Broad Spectrum Of Anticonvulsant Activity Research Articles

Safe Use of Cenobamate in Super Refractory Status Epilepticus: A Case Series.

Cenobamate is an effective new adjunctive antiseizure medication (ASM) for treatment resistant focal epilepsy. It has broad spectrum anticonvulsant activity and may be a useful medication for super refractory status epilepticus (SRSE), but has not yet been studied in generalized seizures or an inpatient setting. Here we describe 2 SRSE cases where cenobamate was added safely to other treatments. It was uptitrated slowly to reduce the risk of hypersensitivity reactions which have been observed previously with rapid increasing dosages. Both patients achieved seizure control and liberation from intensive care. They have remained seizure free with continued treatment and have not experienced any side effects attributable to cenobamate. Cenobamate warrants further examination in patients with refractory status epilepticus.

α-Substituted Lactams and Acetamides: Ion Channel Modulators that Show Promise in Treating Drug-resistant Epilepsy.

The two main problems in the pharmacotherapy of epilepsy are resistance to currently available first-line medications (which occurs in about one third of patients) and the high incidence of side effects. To address these two challenges, extensive efforts are being undertaken to design new, structurally distinct antiepileptic drugs with a broad spectrum of anticonvulsant activity. Tests in animal models of epilepsy indicate that α-substituted lactams and acetamides show a broad spectrum of anticonvulsant activity (including very promising activity in drug-resistant models) as well as an excellent safety profile. Limited clinical results confirm these preclinical findings. In the first part of this review, pharmacology and toxicology of α-substituted lactams and acetamides and their putative protein targets in the brain have been discussed. This is followed by a discussion of structure-activity relationships among α-alkyl-, α-aryl-, and α-aryl-α-alkyl-substituted derivatives. The most promising structures seem to be those related to 3-ethyl-3-phenylpyrrolidin-2-one, 2-phenylbutyramide, and 2- sec-butylvaleramide. The information presented in this review is expected to facilitate rational drug design and development efforts for α-substituted lactams and acetamides.

Remarkably High Efficacy of Cenobamate in Adults With Focal-Onset Seizures: A Double-Blind, Randomized, Placebo-Controlled Trial.

Safety and Efficacy of Adjunctive Cenobamate (YKP3089) in Patients With Uncontrolled Focal Seizures: A Multicentre, Double-Blind, Randomized, Placebo-Controlled, Dose-Responsive Trial Krauss GL, Klein P, Brandt C, et al. Lancet Neurol. 2020;19(1):38-48. https://doi.org/10.1016/S1474-4422(19)30399-0.BACKGROUND:More than a third of patients with epilepsy are treatment resistant, and thus new, more effective therapies to achieve seizure freedom are needed. Cenobamate (YKP3089), an investigational antiepileptic drug, has shown broad-spectrum anticonvulsant activity in preclinical studies and seizure models. We aimed to evaluate the safety, efficacy, and tolerability of adjunctive cenobamate in patients with uncontrolled focal (partial)-onset epilepsy.METHODS:We did a multicenter, double-blind, randomized, placebo-controlled, dose–response study at 107 epilepsy and neurology centers in 16 countries. Adult patients (aged 18-70 years) with focal seizures despite treatment with 1 to 3 antiepileptic drugs were randomly assigned (1:1:1:1) via an interactive web response system, by block sizes of 4 within each country, to adjuvant once daily oral cenobamate at dose groups of 100 mg, 200 mg, or 400 mg, or placebo following an 8-week baseline assessment. Patients, investigators, and study personnel were masked to treatment assignment. The study included a 6-week titration phase and 12-week maintenance phase. The primary efficacy outcomes were percentage change in 28-day focal seizure frequency (focal aware motor, focal impaired awareness, or focal to bilateral tonic–clonic seizures) from baseline analyzed in the modified intention-to-treat population (≥1 dose and any postbaseline seizure data) and responder rates (≥50% reduction) analyzed in the maintenance phase population (≥1 dose in the maintenance phase and any maintenance phase seizure data). The primary efficacy outcomes were analyzed using a hierarchal step-down procedure comparing 200 mg versus placebo, 400 mg versus placebo, then 100 mg versus placebo. Safety and tolerability were compared descriptively across treatment groups for all randomized patients. This study is registered with ClinicalTrials.gov, number NCT01866111.FINDINGS:Between July 31, 2013, and June 22, 2015, 437 patients were randomly assigned to either placebo (n = 108) or cenobamate 100 mg (n = 108), 200 mg (n = 110), or 400 mg (n = 111). Of these patients, 434 (106 [98%] in placebo group, 108 [100%] in 100 mg group, 109 [99%] in 200 mg group, and 111 [100%] in 400 mg group) were included in the modified intention-to-treat population, and 397 (102 [94%] in placebo group, 102 [94%] in 100 mg group, 98 [89%] in 200 mg group, and 95 [86%] in 400 mg group) were included in the modified intention-to-treat maintenance phase population. Median percentage changes in seizure frequency were −24.0% (interquartile range: −45.0 to −7.0%) for the placebo group compared to −35.5% (−62.5 to −15.0%; P = .0071) for the 100 mg dose group, −55.0% (−73.0 to −23.0%; P < .0001) for the 200 mg dose group, and −55.0% (−85.0 to −28.0%; P < .0001) for the 400 mg dose group. Responder rates during the maintenance phase were 25% (26 of 102 patients) for the placebo group compared to 40% (41 of 102; odds ratio: 1.97, 95% confidence interval: 1.08-3.56; P = .0365) for the 100 mg dose group, 56% (55 of 98; 3.74, 2.06-6.80; P < .0001) for the 200 mg dose group, and 64% (61 of 95; 5.24, 2.84-9.67; P < .0001) for the 400 mg dose group. Treatment-emergent adverse events occurred in 76 (70%) of 108 patients in the placebo group, 70 (65%) of 108 in the 100 mg group, 84 (76%) of 110 in the 200 mg group, and 100 (90%) of 111 in the 400 mg group. Treatment-emergent adverse events led to discontinuation in 5 (5%) patients in the placebo group, 11 (10%) in the 100 mg dose group, 15 (14%) in the 200 mg dose group, and 22 (20%) in the 400 mg dose group. One serious case of drug reaction with eosinophilia and systemic symptoms occurred in the 200 mg cenobamate group. No deaths were reported.INTERPRETATION:Adjunctive cenobamate reduced focal (partial)-onset seizure frequency, in a dose-related fashion. Treatment-emergent adverse events were most frequent in the highest dose group. Cenobamate appears to be an effective treatment option in patients with uncontrolled focal seizures.

Safety and efficacy of adjunctive cenobamate (YKP3089) in patients with uncontrolled focal seizures: a multicentre, double-blind, randomised, placebo-controlled, dose-response trial

More than a third of patients with epilepsy are treatment resistant, and thus new, more effective therapies to achieve seizure freedom are needed. Cenobamate (YKP3089), an investigational antiepileptic drug, has shown broad-spectrum anticonvulsant activity in preclinical studies and seizure models. We aimed to evaluate the safety, efficacy, and tolerability of adjunctive cenobamate in patients with uncontrolled focal (partial)-onset epilepsy. We did a multicentre, double-blind, randomised, placebo-controlled, dose-response study at 107 epilepsy and neurology centres in 16 countries. Adult patients (aged 18-70 years) with focal seizures despite treatment with 1-3 antiepileptic drugs were randomly assigned (1:1:1:1) via an interactive web response system, by block sizes of 4 within each country, to adjuvant once daily oral cenobamate at dose groups of 100 mg, 200 mg, or 400 mg, or placebo following an 8-week baseline assessment. Patients, investigators, and study personnel were masked to treatment assignment. The study included a 6-week titration phase and 12-week maintenance phase. The primary efficacy outcomes were percentage change in 28-day focal seizure frequency (focal aware motor, focal impaired awareness, or focal to bilateral tonic-clonic seizures) from baseline analysed in the modified intention-to-treat population (≥1 dose and any post-baseline seizure data) and responder rates (≥50% reduction) analysed in the maintenance phase population (≥1 dose in the maintenance phase and any maintenance phase seizure data). The primary efficacy outcomes were analysed using a hierarchal step-down procedure comparing 200 mg versus placebo, 400 mg versus placebo, then 100 mg versus placebo. Safety and tolerability were compared descriptively across treatment groups for all randomised patients. This study is registered with ClinicalTrials.gov, number NCT01866111. Between July 31, 2013, and June 22, 2015, 437 patients were randomly assigned to either placebo (n=108) or cenobamate 100 mg (n=108), 200 mg (n=110), or 400 mg (n=111). Of these patients, 434 (106 [98%] in placebo group, 108 [100%] in 100 mg group, 109 [99%] in 200 mg group, and 111 [100%] in 400 mg group) were included in the modified intention-to-treat population, and 397 (102 [94%] in placebo group, 102 [94%] in 100 mg group, 98 [89%] in 200 mg group, and 95 [86%] in 400 mg group) were included in the modified intention-to-treat maintenance phase population. Median percentage changes in seizure frequency were -24·0% (IQR -45·0 to -7·0%) for the placebo group compared with -35·5% (-62·5 to -15·0%; p=0·0071) for the 100 mg dose group, -55·0% (-73·0 to -23·0%; p<0·0001) for the 200 mg dose group, and -55·0% (-85·0 to -28·0%; p<0·0001) for the 400 mg dose group. Responder rates during the maintenance phase were 25% (26 of 102 patients) for the placebo group compared with 40% (41 of 102; odds ratio 1·97, 95% CI 1·08-3·56; p=0·0365) for the 100 mg dose group, 56% (55 of 98; 3·74, 2·06-6·80; p<0·0001) for the 200 mg dose group, and 64% (61 of 95; 5·24, 2·84-9·67; p<0·0001) for the 400 mg dose group. Treatment-emergent adverse events occurred in 76 (70%) of 108 patients in the placebo group, 70 (65%) of 108 in the 100 mg group, 84 (76%) of 110 in the 200 mg group, and 100 (90%) of 111 in the 400 mg group. Treatment-emergent adverse events led to discontinuation in five (5%) patients in the placebo group, 11 (10%) in the 100 mg dose group, 15 (14%) in the 200 mg dose group, and 22 (20%) in the 400 mg dose group. One serious case of drug reaction with eosinophilia and systemic symptoms occurred in the 200 mg cenobamate group. No deaths were reported. Adjunctive cenobamate reduced focal (partial)-onset seizure frequency, in a dose-related fashion. Treatment-emergent adverse events were most frequent in the highest dose group. Cenobamate appears to be an effective treatment option in patients with uncontrolled focal seizures. SK Life Science.

Preclinical evaluation of 1,2,4-triazole-based compounds targeting voltage-gated sodium channels (VGSCs) as promising anticonvulsant drug candidates.

Epilepsy is a chronic neurological disorder affecting nearly 65-70 million people worldwide. Despite the observed advances in the development of new antiepileptic drugs (AEDs), still about 30-40% of patients cannot achieve a satisfactory seizure control. In our current research, we aimed at using the combined results of radioligand binding experiments, PAMPA-BBB assay and animal experimentations in order to design a group of compounds that exhibit broad spectrum of anticonvulsant activity. The synthesized 4-alkyl-5-substituted-1,2,4-triazole-3-thione derivatives were primarily screened in the maximal electroshock-induced seizure (MES) test in mice. Next, the most promising compounds (17, 22) were investigated in 6 Hz (32 mA) psychomotor seizure model. Protective effect of compound 22 was almost similar to that of levetiracetam. Moreover, these compounds did not induce genotoxic and hemolytic changes in human cells as well as they were characterized by low cellular toxicity. Taking into account the structural requirements for good anticonvulsant activity of 4-alkyl-5-aryl-1,2,4-triazole-3-thiones, it is visible that small electron-withdrawing substituents attached to phenyl ring have beneficial effects both on affinity towards VGSCs and protective activity in the animal models of epilepsy.

Design, Synthesis, and Docking Study of Pyrimidine-Triazine Hybrids for GABA Estimation in Animal Epilepsy Models.

A series of new pyrimidine-triazine hybrids (4a-t) was designed and synthesized, from which potent anticonvulsant agents were identified. Most of the compounds exhibited promising anticonvulsant activity against the maximal electroshock (MES) and subcutaneous pentylenetetrazole (scPTZ) tests, along with minimal motor impairment with higher safety compared to the standard drugs, phenytoin and carbamazepine. In the series, 5-(4-(4-fluorophenyl)-6-(4-hydroxyphenyl)-2-thioxo-5,6-dihydropyrimidin-1(2H)-yl)-1,2-dihydro-1,2,4-triazin-3(6H)-one (4o) and 5-(6-(4-hydroxy-3-methoxyphenyl)-4-(4-hydroxyphenyl)-2-thioxo-5,6-dihydropyrimidin-1(2H)-yl)-1,2-dihydro-1,2,4-triazin-3(6H)-one (4s) emerged as most potent anticonvulsant agents with median doses of 22.54 and 29.40 mg/kg (MES ED50 ), 285.02 and 293.42 mg/kg (scPTZ ED50 ), and 389.11 and 412.16 mg/kg (TD50 ), respectively. Docking studies were also performed for all synthesized compounds to get insight into the binding pattern toward the GABAA receptor as a possible mechanism of their anticonvulsant action, and in silico ADME studies were carried out to predict the safety and stability of the molecules. The increased GABA level in the experimental animals in the neurochemical estimation assay confirmed their GABAergic modulating activity. The most potent compounds were also evaluated for their neurotoxic and hepatotoxic effects. Fortunately, they did not show any sign of neurotoxicity or hepatotoxicity, suggesting that they have a broad spectrum of anticonvulsant activity with a large safety margin. Together, this research suggested that 4o and 4s may serve as leads in the discovery and development of new anticonvulsant drugs.

Perampanel effects in the WAG/Rij rat model of epileptogenesis, absence epilepsy, and comorbid depressive-like behavior.

Perampanel (PER), a selective non-competitive α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-receptor antagonist, exhibits broad-spectrum anticonvulsant activity in several seizure models, but its potential disease-modifying effects have not been investigated. Because of the relevance of AMPA receptors in epileptogenesis and psychiatric comorbidities, we studied the effects of PER in the WAG/Rij rat model of epileptogenesis, absence epilepsy, and depressive-like comorbidity. We investigated the effects of acute, subchronic, and chronic treatment with PER (0.25-3 mg/kg) on absence seizures, their development, and related psychiatric/neurologic comorbidity in WAG/Rij rats. Depression-related behavior was studied by using the forced swimming and the sucrose preference test; anxiety-related behavior by using the open field and elevated plus maze test; and memory by using the passive avoidance test. PER (3 mg/kg/day orally for 17 weeks starting from P30) significantly reduced the development of absence seizures at 6 months of age (1 month after treatment withdrawal), but this effect was not maintained when reassessed 4 months later. Attenuated absence seizure development was accompanied by reduced depressive-like behavior in the forced swimming test (FST), whereas no effects were observed on anxiety-related behavior and memory. Subchronic (1 and 3 mg/kg/day orally for 1 week) and acute PER (0.25-1 mg/kg, i.p.) dosing did not affect established absence seizures and behavior. These results suggest that AMPA receptors are involved in mechanisms of epileptogenesis in an established model of absence epilepsy, and that these mechanisms differ from those responsible for seizure generation and spread when epilepsy has become established.

Sec-Butylpropylacetamide (SPD), a new amide derivative of valproic acid for the treatment of neuropathic and inflammatory pain

Chronic pain is a multifactorial disease comprised of both inflammatory and neuropathic components that affect ∼20% of the world’s population. sec-Butylpropylacetamide (SPD) is a novel amide analogue of valproic acid (VPA) previously shown to possess a broad spectrum of anticonvulsant activity. In this study, we defined the pharmacokinetic parameters of SPD in rat and mouse, and then evaluated its antinociceptive potential in neuropathic and acute inflammatory pain models. In the sciatic nerve ligation (SNL) model of neuropathic pain, SPD was equipotent to gabapentin and more potent than its parent compound VPA. SPD also showed either higher or equal potency to VPA in the formalin, carrageenan, and writhing tests of inflammatory pain. SPD showed no effects on compound action potential properties in a sciatic nerve preparation, suggesting that its mechanism of action is distinct from local anesthetics and membrane stabilizing drugs. SPD’s activity in both neuropathic and inflammatory pain warrants its development as a potential broad-spectrum anti-nociceptive drug.

Anticonvulsant and antinociceptive activity of new amides derived from 3-phenyl-2,5-dioxo-pyrrolidine-1-yl-acetic acid in mice

The aim of the present experiments was to examine the anticonvulsant and antinociceptive activity of five new amides derived from 3-phenyl-2,5-dioxo-pyrrolidine-1-yl-acetic acid in animal models of seizures and pain. The antiseizure activity was investigated in three acute models of seizures, namely, the maximal electroshock (MES), the subcutaneous pentylenetetrazole (scPTZ), and 6Hz psychomotor seizure tests in mice. The antinociceptive properties were estimated in the formalin model of tonic pain, and in the oxaliplatin-induced neuropathic pain model in mice. Considering drug safety evaluation, acute neurological toxicity was determined in the rotarod test. Three tested compounds (3, 4, and 7) displayed a broad spectrum of anticonvulsant activity and showed better protective indices than those obtained for MES/scPTZ/6Hz active reference drug – valproic acid. Furthermore, three compounds (3, 4, and 6) demonstrated a significant antinociceptive effect in the formalin test, as well as antiallodynic activity in the oxaliplatin-induced neuropathic pain model. Among the tested agents, compounds 3 and 4 displayed not only antiseizure properties, but also collateral prominent analgesic properties. The in vitro binding study indicated that the plausible mechanism of action of chosen compound (4) was the influence on neuronal voltage-sensitive sodium (site 2) and L-type calcium channels.

Design and synthesis of some new 1-phenyl-3/4-[4-(aryl/heteroaryl/alkyl-piperazine1-yl)-phenyl-ureas as potent anticonvulsant and antidepressant agents.

A series of 1-phenyl-3/4-[4-(aryl/heteroaryl/alkyl-piperazine1-yl)-phenyl-urea derivatives (29-42) were designed, synthesized and evaluated for their anticonvulsant activity by using maximal electroshock (MES), subcutaneous pentylenetetrazole (scPTZ) seizure tests. The acute neurotoxicity was checked by rotarod assay. Most of the test compounds were found effective in both seizure tests. Compound 30 (1-{4-[4-(4-chloro-phenyl)-piperazin-1-yl]-phenyl}-3-phenyl-urea) exhibited marked anticonvulsant activity in MES as well as scPTZ tests. The phase II anticonvulsant quantification study of compound 30 indicates the ED50 value of 28.5mg/kg against MES induced seizures. In addition, this compound also showed considerable protection against pilocarpine induced status epilepticus in rats. Seizures induced by 3-mercaptopropionic acid model and thiosemicarbazide were significantly attenuated by compound 30, which suggested its broad spectrum of anticonvulsant activity. Interestingly, compound 30 displayed better antidepressant activity than standard drug fluoxetine. Moreover, compound 30 appeared as a non-toxic chemical entity in sub-acute toxicity studies.

Brivaracetam for the treatment of epilepsy

ABSTRACTIntroduction: Approximately one third of patients with epilepsy fail to respond to existing medications. Levetiracetam is an effective antiepileptic drug (AED) postulated to act by binding to synaptic vesicle protein 2A. Brivaracetam is a novel high affinity SV2A ligand with approximately 20-fold higher affinity for SV2A protein than levetiracetam. It is at an advanced stage of clinical development for treatment of epilepsy.Areas covered: This article reviews animal data, pharmacokinetics, and phase 1-3 data of Brivaracetam treatment of epilepsy. Brivaracetam has broad-spectrum anticonvulsant activity in animal models.Expert Opinion: Phase 1 studies indicated that single oral doses of 5-800 mg and repeated oral doses of up to 600 mg were well tolerated and showed favorable pharmacokinetic profile. Phase 2 studies indicated good safety and tolerability of brivaracetam in the dose range of 5-150 mg/day and provided proof of concept for efficacy in treating refractory partial onset seizures. Efficacy and safety have been evaluated in 4 phase 3 studies with dose range of 5-200 mg which have demonstrated efficacy in the range of 100-200 mg/day dose and, in most studies, also with 50 mg/day dose, and good safety and tolerability profile across 5-200 mg doses in adjunctive treatment of refractory partial onset seizures.

Anticonvulsant and Neurotoxicity of Some Novel 1-([1,3,4]thiadiazino[6,5- b]indol-3-yl Semicarbazides.

In the present study a series of new N(4)-(4-substituted benzylidene)-N(1)-([1,3,4]thiadiazino [6,5-b]indol-3-yl)semicarbazide (1-6), N(4)-([1,3,4]thiadiazino[6,5-b]indol-3-yl)-N(1)-(1-(4-substituted phenyl)ethylidene)semicarbazide (7-10), N(4)-([1,3,4]thiadiazino[6,5-b]indol-3-yl)-N(1)-((4-substituted phenyl)(phenyl)methylene) semicarbazide. (11-14) have been synthesized from isatin and thiosemicarbazide through multiple steps to meet structural necessities for the anticonvulsant activity. All the newly prepared compounds were characterized by spectral techniques like FT-IR, (1)H and (13)C NMR, EI-MS and elemental analysis. All the newly synthesized compounds were investigated for the anticonvulsant activity against maximal electroshock induced seizures (MES) and subcutaneous pentylenetetrazole (scPTZ) models and their neurotoxicity were also evaluated by rotarod test. The results obtained showed that 64% of the compounds showed protection in the MES test and 36% of the compounds showed protection in ScPTZ test. Some of the compounds also showed good activity after oral administration. Among the synthesized compounds, compound 14 was shown to be the most active compound showing activity at 100 and 300 mg/kg in MES and ScPTZ test with prolonged duration of action. In the present study, semicarbazones of hydroxy containing carbonyl compounds were depicted to be the potent molecule with low neurotoxicity and prolong duration of action on oral administration. The result of the present study may be used for the future development of novel anticonvulsants with broad spectrum of anticonvulsant activity.

Psychomotor Seizure Screening and in vitro Neuroprotection Assay of Hydrazones Derived from 2-Acetyl Thiophene

Hydrazone core is a versatile structural linker for the development of various classes of antiepileptic agents. The aim of this study was to investigate the anticonvulsant activity of thiophene based hydrazones according to the antiepileptic drug development program protocol. The maximal electroshock-induced seizure and 6 Hz &quot;Psychomotor&quot; seizure test models in mice were performed. Additionally, the active compounds in the screening test were subsequently subjected to the maximal electroshock-induced seizure test that allowed determination of their median effective doses and median toxic doses. The most active compound was also subjected to the In vitro Hippocampal slice culture neuroprotection assay. Among the synthesized compounds, 1-(thiophen-2-yl) ethylidene] hydrazine carboxamides (THb) and 1-(thiophen-2-yl) ethylidene] hydrazine carbothioamide (THc) showed a broad-spectrum anticonvulsant activity since they were active in both maximal electroshock-induced seizure and 6Hz-Psychomotor induced seizure models with no neurotoxicity. In the mice maximal electroshock-induced seizure screen, compound THb gave an ED50 of 11.8 mg/kg and a TD50 of 39.47 mg/kg, resulting in a good protection index (PI), that is, TD50/ED50, of 3.3 when compared to Phenobarbital and Valproate. THb (100μM) was also found to be effectively suppressing network hyperexcitability in the in vitro mEC-HC spontaneous bursting model, as determined by effects on spontaneous burst activity and duration. The suggested pharmacophore model for lead compounds from thiophene based hydrazones is explained by the hydrophobic domain-thiophene, electron donor-imine and hydrogen bonding domain-carboxamide or carbothioamide unit.

Characterization of Disopyramide derivative ADD424042 as a non-cardiotoxic neuronal sodium channel blocker with broad-spectrum anticonvulsant activity in rodent seizure models

It was reported that antiarrhythmic drugs (AADs) can be useful in controlling refractory seizures in humans or in enhancing the action of antiepileptic drugs (AEDs) in animal models.Disopyramide phosphate (DISO) is an AAD that blocks sodium channels in cardiac myocytes. We evaluated a DISO derivative, 2-(2-chlorophenyl)-2-(pyridin-2-yl)acetamide (ADD424042) for its anticonvulsant activity in a battery of rodent models of epileptic seizures. The compound displayed a broad spectrum of activity in the ‘classical’ models as well as in the models of pharmacoresistant seizures. Furthermore, ADD424042 showed good therapeutic indices between the anticonvulsant activity and the motor impairment. On the contrary, no anticonvulsant effects but severe lethality were observed in the primary anticonvulsant testing of the parent DISO. By performing the whole-cell voltage-clamp experiments in dispersed cortical neurons we demonstrated that ADD424042 decreased the maximal amplitude of voltage-gated sodium channels with an IC50 value in nM range. Moreover, the compound enhanced use-dependent block and decreased excitability in pyramidal neurons in the current-clamp experiments in cortical slices. Importantly, we found that ADD424042 possessed either no, or very small cardiotoxic effect. In contrast to DISO, ADD424042 did not produce any apparent changes in electrocardiogram (ECG) and arterial blood pressure recordings. ADD424042 had no effect on QT and corrected QT intervals, at a dose which was 15 times higher than ED50 for the anticonvulsant effect in the MES model. Taken together, these data suggest that ADD424042 has the potential to become a lead structure for novel broadly acting AEDs with wide margin of cardiac safety.

Pharmacological evaluation of novel 1-[4-(4-benzo[1,3]dioxol-5-ylmethyl-piperazin-1-yl)-phenyl]-3-phenyl-urea as potent anticonvulsant and antidepressant agent.

Earlier, we have identified a number of piperazine derivatives having good anticonvulsant activity in vivo and as a part of our ongoing search for potent anticonvulsant agent, we herein describes the synthesis of an aryl piperazine derivative "1-[4-(4-benzo[1,3]dioxol-5-ylmethyl-piperazin-1-yl)-phenyl]-3-phenyl-urea" (BPPU). The anticonvulsant and antidepressant activity of BPPU was checked in various in vivo models. Anticonvulsant activity was assessed in maximal electroshock test (MES) and subcutaneous pentylenetetrazole (scPTZ) induced seizure tests. Moreover, plausible mechanistic studies were also performed by using several chemical induced seizure models. The antidepressant activity of BPPU was checked in forced swim test (FST) and tail suspension test (TST) in mice. Drug safety profile was studied in sub-acute toxicity rat model at a dose of 100mg/kg, per oral for 14 days. BPPU exhibited excellent protection against seizures induced by MES and scPTZ in mice as well as rats. In pilocarpine induced model of status epilepticus (SE), BPPU demonstrated 50% protection at a dose of 100mg/kg in rats. BPPU also successfully inhibited seizures induced by 3-mercaptopropionic acid (3-MPA) and thiosemicarbazide (TSC) in mice thus, suggested that BPPU might influence GABA-ergic neurotransmission in the brain. Moreover, BPPU showed good antidepressant activity and did not exhibit any significant toxicity. BPPU displayed broad spectrum of anticonvulsant activity in several seizure models along with satisfactory antidepressant activity. Therefore, BPPU may be further developed as a potential therapeutic agent for therapy of epileptic disorders.

From antiarrhythmics to anticonvulsants: ADD424042, a Disopyramide derivative, is a non-cardiotoxic ion channel blocker with broad-spectrum anticonvulsant activity

From antiarrhythmics to anticonvulsants: ADD424042, a Disopyramide derivative, is a non-cardiotoxic ion channel blocker with broad-spectrum anticonvulsant activity

Pharmacodynamic and pharmacokinetic analysis of CNS-active constitutional isomers of valnoctamide and sec-butylpropylacetamide — Amide derivatives of valproic acid

Valnoctamide (VCD) and sec-butylpropylacetamide (SPD) are CNS-active closely related amide derivatives of valproic acid with unique anticonvulsant activity. This study evaluated how small chemical changes affect the pharmacodynamics (PD; anticonvulsant activity and teratogenicity) and pharmacokinetics (PK) of three constitutional isomers of SPD [sec-butylisopropylacetamide (SID) and tert-butylisopropylacetamide (TID)] and of VCD [tert-butylethylacetamide (TED)]. The anticonvulsant activity of SID, TID, and TED was comparatively evaluated in several rodent anticonvulsant models. The PK–PD relationship of SID, TID, and TED was evaluated in rats, and their teratogenicity was evaluated in a mouse strain highly susceptible to teratogen-induced neural tube defects (NTDs). sec-Butylisopropylacetamide and TID have a similar PK profile to SPD which may contribute to their similar anticonvulsant activity. tert-Butylethylacetamide had a better PK profile than VCD (and SPD); however, this did not lead to a superior anticonvulsant activity. sec-Butylisopropylacetamide and TED did not cause NTDs at doses 4–7 times higher than their anticonvulsant ED50 values. In rats, SID, TID (ip), and TED exhibited a broad spectrum of anticonvulsant activity. However, combined anticonvulsant analysis in mice and rats shows SID as the most potent compound with similar activity to that of SPD, demonstrating that substitution of the isobutyl moiety in the SPD or VCD molecule by tert-butyl as well as a propyl-to-isopropyl replacement in the SPD molecule did not majorly affect the anticonvulsant activity.

The Pharmacology of Imepitoin: The First Partial Benzodiazepine Receptor Agonist Developed for the Treatment of Epilepsy

Although benzodiazepines (BZDs) offer a wide spectrum of antiepileptic activity against diverse types of epileptic seizures, their use in the treatment of epilepsy is limited because of adverse effects, loss of efficacy (tolerance), and development of physical and psychological dependence. BZDs act as positive allosteric modulators of the inhibitory neurotransmitter GABA by binding to the BZD recognition site ("BZD receptor") of the GABAA receptor. Traditional BZDs such as diazepam or clonazepam act as full agonists at this site, so that one strategy to resolve the disadvantages of these compounds would be the development of partial agonists with lower intrinsic efficacy at the BZD site of the GABAA receptor. Several BZD site partial or subtype selective compounds, including bretazenil, abecarnil, or alpidem, have been developed as anxioselective anxiolytic drugs, but epilepsy was not a target indication for such compounds. More recently, the imidazolone derivatives imepitoin (ELB138) and ELB139 were shown to act as low-affinity partial agonists at the BZD site of the GABAA receptor, and imepitoin was developed for the treatment of epilepsy. Imepitoin displayed a broad spectrum of anticonvulsant activity in diverse seizure and epilepsy models at tolerable doses, and, as expected from its mechanism of action, lacked tolerance and abuse liability in rodent and primate models. The more favorable pharmacokinetic profile of imepitoin in dogs versus humans led to the decision to develop imepitoin for the treatment of canine epilepsy. Based on randomized controlled trials that demonstrated antiepileptic efficacy and high tolerability and safety in epileptic dogs, the drug was recently approved for this indication in Europe. Hopefully, the favorable profile of imepitoin for the treatment of epilepsy in dogs will reactivate the interest in partial BZD site agonists as new treatments for human epilepsy.

Stereoselective anticonvulsant and pharmacokinetic analysis of valnoctamide, a CNS-active derivative of valproic acid with low teratogenic potential.

Valnoctamide (VCD), a central nervous system (CNS)-active chiral constitutional isomer of valpromide, the corresponding amide of valproic acid (VPA), is currently undergoing phase IIb clinical trials in acute mania. VCD exhibits stereoselective pharmacokinetics (PK) in animals and humans. The current study comparatively evaluated the pharmacodynamics (PD; anticonvulsant activity and teratogenicity) and PK of the four individual stereoisomers of VCD. The anticonvulsant activity of VCD individual stereoisomers was evaluated in several rodent anticonvulsant models including maximal electroshock, 6Hz psychomotor, subcutaneous metrazol, and the pilocarpine-induced and soman-induced status epilepticus (SE). The PK-PD (anticonvulsant activity) relationship of VCD stereoisomers was evaluated following intraperitoneal administration (70mg/kg) to rats. Induction of neural tube defects (NTDs) by VCD stereoisomers was evaluated in a mouse strain that was highly susceptible to teratogen-induced NTDs. VCD had a stereoselective PK, with (2S,3S)-VCD exhibiting the lowest clearance, and consequently a twice-higher plasma exposure than all other stereoisomers. Nervertheless, there was less stereoselectivity in VCD anticonvulsant activity and each stereoisomer had similar median effective dose (ED)50 values in most models. VCD stereoisomers (258 or 389mg/kg) did not cause NTDs. These doses are 3-12 times higher than VCD anticonvulsant ED50 values. VCD displayed stereoselective PK that did not lead to significant stereoselective activity in various anticonvulsant rodent models. If VCD exerted its broad-spectrum anticonvulsant activity using a single mechanism of action (MOA), it is likely that it would exhibit a stereoselective PD. The fact that there was no significant difference between racemic VCD and its individual stereoisomers suggests that VCD's anticonvulsant activity is due to multiple MOAs.

Synthesis and anticonvulsant activity of novel 2,6-diketopiperazine derivatives. Part 2: Perhydropyrido[1,2- a]pyrazines

A new series of chiral pyrido[1,2- a]pyrazine derivatives was synthesised and evaluated in in vivo animal models of epilepsy. A significant influence of the stereochemistry of the pyrido[1,2- a]pyrazine framework on the pharmacological activity was observed. Compounds with (4 R,9a S) absolute configuration proved inactive, whereas other stereoisomers exhibited markedly dissimilar spectra of anti-seizure efficacy in the maximal electroshock seizure (MES), subcutaneous Metrazol seizure (scMET) and Pilocarpine-induced status prevention (PISP) tests. Importantly, the investigated agents revealed high potency in the 6 Hz model, with the ED 50 values comparable to the reference drug Levetiracetam. Derivatives (4 S,9a R)-6 and (4 R,9a R)-6 emerged as promising new lead structures, the former having a broad spectrum of anticonvulsant activity and the latter showing high potency in 6 Hz and PISP models.