Evaluation of Carbamazepine Pharmacokinetic Profiles in Mice with Kainic Acid-Induced Acute Seizures

Abstract

Approximately 30% of epileptic patients do not respond to the usual antiepileptic drugs (AEDs), representing a major problem associated with increased morbidity and mortality. 1) The underlying mechanisms are not completely understood; it has been believed that mechanisms leading to AEDs resistance are most likely complex network phenomena including development of tolerance to antiepileptic drugs' action or alterations in drug targets based on pharmacogenomic factor. 2) Among various transporters, P-glycoprotein (P-gp) has been identified as being important regulators of bioavailabily of drugs, which is located in the endothelial cells of the blood-brain barrier and/or the small intestine, and its outwardly directed active efflux mechanisms from the blood to intestinal lumen or cerebral cell to the blood appear to act as a second line defense mechanism. P-gp, gene product of the multidrug resistance 1 (MDR1 gene ), limiting brain accumulation and intestinal absorption of many lipophilic drugs. [3][4][5][6] Because of lipophilic properties, some AEDs have been established as a substrate of P-gp, and P-gp participates in the regulation of their extracellular brain concentrations. 7) In case of carbamazepine (one of major AEDs), however, there are contradictions among the papers on the relationship between P-gp function and CBZ disposition. One reports concluded that CBZ is not a substrate for P-gp using mdr1a/1b(Ϫ/Ϫ) knockout mice or P-gp transfected cell lines, 8,9) and the other reports concluded that CBZ is appropriate substrate for P-gp using P-gp transfected cell lines or normal rats with a microdialysis method. 2,7) In addition, study on pharmacoresistance in patients with epilepsy using a radio-labeled P-gp substrate (verapamil) and positron-emission tomography (PET) method showed that regionally enhanced P-gp activity in brain might contribute to drug resistance in some patients with temporal lobe epilepsy. 10) These reports indicate that there is complexity to explain the relationship between CBZ therapy and drug resistance through the P-gp function, and it is not known to what extent the P-gp is involved in the transport of CBZ in a living body in epileptic patients. Therefore, it is important that confirmation of Pgp function during seizure in the living organism should be conducted to relief contradictions among those literatures. (Wayne NJ, U.S.A.) and Nikko Chemical Co., Ltd. (Tokyo, Japan). As a primary antibody for P-glycoprotein (P-gp), C219 antibody was purchased from Calbiochemi, Co. (CA, U.S.A.). As a secondary antibody, anti-mouse IgG, immunestar HRP chemiluminescent (ECL) kit was purchased from Bio-Rad Laboratory, Inc. (CA, U.S.A.). All other chemicals were of the highest grade available. MATERIALS AND METHODS MaterialsAnimals All animal experiments were performed in accordance with the Guidelines for Animal Experiments of Kyoto Pharmaceutical University. Male ddy mice (6 weeks old, 28-35 g) were purchased from Japan SLC Inc. (Hamamatsu, Japan), and housed in a temperature and humiditycontrol...

Knockout of P-glycoprotein does not alter antiepileptic drug efficacy in the intrahippocampal kainate model of mesial temporal lobe epilepsy in mice

“…Similarly, increased hippocampal Pgp protein expression was found in mice and rats after systemic kainate administration (Zhang et al, 1999;Seegers et al, 2002;Volk et al, 2004;Nishimura et al, 2008). Brain levels of carbamazepine were significantly lower at time of Pgp overexpression following systemic kainate injection in mice (Nishimura et al, 2008).…”

Tissue-specific alterations in expression and function of P-glycoprotein in streptozotocin-induced diabetic rats

“…This hypothesis is supported by a previous report [33] . Rho123, a typical substrate of P-GP, has been widely used as an index of P-GP mediated transport in in vitro and in vivo studies [34][35][36][37][38][39][40] . In the present study, Rho123 also served as a marker for evaluating P-GP function.…”

Evaluating an Etiologically Relevant Platform for Therapy Development for Temporal Lobe Epilepsy: Effects of Carbamazepine and Valproic Acid on Acute Seizures and Chronic Behavioral Comorbidities in the Theiler’s Murine Encephalomyelitis Virus Mouse Model

“…Because physical handling was required to perform the twice-daily drug dosing, which could also provoke a handling-induced seizure, animals were also monitored during the drug-dosing session for the presence or absence of any provoked, for example, handling-induced, seizures (i.e., dosing). Twice-daily handling sessions occurred 30 minutes after drug dosing; this time best suited the pharmacokinetic profile of the ASDs under evaluation [in mice, VPA T 1/2 5 30 minutes (Ben-Cherif et al, 2013); CBZ T 1/2 5 60 minutes (Nishimura et al, 2008)]. Each drug-dosing session was separated by at least 7 hours, occurring daily at 9:00 AM and 4:00 PM.…”

“…We conducted this in-depth evaluation of the seizure burden and severity during the observation sessions pre-and postdrug administration (dosing and handling, Fig. 4, G and H, respectively), theoretically when the ASDs under investigation were at minimal and peak plasma concentrations, respectively (Nishimura et al, 2008;Ben-Cherif et al, 2013). This analysis sought to determine whether the therapeutic doses of these ASDs could alter seizure burden before and after drug administration (see Fig.…”