Ethosuximide dosage regimens.

A study was conducted in 9 children with petit mal epilepsy to compare the plasma levels of ethosuximide after divided daily administration with those after single daily administration. The children received their previously established dose in divided doses for 4 wk, single morning doses for 4 wk, and again in divided doses for 4 wk. None of the children suffered petit mal seizures during the study. Three had grand mal seizures but the frequency did not differ between the dosage regimens. Plasma levels during the single-dose period peaked more rapidly and fell more quickly than during the other periods, but mean levels remained in the therapeutic range. The mean half-life of the drug in these children was 29 hr. For reasons not understood, plasma levels generally were lower in the second divided dose period than in the other two periods. No adverse experiences were reported during the study. The data indicate that ethosuximide is clinically effective when given in a single daily dose. This regimen offers advantages in convenience and possibly in patient compliance.