Swiader M

Interactions between oxcarbazepine and conventional antiepileptic drugs in the maximal electroshock test in mice: An isobolographic analysis

Summary:  Purpose: The aim of this study was to determine the types of interactions between oxcarbazepine (OCBZ) and conventional antiepileptic drugs (AEDs) against maximal electroshock‐induced seizures (MES test) in mice, by using a method of isobolographic analysis.

Interactions of Lamotrigine with Topiramate and First‐generation Antiepileptic Drugs in the Maximal Electroshock Test in Mice: An Isobolographic Analysis

Summary:  Purpose: The study investigated the types of interactions between lamotrigine (LTG) and first‐generation antiepileptic drugs (AEDs) or topiramate (TPM) with isobolographic analysis.

Effect of Gabapentin on the Anticonvulsant Activity of Antiepileptic Drugs against Electroconvulsions in Mice : An Isobolographic Analysis

Summary:  Purpose: The objective of this study was the isobolographic evaluation of the interactions between the novel antiepileptic drug (AED) gabapentin (GBP) and a number of other AEDs against electroconvulsion‐induced convulsions in mice.

Anticonvulsant and acute adverse effect profiles of picolinic acid 2-fluoro-benzylamide in various experimental seizure models and chimney test in mice.

The objective of this study was to evaluate the anticonvulsant properties of picolinic acid 2‐fluoro‐benzylamide (Pic‐2F‐BZA) in numerous experimental seizure models [maximal electroshock (MES), bicuculline (BIC), pentylenetetrazole (PTZ), pilocarpine (PILO), α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionic acid (AMPA), kainic acid (KA) and N‐methyl‐d‐aspartic acid (NMDA)‐induced seizures]. Moreover, the acute adverse‐effect profile of the agent with respect to impairment of motor performance was assessed in animals subjected to the chimney test. Results indicate that Pic‐2F‐BZA in time‐ and dose‐dependent manners produced both the anti‐electroshock action and acute adverse effects in the MES and chimney tests in mice respectively. The experimentally derived median effective dose (ED50 value) in the MES test was 24.2 mg/kg (at 5 min after i.p. administration), whereas the median toxic dose (TD50 value) in the chimney test was 71.7 mg/kg. Furthermore, Pic‐2F‐BZA produced clear‐cut antiseizure effects in all chemically induced seizure models and its ED50 values amounted to 19.9 mg/kg for KA‐, 39.5 mg/kg for AMPA‐, 56.2 mg/kg for PTZ‐, 76.4 mg/kg for BIC‐, 160.1 mg/kg for PILO‐ and 165.2 mg/kg for NMDA‐induced seizures. Based on this study, one can conclude that Pic‐2F‐BZA, because of its broad spectrum of anticonvulsant action and the short time to peak of its maximum anticonvulsant effects (5 min after its i.p. administration), deserves more attention as a potential antiepileptic drug for status epilepticus patients.

Influence of agents affecting voltage-dependent calcium channels and dantrolene on the anticonvulsant action of the AMPA/kainate receptor antagonist LY 300164 in mice

It was previously documented that calcium (Ca(2+)) channel inhibitors intensified the protective effects of conventional antiepileptics against electroconvulsions in mice. The aim of this study was to evaluate the effects of Ca(2+) channel inhibitors (nifedipine, nicardipine and flunarizine) on the anticonvulsant action of the new AMPA/kainate receptor antagonist, 7-acetyl-3-(4-aminophenyl)-8,9-dihydro-8-methyl-7H-1,3-dioxazolo[4,5-h][2,3]-benzodiazepine (LY 300164), against maximal electroshock (MES)-induced seizures in mice. Dantrolene (an inhibitor of Ca(2+)release from intracellular stores) was also included. Nifedipine (30 mg/kg) and flunarizine (15 mg/kg) raised the threshold for electroconvulsions, being ineffective at lower doses. Nicardipine (up to 30 mg/kg) and dantrolene (up to 20 mg/kg) did not affect this parameter. Flunarizine (10 mg/kg), nicardipine (20 mg/kg) and dantrolene (20 mg/kg) potentiated the efficacy of LY 300164 against MES. However, nicardipine (at 20 mg/kg) raised the free plasma concentration of LY 300164. Nifedipine (30 mg/kg), given even in a dose raising the electroconvulsive threshold, did not significantly alter the protective effect of LY 300164 against MES. Furthermore, the Ca(2+) channel agonist-BAY k-8644 (at 5 mg/kg) did not influence the protection offered by LY 300164 against MES. Finally, this Ca(2+) channel activator did not affect the enhanced efficacy of LY 300164 by Ca(2+) channel modulators. The only exception was the combination of LY 300164 with flunarizine. Combined treatment with LY 300164 and dantrolene (20 mg/kg), compared to LY 300164 alone, resulted in an impairment of motor performance in mice. Ca(2+) channel inhibitors were without effect upon this parameter evaluated in the chimney test. As shown in the passive avoidance task, LY 300164 alone (at its ED(50)) or combined with agents affecting neuronal Ca(2+) concentration did not disturb long-term memory. The present results suggest that agents preventing influx of Ca(2+) ions into neurons may enhance the protective action of LY 300164.

Interaction of astemizole, an H1 receptor antagonist, with conventional antiepileptic drugs in mice

Histamine is one of the aminergic neurotransmitters, playing an important role in the regulation of a number of physiological processes. There are several subtypes of histamine receptors-H(1), H(2), H(3) and the recently discovered H(4). H(1) receptors exist on mast cells, basophils, enterochromaffin cells and in the central nervous system, being located postsynaptically. H(1) receptor antagonists, including classical antiallergy drugs, occasionally have been expected to induce convulsions in children and epileptics. The aim of this study was to evaluate the effects of astemizole-given intraperitoneally, singly or for 7 days on the anticonvulsant activity of antiepileptic drugs (AEDs) against maximal electroshock (MES)-induced convulsions in mice. The following AEDs were administered intraperitoneally: valproate magnesium, carbamazepine, diphenylhydantoin and phenobarbital. Adverse effects were evaluated in the chimney test (motor performance) and passive avoidance task (long-term memory). Brain and plasma levels of AEDs were measured by immunofluorescence. Astemizole (a single dose and following a 7-day treatment at 2-6 mg/kg) reduced the threshold for electroconvulsions, being without effect upon this parameter at lower doses. Astemizole (1 mg/kg) did not significantly alter the protective effect of AEDs against MES (after acute and 7-day administration). Also, acute astemizole (2 mg/kg) remained ineffective in this respect. Astemizole (2 mg/kg), following chronic administration, significantly reduced the protective efficacy of phenobarbital and diphenylhydantoin, reflected by an increase in their ED(50) values (50% effective dose necessary to protect 50% of animals tested against MES) from 21.1 to 34.0 mg/kg and from 10.4 to 19.2 mg/kg, respectively. Astemizole (2 mg/kg) did not alter the protective activity of the remaining AEDs. Moreover, astemizole (2 mg/kg) did not influence the free plasma levels and brain concentration of the studied AEDs. Also, this H(1) receptor antagonist did not impair long-term memory or motor coordination when given acutely. However, 7-day treatment with astemizole (2 mg/kg) significantly decreased TD(50) (50% toxic dose required to induce motor impairment in 50% of animals) value of phenobarbital, being without effect on carbamazepine, valproate and diphenylhydantoin in this respect. Similarly, phenobarbital and diphenylhydantoin, administered alone at their ED(50)s against MES, or combined with astemizole, disturbed long-term memory in mice. The results of this study indicate that astemizole may need to be used with caution in epileptic patients.

Characterization of the anticonvulsant profile of isonicotinic acid benzylamide in various experimental seizure models in mice.

This study focused on the evaluation of anticonvulsant properties of isonicotinic acid benzylamide (iso-Nic-BZA) in numerous experimental seizure models (maximal electroshock [MES]-, bicuculline [BIC]-, pentylenetetrazole [PTZ]-, pilocarpine [PILO]-, alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid [AMPA]-, kainic acid [KA]- and N-methyl-d-aspartic acid [NMDA]-induced seizures). Moreover, acute adverse-effect profile of the agent with respect to impairment of motor coordination was assessed in animals subjected to the chimney test. The evaluation of time-course and dose-response relationships for iso-Nic-BZA provided evidence that the compound produced the peak to maximum antielectroshock action and acute adverse effects at 5min after its systemic (i.p.) administration. Iso-Nic-BZA exerted a clear-cut anticonvulsant action against maximal electroshock-induced seizures in mice and its ED(50) value was 70.6 (56.4-88.4)mg/kg. The assessment of acute adverse effects in the chimney test revealed that the agent produced acute neurotoxic effects and its TD(50) value was 135.6 (108.8-169.0)mg/kg. Additionally, iso-Nic-BZA showed the anticonvulsant activity in numerous chemically-induced seizures (AMPA-, BIC-, KA-, and PTZ-evoked clonic convulsions), remaining virtually ineffective (at doses up to 200mg/kg) in PILO- and NMDA-induced seizures in mice. Based on this study, one can conclude that iso-Nic-BZA due to the short time to peak of its maximum anticonvulsant effects (5min after its i.p. administration), deserves more attention as a potential antiepileptic drug for patients in status epilepticus.