Oral contraceptives Co-administration of rufinamide 800 mg b. i. d. and a combined oral contraceptive (ethinyloestradiol 35 μ g and norethindrone 1 mg) for 14 days resulted in a mean decrease in the ethinyl estradiol AUC0-24 of 22% and in norethindrone AUC0-24 of 14%.