[Antiepileptic drugs and oral contraceptives: preliminary note]

Several cases of unwanted pregnancy in women on oral contraception and utilizing also antiepileptic drugs have been reported in the literature. Such observation shows a metabolic interaction of the 2 types of drugs interaction which causes a diminished effectiveness of the estroprogestational agents. To investigate such interaction the authors have observed 10 women under treatment with idantoine for epilepsy and who were at the same time on oral contraception. 10 controls only on oral contraception were also observed. Results showed that ovulation was not suppressed in all cases in the first group of women while it was always suppressed in the second group. Moreover spotting and breakthrough bleeding appeared frequently in the first group. The mechanism of action of antiepileptics and contraceptive agents taken together is still not known. It is obvious that mechanical or topical contraception instead of hormonal would be more indicated for women on antiepileptic drugs.