic and antihyperalgesic activity was estimated in the oxaliplatin-induced neuropathic pain model of chemotherapy-induced peripheral neuropathy and in the streptozotocin-induced model of painful diabetic neuropathy in mice. Considering the drug safety evaluation, the influence on locomotor activity was checked. Moreover, using in vitro methods, selected compound was tested for potential hepatotoxicity on human hepatocellular carcinoma cell line and for metabolic stability. To determine the plausible mechanism of anticonvulsant and antinociceptive action, in vitro binding and functional assays were carried out. Among tested molecules two of them JOA 122 (3p) and JOA 123 (3q) revealed significant antinociceptive activity in the model of tonic pain – the formalin test and neuropathic pain models – the oxaliplatin and streptozotocin-induced peripheral neuropathy. In the binding studies JOA 122 (3p) revealed the high affinity to voltage-gated sodium channels (Nav1.2), as well as for 5-HT1A receptors. Metabolism studies in mouse liver microsomes showed a low metabolic stability of this compound.

Influence of MPEP (a selective mGluR5 antagonist) on the anticonvulsant action of novel antiepileptic drugs against maximal electroshock-induced seizures in mice

The aim of this study was to determine the effects of 2-methyl-6-(phenylethynyl)pyridine (MPEP — a selective antagonist for the glutamate metabotropic receptor subtype mGluR5) on the protective action of some novel antiepileptic drugs (lamotrigine, oxcarbazepine, pregabalin and topiramate) against maximal electroshock-induced seizures in mice. Brain concentrations of antiepileptic drugs were measured to determine whether MPEP altered pharmacokinetics of antiepileptic drugs. Intraperitoneal injection of 1.5 and 2mg/kg of MPEP significantly elevated the threshold for electroconvulsions in mice, whereas MPEP at a dose of 1mg/kg considerably enhanced the anticonvulsant activity of pregabalin and topiramate, but not that of lamotrigine or oxcarbazepine in the maximal electroshock-induced seizures in mice. Pharmacokinetic results revealed that MPEP (1mg/kg) did not alter total brain concentrations of pregabalin and topiramate, and the observed effect in the mouse maximal electroshock seizure model was pharmacodynamic in nature. Collectively, our preclinical data suggest that MPEP may be a safe and beneficial adjunct to the therapeutic effects of antiepileptic drugs in human patients.

Effect of xanthotoxin (8-methoxypsoralen) on the anticonvulsant activity of classical antiepileptic drugs against maximal electroshock-induced seizures in mice

The effects of xanthotoxin (8-methoxypsoralen) on the anticonvulsant activity of four classical antiepileptic drugs (carbamazepine, phenobarbital, phenytoin and valproate) were studied in the mouse maximal electroshock seizure model.Tonic hind limb extension (seizure activity) was evoked in adult male albino Swiss mice by a current (25mA, 500V, 50Hz, 0.2s stimulus duration) delivered via auricular electrodes. Total brain concentrations of antiepileptic drugs were measured by fluorescence polarization immunoassay to ascertain any pharmacokinetic contribution to the observed anticonvulsant effects.Results indicate that xanthotoxin (50 and 100mg/kg, i.p.) significantly potentiated the anticonvulsant activity of carbamazepine against maximal electroshock-induced seizures (P<0.05 and P<0.001, respectively). Similarly, xanthotoxin (100mg/kg, i.p.) markedly enhanced the anticonvulsant action of valproate in the maximal electroshock seizure test (P<0.001). In contrast, xanthotoxin (100mg/kg, i.p.) did not affect the protective action of phenobarbital and phenytoin against maximal electroshock-induced seizures in mice. Moreover, xanthotoxin (100mg/kg, i.p.) significantly increased total brain concentrations of carbamazepine (P<0.001) and valproate (P<0.05), but not those of phenytoin and phenobarbital, indicating pharmacokinetic nature of interactions between drugs.In conclusion, the combinations of xanthotoxin with carbamazepine and valproate, despite their beneficial effects in terms of seizure suppression in mice, were probably due to a pharmacokinetic increase in total brain concentrations of these antiepileptic drugs in experimental animals.

Synthesis, structure–activity relationships, and anticonvulsant activities of 2-amino-4H-pyrido[3,2-e][1,3]thiazin-4-one derivatives as orally active AMPA receptor antagonists

As part of a program aimed at discovering orally active 2-amino-3-(3-hydroxy-5-methyl-4-isoxazolyl)propionic acid (AMPA) receptor antagonists, we screened our compound library and identified 2-[allyl(4-methylphenyl)amino]-4H-pyrido[3,2-e][1,3]thiazin-4-one (7) as a lead compound that inhibited kainate-induced neurotoxicity mediated by AMPA receptors in rat hippocampal cultures. Structure–activity relationship studies of a series of 2-amino-4H-pyrido[3,2-e][1,3]thiazin-4-one derivatives revealed that substituents on the phenyl ring attached to the 2-amino group and the 4H-pyrido[3,2-e][1,3]thiazin-4-one ring system play an important role in inhibitory activity against kainate-induced neurotoxicity. Several analogs bearing a phenyl group with a 4-substituent or five- or six-membered ring fused at the 3,4-positions exhibited potent inhibitory activity against kainate-induced neurotoxicity. Further, some of these compounds exhibited significant suppression of maximal electroshock seizure in mice following oral administration. Of these compounds, 2-[(4-chlorophenyl)(methyl)amino]-4H-pyrido[3,2-e][1,3]thiazin-4-one (16i) (YM928) demonstrated the most potent inhibitory effect with an ED50 value of 7.4mg/kg.

Citrus aurantium increases seizure latency to PTZ induced seizures in zebrafish thru NMDA and mGluR's I and II.

Epilepsy is a serious neurological condition and pharmacotherapy is not effective for all patients and causes serious adverse effects and pharmacokinetic and pharmacodynamic interactions. Natural products and ethnobotanical resources can help develop new therapeutic options for conditions like epilepsy. In Puerto Rico, ethnobotanical resources highlight the anxiolytic properties of a tea like preparation made from the leaves of the Citrus aurantium tree or bitter orange. Studies performed with essential oils from the peel of the fruit have shown to increase seizure latency to pentylenetetrazole (PTZ) and maximal electroshock seizure in mice. We characterized the extract composition, and used a model of PTZ induces seizures in the zebrafish and a receptor-ligand binding assay to determine if this preparation has anticonvulsant properties and its mechanism of action. We determined that the aqueous extract made from the leaves of the C. aurantium tree contains hesperidin, neohesperidin, and neohesperidin dihydrochalcone. Using our zebrafish model, we determined that exposure to the C. aurantium 28 mg/mL extract in aquarium water increases seizure latency by 119% compared to controls. We ruled out a mechanism involving GABAA receptors using the selective antagonist gabazine. We used two approaches to study the role of glutamate in the mechanism of the C. aurantium extract. The ligand binding assay revealed C. aurantium extracts at concentrations of 0.42 to 5.6 mg/mL significantly reduced [3H]Glu binding indicating an interaction with glutamate receptors, in particular with NMDA receptors and mGluR II. This interaction was confirmed with our animal model using selective receptor antagonists and we identified an interaction with mGluR I, not observed in the ligand binding experiment. These study provide evidence of the anticonvulsant properties of the aqueous extract made from the leaves of the C. aurantium tree and a mechanism involving NMDA and mGluR's I and II.

Effects of WIN 55,212-2 mesylate on the anticonvulsant action of lamotrigine, oxcarbazepine, pregabalin and topiramate against maximal electroshock-induced seizures in mice

The aim of this study was to determine the effect of WIN 55,212-2 mesylate (WIN – a non-selective cannabinoid CB1 and CB2 receptor agonist) on the protective action of four second-generation antiepileptic drugs (lamotrigine, oxcarbazepine, pregabalin and topiramate) in the mouse maximal electroshock seizure model. Tonic hind limb extension (seizure activity) was evoked in adult male albino Swiss mice by a current (sine-wave, 25mA, 500V, 50Hz, 0.2s stimulus duration) delivered via auricular electrodes. Drug-related adverse effects were ascertained by use of the chimney test (evaluating motor performance), the step-through passive avoidance task (assessing long-term memory) and the grip-strength test (evaluating skeletal muscular strength). Total brain concentrations of antiepileptic drugs were measured by high-pressure liquid chromatography to ascertain any pharmacokinetic contribution to the observed antiseizure effect. Results indicate that WIN (5mg/kg, i.p.) significantly enhanced the anticonvulsant action of lamotrigine (P<0.05), pregabalin (P<0.001) and topiramate (P<0.05), but not that of oxcarbazepine in the maximal electroshock-induced tonic seizure test in mice. Furthermore, none of the investigated combinations of WIN with antiepileptic drugs were associated with any concurrent adverse effects with regards to motor performance, long-term memory or muscular strength. Pharmacokinetic characterization revealed that WIN had no impact on total brain concentrations of lamotrigine, oxcarbazepine, pregabalin and topiramate in mice. These preclinical data would suggest that WIN in combination with lamotrigine, pregabalin and topiramate is associated with beneficial anticonvulsant pharmacodynamic interactions in the maximal electroshock-induced tonic seizure test.

Supraadditive effect of hydroethanolic extract of Valeriana wallichii (Indian valerian) root and phenobarbitone against maximal electroshock seizure in mice.

There was a drastic increase in use of herbal preparations in recent years which raise concerns about their toxic and interactive propensity with concomitant diseases and other drugs consumed. Valerian is one of the most widely used herbal medicines in the world. This study analyzed the interaction of Valeriana wallichii (Indian valerian) and Phenobarbitone on anticonvulsant activity using maximal electroshock seizures (MES) in Swiss albino mice. Valeriana wallichii hydroethanolic extract reduced the duration of HLTE with a dose dependant increase in potency at 450 and 900 mg/kg given as intra-peritonial injections. Combination analysis show synergistic interaction between VwHE extract and Phenobarbitone at 50:50, and 25:75 (Vw: PBT) dose ratios, and antagonistic interaction at 75:25 (Vw: PBT) dose ratio in anticonvulsant activity, as indicated by the reduction in duration of HLTE phase of Maximal electroshock seizure model in mice. Phytochemical profile of Valeriana wallichii suggests many active constituents with more than one possible mechanism of action. The interaction could be pharmacokinetic or pharmacodynamic. Large scale studies at various dose ratios and with more parameters including the adverse effect profile of the combination at preclinical and clinical level are required to explore potential therapeutic applications of the combination.

The interactions of atorvastatin and fluvastatin with carbamazepine, phenytoin and valproate in the mouse maximal electroshock seizure model

The aim of this study was to determine the influence of acute (single) and chronic (once daily for 7 consecutive days) treatments with atorvastatin and fluvastatin on the anticonvulsant potential of three antiepileptic drugs: carbamazepine, phenytoin and valproate in the mouse maximal electroshock-induced seizure model. Additionally, the effects of acute and chronic administration of both statins on the adverse effect potential of three antiepileptic drugs were assessed in the chimney test (motor performance) and passive avoidance task (long-term memory). To evaluate the pharmacokinetic characteristics of interaction between antiepileptic drugs and statins, the total brain concentrations of antiepileptic drugs were estimated with the fluorescence polarization immunoassay technique. Results indicate that atorvastatin at doses up to 80mg/kg in chronic experiment attenuated the anticonvulsant potential of carbamazepine by increasing its ED50 value against maximal electroconvulsions. Acute fluvastatin (80mg/kg) enhanced the anticonvulsant potential of carbamazepine and valproate by decreasing their ED50 values. Acute fluvastatin (80mg/kg) also markedly increased the total brain carbamazepine concentration by 61% in a pharmacokinetic reaction. Atorvastatin (acute and chronic) and fluvastatin (chronic) in combinations with valproate impaired long-term memory in mice. Both statins in combinations with all three antiepileptic drugs had no impact on their adverse effects in the chimney test. Based on this preclinical study, one can conclude that chronic administration of atorvastatin reduces the anticonvulsant action of carbamazepine and acute fluvastatin can enhance the anticonvulsant potency of the carbamazepine and valproate. The former interaction was pharmacokinetic in nature.

Synthetic cannabinoid WIN 55,212-2 mesylate enhances the protective action of four classical antiepileptic drugs against maximal electroshock-induced seizures in mice

The aim of this study was to determine the effect of WIN 55,212-2 mesylate (WIN — a non-selective cannabinoid CB1 and CB2 receptor agonist) on the protective action of four classical antiepileptic drugs (carbamazepine, phenytoin, phenobarbital, and valproate) in the mouse maximal electroshock seizure (MES) model. The results indicate that WIN (10mg/kg, i.p.) significantly enhanced the anticonvulsant action of carbamazepine, phenytoin, phenobarbital and valproate in the MES test in mice. WIN (5mg/kg) potentiated the anticonvulsant action of carbamazepine and valproate, but not that of phenytoin or phenobarbital in the MES test in mice. However, WIN administered alone and in combination with carbamazepine, phenytoin, phenobarbital and valproate significantly reduced muscular strength in mice in the grip-strength test. In the passive avoidance task, WIN in combination with phenobarbital, phenytoin and valproate significantly impaired long-term memory in mice. In the chimney test, only the combinations of WIN with phenobarbital and valproate significantly impaired motor coordination in mice. In conclusion, WIN enhanced the anticonvulsant action of carbamazepine, phenytoin, phenobarbital and valproate in the MES test. However, the utmost caution is advised when combining WIN with classical antiepileptic drugs due to impairment of motor coordination and long-term memory and/or reduction of skeletal muscular strength that might appear during combined treatment.

Effects of three N-(carboxyanilinomethyl) derivatives of p-isopropoxyphenylsuccinimide on the anticonvulsant action of carbamazepine, phenobarbital, phenytoin and valproate in the mouse maximal electroshock-induced seizure model

The aim of the study was to determine the influence of N-( ortho-carboxyanilinomethyl)-p-isopropoxyphenylsuccinimide [ o-CAMIPPS], N-( meta-carboxyanilinomethyl)-p-isopropoxyphenylsuccinimide [ m-CAMIPPS], and N-( para-carboxyanilinomethyl)-p-isopropoxyphenylsuccinimide [ p-CAMIPPS] on the protective activity of four classical antiepileptic drugs (carbamazepine, phenobarbital, phenytoin and valproate) in the mouse maximal electroshock seizure model. The results indicate that all tested succinimide derivatives administered intraperitoneally at doses of 75 and 150 mg/kg significantly elevated the threshold for electroconvulsions in mice. Succinimide derivatives at a dose of 37.5 mg/kg had no effect on the threshold for electroconvulsions in mice. Furthermore, o-CAMIPPS (37.5 mg/kg) significantly reduced the anticonvulsant activity of carbamazepine, but not that of phenobarbital, phenytoin and valproate in the maximal electroshock-induced seizures in mice. Anticonvulsant efficacy of carbamazepine, phenobarbital, phenytoin and valproate in the maximal electroshock-induced seizures in mice was not changed after administration of m-CAMIPPS or p-CAMIPPS. Pharmacokinetic experiment revealed that o-CAMIPPS significantly increased total brain concentrations of carbamazepine in mice. In conclusion, the reduced anticonvulsant action of carbamazepine by o-CAMIPPS in the maximal electroshock-induced seizures, despite the increased total brain carbamazepine concentrations after combined administration of carbamazepine with o-CAMIPPS, may suggest the antagonistic interaction between drugs. The combinations of m-CAMIPPS or p-CAMIPPS with carbamazepine, phenobarbital, phenytoin and valproate were neutral from a preclinical viewpoint.

Influence of ethacrynic acid on the anticonvulsant activity of conventional antiepileptic drugs in the mouse maximal electroshock seizure model

The aim of this study was to determine whether ethacrynic acid (EA), a loop diuretic with anticonvulsant activity, would affect the protective action of the conventional antiepileptics (AEDs) carbamazepine (CBZ), phenytoin (PHT), valproate (VPA) and phenobarbital (PB) in the mouse maximal electroshock seizure (MES) model. The effects of acute and chronic treatment with EA on these AEDs were examined. At a single dose of 100mg/kg ip, EA enhanced the antielectroshock activity of VPA, decreasing its ED50 value from 225.6 to 146.6mg/kg (p<0.05), but enhancement was not observed following continuous administration of EA (12.5mg/kg) for seven days. Combined treatment of EA with other AEDs had no effect on their ED50 values. The observed interaction between EA and VPA was pharmacodynamic in nature as EA did not alter free plasma (non-protein-bound) and total brain concentrations of VPA. Taking into consideration the clinical use of both drugs, this interaction between EA and VPA can be important for patients receiving these drugs.

Captopril potentiates the anticonvulsant activity of carbamazepine and lamotrigine in the mouse maximal electroshock seizure model

Some studies suggest a higher risk of hypertension in people with epilepsy. Captopril, a potent and selective angiotensin-converting enzyme (ACE) inhibitor, is a well known antihypertensive drug. Besides the peripheral renin-angiotensin system (RAS), ACE inhibitors are also suggested to affect the brain RAS which might participate in the regulation of seizure susceptibility. The purpose of the current study was to evaluate the effect of captopril on the protective action of numerous antiepileptic drugs (carbamazepine [CBZ], phenytoin [PHT], valproate [VPA], phenobarbital [PB], oxcarbazepine [OXC], lamotrigine [LTG] and topiramate [TPM]) against maximal electroshock-induced seizures in mice. This study was accompanied by an evaluation of adverse effects of combined treatment with captopril and antiepileptic drugs in the passive avoidance task and chimney test. Captopril (25 and 50 mg/kg i.p.) did not influence the threshold for electroconvulsions. Among the tested antiepileptics, captopril (25 and 50 mg/kg i.p.) potentiated the antiseizure action of CBZ, decreasing its ED(50) value from 12.1 to 8.9 and 8.7 mg/kg, respectively. Moreover, captopril (50 mg/kg i.p.) enhanced the anticonvulsant activity of LTG. ED(50) value for LTG was lowered from 5.1 to 3.5 mg/kg. The observed interactions between captopril and CBZ or LTG were pharmacodynamic in nature as captopril did not alter plasma and total brain concentrations of these antiepileptics. The combinations of captopril with antiepileptic drugs did not lead to retention deficits in the passive avoidance task or motor impairment in the chimney test. Based on the current preclinical data, it is suggested that captopril may positively interact with CBZ and LTG in epileptic patients. The combinations of captopril with the remaining antiepileptics (PHT, VPA, PB, OXC and TPM) seem neutral.

Comparative pharmacodynamic and pharmacokinetic analysis of two anticonvulsant halo derivatives of 2,2,3,3‐tetramethylcyclopropanecarboxamide, an amide of a cyclic analog of valproic acid

α-Fluoro-2,2,3,3-tetramethylcyclopropanecarboxamide (α-F-TMCD) and α-Cl-TMCD, are α-halo derivatives of TMCD, the corresponding amide of a cyclopropane analog of valproic acid (VPA). This study aimed to comparatively evaluate the pharmacodynamics and pharmacokinetics of α-F-TMCD and α-Cl-TMCD in rodent models of epilepsy and for antiepileptic drug (AED)-induced teratogenicity. The potential of α-F-TMCD as an antiallodynic and antinociceptive compound was also evaluated. α-F-TMCD and α-Cl-TMCD were synthesized. α-Cl-TMCD anticonvulsant activity was evaluated in comparison to VPA in the mouse maximal-electroshock-seizure (MES), Metrazol (scMet), and 6-Hz psychomotor-seizure tests. Neurotoxicity was assessed by the Rotorod-ataxia test. Induction of neural tube defects (NTDs) by α-Cl-TMCD and α-F-TMCD was evaluated after intraperitoneal administration to a mouse strain highly susceptible to VPA-induced teratogenicity. The ability of α-F-TMCD to reduce pain was evaluated in the rat spinal nerve ligation (SNL) model for neuropathic pain and in the formalin test. α-F-TMCD and α-Cl-TMCD pharmacokinetics was evaluated following intraperitoneal (40 mg/kg) and oral (60 mg/kg) administration to rats. α-F-TMCD and α-Cl-TMCD had similar potencies in the 6-Hz test and were more potent than VPA in this model and in the scMet test. Neither induced NTDs, and both exhibited wide safety margins. α-F-TMCD was active in the two pain models, and was found to be equipotent to gabapentin in the SNL model (ED(50) = 37 and 32 mg/kg, respectively). Comparative pharmacokinetic analysis showed that α-Cl-TMCD is less susceptible to liver first-pass effect than α-F-TMCD because of lower total (metabolic) clearance and liver extraction ratio. Based on their potent anticonvulsant activity and lack of teratogenicity, α-F-TMCD and α-Cl-TMCD have the potential for development as new antiepileptics and central nervous system (CNS) drugs.

Isovaleramida, principio anticonvulsivo aislado de Valeriana pavonii

Fractioning of an extract of Valeriana pavonii, a native species used in Colombian folk medicine as tranquilizer, led to the isolation and identification of isovaleramide, one of the active constituents responsible for its central nervous system activity as anticonvulsant. Description of the isolation and identification of isovaleramide, an active principle on central nervous system from Valeriana pavonii. The purification of isovaleramide was carried out by chromatographic techniques. Its structural elucidation was determined by nuclear magnetic resonance and mass spectrometry. Maximal electroshock seizure was used as in vivo pharmacological test, additionally in vitro GABA-A/BDZ-binding site studies were performed. Isovaleramide was isolated from the most active fraction of Valeriana pavonii. This compound, at 100 mg/Kg, p.o, evidenced a 90% index protection against the maximal electroshock seizure in mice (MES), comparable to the reference agent: sodium phenytoin (20 mg/kg, p.o, 100%). In the in vitro assay, isovaleramide (300 µM) exhibited a 42% of inhibition of the binding of ³H-FNZ to its sites. Isovaleramide is one of the active anticonvulsant constituents of Valeriana pavonii, for the first time reported in this species. These results support the traditional use of Valeriana pavonii and its interest as a therapeutic source.