Plasma total glutathione concentrations in epileptic patients taking anticonvulsants

Glutathione plays an important role in protecting cells against oxidative damage as a free radical scavenger. Since several anticonvulsants have been associated with decreased intrahepatic glutathione levels, we investigated plasma concentrations of total glutathione (including reduced and oxidized forms, tGSH=GSH+GSSG) in 45 epileptic patients taking anticonvulsant drugs. Plasma tGSH concentrations were significantly lower than in controls in patients treated with carbamazepine or phenytoin monotherapy, or with multiple drugs. Plasma tGSH concentrations in patients treated with valproic acid and in patients treated with phenobarbital did not differ significantly from those in controls. In no patient group was a significant correlation evident between duration of treatment or drug concentration and plasma tGSH concentration. No significant differences in plasma total cysteine concentrations were found between any patient group and controls. We conclude that some anticonvulsant drugs can lower plasma tGSH levels, reflecting treatment-related oxidative stress.