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

Sister chromatid exchange (SCE) frequency has been studied from the periphe ral blood lymphocyte cultures of 42 epileptic patients on the anticonvulsan t drug phenytoin (PHT) for 3 months and their follow-up (6 and 9 months), o f 33 epileptics who had not started therapy (PHT-untreated), and of 40 norm al healthy controls, all in the same age group, i.e., 10-30 years. PHT-trea ted epileptic patients at all three durations of therapy (3, 6, and 9 month s) showed higher SCE frequency (P < 0.001) than healthy controls and PHT-un treated patients. There was no significant difference in SCE frequency betw een control and PHT-untreated patients, suggesting that disease is not asso ciated 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) s howed 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 l inearly with the duration of therapy, i.e., from 3 months to 9 months. No c orrelation was found between SCE frequency and sex with respect to controls , PHT-untreated, and PHT-treated subjects. In conclusion, the modulating ef fect on SCE frequencies elicited by age and duration of therapy has been cl early demonstrated by SCE mean analysis. (C) 2001 Wiley-Liss, Inc.