Conference Coverage
More women on hormonal contraceptives also reported having a decrease in seizures after starting contraception, compared with women starting on a nonhormonal method (9.5% vs 5.2%), which resulted in an 85% relative rate increase for decreased seizures. Depot medroxyprogesterone acetate was the only specific hormonal contraceptive that was associated with a higher rate of seizure decreases (95% higher), compared with combined oral pills.
In a second analysis of the results, Dr. Herzog and his associates examined the frequencies of seizure outcomes on hormonal and nonhormonal contraceptives, stratifying by the type of antiepileptic drug the women used when starting a particular contraceptive method. This analysis categorized antiepileptic drugs into the following four types: enzyme-inducing (29%), glucuronidated (such as lamotrigine, 27%), nonenzyme-inducing (such as levetiracetam, 22%), and enzyme-inhibiting (valproate, 8%). A fifth category included women who were not on any antiepileptic drug (14%).
This analysis showed that the frequency of seizure increases was significantly greater with hormonal contraceptive use, compared with nonhormonal methods, across all five subgroups of antiepileptic drug type. In addition, the frequency of seizure increases with hormonal contraceptives differed significantly, depending on which antiepileptic drug type women used, but these significant differences among the antiepileptic drug types also occurred among women who used nonhormonal contraception.Women receiving a nonenzyme-inducing drug when starting a hormonal contraceptive reported the lowest frequency of seizure increases, a rate of 12%. In contrast, women on an enzyme-inhibiting drug, valproate, had the highest rate of increased seizures when starting a hormonal contraceptive: 29%. Women who started hormonal contraception while on valproate thus had about a 2.5-fold relative risk increase for having more seizures, compared with women on a nonenzyme-inducing drug, Dr. Herzog reported.
Physicians “need to be on the lookout for the possibility that seizures could increase when women start a hormonal contraceptive,” he concluded.
—Mitchel L. Zoler