Interaction of anticonvulsants and oral contraceptives in epileptic adolescents

Oral contraceptives are in widespread use, and are commonly prescribed for contraception in patients taking other medications. An example of this is the concomitant use of oral contraceptives and anticonvulsants in epileptic patients. This combination creates a potential for drug interactions which may alter the efficacy of both medications. An apparent interaction between oral contraceptives and anticonvulsants was observed in this study of epileptic adolescent females. This interaction was evidenced by menstrual irregularities which occurred in 65% (7 of 11) of adolescents on both medications concomitantly. The frequency of irregularity was significantly higher in these adolescents when compared to adolescents on either medication alone. Irregularities appeared to be alleviated by increasing the strength of the oral contraceptive, and although a concern, the increased dosage did not affect seizure control.