Summary Purpose Lacosamide (LCM, Vimpat) is an anticonvulsant with a unique mode of action. This provides lacosamide with the potential to act additively or even synergistically with other antiepileptic drugs (AEDs). The objective of this study was to determine the presence of such interactions by isobolographic analysis. Methods The anticonvulsant effect of LCM in combination with other AEDs including carbamazepine (CBZ), phenytoin (PHT), valproate (VPA), lamotrigine (LTG), topiramate (TPM), gabapentin (GBP), and levetiracetam (LEV) at fixed dose ratios of 1:3, 1:1, and 3:1, was evaluated in the 6‐Hz–induced seizure model in mice. In addition, the impact of the combinations of LCM with the other AEDs on motor coordination was assessed in the rotarod test. Finally, AED concentrations were measured in blood and brain to evaluate potential pharmacokinetic drug interactions. Key Findings All studied AEDs produced dose‐dependent anticonvulsant effects against 6‐Hz–induced seizures. Combinations of LCM with CBZ, LTG, TPM, GBP, or LEV were synergistic. All other LCM/AED combinations displayed additive effects with a tendency toward synergism. Furthermore, no enhanced adverse effects were observed in the rotarod test by combining LCM with other AEDs. No pharmacokinetic interactions were seen on brain AED concentrations. Coadministration of LCM and TPM led to an increase in plasma levels of LCM, whereas the plasma concentration of PHT was increased by coadministration of LCM. Significance The synergistic anticonvulsant interaction of LCM with various AEDs, without exacerbation of adverse motor effects, highlights promising properties of LCM as add‐on therapy for drug refractory epilepsy.

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We investigated the role of two cytokines, IL-1β and TNF-α, in the development of absence seizures using a genetic model of absence epilepsy in WAG/Rij rats. We administered these cytokines to animals systemically and measured the number of spike-wave discharges (SWDs) in the EEG. We also coadministered IL-1β with the GABA reuptake inhibitor tiagabine and measured the levels of IL-1β and TNF-α in the brain and blood plasma of 2-, 4-, and 6-month-old WAG/Rij rats and animals that served as a non-epileptic control (ACI). We found that IL-1β induced a significant increase in SWDs 2-5 h after administration, while TNF-α enhanced SWDs much later. Both cytokines enhanced passive behavior; body temperature was elevated only after TNF-α. The action of tiagabine was potentiated by earlier IL-1β injection, even when IL-1β was no longer active. Young WAG/Rij rats showed higher levels of TNF-α in blood serum than young ACI rats; the effects in the brain tended to be opposite. The marked differences in timing of the increase in SWDs suggest different time scales for the action of both cytokines tested. It is proposed that the results found after TNF-α are due to the de novo synthesis of IL-1β. TNF-α may possess neuroprotective effects. IL-1β might increase GABAergic neurotransmission. The changes in the efficacy of antiepileptic drugs related to changes in the cytokine systems may have some clinical relevance.

Acute experiments on rats showed that the ED100 of NMDA for induction of clonic convulsions was 0.53 microgram, while the ED100 of NMDA for inducing tonic extension of the forelimbs was 5.02 micrograms/animal. Determination of these parameters after administration of delta-sleep-inducing peptide (100 micrograms/kg, i.p.) revealed 2.3- and 4.46-fold increases. These results provide evidence for a neuroprotective role of delta-sleep-inducing peptide in relation to excitatory amino acid receptor agonists.

The efficacy of phenobarbital (PB) and phenytoin (PHT) was evaluated against the convulsions in chemically (picrotoxin, PTX) kindled rats. Two protocols were used: assessment of seizures immediately after the completion of the kindling procedure and after the 2-week postkindling PTX-free period, as compared with acute PTX seizures. Kindled convulsions were more sensitive than acute PTX seizures to the antiepileptic action of PB and PHT. On the other hand, the "postkindling state" was characterized by the enhancement of the severity of the convulsions in comparison with both kindled and acute PTX seizures and dramatic increase in the resistance to the action of antiepileptic drugs (AEDs). It is concluded that the two paradigms--kindling proper and "postkindling"--could be applied as models for AED-sensitive and AED-resistant animal epilepsy models correspondingly.