20,24,48,49 The negative impact of RSM has been questioned elsewhere,50 and the influence of AEDs that

are not potent enzyme inducers, such as TPM or LTG, may result from different mechanisms, since TPM induces the estrogenic and LTG the gestagenic components.51 It is unclear to what extent these findings are clinically relevant, since unintentional pregnancies were hitherto not reported in women who were treated Inhibitors,research,lifescience,medical with LTG and continued oral hormonal contraception.24 AEDs that induce the cytochrome P450 enzymes reduce the efficacy of oral contraceptives markedly. Under the influence of CBZ the levels of norcthindrone and ethinyl estradiol drop by 58% and 42%, respectively,48 OXC decreases Inhibitors,research,lifescience,medical the levels of ethinyl estradiol and levonorgestrel if a daily dosage of 1200 mg is given.52,53 Other enzyme inducers such as PB, PHT, or PRM. also unequivocally influence the metabolism of oral contraceptives so markedly that one cannot expect, an acceptable contraceptive effect.20,24,49,51 In a survey among neurologists and obstetricians, 27% of the former and 21% of the latter group reported failures of oral contraception in Inhibitors,research,lifescience,medical women taking AEDs. Surprisingly, in the very same survey, only 4% of the neurologists and 0% of the obstetricians knew

the potential impact of the six most common AEDs on hormonal contraception.54 AEDs that supposedly do not affect hormonal contraception are VPA, gabapentin Inhibitors,research,lifescience,medical (GBP), lcvctiracetam (LEV), pregabaline (PGB), tiagabine (TGB), vigabatrin (VGB), and zonisamide (ZNS).20,24,49,51 One has to consider that the extent of this impact, and the quality of the individual trial on the AEDs mentioned above vary widely.20 Table I. Most Inhibitors,research,lifescience,medical Doramapimod mouse relevant findings in polycistic ovary syndrone; main features are displayed

in bold letters24. LH, luteinizing hormone; FSH, follicle-stimulating hormone If oral hormonal contraception is the method of choice for a patient who is treated with enzyme-inducing AEDs, it. is strongly recommended that, preparations containing more than 50 ug of estrogen be considered.55 If intermittent breakthrough bleeds occur, dosage should be increased Tryptophan synthase to 75 to 100 ug.56 Since the number of breakthrough bleeds and contraceptive failure differs significantly between ethinyl estradiol dosages of 50 and 100 ug, it has even been proposed that the higher dose be chosen from the start of the oral contraceptive treatment.50 Breakthrough bleeding does not always indicate an unsatisfactory effect, of the hormonal contraception. Conversely, one has to take into consideration that the suppression of breakthrough bleeds does not necessarily reflect a sufficient contraceptive effect.24 Another, though less important, mechanism that leads to reduced efficacy of oral contraceptives is the reduction in the free progesterone serum level that was described for PB.