Mutagenic potential of anticonvulsant diphyenylhydantoin (DPH) on human lymphocytes in vitro.

Diphenylhydantoin (DPH)-treated human peripheral blood cultures were examined for sister chromatid exchange (SCE) frequency and mitotic index. A significantly enhanced SCE frequency in DPH-treated cultures was observed at a 15 micrograms/ml concentration (10-20 micrograms/ml DPH therapeutic range) and above. These results suggest an enhanced SCE response of lymphocytes in the therapeutic blood level of DPH. A significant linear fall in mitotic index was observed with increasing DPH concentrations. It is postulated that even in therapeutic doses DPH possibly affects nucleic acid metabolism.