Polygonogram with isobolographic synergy for three-drug combinations of phenobarbital with second-generation antiepileptic drugs in the tonic–clonic seizure model in mice

Abstract

Background Combination therapy consisting of two or more antiepileptic drugs (AEDs) is usually prescribed for patients with refractory epilepsy. The drug–drug interactions, which may occur among currently available AEDs, are the principal criterion taken by physicians when prescribing the AED combination to the patients. Unfortunately, the number of possible three-drug combinations tremendously increases along with the clinical approval of novel AEDs. Aim To isobolographically characterize three-drug interactions of phenobarbital (PB) with lamotrigine (LTG), oxcarbazepine (OXC), pregabalin (PGB) and topiramate (TPM), the maximal electroshock-induced (MES) seizure model was used in male albino Swiss mice. Materials and method The MES-induced seizures in mice were generated by alternating current delivered via auricular electrodes. To classify interactions for 6 various three-drug combinations of AEDs (i.e., PB + TPM + PGB, PB + OXC + TPM, PB + LTG + TPM, PB + OXC + PGB, PB + LTG + PGB and PB + LTG + OXC), the type I isobolographic analysis was used. Total brain concentrations of PB were measured by fluorescent polarization immunoassay technique. Results The three-drug mixtures of PB + TPM + PGB, PB + OXC + TPM, PB + LTG + TPM, PB + OXC + PGB, PB + LTG + PGB and PB + LTG + OXC protected the male albino Swiss mice from MES-induced seizures. All the observed interactions in this seizure model were supra-additive (synergistic) (p < 0.001), except for the combination of PB + LTG + OXC, which was additive. It was unable to show the impact of the studied second-generation AEDs on total brain content of PB in mice. Conclusions The synergistic interactions among PB and LTG, OXC, PGB and TPM in the mouse MES model are worthy of being transferred to clinical trials, especially for the patients with drug resistant epilepsy, who would benefit these treatment options.

Antiseizure Effects of Scoparone, Borneol and Their Impact on the Anticonvulsant Potency of Four Classic Antiseizure Medications in the Mouse MES Model—An Isobolographic Transformation

“…Calculation of fractions of the drugs in mixture contributes to the proper classification of interactions between the studied drugs, as reported earlier [ 28 , 29 ]. Interactions observed in the mouse MES model were presented graphically by means of polygonograms for two-drug and three-drug mixtures, as reported earlier [ 43 , 44 ] The polygonogram is the simplest and quickest way to illustrate synergistic interactions among the tested combinations, and this method of presentation is widely applied in isobolographic studies [ 45 ].…”

“…The content of PB and VPA in the brain tissue of experimental animals was measured by fluorescence polarization immunoassay, as reported earlier [ 44 , 46 ]. Both PB and VPA were administered i.p.…”

Interactions among Lacosamide and Second-Generation Antiepileptic Drugs in the Tonic-Clonic Seizure Model in Mice

“…Similarly, the transformation of increasing doses of the three-drug mixtures for the respective combinations (in a constant ratio combination of 1:1:1) to the logarithms to the base 10, and the antiseizure activity produced by the three-drug combinations from the mouse MES model to probits of response, allowed for the calculation of the experimentally-derived median effective doses (ED 50 exp values ±S.E.M.) for the investigated three-drug combinations against tonic-clonic seizures in mice, as described earlier [ 17 , 23 , 24 , 26 , 28 , 30 ]. The number of mice used for the calculation of 5 ED 50 values for LCM, LTG, OXC, PGB, and TPM when administered alone was 136.…”

“…To date, several dual and triple combinations of ASMs have been tested in preclinical studies using the maximal electroshock-induced seizure (MES) test, which is thought to be a model of generalized tonic-clonic seizures in mice [ 17 ]. Although various ASMs can be theoretically combined together, taking into account their various molecular mechanisms of action, only experimental verification can assess the in vivo efficacy of ASMs in animals.…”

“…Understanding which combinations of ASMs are favorable will be essential for selecting the novel therapies for the patients with refractory epilepsy [ 20 ]. Of note, the studied 5 ASMs (LCM, LTG, OXC, PGB, and TPM) are effective in suppressing tonic-clonic seizures in both preclinical in vivo studies in mice [ 17 ] and clinical settings in humans [ 21 ].…”