Characterization in Inhibitory Effectiveness of Carbamazepine in Voltage-Gated Na+ and Erg-Mediated K+ Currents in a Mouse Neural Crest-Derived (Neuro-2a) Cell Line.

Carbamazepine (CBZ, Tegretol®) is an anticonvulsant used in the treatment of epilepsy and neuropathic pain; however, several unwanted effects of this drug have been noticed. Therefore, the regulatory actions of CBZ on ionic currents in electrically excitable cells need to be reappraised, although its efficacy in suppressing voltage-gated Na+ current (INa) has been disclosed. This study was undertaken to explore the modifications produced by CBZ on ionic currents (e.g., INa and erg-mediated K+ current [IK(erg)]) measured from Neuro-2a (N2a) cells. In these cells, we found that this drug differentially suppressed the peak (transient, INa(T)) and sustained (late, INa(L)) components of INa in a concentration-dependent manner with effective IC50 of 56 and 18 µM, respectively. The overall current-voltage relationship of INa(T) with or without the addition of CBZ remained unchanged; however, the strength (i.e., ∆area) in the window component of INa (INa(W)) evoked by the short ascending ramp pulse (Vramp) was overly lessened in the CBZ presence. Tefluthrin (Tef), a synthetic pyrethroid, known to stimulate INa, augmented the strength of the voltage-dependent hysteresis (Hys(V)) of persistent INa (INa(P)) in response to the isosceles-triangular Vramp; moreover, further application of CBZ attenuated Tef-mediated accentuation of INa(P)'s Hys(V). With a two-step voltage protocol, the recovery of INa(T) inactivation seen in Neuro-2a cells became progressively slowed by adding CBZ; however, the cumulative inhibition of INa(T) evoked by pulse train stimulation was enhanced during exposure to this drug. Neuro-2a-cell exposure to CBZ (100 µM), the magnitude of erg-mediated K+ current measured throughout the entire voltage-clamp steps applied was mildly inhibited. The docking results regarding the interaction of CBZ and voltage-gate Na+ (NaV) channel predicted the ability of CBZ to bind to some amino-acid residues in NaV due to the existence of a hydrogen bond or hydrophobic contact. It is conceivable from the current investigations that the INa (INa(T), INa(L), INa(W), and INa(P)) residing in Neuro-2a cells are susceptible to being suppressed by CBZ, and that its block on INa(L) is larger than that on INa(T). Collectively, the magnitude and gating of NaV channels produced by the CBZ presence might have an impact on its anticonvulsant and analgesic effects occurring in vivo.

Comparison of the efficacy of Tegatard and Tegretol as a monotherapy in patients with focal seizure with or without secondary generalization.

BACKGROUND: Carbamazepine is a first line treatment for focal epilepsy. Tegretol and Tegatard are two trade name of Carbamazepine. Tegretol is produced by Novartis Pharmaceutical Company, Switzerland. Recently, Raha pharmaceutical Company in Iran has produced CBZ which trade named is Tegatard. Extended usage of Tegatard instead of Tegretol has economic benefits for Iranian families. In this clinical trial, we aimed to compare therapeutic efficacy and safety of Tegretol and Tegatard in patients suffering from focal seizures with or without secondary generalization. METHODS: 200 patients with provoked or non-provoked focal seizure with or without secondary generalization were screened and 180 patients were fulfilled the criteria to enter this double blinded clinical trial study. Patients were divided into two groups, the first group (A) received Tegretol and the second group (B) Tegatard. Carbamazepine (CBZ) was prescribed with doses 10-20 mg/kg every 12 hours by neurologists. The patients were visited after 1, 3 and 6 months and the side effects and lab data in patients were investigated. RESULTS: Patients were divided into two groups, 88 patients in group A (Tegretol) (50 males and 38 females) and 92 in group B (Tegatard) (51 males and 41 females). Mean age of patients was 35.39±11.17 years. There was no significant difference according to age and gender, Carbamazepine dosage, EEG recording, neuroimaging change and adverse effects of antiepileptic drug between two groups (P>0.05). Regarding the drug efficacy, in group A and B, 60 (68%) and 58 (63%) patients were seizure free after 6 month follow up; respectively. The differences between two groups were not statistically significant (P value =0.46). CONCLUSION: Tegatard is an effective drug with similar efficacy, similar side effects and cost-effectiveness compared with Tegretol and could be used widely when indicated.

Bioequivalencia de una formulación cubana de carbamazepina con el producto líder / Bioequivalent of a Cuban formula of Carbamazepine with the leader product

Se demostró la intercambiabilidad terapéutica mediante un estudio de bioequivalencia en 25 voluntarios sanos de una formulación cubana de carbamazepina de 200 mg con respecto al producto innovador (Tegretol®), en condiciones de administración a dosis única; el diseño experimental fue cruzado a doble ciegas y aleatorizado; el periodo de lavado fue de 15 días. Las extracciones para la obtención del plasma, se realizaron a las 0; 0,5; 1; 1,5; 2; 3; 4; 6; 8; 10; 12; 16; 20; 24; 48; 72; 96 y 120 h. Para el análisis se empleó un método analítico por cromatografía líquida de alta eficiencia, isocrático en fase reversa con detección ultravioleta. Se estimaron mediante técnicas no compartimentales los parámetros farmacocinéticos (AUC0-t, AUCt-¥, Cmax, Tmax y T1/2) representativos de la biodisponibilidad en magnitud y velocidad. Sobre la base de los resultados estadísticos, ambas formulaciones resultaron bioequivalentes.

It was possible to demonstrate the therapeutic interchange level by means of a bioequivalence study in 25 healthy volunteers of a Cuban formula of Carbamazepine(200 mg) according to the innovative product (Tegretol®) for a administration of unique dose; the experimental design was of crossed, double-blind and random type; washing period was of 15 days. Extractions for plasma obtaining were performed at 0, 0,5, 1, 1,5, 2, 3, 4, 6, 8, 10, 12, 16, 20, 24, 48, 72, 96 and 120 hours. In analysis we used an analytical method by high performance liquid chromatography, isocratic type in reverse phase with UV detection. By means of non-compartment techniques pharmacokinetic parameters (AUC0-t, AUC t-¥, Cmax, Tmax, and T½) were estimated, which are representative of bioavailability in magnitude and speed. On the base of statistical results, both formulae were bioequivalent.

Bioequivalencia de una formulación cubana de carbamazepina con el producto líder / Bioequivalent of a Cuban formula of Carbamazepine with the leader product

Se demostró la intercambiabilidad terapéutica mediante un estudio de bioequivalencia en 25 voluntarios sanos de una formulación cubana de carbamazepina de 200 mg con respecto al producto innovador (Tegretol®), en condiciones de administración a dosis única; el diseño experimental fue cruzado a doble ciegas y aleatorizado; el periodo de lavado fue de 15 días. Las extracciones para la obtención del plasma, se realizaron a las 0; 0,5; 1; 1,5; 2; 3; 4; 6; 8; 10; 12; 16; 20; 24; 48; 72; 96 y 120 h. Para el análisis se empleó un método analítico por cromatografía líquida de alta eficiencia, isocrático en fase reversa con detección ultravioleta. Se estimaron mediante técnicas no compartimentales los parámetros farmacocinéticos (AUC0-t, AUCt-¥, Cmax, Tmax y T1/2) representativos de la biodisponibilidad en magnitud y velocidad. Sobre la base de los resultados estadísticos, ambas formulaciones resultaron bioequivalentes(AU)

It was possible to demonstrate the therapeutic interchange level by means of a bioequivalence study in 25 healthy volunteers of a Cuban formula of Carbamazepine(200 mg) according to the innovative product (Tegretol®) for a administration of unique dose; the experimental design was of crossed, double-blind and random type; washing period was of 15 days. Extractions for plasma obtaining were performed at 0, 0,5, 1, 1,5, 2, 3, 4, 6, 8, 10, 12, 16, 20, 24, 48, 72, 96 and 120 hours. In analysis we used an analytical method by high performance liquid chromatography, isocratic type in reverse phase with UV detection. By means of non-compartment techniques pharmacokinetic parameters (AUC0-t, AUC t-¥, Cmax, Tmax, and T½) were estimated, which are representative of bioavailability in magnitude and speed. On the base of statistical results, both formulae were bioequivalent(AU)