Hyperhomocysteinaemia is a risk factor of atherosclerosis. Homocysteine is an experimental convulsant. Various drugs can influence homocysteine levels. The aim of this study was to investigate the effect of antiepi- leptic drugs on plasma total homocysteine. 64 patients suffering from different types of epilepsy were divided into 3 comparable age groups: „phenytoin“ group (n = 20; 13 men), „carbamazepine“ group (n = 26; 12 men), „valproic acid“ group (n = 18; 9 men). The results were compared with those of the healthy control group (n = 26; 12 men). Plasma total homocysteine (tHcy), vitamins [serum and RBC (red blood cell) folate, plasma vitamin B6 and serum vitamin B12], serum levels of antiepileptic drugs, serum creatinine, blood glucose, liver enzymes and lipid parameters were determined. The mean tHcy in the „phenytoin“ (13.6 ± 4.1 mmol/l) and „carbamazepine“ group (16.5 ± 11+.4 mmol/l) were significantly higher than in the control group (10.9 ± 2.0 mmol/l) (p<0.05) and „valproic acid“ group (8.6 ± 2.1 mmol/l) (p<0.005). Mean RBC folate in the „phenytoin“ group (555.5 ± 224.4 nmol/ml) and „carbamazepine“ group (651.6 ± 395.2 nmol/ml) were lower compared with the control group (733.9 ± 187.0 nmol/ml) (p<0.005) and „valproic acid“ group (847.8 ± 307.9 nmol/ml (p<0.005). In the „carbamazepine“ group levels of serum folate (13.7 ± 6.9 nmol/l) were significantly lower than in the „valproic acid“ group (18.4 ± 7.8 nmol/l) (p<0.05). Antiepileptic drug treatment (phenytoin, carbamazepine) may increase plasma concentrations of total homo- cysteine. As the cause of hyperhomocysteinaemia we assume folate deficiency – c ofactor in the remethylation of homocysteine. The significant role of other vitamins (B6, B12) was not elucidated in this study.

        Key words: homocysteine, hyperhomocysteinaemia, vitamins, anticonvulsants, phenytoin, carbamazepine.