Chromosome studies of bone marrow cells and peripheral blood lymphocytes from diphenylhydantoin-treated patients

In vivo cytogenetic activity of diphenylhydantoin in mice

Diphenylhydantoin was tested in vivo in mice using a variety of cytogenetic endpoints to evaluate its genotoxicity. Injected doses of 125, 250 and 500 mg/kg failed to increase the number of chromosome aberrations in marrow cells at 17 h post-treatment, and 37.5, 75 and 150 mg/kg doses were likewise ineffective at 36 h. SCEs were significantly increased by doses of 125 mg/kg (but not 250 mg) after 23 h and modestly, in relation to dose, at 42 h. No increase in the number of micronuclei among marrow PCEs was seen following single i.v. injections ranging from 0.1 to 20 mg/kg. Three daily i.p. injections of doses up to 70 mg/kg also failed to increase the number of micronuclei in either marrow or peripheral blood PCEs. Some cytotoxic effect was evident following relatively high doses.

Effect of anticonvulsants on human chromosomes. 2. In vitro studies

The effects of 3 anticonvulsant drugs (diphenylhydantoin, ethosuximide, and phenobarbital) on human peripheral lymphocytes in vitro were studied. The rate of chromosomal aberrations induced by the 3 anticonvulsants was significantly increased from the first concentration analyzed, similar to half the therapeutic serum concentration. These findings are compared with other previous reports.

Diphenylhydantoin and mitotic spindle abnormalities in cultured mouse and human cells

The present study demonstrates that the antiepileptic drug diphenylhydantoin (DPH) is capable of inducing aneuploidy but not structural aberrations in cultured mouse embryonic fibroblasts. A high concentration of 200 micrograms/ml was found to increase the percentage of hyperdiploidy from 4.8 (control) to 16.0. The treatment was found to increase mitotic indices as a consequence of a mitotic-arresting action of the drug. These effects are probably due to the effect of the drug on the structure of the mitotic apparatus. Abnormal cell divisions and mitotic disturbance were found to increase in a dose-dependent manner after DPH treatment. In a parallel study, human amnion cells were found to show similar response to DPH treatment.

Chromosomal studies of peripheral blood from epileptic patients treated with phenobarbital and/or diphenylhydantoin

Chromosome studies were carried out on the peripheral blood of 26 epilepsy patients treated with phenobarbital and/or diphenylhydantoin, on ten healthy controls and on eight untreated epileptic controls. There was a significant increase in the individual numbers of sister chromatid exchanges per metaphase for all the patients treated with drugs compared with the mean of the pooled values from all the controls. There was no significant increase in the number of chromosome aberrations in the treated patients compared with the controls. There were very few structural aberrations in either the treated patients or the controls.

The effect of diphenylhydantoin on the frequency of micronuclei in bone-marrow polychromatic erythrocytes of mice

Using the micronucleus test to evaluate the mutagenic effect of 5,5-diphenylhydantoin (DPH) on bone marrow polychromatic erythrocytes, male Balb-C mice were treated with the drug in single and multiple injection tests. A significant increase in the frequency of micronucleated polychromatic erythrocytes (MPE), P less than 0.05, was found when the mice received a single injection of DPH at doses of 0.5 and 1.0 mg/kg, and this frequency did not increase at higher doses. When mice were treated 3 times, at 24-h intervals, with 1.0 mg/kg of DPH, a significant increase in MPE was also observed (P less than 0.05) but this was lower than when they received a single injection of the same dose. A cytotoxic effect of NaOH, 0.1 N, which was used as solvent, was also observed either when alone or when DPH (1.0 mg/kg) was injected 3 times. This effect was comparable to the one produced by mitomycin C (MMC) at a dose of 0.5 mg/kg.

Sister chromatid exchange (SCE) and structural chromosome aberration in mutagenicity testing

Data from previous studies published on the induction by mutagens of sister chromatid exchanges (SCEs) and structural chromosome damage were compared qualitatively and quantitatively. Although a good correlation between the incidence of both cytogenetic phenomena has been pointed out in many previous publications, about 30% of the agents for which comparable data were available yielded non-corresponding qualitative results concerning both indicator effects. However, even in groups with good qualitative agreement distinct quantitative differences indicated different molecular mechanisms of the formation of SCEs and breaks. Additional information supporting the importance of these differences for the validity of both indicator systems has been derived from the results obtained using strong clastogens exhibiting a low or no SCE-inducing activity and vice versa, from special observations on chromosomal breakage syndromes, and from studies on the action of known co- and anti-clastogens on SCE-induction by chemical mutagens. As a result, it has been suggested that the SCE-technique should be considered as a valuable additional method for cytogenetic mutagenicity testing, which, however, is not adequate to replace the classical methods of analysis of structural chromosome damage.