The interaction of chlordiazepoxide and sodium valproate in the nucleus accumbens of the rat

A New Sensitive Fluorescence Sensor and Photocatalyst for Determination and Degradation of Sodium Valproate Using g-C3N4@Fe3O4@CuWO4 Nanocomposite and FCCD Optimization

In this research, carbon nitride nanocomposite coupled with Fe3O4 and CuWO4 was thermally synthesized and characterized by different techniques, including SEM, TEM, XRD, EDX, and FTIR. Due to sodium valproate's luminescence quenching of this nanocomposite, a reliable, accurate, sensitive, selective, and fast-acting sodium valproate assay was proposed. Optimization of this fluorescent sensor was carried out by the FCCD approach. In the optimum conditions, the plot of sodium valproate concentration versus nanocomposite fluorescence emission showed a linear response (R2 = 0.9918), with a range of 0-0.55 µM, the limit of detection (S/N = 3) equal to 0.85 nM and limit of qualification equal to 2.82 nM. Photocatalytic activity of g-C3N4@Fe3O4@CuWO4 (40%) nanocomposite exhibited a good potency to sodium valproate degradation. Active species of degradation including superoxide radicals, holes, and hydroxyl radicals were investigated using ammonium oxalate, benzoquinone, and 2-propanol to identify the mechanism of photodegradation action. The activity of benzoquinone in the photocatalytic process led to a reduction in the rate of analyte degradation, which indicates the prominent role of superoxide radicals compared to other species in the degradation process. The degradation rate of the analyte using the Fenton reagent was found to be around two times more than in the Fenton reagent-free process. The possible mechanism for the fluorescence sensor and photocatalytic degradation reaction was also discussed.

How chronically administered valproate increases chlordiazepoxide transfer through the blood-brain barrier

Sodium valproate (VPA) is a drug widely used in the treatment of epileptics often in association with benzodiazepines. Recent animal studies have shown that the addition of valproate increases diazepam levels in the cortex and the cerebellum (Hariton et al, 1985). The aim of our study was to determine the effect of VPA on the transfer of benzodiazepines through the blood-brain barrier. They were investigated using the intracarotid injection technique in rats as described by Oldendorf (1971). Our results show that the 14C-chlordiazepoxide brain extraction is significantly higher in rats on prolonged valproate treatment than in controls. With regard to plasma protein binding effects on chlordiazepoxide transport, our data indicate that a fraction of the protein-bound chlordiazepoxide could transfer from the intracapillary space to the brain tissue space because of enhanced drug dissociation from albumin in the brain microcirculation (Kd in vitro = 74.1 microM; Kd in vivo = 793.7 microM). Two distinct mechanisms can be deduced from this study: 1) chlordiazepoxide is displaced from HSA by valproate, 2) in addition, this fatty acid could increase drug permeation through the blood brain barrier (PS/F (chlordiazepoxide) = 0.60 in controls, PS/F (chlordiazepoxide) = 0.97 in treated rats). On the contrary, the washout of the benzodiazepine from the rat brain does not seem to be modified by the addition of valproate.

The role of GABA and excitatory amino acids in the development of the leptazol-induced epileptogenic EEG

The developing epileptogenic electroencephalogram (EEG), seen during the slow intravenous infusion of leptazol, is sensitive to various anticonvulsant drugs, particularly those known to augment the function of gamma-aminobutyric acid (GABA), such as clonazepam and sodium valproate, which specifically prolong the earlier wave-like (pre-spiking) phases. Thus, whilst antagonism of GABA may be responsible for spiking, the early wave-like phases may be due to GABA released in the cortex as a feedback control to delay spiking. Intravenous infusion of the GABA antagonists, bicuculline and picrotoxin, produced a developing EEG with spiking the first abnormal feature noted and no wave-like phase, like that seen with leptazol. Cortical superfusion of GABA during the infusion of leptazol, enhanced kand prolonged the wave-like phase, whilst bicuculline reduced it. Cortical superfusion of leptazol, picrotoxin or larger concentrations of bicuculline produced spiking but no wave-like activity. When leptazol and GABA were superfused together they produced wave-like activity similar to that seen during infusions of leptazol. Of the excitatory amino acid antagonists, only those active at receptors for N-methyl-D-aspartate (NMDA) influenced the EEG changes induced by leptazol. It is suggested that leptazol produces waves in the EEG by stimulating subcortical pathways to release GABA in the cortex and that spiking occurs as the cortex is further stimulated by GABA antagonism and the release of excitatory amino acids.

Effects of sodium valproate on diazepam: kinetic profiles in plasma, erythrocytes, and different brain areas in the rat

The kinetic profiles of diazepam (DZP) were investigated in plasma, erythrocytes, and discrete brain areas in the rat, and the effects of valproic acid (VPA), given as sodium valproate, on kinetic parameters were analyzed. The experiments were performed on two groups of rats treated daily for 15 days, the first receiving only DZP (5 mg/kg/day i.m.), the second treated with DZP (5 mg/kg/day i.m.) and VPA (200 mg/kg/day i.p.). Our results indicate that VPA influences the plasma-protein binding and erythrocyte levels of DZP, as well as its kinetic profile. These data are discussed with regard to the modifications observed in the different brain areas (cerebellum, hippocampus, whole cortex, and pons-medulla) during administration of VPA and DZP. The results presented in this study offer evidence that VPA exerts a peculiar action on the "impregnation" and kinetics of DZP in the CNS, and therefore these findings may be of importance in clinical pharmacology and treatment of epilepsies.