Maria Kondrat-Wróbel

Effects of WIN 55,212-2 (a synthetic cannabinoid CB1 and CB2 receptor agonist) on the anticonvulsant activity of various novel antiepileptic drugs against 6 Hz-induced psychomotor seizures in mice

The purpose of this study was to determine the influence of WIN 55,212-2 mesylate (WIN-a non-selective cannabinoid CB1 and CB2 receptor agonist) on the anticonvulsant activity of various second- and third-generation antiepileptic drugs (i.e., gabapentin, lacosamide, levetiracetam, oxcarbazepine, pregabalin and tiagabine) in the mouse 6 Hz-induced psychomotor seizure model. Psychomotor seizures were evoked in albino Swiss mice by a current (32 mA, 6 Hz, 3s stimulus duration) delivered via ocular electrodes. Additionally, total brain antiepileptic drug concentrations were measured. Results indicate that WIN (5 mg/kg, administered i.p.) significantly potentiated the anticonvulsant action of gabapentin (P < 0.05) and levetiracetam (P < 0.01), but not that of lacosamide, oxcarbazepine, pregabalin or tiagabine in the mouse psychomotor seizure model. Moreover, WIN (2.5 mg/kg) had no significant effect on the anticonvulsant activity of all tested antiepileptic drugs in the 6 Hz test in mice. Measurement of total brain antiepileptic drug concentrations revealed that WIN (5 mg/kg) had no impact on gabapentin or levetiracetam total brain concentrations, indicating the pharmacodynamic nature of interaction between these antiepileptic drugs in the mouse 6Hz model. In conclusion, WIN in combination with gabapentin and levetiracetam exerts beneficial anticonvulsant pharmacodynamic interactions in the mouse psychomotor seizure model.

Assessment of the Combined Treatment with Umbelliferone and Four Classical Antiepileptic Drugs Against Maximal Electroshock-Induced Seizures in Mice

Background/Aims: The aim of this study was to determine the effects of umbelliferone (7-hydroxycoumarin; UMB) on the anticonvulsant potency of four classical antiepileptic drugs (carbamazepine (CBZ), phenytoin (PHT), phenobarbital (PB) and valproate (VPA)) in the mouse maximal electroshock-induced seizure (MES) model. Results: UMB administered systemically intraperitoneally (ip) in a dose of 150 mg/kg significantly elevated the threshold for maximal electroconvulsions (p < 0.05) in mice. Moreover, UMB (150 mg/kg) co-administered with PB and VPA significantly enhanced the anticonvulsant potency of these drugs by reducing their median effective doses (ED50 values) from 35.39 to 21.78 mg/kg (p < 0.01) for PB, and from 281.4 to 215.5 mg/kg (p < 0.01) for VPA. In contrast, UMB (150 mg/kg, ip) had no significant effect on the antiseizure activity of CBZ and PHT in the mouse MES model. Neither total brain PB, nor total brain VPA concentrations were altered after ip administration of UMB, indicating a pharmacodynamic nature of interactions between the tested drugs. Conclusions: The selective potentiation of the anticonvulsant potency of PB and VPA by UMB, and lack of any pharmacokinetic interactions between drugs, make the combinations of UMB with PB or VPA worthy of consideration for epileptic patients who are refractory to standard antiepileptic treatment.

Beneficial Combination of Lacosamide with Retigabine in Experimental Animals: An Isobolographic Analysis

Background/Aim: To isobolographically determine the types of interactions that occur between retigabine and lacosamide (LCM; two third-generation antiepileptic drugs) with respect to their anticonvulsant activity and acute adverse effects (sedation) in the maximal electroshock-induced seizures (MES) and chimney test (motor performance) in adult male Swiss mice. Methods: Type I isobolographic analysis for nonparallel dose-response effects for the combination of retigabine with LCM (at the fixed-ratio of 1:1) in both the MES and chimney test in mice was performed. Brain concentrations of retigabine and LCM were measured by high-pressure liquid chromatography (HPLC) to characterize any pharmacokinetic interactions occurring when combining these drugs. Results: Linear regression analysis revealed that retigabine had its dose-response effect line nonparallel to that of LCM in both the MES and chimney tests. The type I isobolographic analysis illustrated that retigabine combined with LCM (fixed-ratio of 1:1) exerted an additive interaction in the mouse MES model and sub-additivity (antagonism) in the chimney test. With HPLC, retigabine and LCM did not mutually change their total brain concentrations, thereby confirming the pharmacodynamic nature of the interaction. Conclusion: LCM combined with retigabine possesses a beneficial preclinical profile (benefit index ranged from 2.07 to 2.50) and this 2-drug combination is worth recommending as treatment plan to patients with pharmacoresistant epilepsy.

Isobolographic additivity among lacosamide, lamotrigine and phenobarbital in a mouse tonic-clonic seizure model

BACKGROUND Epilepsy is a serious neurological disease affecting about 1% of people worldwide (65 million). Seizures are controllable with antiepileptic drugs (AEDs) in about 70% of epilepsy patients, however, there remains about 30% of patients inadequately medicated with these AEDs, who need a satisfactory control of their seizure attacks. For these patients, one of the treatment options is administration of 2 or 3 AEDs in combination. OBJECTIVES To determine the anticonvulsant effects of a combination of 3 selected AEDs (i.e., lacosamide - LCM, lamotrigine - LTG and phenobarbital - PB) at the fixed-ratio of 1:1:1 in a mouse maximal electroshock-induced (tonic-clonic) seizure model by using isobolographic analysis. MATERIAL AND METHODS Seizure activity was evoked in adult male albino Swiss mice by a current (sinewave, 25 mA, 500 V, 50 Hz, 0.2 s stimulus duration) delivered via auricular electrodes. Type I isobolographic analysis was used to detect interaction for the 3-drug combination. RESULTS With type I isobolographic analysis, the combination of LCM, LTG and PB (at the fixed-ratio of 1:1:1) exerted additive interaction in the mouse maximal electroshock-induced (tonic-clonic) seizure model. CONCLUSIONS The combination of LCM with LTG and PB produced additive interaction in the mouse tonicclonic seizure model, despite various molecular mechanisms of action of the tested AEDs.

Effects of arachidonyl-2’-chloroethylamide (ACEA) on the protective action of various antiepileptic drugs in the 6-Hz corneal stimulation model in mice

Accumulating evidence indicates that cannabinoid CB1 receptor ligands play a pivotal role in seizures, not only in preclinical studies on animals, but also in clinical settings. This study was aimed at characterizing the influence of arachidonyl-2′-chloroethylamide (ACEA–a selective cannabinoid CB1 receptor agonist) co-administered with phenylmethylsulfonyl fluoride (PMSF) on the anticonvulsant potency of various antiepileptic drugs (clobazam, lacosamide, levetiracetam, phenobarbital, tiagabine and valproate) in the 6-Hz corneal stimulation model. Psychomotor seizures in male albino Swiss mice were evoked by a current (32 mA, 6 Hz, 3 s stimulus duration) delivered via corneal electrodes. Potential adverse effects produced by the antiepileptic drugs in combination with ACEA+PMSF were assessed using the chimney test (motor performance), passive avoidance task (remembering and acquisition of learning), and grip-strength test (muscular strength). Brain concentrations of antiepileptic drugs were measured by HPLC to exclude any pharmacokinetic contribution to the observed effect. ACEA (5 mg/kg, i.p.) + PMSF (30 mg/kg, i.p.) significantly potentiated the anticonvulsant potency of levetiracetam (P<0.05), but not that of clobazam, lacosamide, phenobarbital, tiagabine or valproate in the 6-Hz corneal stimulation model. Moreover, ACEA+PMSF did not significantly affect total brain concentrations of levetiracetam in mice. No behavioral side effects were observed in animals receiving combinations of the studied antiepileptic drugs with ACEA+PMSF. In conclusion, the combined administration of ACEA+PMSF with levetiracetam is associated with beneficial anticonvulsant pharmacodynamic interaction in the 6-Hz corneal stimulation model. The selective activation of cannabinoid CB1 receptor-mediated neurotransmission in the brain may enhance levetiracetam-related suppression of seizures in epilepsy patients, contributing to the efficacious treatment of epilepsy in future.

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.

Comparison of the anticonvulsant potency of various diuretic drugs in the maximal electroshock-induced seizure threshold test in mice

BACKGROUND The coexistence of seizures and arterial hypertension requires an adequate and efficacious treatment involving both protection from seizures and reduction of high arterial blood pressure. Accumulating evidence indicates that some diuretic drugs (with a well-established position in the treatment of arterial hypertension) also possess anticonvulsant properties in various experimental models of epilepsy. OBJECTIVES The aim of this study was to assess the anticonvulsant potency of 6 commonly used diuretic drugs (i.e., amiloride, ethacrynic acid, furosemide, hydrochlorothiazide, indapamide, and spironolactone) in the maximal electroshock-induced seizure threshold (MEST) test in mice. MATERIAL AND METHODS Doses of the studied diuretics and their corresponding threshold increases were linearly related, allowing for the determination of doses which increase the threshold for electroconvulsions in drug-treated animals by 20% (TID20 values) over the threshold in control animals. RESULTS Amiloride, hydrochlorothiazide and indapamide administered systemically (intraperitoneally - i.p.) increased the threshold for maximal electroconvulsions in mice, and the experimentally-derived TID20 values in the maximal electroshock seizure threshold test were 30.2 mg/kg for amiloride, 68.2 mg/kg for hydrochlorothiazide and 3.9 mg/kg for indapamide. In contrast, ethacrynic acid (up to 100 mg/kg), furosemide (up to 100 mg/kg) and spironolactone (up to 50 mg/kg) administered i.p. had no significant impact on the threshold for electroconvulsions in mice. CONCLUSIONS The studied diuretics can be arranged with respect to their anticonvulsant potency in the MEST test as follows: indapamide > amiloride > hydrochlorothiazide. No anticonvulsant effects were observed for ethacrynic acid, furosemide or spironolactone in the MEST test in mice.

Synergistic interaction of levetiracetam with gabapentin in the mouse 6 Hz psychomotor seizure model – a type II isobolographic analysis

Abstract This study was aimed at characterizing the anticonvulsant effects of levetiracetam in combination with gabapentin, in the mouse 6 Hz psychomotor seizure model. Herein, psychomotor seizures were evoked in male albino Swiss mice by a current (32 mA, 6 Hz, 3 s stimulus duration) delivered via ocular electrodes. Type II isobolographic analysis was used to characterize the anticonvulsant interactions between the drugs in combination, for fixed-ratios of 1:1, 1:2, 1:5 and 1:10. The type II isobolographic analysis revealed that the combinations of levetiracetam with gabapentin for the fixed-ratios of 1:5 and 1:10 were supra-additive (synergistic; P<0.05) in terms of seizure suppression, while the combinations for the fixed-ratios of 1:1 and 1:2 were additive in the mouse 6 Hz psychomotor seizure model. We conclude that, as the combinations of levetiracetam with gabapentin for the fixed-ratios of 1:5 and 1:10 exerted supra-additive (synergistic) interaction in the mouse 6 Hz psychomotor seizure model, this may be considered as particularly favorable combinations in further clinical practice.

Effect of N-(m-bromoanilinomethyl)-p-isopropoxyphenylsuccinimide on the anticonvulsant action of four classical antiepileptic drugs in the mouse maximal electroshock-induced seizure model

Abstract The purpose of this study was to determine the effects of N-(m-bromoanilinomethyl)- p-isopropoxyphenylsuccinimide (BAM-IPPS - a new succinimide derivative) on the protective action of four classical antiepileptic drugs (AEDs: carbamazepine [CBZ], phenobarbital [PB], phenytoin [PHT] and valproate [VPA]) in the mouse maximal electroshock (MES)-induced tonic seizure model. Tonic hind limb extension (seizure activity) was evoked in adult male albino Swiss mice by a current (sine-wave, 25 mA, 500 V, 50 Hz, 0.2 s stimulus duration) delivered via ear-clip electrodes. BAM-IPPS administered (i.p.) at a dose of 150 mg/kg significantly elevated the threshold for electroconvulsions in mice (P<0.05). Lower doses of BAM-IPPS (50 and 100 mg/kg) had no significant impact on the threshold for electroconvulsions in mice. Moreover, BAM-IPPS (100 mg/kg) did not significantly affect the anticonvulsant potency of CBZ, PB, PHT and VPA in the mouse MES model. BAM-IPPS elevated the threshold for electroconvulsions in mice in a dosedependent manner. However, BAM-IPPS (100 mg/kg) did not affect the anticonvulsant action of various classical AEDs in the mouse MES model, making the combinations of BAM-IPPS with CBZ, PB, PHT and VPA neutral, from a preclinical point of view.

SYM 2206 (a potent non-competitive AMPA receptor antagonist) elevates the threshold for maximal electroshock-induced seizures in mice

Abstract The aim of this study was to determine the effect of SYM 2206 (a potent non-competitive AMPA receptor antagonist) on the threshold for maximal electroshock (MEST)-induced seizures in mice. Electroconvulsions were produced in mice by means of a current (sinewave, 50 Hz, maximum 500 V, strength from 4 to 14 mA, 0.2-s stimulus duration, tonic hind limb extension taken as the endpoint) delivered via ear-clip electrodes. SYM 2206 administered systemically (i.p.), 30 min before the MEST test, at doses of 2.5 and 5 mg/kg, did not alter the threshold for maximal electroconvulsions in mice. In contrast, SYM 2206 at doses of 10 and 20 mg/kg significantly elevated the threshold for maximal electroconvulsions in mice (P<0.01 and P<0.001). Linear regression analysis of SYM 2206 doses and their corresponding threshold increases allowed for the determination of threshold increasing doses by 20% and 50% (TID20 and TID50 values) that elevate the threshold in drug-treated animals over the threshold in control animals. The experimentally derived TID20 and TID50 values for SYM 2206 were 4.25 and 10.56 mg/kg, respectively. SYM 2206 dose-dependently increased the threshold for MEST-induced seizures, suggesting the anticonvulsant action of the compound in this seizure model in mice.