Homocysteine, folate, vitamin B-12 and vitamin B-6 in patients receiving antiepileptic drug monotherapy

We hypothesized that elevated plasma homocysteine concentrations (hyperhomo cysteinemia) exist in patients receiving antiepileptic drugs (AED), and a l ong-term administration of AED may result in an increased risk of occlusive vascular disease in these patients. A total of 62 patients who received AE D monotherapy (phenytoin, lamotrigine, carbamazepine or valproate) particip ated in this study. Blood concentrations of homocysteine, folate, vitamin B -12 and pyridoxal-5'-phosphate (PLP, a coenzyme form of vitamin S-6) were m easured, and thermolabile genotypes of 5,10-methylenetetrahydrofolate reduc tase (MTHFR) were also determined. Of 62 patients, only seven (11.4%) had h yperhomocysteinemia. Of 20 patients who received phenytoin, three (15.0%) h ad hyperhomocysteinemia, whereas 85% of these had plasma folate concentrati ons below the normal range. However, erythrocyte folate concentrations were abnormally low in only 25% of the patients who received phenytoin. Valproa te administration increased serum vitamin B-12 concentrations. Over 55% of the entire patients had PLP concentrations below the normal range, although the reason is unknown. Only three patients had the homozygous thermolabile genotype of MTHFR; therefore, meaningful statistical analysis was not poss ible in this study. However, one patient with homozygous genotype who recei ved phenytoin therapy had hyperhomocysteinemia with poor folate nutritional status, and the other two had normal homocysteine concentrations with norm al folate status. Our data suggest that hyperhomocysteinemia is not a serio us clinical concern in epileptic patients when folate nutriture is adequate . (C) 2000 Elsevier Science B.V. All rights reserved.