I. The modulatory effect in genotoxic responses due to age and duration of PHT-therapy in epileptic patients

Sister chromatid exchange (SCE) frequency has been studied from the peripheral blood lymphocyte cultures of 42 epileptic patients on the anticonvulsant drug phenytoin (PHT) for 3 months and their follow-up (6 and 9 months), of 33 epileptics who had not started therapy (PHT-untreated), and of 40 normal healthy controls, all in the same age group, i.e., 10-30 years. PHT-treated epileptic patients at all three durations of therapy (3, 6, and 9 months) showed higher SCE frequency (P < 0.001) than healthy controls and PHT-untreated patients. There was no significant difference in SCE frequency between control and PHT-untreated patients, suggesting that disease is not associated with an increased frequency of SCEs. The frequency of SCEs seems to be influenced by an age factor, when older treated patients (21-30 years) showed higher SCE frequencies at 3 and 6 months (P < 0.001) and 9 months (P < 0.05) than the younger age group (10-20 years). SCE frequency increased linearly with the duration of therapy, i.e., from 3 months to 9 months. No correlation was found between SCE frequency and sex with respect to controls, PHT-untreated, and PHT-treated subjects. In conclusion, the modulating effect on SCE frequencies elicited by age and duration of therapy has been clearly demonstrated by SCE mean analysis. Teratogenesis Carcinog. Mutagen. 21:135-149, 2001.