Antiepileptics with oral contraceptives

Co-cyprindiol is a mixture of the anti-androgenic progestogen, cyproter-one acetate 2 mg, with ethinylestradiol 35 micrograms. It is used for the treatment of acne and moderately severe hirsutism in women who may also wish to use it as an oral contraceptive, and its contraceptive efficacy is expected to be reduced by the same hepatic enzyme inducers (see Table 28. r, (p.975)) that interact with conventional combined oral contraceptives. The precautions described in this section for the combined hormonal contraceptives with the various drugs listed in Table 28.1 , (p.975), should therefore be followed, see Hormonal contraceptives + Antiepileptics Barbiturates or Phenytoin , p.985. 

Preliminary results of a study show that rufinamide 800 mg twice daily for 14 days decreased the AUC of ethinylestradiol 35 micrograms hy 22% and of norethisterone 1 mg by 14% in healthy women taking a combined oral contraceptive. Inhibition of ovulation was not assessed. These reductions in plasma levels of the contraceptive hormones are similar to those seen with topiramate (see Hormonal contraceptives + Antiepileptics Topiramate , below), and their clinical relevance is unknown. However, given these findings, low-dose contraceptives (ethinylestradiol 20 micrograms) may be considered unsuitable for use with rufinamide. Further study is needed. 

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